Radio receivers

My hobby also covers wave-surfing, but not as a radio amateur, just as a DX-er, mostly on FM (regarding its higher quality), but also on medium and short waves.

If we examine the development of radios over time, we can say that until the early 1980s, well-known brand manufacturers (such as Philips, Marantz, Dual, Denon, Sony, Onkyo, Kenwood, JVC, Pioneer/Technics, etc.) aimed to produce equipment of an incredibly high quality. After that, any air radio wave reception equipment, like radios/tuners/receivers degrades, especially on AM bands. If you buy a radio today for on-air bands, you will encounter low-quality audio (the compression used by DAB, DAB+, and the internet, only theoretically achieves the FM stereo signal quality, in reality, is less listenable), as well as low-quality receivers/tuner parts (sensitivity decreased, or now the conversion are using DSP circuits instead of linear or PLL ones). Since the 1990s, the LW and MW have been neglected (as well as the SW, but this was popular in the Far East/Japan, America, etc.). As a result, receiver sensitivity on LM and MW has decreased from 8 uV to a few hundred uV-s, forcing consumers to use only FM/DAB, which has a smaller coverage area but marketed as better reception quality. The importance of FM radio is beginning to decline as internet radios (which stream signals that have been coded or packed) become more prevalent. There are more and more DAB/DAB+ capable receivers on the market right now, but without stations that can broadcast such programming in high quality, I don't think this will be a success story. Based on the European Parlament decision: since 1st Jan 2021 new automobiles sold in the EU must have multimedia on board with DAB reception possibility.

Regarding sound, analog radios are my preference, but I'm also curious about emerging technology in this area. Due to this, I collected a number of radios and receivers, starting with those that belonged to my great- and great-grandparents and continuing up to modern PLL digital tuned receivers with DSP conversions and DAB capability. Most of the time, I refurbish them by replacing worn-out parts to maintain peak radio and audio performance.

Some words about FM band:

The FM broadcast band is a range of radio frequencies used for FM broadcasting by radio stations (Wikipedia). It runs from 87.5 to 108 MHz in Europe, Africa, and Australia (also known as CCIR). Japan's FM broadcast band ranges from 76 to 95 MHz. Eastern Europe's International Radio and Television Organization (OIRT) spectrum spans 65.8-74.0 MHz. As in the case of Russia, these Eastern European nations currently largely utilize the 87.5 to 108 MHz range, while some of them have already switched from the OIRT spectrum to the CCIR band.
The FM bandwidth in Europe was first available between 87.5 to 100 MHz (the first FM transmission in Europe began in the Netherlands in 1953), and this was extended in 1968 to 104MHz, and since 1979 to 108MHz. Due to this reason, some vintage radios' produced before 1980 have the coverage of FM from 87.5 to 104MHz, like in the case of old DUAL, ITT, or WEGA tuners/receivers.

Channel spacings: Pre/De-emphasis in FM modulated transmission systems:

There is greater noise during FM modulation transmission at higher audio frequencies than at lower audio frequencies. The broadcasting industry developed some guidelines for Pre-emphasis and corresponding De-emphasis to correct for this imbalance and even out the noise across the audio spectrum. Pre-emphasis is used in a modulator to enhance the audio before modulation. After demodulation, the receiver employs de-emphasis to restore a flat audio frequency response. As a result, the Signal-to-Noise Ratio of any particular FM transmission technology is greatly enhanced. The FM radio de-emphasis standard in Europe is 50 microseconds, while it is 75 microseconds in the USA.

Some words about DAB (Digital audio broadcasting) radio:

Digital audio broadcasting (DAB) is a digital radio technology for broadcasting Digital audio radio services, used in several countries across Europe and the Asia Pacific.
DAB may offer more radio programs over a specific spectrum than analog FM radio. DAB is more robust with regard to noise and multi-path fading for mobile listening since DAB reception quality first degrades rapidly when the signal strength falls below a critical threshold, whereas FM reception quality degrades slowly with the decreasing signal.
Audio quality varies depending on the bit rate used and the material. Most stations use a bit rate of 128 kbit/s or less with the MP2 audio codec, which requires 160 kbit/s to achieve perceived FM quality. 128 kbit/s gives a better dynamic range or signal-to-noise ratio than FM radio, but a more smeared stereo image, and an upper cut-off frequency of 14 kHz, corresponding to 15 kHz of FM radio. However, "CD sound quality" with MP2 is possible just "with 256...192 kbit/s" - which remains a dream using DAB.
An upgraded version of the system was released in February 2007, which is called DAB+. DAB is not forward compatible with DAB+, which means that DAB-only receivers are not able to receive DAB+ broadcasts. However, broadcasters can mix DAB and DAB+ programs inside the same transmission and so make a progressive transition to DAB+. DAB+ is approximately twice as efficient as DAB due to the adoption of the AAC+ audio codec (HE-AAC version 2 audio codec, or 'aacPlus'), and DAB+ can provide high-quality audio with bit rates as low as 64 kbit/s (but will never achieve CD-s quality). Reception quality is also more robust on DAB+ than on DAB due to the addition of Reed-Solomon error correction coding. DAB uses a wide-bandwidth broadcast technology and typically spectra have been allocated for it in Band III (174-240 MHz).
Hungary has chosen DAB+ for its digital radio standard. On 23 January 2009 Antenna Hungaria started experimental broadcasting on its DAB+ digital terrestrial radio network on one channel: 11D. From 3 January 2011, with 7 available radio programs within the frames of the experimental DAB+ broadcasting in Hungary: All above radio broadcasts were transmitted on one channel 11D (222.064 MHz).
The DAB+ transmission was stopped in Hungary at 12.09.2020.


Below you can see my radios collection by manufacturers in chronological order.

Manufacturers



Aiwa


The company was founded on June 20, 1951, as AIKO Denki Sangyo Co., Ltd., manufacturing microphones, and changed its name to Aiwa Co., Ltd. on March 10, 1959. The company was a leading manufacturer of audio products, including headphone stereos, minicomponent stereo systems, portable stereo systems, minidisc players, CD, and cassette players, and car stereo systems throughout the 1970s, 1980s, and 1990s. Nearly 86 percent of company revenues were derived from such audio products.
Aiwa manufactured more than 89 percent of its output outside Japan, with a heavy emphasis on the lower-cost South-East Asian nations of Singapore, Malaysia, and Indonesia. The company was also heavily dependent on overseas sales, with more than 80 percent of total revenues being generated outside Japan, with 43 percent in North and South America, 25 percent in Europe, and 13 percent in areas of Asia outside Japan and in other regions.
Although not then officially an affiliated company of consumer electronics giant Sony Corporation, by 1982, Sony had a 54.6% stake in the company, effectively giving it majority control. With growing competition throughout the late 1990s, the company slid towards bankruptcy, and the troubled company was then fully purchased by Sony Corporation in 2003. However, the new direction of Aiwa under Sony did not meet consumer and sales expectations. On January 21, 2005, new product development ended, and by 2006, Aiwa products were discontinued and no longer sold in the market. Sony announced the termination of the brand entirely on May 14, 2008.


Aiwa XT003

Aiwa XT003

Is a simple, low-grade receiver made by Aiwa in Singapore 1992-94 (in some pages is mentioned between 1990-1996), predecessor of XT-005 model.

General information:

  • Digital 3 band PLL tuner (superheterodyne)
  • Frequency range: FM 87.5-108 MHz, MW 522-1611kHz, LW 144-290kHz
  • Usable sensitivity: 0.9uV on FM mono, 300uV/m on MW and 1000uV/m on LW
  • Tunning steps: LW 3kHz, MW 9kHz, FM: 25kHz
  • Preset memories: 30, mixed for AM and FM
  • Used integrated circuits: AM/FM tuner and IF: LA1265G, MPX decoder: LA3401, PLL frequency syntheser LA7218, microcontroller and display driver LC65148-4431, voltage regulator 78M12L
  • Antenna: for FM 75 ohm unbalanced, for AM loop antenna or aerial
  • Signal to noise ratio: FM 80dB in mono, 74dB on stereo, AM 52dB
  • Total harmonic distortion (1kHz): on FM 0.12% in mono, 0.2% in stereo, on AM is 0.5%
  • Alternate channel separation: 70dB on FM, and 20dB on AM
  • Stereo separation: 40dB at 1kHz
  • Frequency response: 30-15kHz, +0.5...-2dB
  • Output signal level: 700mV on 47Kohm
  • AM (MW) suppression ratio: on FM 50dB
  • Power source: 220Vac, 50Hz
  • Power consumption: 7W
  • Dimension: 430 x 73 x 255 mm (W x H x D)
  • Weight: 2.5 kg
  • Original price at 1992: 350 DM

Good things:

  • Is a 4 gang tuner on FM with a good sensibility
  • The sound at AM reception is clear, low background noise
  • Has a Preset Scan mode: will scan the stored programs
  • Very clear display with good intensity, and can be seen from a wide-angle!

Problems:

  • The IF bandwidth cannot be selected (ex. normal and narrow)
  • No signal meter, just a Tune mark on the display
  • In stereo mode, the manual search is canceled, which means will stop just on stations with a high signal level
Is a very underrated tuner - can be purchased from 10Euro. Use mixed components, through-hole and passive SMDs soldered with wave soldering. Easily can be serviced. The power board is separated, the regulator with the heatsink is on the radio board. The heatsink is just warm, not hot - has a low heat dissipation.

Upgrades:

  • All electrolytic capacitors changed
  • Modification:
    - Audio path: all capacitors are PP, on the output (C69 and C70) were increased from 2.2uF to 4.7uF. On the output board, the ground capacitor was changed from 0.01uF ceramic to 0.1uF PP and the 2 noise-canceling to 220pF COG ceramic.
    - Power path - mentioned just the modified values, voltage ratings remain same or higher: C33 390uF, C61 470uF, C75 390uF, C80 390uF, C83 390uF, C85 100uF, C88 4700uF, C91 100uF, C94 330uF, C206 0.22F, C205 470uF (in some places I mounted solid electrolyte capacitors or tantalum, below 1uF PP type).
    - AC line input get an EMI filter formed with 1uF + 2x27mH coil + 1uF
This tuner has a pleasant, clear, and natural sound, without any extra coloration. Sometimes I feel from the bottom line are missing a bit of bass.



Akai


Akai was founded by Masukichi Akai and his son, Saburo Akai as Akai Electric Company Ltd. (Akai Denki Kabushiki Kaisha), a Japanese manufacturer in 1946. Akai's products included reel-to-reel audiotape recorders (such as the GX series), tuners (top-level AT, mid-level TR, and TT series), audio cassette decks (top-level GX and TFL, mid-level TC, HX, and CS series), amplifiers (AM and TA series), microphones, receivers, turntables, video recorders, and loudspeakers. Many Akai products were sold under the name Roberts in the US, as well as A&D in Japan (from 1987 after a partnership with Mitsubishi Electric), Tensai and Transonic Strato in Switzerland and Western Europe (until 1988). During the late 1960s, Akai adapted Tandberg's cross-field recording technologies (using an extra tape head) to enhance high-frequency recording and switched to the increasingly reliable Glass and crystal (X'tal) (GX) ferrite heads a few years later. The company's business eventually became troubled and it left the audio industry in 1991. Akai Holding filed for insolvency in November 2000. It emerged that ownership of Akai Holdings had somehow passed in 1999 to Grande Holdings, a company founded by Akai's chairman James Ting. In early 2003, Grande Holdings began undergoing a re-exposure of Akai's brands by marketing various audio-visual products manufactured by Samsung.


Akai AT-2400

Akai AT-2400


Is a middle-grade receiver made between 1976-1976 in Japan by Akai Electric Co, Toho. Was made in 2 versions: with a silver front and brown wood cabinet, and with a black front and wood cabinet. The difference between the top model, AT-2600, is the AGC of the front stage full with MOSFETs, has 5 gangs on FM, 3 on AM, and the signal meter can be switched to show the deviation (distortion) of signal, which gives a more precise adjustment of received station by the tuner.

General information:

  • Analog 2 band receiver
  • Coverage: FM 88MHz - 108MHz, AM 520kHz - 1605kHz
  • Sensitivity: for FM 1.8uV (no data for stereo); for MW 180uV/m with bar antenna and 15uV with external antenna
  • No presets
  • Signal to noise ratio: 75dB on FM in mono and 70dB for stereo, and better than 50dB on AM
  • Harmonic distortion: less than 0.2% on mono, and less than 0.3% on stereo FM
  • Image rejection: more than 90dB at 98MHz
  • IF rejection: more than 100dB at 98MHz
  • Spurious rejection: more than 100dB at 98MHz
  • Muting level control: 5uV to 100uV/switchable ON/OFF
  • AM suppression: 55dB
  • Stereo separation: more than 45dB
  • Subcarrier suppression: more than 65dB
  • Antenna input impedance: 300 ohms balanced, 75 ohms unbalanced, for AM external and ground connection via screw type connection, or built in ferrite bar for AM
  • Used integrated circuits: AM tuner and IF: uPC30C, FM IF: LA1230, MPX decoder: LA3350, operational amplifier LA3122 (for output audio buffer)
  • Output audio bandwidth: 20 - 15kHz with +0.2dB...-1.5dB
  • Output signal level: Variable between0...1.6V, Fixed 0.77V/1 kohm (100% modulation
  • Power: 220Vac, 50Hz
  • Dimensions/weight: 440 x 141 x 335 mm (WxHxD)
  • Weight: 6.6 kg
  • Price at 1977: 648 DM

Good things:

  • Very clear and pleasant sound, is better than Marantz or Dual from same era
  • Separate audio buffer IC at the output
  • Adjustable and fixed audio outputs with RCA sockets
  • Adjustable and switchable muting for FM
  • Simple and classic design with white backlight

Difficult, problematic items:

  • Backlight bulbs are difficult to be found on the market, no any marks on them, are powered from 10.3Vac. In the AT-2600 service manual are mentioned bulbs are same with AT-2400 model, and is 8V/300mA type, which is high overpowering/shorter life for bulbs.
  • No datasheet can be found about uPC30C integrated circuit

Always, when I start to repair, refurbish or upgrade one tuner, I check the upper version of that product range. In this case, the AT-2600 model schematic was checked. Pin 10 of IC1, uPC30C, is connected to the ground via 4.7uF/35V and to +5.9V via an 82kohm resistor. Also, the C12 was replaced with 0.1uF (AM audio output), and R7 with 100kohm.
Power board: C4 changed to 2200uF/35V, C5 and C9 to 470uF/35V, C6 and C8 to 330uF/16V dry electrolyte capacitor.
Front end/AM board: C8 changed to 270uF/16V, C8 and C13 47uF/16V - all of them with dry electrolyte capacitor type.
Main board: C33 to 470uF/35V Rubycon, all audio related capacitors changed to Nichicon Fine Gold or Muse type, same values.
The tuner supply from the secondary of the power line transformer received an EMI filter formed with 2x1uF/100V pp type and noise canceling coil 2x6.2mH.
Bulbs replacement: each bulb was replaced with 3 warm white LEDs in series connection, in parallel with them received a 10uF/25V MLCC capacitor and 2 of 62 ohms resistors used as terminals - all 4 assemblies connected in parallel to 10.3Vac of power transformed 2-2 reversed, to have an uniform loading in + and - cycles.


Akai AA-1015PL

Akai AA-1015PL


Is a middle-grade receiver made between 1977-1979 in Japan. Is the varicap version with presets of the AA-1010L model, previous model was the AA-1010DB started one year earlier, in 1976.

General information:

  • Analog 2 band receiver
  • Coverage: FM 88MHz - 108MHz, AM 520kHz - 1605kHz
  • Sensitivity: for FM 2uV (no data for stereo); for MW 200uV/m with bar antenna and 20uV with external antenna; for LW 300uV/m with bar antenna and 30uV with external antenna;
  • 5 presets just for FM via touch sensors
  • Signal to noise ratio: 65dB on FM and >45dB on AM
  • Harmonic distortion: 0.3% on mono, 0.6% on stereo FM
  • Antenna input impedance: 300 ohms balanced, 75 ohms unbalanced
  • Used integrated circuits: AM tuner and IF: uPC30C, FM IF: LA1230Z, MPX decoder: LA3350S, touch switch controller: uPC1009C, operational amplifier LA3122 (for RIAA)
  • Output: 15W/channel on 8 ohm
  • Signal to noise ratio: Phono >75dB, AUX >90dB
  • Power bandwidth: 40 - 20kHz with 0.8% THD
  • Channel separation: better than 50dB on from Phono at 1kHz
  • Residue noise measured at the output on 8 ohms load: 0.8mV
  • Damping factor: more than 30 at 1kHz on 8ohm
  • Input sensitivity and impedance: Phono 3mV/47kohm, AUX 150mV/100kohm
  • Tape monitor: input pin/DIN 150mV/100kohm; Output pin 150mV/2kohm, DIN 30mV/30kohm
  • Frequency response: Phono/RIAA 30 - 15kHz +1dB...-1dB, Tuner/Aux/Tape monitor 10 - 70Khz 0..-2dB
  • Tone control: Bass +-10dB at 100Hz, Treble +-10dB at 10kHz
  • Loudness control: +10dB at 100Hz, +5dB at 10kHz (volume control set at -30dB position)
  • Power: 220Vac, 50Hz
  • Dimensions/weight: 440 x 125 x 265 mm (WxHxD)
  • Weight: 6.2 kg
  • Preise at 1977: 600DM



Audion/Innerein/Rosita


Looks almost like a completely undocumented history, but based on my research, the equipment comes from Rosita Tonmöbel company, founded on November 9, 1954. Over years Rosita become a factory for "sound furniture" that just bought individual components from different manufacturers and built them into their unique design music cabinets. The electronics come from different famous companies of that era, like Grundig, Philips, Marantz, Dual, to name just a few of them, but cheap devices, like cassette recorders, come from the Far East (Korea). Seems Südfunk-Apparatebau was the assembly company of those devices into one system (like also for Neckermann). The company used different brand names to sell their assembled final products, which had the almost same internal or external design, style, and functions and appears under brand names like Audion, Rosita, Innerein, or Südfunk. On March 31, 1988, after 33 years, bankruptcy proceedings were opened.


Audion T6800


Audion T6800

This tuner is almost a copy-paste of the Dual's CT1640, with no clock function, and instead of 2 analog instruments has a tube display for signal and tune. The main plate from Dual is replaced with several smaller boards: 2 for LEDs, one for tune/signal display unit, one for memory control and remote antenna system, one for "memory" settings, and the switchboards and commands as the main board. The audio output contains the improvements introduced by Dual on its CT1641 model. All components, PCBs, and their design style are the same as was used by DUAL in that era.

General information:

  • Manufactured between 1977-78 by Rosita, but the electronics with high probability is from Dual Gebrüder Steidiner St. George/Schwarzwald
  • 4 band analog PLL tuner LW, MW, SW, and FM
  • Coverage: LW 150 - 340 kHz, MW 510 - 1620 kHz, SW1 5.75 - 7.4 MHz, and FM 87.5 - 104.0 MHz
  • Tunning steps: fully analog, with additional digital display
  • Antenna input impedance for FM: 60/75 ohms unbalanced and 240/300 ohms balanced
  • 7 preset memory for FM, and no for AM (LW+MW+SW)
  • Usable sensitivity: 20uV on MW, 30uV on LW, 10uV for SW, 0.7uV on FM (mono) and 2.5uV for stereo
  • Intermediate frequencies: 460kHz for AM, and 10.7MHz for FM
  • AM tuner IC: TDA1046; FM det. CA3089; stereo decoder (MPX) MC1310P; prescaller: 10131, 74LS90, 74LS93; radio receiver frequency counter & display driver AY-5-8100; voltage regulators uA78M05C and uA78M15C; LM3302 comparator, program setting ICs SN29770 and SN29771,
  • Output frequency range:20Hz - 16kHz (for 50us pre-emphasis -3dB)
  • Channel separation: 40dB at 1kHz
  • Automatic mono/stereo switchover (FM): 6uV
  • Muting level adjustment: 1.5 - 200uV
  • FM IF bandwidth: 140kHz
  • Signal to noise ratio: mono 66dB, stereo 62dB
  • Harmonic distortion_ mono 0.15%, stereo 0.3%
  • Stereo separation: higher than 40dB
  • 19/38kHz suppression: better than 35/45 dB
  • Power: ~110/220V, 50/60Hz internally selectable via fuse position, consumption 35W
  • Output signal level and impedance: 750mV/5.1kohm
  • Dimensions: 440x150x384mm, weight 9 kg.

Good things:

  • Very clear and pleasant sound
  • Audio buffer at the output is made from discrete components, and at the output has a 19KHz LC filter
  • Adjustable muting not just on FM, also for AM
  • In Germany the FM was divided in numbered channels. The tuner has a switch to change on the display the received frequency or the channel number (CH)

Difficult, problematic items:

  • Has just DIN audio output, no RCA
  • The signal level and also the tuning indicator has just 3, respectively 7 values, the analog instrument is more precise and continuous.
  • Both PCBs with LEDs are just attached with double side tape to front panel, also the memory buttons, one by one.
  • Very heavy and robust chassis, 9kg!
  • No ferrite rod antenna, AM can listen just with an external antenna
  • FM band is shorter, going from 87.5MHz till 104MHz
  • Difficult to repair: the memory setting boars are screwed to the command unit with plastic spacers between panels on screws. The multiwire-cables are directly soldered on one side to PCB, LED's PCBs are glued to front-panel.

The whole electronics seems to be from Dual CT1640 or CT1641.
Problems: the main unit oscillator fine adjustment missing, is just simply mounted, not like in Dual CT1640.
All 0.1uF ceramic capacitors' capacitance was between 71-76nF, recommended to be changed (like in the case of Dual CT1640), were changed to SMD (3212 size, X5R, Samsung) type soldered on soldering side of PCBs. The service manual found on the net contains mistakes. The C309 value in the loop filter mounted is 220nF, not 22nF like in the schematic. The units connection in the schematic is a nightmare, is quite difficult to find some links where goes.
Modifications: C211 47nF, to IC201 (CA3089) pin 15 and 13 added 1nF to ground (recommended by datasheet), C303 470uF/25V + 22nF, C313, C314, CC1102, C1103, C1411, C1412 to 470nF, C416 47uF dry cap, C601 to 3300uF/25V, C603 to 4700uF/35V, C1111 and C1112 to 4.7uF pp, C1212 and C1244 to 100uF/16V dry caps, C1246 100uF/35V dry cap, C1402 to 4700/50V, C1405 1000uF/50V. Between pin 3 of IC301 (MC1310) and ground mounted 820pF (recommended by datasheet) to compensate the phase lead of 5.5 degrees.
Conclusion: this purple-blue design, used by Marantz, and inside with Dual CT1640 design make this tuner a very good one, underappreciated regarding its unknown brand name. On FM sounds better than the Dual AT1640, but on AM (MW and SW), is very poor, low sensibility - eventually if you have a good external antenna, can be also one of the best ones.


Blaupunkt


Founded in 1923 in Berlin as "Ideal", the company was acquired by Robert Bosch AG in 1933. In 1938 it changed its name to "Blaupunkt", German for "blue point" or "blue dot", after the blue dot painted onto its headphones that had passed quality control. After the World War II, Blaupunkt moved its headquarters and production to Hildesheim. Blaupunkt took over a former Philips/Grundig factory in Portugal to produce automotive head units. Later, factories were set up in Tunisia (speakers) and Malaysia (speakers and electronics). At 1 March 2009 was sold to Aurelius AG of Germany. After the 2011 take-over, Blaupunkt became a managed brand name with all production outsourced to China. It filed for bankruptcy in late 2015 with liquidation proceedings completed in early 2016. The brand is now managed by GIP Development SARL of Luxembourg and is used on various product groups worldwide. Unfortunately, I did not recommend any new equipment from this brand. They are characterized by low cost and low quality.


Blaupunkt RX+ 12

Blaupunkt RX+ 12


This was my first DAB+ radio, and frankly, I was disappointed by DAB+ reception quality, compared to FM transmission received with good tuners.

General information:

  • Digital FM and DAB+ radio with alarm clock function
  • Coverage: FM 87.5MHz - 108MHz (just one speaker, and no stereo in phones), DAB+ 170-240 MHz (band III, channels 5A-13F)
  • 50 kHz steps on FM
  • One chip radio, without any filters and resonant circuits
  • Full RDS on FM and DAB+ bands
  • 20 presets (10 for FM / 10 for DAB+) + timer memories
  • Rec out jack (stereo, line level - I never try it)
  • Frequency synthesizer DSP / microcontroller: Q88 BV158MOA or 57297AOD (I did not find any data about it on the net)
  • Other ICs:F40-100GCP 4k serial static memory, LM4871 boomer 3W audio opamp, XC6206 3.3V LDO regulator
  • Output: 1.2 W max. on 8 ohm
  • Power consumption: 3 W via 4 AAA batteries or via 5V/500mA external power plug. In standby mode: < 1 W
  • Dimensions/weight: 191 x 118 x 32 mm, 615 g (incl. batteries)
  • Produced: since 2014 by M3 Electronic GmbH under Blaupunkt brand name

Good things:

  • Quite sensible on both FM and DAB+ bands, no any more accurate specification (like service manual, info about sensibility, signal level, noise level etc.) about radio on user manual or on the net
  • Clock adjustment is instant in DAB+ mode, but also are made on FM via RDS data, but more slowly.
  • The Radio Text function is very good. You can select via Info/Alarm button

Problems:

  • High consumption, with batteries the operation is meaningless, because in 2 days the cells are over. Stand by consumption is high (few mA-s) regarding continuous backlight of LCD.
  • Sound quality is poor, regarding one small speaker with <5 cm diameter.
  • Backlight LED is always on - has 2 light levels, a high one when the keypad are touched, and after 40 sec goes into low level, which is still high intensity in my opinion
  • If the external power socket are taken out or in, the radio goes into standby mode, loosing all presets and time/alarm adjustments.
  • Just 10+10 presets are not enough for today's radio listening in urban life.

Upgrades:

  • Modification for AAA accumulator usage instead of batteries: one diode 1U4007 and one 100 ohm resistor added to power socket to have charging possibility using 4 pcs of NiMH AAA accumulators.
  • The radio design from outside looks like to have 2 speakers (see the picture of radio above), but is not true. On the left side the radio has a 92 grams metal weight to balance the right side speaker weight (magnet). I added one more 8 ohm 1.5W speaker (same as original one) on left side instead of weight. Speakers are connected serially, now the load is 16 ohm. Sound level seems same (theoretically should be half), and sound quality seems to be a bit better, but do not expect significant improvement.

Verdict: not recommended. Regarding high consumption is not a portable radio, and the sound quality is poor (after modification is a bit better). Has just only one good point: sensibility on both bands, FM and DAB+, is good.



Denon


Denon is a Japanese electronics company started in 1910 by Frederick Whitney Horn, an American entrepreneur. Denon produced the first cylinder audio media in Japan and players to play them. Decades later, Denon was involved in the early stages of development of digital audio technology, while specializing in the manufacture of high-fidelity professional and consumer audio equipment. Denon made Japan's first professional disc recorder and used it to record Emperor Hirohito's voice. For many decades, Denon was a brand name of Nippon-Columbia, including the Nippon Columbia record label. The Denon brand came from a merger of Denki Onkyo (not to be confused with the other Onkyo) and others in 1939. In 2001, Denon was spun off as a separate company with 98% held by Ripplewood Holdings and 2% by Hitachi. In 2002, Denon merged with Marantz to form D&M Holdings. On March 1, 2017, Sound United LLC completed the acquisition of D+M Holdings.


Denon TU-747


Denon TU-747

The TU-747 is a basic, inexpensive digital tuner, and has a good reputation compared with TU-767, but has a lack of muting circuit compared with it. In general "looks good, sounds great, and for DXing is on a par with mid-line Kenwoods like the KT-7300 and KT-6500 when modified" - based on FM Tuner Info. Has 4 gangs on FM and 3 ceramic filters

General information:

  • Manufactured by Denon/Nippon Columbia, Tokyo, Japan 1985 - 1987
  • Digital 2 bands (MW-FM) PLL radio (has also 3 band version, with LW named TU-747L),
  • 2x8 memory presets, 8 for AM and 8 for FM
  • Coverage: MW 520kHz - 1.710MHz, FM 87.5MHz - 108.0MHz
  • Tuning increments: 0.1MHz on FM, and 9/10 kHz on AM
  • Usable sensitivity: 18uV on AM, 0.8uV on FM (mono) and 23uV for stereo
  • FM tuner IC: HA11225, stereo decoder: HA12016, AM tuner: LA1245, FM IF amplifier TA7060AP, prescaller: TD6104P, uController: TC9147P, display driver TD6301AP, signal indicator: LB1426, OP: NJM4558D
  • Muting level: 22dB
  • Image rejection: 80dB on FM, 45dB on AM
  • IF rejection: 85dB
  • AM suppression: 60dB
  • Output frequency range: 20Hz - 15kHz (-1.5...+0.2dB)
  • Signal/noise ratio: AM 50dB, FM 82dB mono, 78dB stereo (for EU version)
  • THD: on FM 0.1% for mono, 0.3% for stereo; 0.6% for AM
  • Stereo separation: 45dB
  • Line output level and impedance: 0.6V for FM, 0.2V for AM, 3 kohm
  • Antenna input impedance for FM: 75 ohm, unbalanced
  • Power: 230V/50Hz, consumption: 8W
  • Dimensions: 434x66x281mm, 3.3kg
  • Original price at 1986: 250$

Good things:

  • Clear sound, good readable display
  • Very simple and elegant front design

Difficult, problematic items:

  • Auto/mute or mono switch, which means in stereo mode the mute is activated. Below muting level, the stereo program cannot listen in stereo
  • Has just only 220V/50Hz input, but nowadays in EU we have 230V/50Hz+deviatio -> in my home the supply voltage is higher by 10% than the rated voltage of the tuner.
  • Low sensibility and sensitivity on AM band
  • The AM output is just the 3rd of FM output level - which means when you switch from FM to AM, you should increase the volume on the amplifier. When you switch back to FM and forget to decrease the volume, you will have a heart attack regarding instant high sound level

This tuner appears 2 years after TU-767, an older and midrange brother - can be mentioned is a low-cost version of TU-767. Compared with TU-767 has one common buffer to drive varicaps for AM and FM, no output buffer, no narrow/wide IF filtering for FM, and the signal level indicator shows just 3 levels, not 7, a simpler power supply circuit. The display driver and memory selection PCBs are the same
Modifications:
To improve the AM output level, R512 was changed from 27K to 3.3k, and C513 (based on the schematic should be 68nF) from 22nF was changed to 0.1uF foil capacitor. To improve the noise suppression between stages, the power line of HA11225 received a 3.3uH inductor (pin 11) in jumper position J37, and the digital stage also a 100uH inductor instead of jumper J26 (this is the supply line for prescaller and microcontroller). Deviations from the service manual: C513 value was just 22nF instead of 68nF, C611 value was 100uF/10V instead 470uF/6.3V. Between pins 4 and 11 of IC2/HA11225 are mounted one 22nF ceramic capacitor, at tuner section between AGC and Vt inputs are mounted one 1Mohm resistor, and between AGC and Gnd another of 910kohm - all not existing on the schematics.
Changes in power line C203 changed to 1500uF/25V, C529 changed to 270uF/16V, C607 changed to 100uF/16V, C611 changed to 470/6.3V, C804 220uF/25V, C805 and C807 to 270uF/16V. Change in AM signal output: R512 to 3.3kohm, C513 0.1uF. Tuning buffer: C603 to 1uF/63V foil. AM section: C521, C522, and C523 22nF. FM section: C7 and C8 47nF, C14 1uF/63V. Audio signal: C101, C102, C201, C211 and C212 4.7uF/50V foil capacitor (Wima).


Denon TU1500RD


Denon TU1500RD

Is one of my best tuner, used especially for FM classical music programs in my audio system. Has a very good sensitivity and selectivity on FM, I can receive some stations, which I can't receive with any other tuners owned by me (excepting some Duals, Kenwoods, and Marantz tuners). Is possible to use RDS for "smart searching", for instance, you can select as an example to search only classical music or news stations, etc.

General information:

  • Manufactured by Denon in Japan between 1999 - 2006
  • Digital 2 bands (MW-FM) PLL radio with RDS+EON capability,
  • 40 memory presets
  • Coverage: MW 520kHz - 1.710MHz, FM 87.5MHz - 108.0MHz
  • Usable sensitivity: 12uV on AM, 0.9uV on FM (mono) and 16uV for stereo - via a very sensitive MOSFET FM tuner
  • FM/AM tuner IC: FM/AM tuner: LA1265, stereo decoder: LA3401, PLL freq. synthetizer: LC72131, uController: TMP87CM71F, dot matrix VFD display driver LC75711, RDS decoder: SAA6579T & LC7074
  • Output frequency range: 20Hz - 15kHz (-1...+0.5dB)
  • Signal/noise ratio: AM 53dB, FM 82dB mono, 78dB stereo
  • THD: on FM 0.08% for mono, 0.12% for stereo
  • Stereo separation: 50dB
  • Line output impedance: 100 ohm
  • Antenna input impedance for FM: 75 ohm
  • Power: 230V/50Hz, consumption: 9W
  • Dimensions: 434x75x242mm, 2.5kg
  • Original price at 1999: 600$

Good things:

  • Has a very clean sound, beautiful bass, low noise, good channel separation (as radio, cannot be compared with CD, SACD or DVD-A), good readable dot matrix display, perfect "narrow" IF selection feature.
  • RF-attenuation for strong stations.
  • Remote has digit button to direct access the memory and keys for RDS (I just try it, but I did not use the remote).
  • Has Radio Text
  • Has a Postdetection Filter to eliminate HD FM radio noise (used in America)

Difficult, problematic items:

  • Has no signal level indicator (could make antenna placement more easier)
  • Memory is organized like 5 x 8 = 40 positions (A:1-8, B:1-8, ... ,E:1-8). Should be more natural 4x10 = 40
  • Has just only 1 antenna input. Some tuners have 2, and for DXing could be more suitable.

DX-ing:
On dedicated webpages are recommended to modify the IF filter for FM from 230kHz bandwidth with a 150 or 110kHz type. Nowadays, ex. Murata or TDK has low loss type narrow band (150 or 130 kHz) ceramic filters. What is the advantage to change the filters with a narrow band low loss type ones? Muting the adjacent channels without sensibility decrease! I changed the narrow filter part (CF102 and CF103 position) with low loss, narrow band TDK filters: 107MJ 150kHz+-20kHz, 4.5dB loss type. Original filters were Murata type, in CF101 positions SFE10.7MXHA (low distortion, 230kHz+-25kHz), 2 pcs of SFE10.7MS3GKA (180kHz+-20kHz) at CF102 and CF103 position, and SFE10.7MM (230kHz, +-25kHz) in position CF104.
Related links:
       Audioreview, is a review site with several reviews about this tuner. Do not be surprised when you saw just 4/5 score, because some reviews referring to TU-1500AE, and are written by novice members, not technical gurus. Almost all of them write about exceptional selectivity and sensibility of this radio, mentioning no signal indicator and 5x8 memory location, and high price (at that time).
       Tuner Information Center - Vintage stereo tuners - tuners review from D to G. Is a good review of TU-1500RD tuner
       The FM Ceramic Filter Page mentioning, in general, the Denon TU-1500RD "is the best tuner for high-quality FM DX audio program listening".


Denon TU1500AE


Denon TU1500AE

Is an upgraded version of TU-1500RD - based on Denon. Personally, I have a different opinion. From design and used semiconductors can be mentioned that, but for DX-ing cannot be used (see later the explanation).

General information:

  • Manufactured by Denon in Japan between 2005 - 2010
  • Digital 2 bands (MW-FM) PLL radio with RDS+PTY+TP and Radio Text capability,
  • 100 memory presets
  • Coverage: MW 522kHz - 1.611MHz, FM 87.5MHz - 108.0MHz
  • Usable sensitivity: 18uV on AM, 1.0uV on FM (mono) and 23uV for stereo - via a very sensitive MOSFET FM tuner
  • FM/AM tuner with IF section: one module, uController: MB90C950, RDS decoder: BU1924, and opamp: SE5532
  • Output frequency range: 20Hz - 15kHz (-1...+0.5dB)
  • Signal/noise ratio: AM 50dB, FM 73dB mono, 68dB stereo
  • THD: on FM 0.15% for mono, 0.3% for stereo
  • Stereo separation: 43dB
  • Line output impedance: 300 ohm
  • Antenna input impedance for FM: 75 ohm
  • Power: 230V/50Hz, consumption: 10W, less than 1W in standby
  • Dimensions: 434x73x286mm (WxHxD), 3.6kg

Good things:

  • Has a good readable dot matrix display, good channel separation, low noise, clean sound, but not as pleasant or as musical as its predecessor, TU-1500RD.
  • RF-attenuation for strong stations.

Difficult, problematic items:

  • Has no signal level indicator (could make antenna placement more easier)
  • No any selection possibility of wide or narrow IF bandwidth
  • No direct memory recall buttons, all can be selected via rotating knob.
  • Cannot be switched off the stereo mode (at weak signals should be better if you can switch into mono mode) or to listen something in mono.
Remarks
  • This tuner is not good for DX-ing. Is quite difficult to often change between tunning modes (manual and automatic searching modes) in case of weak signals.
  • The tuner and IF part are placed into a metal box inside, highly populated with components, which makes it difficult to change the ceramic filters and electrolytic capacitors in IF part.
  • In flyer are mentioned the output impedance is less than 300 ohm, but the output coupling capacitors value is just 10uF, which means the lower output frequency should be around 55-60Hz
  • In several reviews are highlighted the clear sound of this tuner, but in reality, the electrolyte capacitors' quality is poor. Is better to change them with higher quality and values (ex. 47uF/25V Nichicon Fine Gold).
  • Not necessary, but improving the sound quality: changing the opamp power capacitors from 100uF/16V with 220V/16V, and using Ta capacitors around microcontroller and RDS decoder instead of electrolytic for the noise canceling, and insert the power line noise filter components on PCB, etc.
  • I did not found the Service Manual of this radio, but I recognized, the PCB is same with TU-1800DAB model, so also the related part of the schematic. Can be very helpful!

I recommend it just for daily listening, in urban area, with a lot of stations around. Is a very good tuner, but just within mentioned conditions.



Dual


In 1907, brothers Christian and Joseph Steidinger began manufacturing clockwork and gramophone parts in the Black Forest town of St. Georgen. In 1927, Gebrüder Steidinger (Steidinger Bros.) adopted the name Dual in reference to the dual-mode power supplies it pioneered. The power supplies allowed gramophones to be powered from mains electricity or with a wind-up mechanism. Soon thereafter, Dual began producing turntables of its own. After World War II, Dual became the biggest manufacturer of turntables in Europe, with more than 3,000 employees working in several factories. Throughout the 1970s, 1980s, and 1990s, Dual introduced audio cassette players, VCRs, CD players, and other consumer electronics. When Japanese consumer electronics started entering European markets in the 1970s on a large scale, Dual went bankrupt in 1982, and was sold to French electronic manufacturer Thomson SA. In 1988, Thomson sold Dual to German manufacturer Schneider Rundfunkwerke AG. After the insolvency of Schneider Rundfunkwerke AG in 2001, TCL Holdings, a Chinese company, purchased the Dual assets and brand, and it began marketing its own products under the name. In 2002, Namsung Electronics, a Korean company, bought the rights to use the name in the Americas and began selling lower-priced (but generally well-reviewed) consumer electronics under the Dual marque. The main product lines are home audio, mobile audio, marine audio and GPS receivers.


Dual CT-1640

Dual CT-1640

It is the first digital tuner from DUAL, the top of the line model, and was available for sale from mid-1977 (next was the CT1740 from 1979, which has often a problem with controller, CT1640 is more stable). When the unit is turned off the display will turn into a digital clock. Later appears an upgrade named CT1641, which has a slightly improved stereo decoder and output buffer.

General information:

  • Manufactured between 1977-78 by Dual Gebrüder Steidiner St. George/Schwarzwald
  • 5 band analog PLL tuner LW, MW, and FM
  • Coverage: LW 150 - 340 kHz, MW 500 - 1640 kHz, SW1 5.7 - 9.1 MHz, SW2 9 - 16 MHz, FM 87.5 - 104.0 MHz
  • Tunning steps: LW and MW 1kHz, SW 5kHz, FM 50kHz
  • Antenna input impedance for FM: 60/75 ohms unbalanced and 240/300 ohms balanced
  • 8 preset memory for FM, and no for AM (LW+MW+SW1+SW2)
  • Usable sensitivity: 20uV on MW, 30uV on LW, 10uV for SW, 0.8 uV on FM (mono) and 20 uV for stereo
  • Intermediate frequencies: 460kHz for AM, and 10.7MHz for FM
  • AM tuner IC: TCA440; FM det. CA3089; stereo decoder (MPX) MC1310P; prescaller: 10131, 74LS90, 74LS93; radio receiver frequency counter & display driver AY-5-8100; 4 digit clock AY-5-1202; voltage regulators uA78M05C and uA78M15C; LM3302 comparator
  • Output frequency range:20Hz - 15kHz (for 50us pre-emphasis -3dB)
  • Channel separation: 40dB at 1kHz
  • Automatic mono/stereo switchover (FM): 4uV
  • FM IF bandwidth: 140kHz
  • Signal to noise ratio: mono 68dB, stereo 63dB
  • Harmonic distortion_ mono 0.15%, stereo 0.3%
  • Stereo separation: higher than 38dB
  • 19/38kHz suppression: better than 35/45 dB
  • Power: ~110/220V, 50/60Hz internally selectable via fuse position, consumption 15W
  • Output signal level and impedance: 750mV/5.1kohm
  • Dimensions: 440x150x384mm, weight 9 kg.
  • Price at 1977: 1080 DM

Good things:

  • Very clear sound and stereo picture.
  • Easy to repair regarding its modular structure
  • Adjustable muting not just on FM, also for AM
  • Switch to select the ferrite rod and aerial antenna (FA)
  • Very heavy and robust chassis, 9kg!
  • In Germany the FM was divided in numbered channels. The tuner has a switch to change on the display the received frequency and channel number (CH)

Difficult, problematic items:

  • Has just DIN audio output, no RCA (for example Telefunken RT300 has both)
  • The clock has no memory or battery. After each power line break must be readjusted.
  • FM band is shorter, going from 87.5MHz till 104MHz, but can be modified
Is a very sensitive tuner. Has one main plate, and into that are connected several modules. The digital part is screwed to the backplate. All electrolytes inside were dried (instead of 47uF I measured a few hundred nF). C1212, C1244, and C1246 were replaced with 100uF/25V, C1228 value remains, all Oscon, dry electrolytic type.
In the case of the analog part, also all electrolytes should be changed. The most common capacitor is the 2.2uF, I replaced them with Wima 2.2uF foil type (C117, C207, C210, C303, C409, C734, C737). In power part 2200uF/40V was replaced with 3300uF/35V (C601, C603, and C702), C705 was replaced with 1000uF/35V.
All 0.1uF ceramic disk capacitors (C101, C306, C307, C317, C318, C403, C405, C407, C408, C411, C602, C604, C703, C723, C733, C735, C1102, C1103, C1104) were replaced with 0.1uF/63V PP foil type. Reason: their capacitance decreased by 30% and loss increased to 0.3%. This change has also a good effect on sound because this type of capacitor is used also on the signal path in the FM IF module at the input of audio buffer.
Modification in stereo decoder: received a puffer capacitor on the power line (100uF/25V Oscon), C305 was changed to completely same value PP foil type - has better temperature stability than the ceramic disk capacitor. R313 and R314 at audio output changed to 5.6kohms, and the opposite side connected to pin 11 of decoder IC via two 100kohms resistors (an idea used in CT1641 model). The audio buffer output coupling capacitors (C1111 and C1112) changed to 10uF/50V bipolar Nichicon Fine Gold. C1101 was replaced with 100uF/35V Oscon.
Originally the FM bandwidth was 87.5 - 104 MHZ, but easily can be modified to listen to stations till 108.0MHz: replace the R121 with 1kohms, move the scale to the bottom of the band and adjust L102 till you can read on display 87.5MHz, and move the scale to the top of the band, and adjust R103 till you read 108.05MHz on the display. Select a program near to 89MHz and adjust the L101, L104, and L105 for maximum signal and low distortion. After looking for a program around 106MHz, and set for maximum signal and low distortion with R109, R113, and R120. You can repeat the last 2 steps for fine adjusting. If you cannot set the L101 or R109 because the coil comes out from the body or with R109 you reach the end, change the C103 from 20pF to 15pF C0G/NP0. That is all.


Dual CR-1780

Dual CR-1780

This Hi-Fi receiver was the top of the Dual range produced in 1979, and the first to feature synthesizer technology. Tuner section: synthesizer technology for FM and MW wavebands. Quartz stabilized digital frequency display, station selector with 2 speeds, features automatic station search for FM. It has 6 electronic programming keys, each for FM and MW. Muting, center indicator, stereo/mono mode switch, LED bargraph display for field strength, center tuning, and quartz stabilized digital clock. Amplifier section: max. 2x90W real, 2x120W music power on 8 ohm speakers. Connections for tape recorders (1 & 2), Aux inputs on the front panel, Monitor switch. Tape Duplicate for direct tape duplication between two tape recorders. Bass, treble, balance control, low/rumble and high/noise filters, loudness control. External isolation between preamp and power amp sections for connection of graphic equalizer or additional amplifier stages. 2 type of phono inputs: RCA and DIN, selector of 2 pair of speakers: A and B, headphone output on the front panel.

General information:

  • Manufactured between 1979-81 by Dual Gebrüder Steidiner St. George/Schwarzwald, but on some webpages is mentioned was made by Rotel in Japan for Dual (this is plausible because the whole internal circuitry is Japan made)
  • 2 band analog PLL tuner MW, and FM
  • Coverage: MW 513 - 1602 kHz, FM 87.5 - 104.0 MHz
  • Tunning steps: MW 1kHz, FM 50kHz
  • Antenna input impedance for FM: 60/75 ohms unbalanced and 240/300 ohms balanced (via DIN and screw connection). For AM: ferrite rod or external (high impedance)
  • 6 preset memory for FM and AM
  • Usable sensitivity: 15uV on MW, 0.6 uV on FM (mono) and 1,8 uV for stereo
  • Automatic mono/stereo switchover: 5uV
  • Muting control: insertion point 4uV, can be switched off
  • Intermediate frequencies: 460kHz for AM, and 10.7MHz for FM
  • Used intergrated circuits: AM tuner IC: HA1197; IF amplifier HA1211, FM det. HA12412; stereo decoder (MPX) HA1196; prescaller TD6101P, freq. counter e1133, clock display driver MP1096, timebase TC5048 and 14040, other ICs 3x 14081,tunning indicator SI901P, signal strengths indicator 2x LB1405, opa for inputs and correctors 4x C4558C, RIAA 2x HA1457, protection circuit HA12002.
  • Output frequency range:20Hz - 15kHz (for 50us pre-emphasis -3dB)
  • Channel separation: 40dB at 1kHz
  • Automatic mono/stereo switchover (FM): 4uV
  • FM IF bandwidth: 140kHz
  • Signal to noise ratio: mono 63dB, stereo 63dB related to 1kHz/40kHz deviation, weighted
  • Pilot-tone attenuation: 65dB (measured via low pass filter)
  • Harmonic distortion: mono 0.3%, stereo 0.3% - both measured at 1kHz/40kHz deviation
  • Stereo separation: higher than 40dB at 1kHz
  • Selectivity: 85dB
  • Image rejection: 75dB
  • Spurious signal rejection: 100dB
  • Output power (measured on 8 ohms): 2x80W continuous, 2x120W music
  • Harmonic distortion (at 2x80W/1kHz): 0.04%
  • Power bandwidth (as per DIN45500): 10Hz - 60kHz
  • Frequency response: 10Hz - 40kHz +-1.5dB
  • Inputs: Tape1, Tape2, AUX and Monitor 150mV/470kohms, Phono MM 1.5mV/47kohms
  • Maximum input levels: for high imp. inputs 11V, for Phono MM 120mV
  • Tone controls: Bass at 50Hz +-15dB, Treble at 15kHz +-15dB
  • Balance control: range over 55dB
  • Rumble filter: limit frequency 70Hz (-3dB) 12dB/octave
  • Noise filter: limit frequency 8.5kHz (-3dB) 12dB/octave
  • Outputs: 2 pressure terminal strips for 2 speaker pairs switchable, 1 stereo headphone jack 6.3mm, 2 tape outputs RCA, 1 tape output DIN, 1 tape output stereo jack 3.5mm with switch contract
  • Output voltage: for tape recording RCA 320mV, and 10mV for DIN jacks
  • S/N ratio: for Tape1, Tape2, Aux and Monitor higher than 80dB, for Phono MM higher than 62dB
  • Channel separation (at 1kHz): between inputs higher than 66dB, between channels higher than 57dB
  • Power: ~115/230V, 50/60Hz internally selectable via fuse position, consumption 450W
  • Dimensions: 440x150x405mm, weight 14 kg.
  • Price at 1979: 1398 DM

Good things:

  • Clear sound and nice stereo picture, similar to Japanese sets (because is an OEM Rotel).
  • Shielded structure: top side the radio, display, and power amplifier, on the bottom side the RIAA, power supply regulator, and tone control circuits.
  • Fast station searching circuit
  • DIN and RCA tape and phono jacks
  • Very heavy and robust chassis, 14kg!

Difficult, problematic items:

  • The FM band goes up just till 104MHz, and regarding the synthesiser circuit, cannot be modified to receive the stations between 104-108MHz. You can use an extranal downconverter, to transfer this 4MHz bandwidth (104-108MHz) to some low density area within 87.5-104MHz, but that depends by your geographical location. In my case, thin means a shifting with 4.8MHz.
  • The clock and the programmed stations have no back-up circuitry/ battery. After each power line break or disconnecting the set from power line, should be readjusted the clock and preset again the station memories.
Is a very sensitive receiver with a typical Japanese sound: warm, clear, and enjoyable. On FM has 5 gangs (2x5 varicap diodes) and 3 ceramic filters with one IF amplifier (HA1211), on AM has 3 gangs.
Unfortunately, the digital section's soldering process or that PCB's soldering joints treatment was incorrect. Several claims regarding this issue can be found on the net. The problem: looks like the solder did not adhere to the soldering pad. In several points, if you remove it (ex. during components change), can be seen the whole pad was oxidized, just on the perimeter has contact with the solder. This means if the components receive a minor force from the top, the soldering joint will be cracked. Is better, if you resolder all joints very carefully. During resoldering, you must check mechanically and via lupe the correctness of the joint.
The main intergrated circuits used in digital and display parts are very specific, and I did not find any datasheet about them (e1133, MP1096, SI901P). If you have any datasheets about them, I will be delighted if you can send me.
On my set, I found several problems: the before-mentioned digital parts soldering, the programming of stations does not work, and the sound was without clear bass (seems buffing) and treble seems "washed" and weak. Immediately I start to change all capacitors from the power lines of each circuit - and they mostly solved this issue. The most problematic capacitors: C434 instead of 1000uF, I measured 648uF with 4.3% loss and almost 2 ohms ESR. In the digital part's power supply the C445 was completely dead (instead of 220uF I measured 1.2uF, 8.3ohms ESR, and 5% loss) - this was responsible for the programming failure. In general other capacitors still have their nominal values, but their loss was all over 2%, and ESR were higher than 0.1 ohms.
The downloadable schematic has several errors, not just as component values (ex. C443 are mentioned as 10nF, but is 100uF, or C902 and C904 is 1500uF instead of 15000uF, etc.), but also as a circuit (power supply of the protection circuit, muting, and radio, but also in the digital part).
Modifications (not the changed copmonents list!):
In power line: C416, C423 470uF/63V, C430 330uF/50V, C445 270uF/16V, C466 47uF/35V.
In audio: all C4558C opa was changed to NE5532. In the correction network of the RIAA both capacitros (6.8nF and 1930pF) were changed with mica capacitors. For me was a surprise one capacitor's value: 1930pF with 10% tolerance. Such value shoud fit in the 0.5% or 1% range, not in 10%. All 4 original capacitors were 10% type, related resistors in 5%, but their measured values fits in 3% tolerance range. In my opinion, for a RIAA network this is too much. The RIAA circuit used is completely the same as in the datasheet of HA1457.
In the radio part: C509 and C556 270uF, C549 1500uF.
Chassis: the station searching the push buttons (in total 5 pcs) were wobbly, no counterforce from the back (I don't know this was their original status, or somedody try to fix it and left out some springs). I inserted a rubber-sponge of 3mm between the buttons and the switches from the PCB. Now works fine.
Conclusion: is a fine tuner (especially after refurbishing), very sensible (0.6uV of FM!), warm sound (after changing the opa-s to NE5532 still with good bass, and clear trebles), and with a high power (90W on 8 ohms!). With silver front looks very brave.


Dual CT-1250


Dual CT-1250

General information:

  • Manufactured at 1980-81 by Dual Gebrüder Steidiner St. George/Schwarzwald
  • 3 band analog PLL tuner LW, MW, and FM
  • Coverage: LW 150 - 340 kHz, MW 515 - 1620 kHz, FM 87.5 - 108.0 MHz
  • Antenna input impedance for FM: 60/75 ohm unbalanced,
  • 6 preset memory for FM
  • Usable sensitivity: 15uV on MW, 30uV on LW, 0.8 uV on FM (mono) and 25 uV for stereo
  • Intermediate frequencies: 460kHz for AM, and 10.7MHz for FM
  • AM tuner IC: TDA1072 amp, osc, IF and det; FM det. TDA1576A; stereo decoder (MPX) TDA1578; tunning indicator TBB4331A
  • Output frequency range:40Hz - 12.5kHz (-0.5...+0.5dB)
  • Power: ~220V/50Hz, consumption 15W
  • Output level and impedance: 750mV/4.7kohm
  • Dimensions: 430x55x380mm, 3.4 kg.
Has a pleasant warm sound, selectivity is very very good. When the signal is weak, the switchback from stereo to mono is smooth, cannot be heard any noise.


Dual CT-1450

Dual CT-1450

General information:

  • Manufactured between 1981-82 by Dual Gebrüder Steidiner St. George/Schwarzwald
  • 3 band analog PLL tuner LW, MW, and FM
  • Coverage: LW 146 - 353 kHz, MW 522 - 1611 kHz, FM 87.5 - 108.0 MHz
  • Antenna input impedance for FM: 75/300 ohms unbalanced,
  • 6 preset memory for FM, and 6 for AM (LW+MW)
  • Usable sensitivity: 15uV on MW, 25uV on LW, 0.6 uV on FM (mono) and 20 uV for stereo
  • Intermediate frequencies: 455kHz for AM, and 10.7MHz for FM
  • AM tuner IC: HA1197; FM IF opamp: LA1222; FM det. uPC1167C2; stereo decoder (MPX) uPC1161; tunning indicator: LB1416; prescaller: uPB553AC; PLL freq. synthesizer and controller: uPD1703-016
  • Output frequency range:10Hz - 16kHz (for 50us pre-emphasis -3dB)
  • Automatic mono/stereo switchover (FM): 4uV
  • FM IF bandwidth: 140kHz
  • Signal to noise ratio: mono 76dB, stereo 74dB
  • Harmonic distortion_ mono 0.15%, stereo 0.2%
  • Power: ~115/230V, 50/60Hz, consumption 13W
  • Output level and impedance: 750mV/5.1kohm
  • Dimensions: 440x55x350mm, 3.4 kg.
Is the most sensitive tuner that I have (0.6uV on FM), and with the widest audio bandwidth. The sound is warm, clear, more than in the case of Marantz, Denon, or Philips.
Problem: the LW starts from 146kHz and the steps are 9kHz -> means cannot be received any LW station, because the normal LW station frequencies start from 153 + Nx9 kHz, and this radio is shifted with 2kHz, and originally are made in this way. In all specifications and catalogs are written for this radio LW band 146-353 kHz. I did not know why at tuners made before 1985 the LW band is shifted (Akai, Rotel, ...).
Accumulator was out of order (3.6V 30mAh NiCd type, made by Yuasa, Japan) - was necessary to be replaced. To be remarked: after more, than 40 years operation no any surge or oxidation mark on it! Same as all 470uF/6.3V capacitors in control board (measured capacitance was 291uF!). Basically, all electrolytics were changed.
In general, the Dual use low coupling capacitors values in its equipment between audio stages, is better to be changed into higher values.



Fisher


Fisher Electronics was an American audio equipment manufacturer founded in 1945 by Avery Fisher in New York City, New York. Originally named the Fisher Radio Corporation, the company is considered a pioneer in high fidelity audio equipment. Fisher initially developed, manufactured, and marketed high-performance audio products under the trade name "The Fisher". In February 1969, Emerson Electric announced plans to purchase Fisher Radio. The purchase was completed later that year. Emerson subsequently sold Fisher to Sanyo Electric of Japan in 1975, where it remained until 2010 when Sanyo was purchased by Panasonic, but the Fisher brand was phased out owing to the termination of Sanyo by Panasonic in 2012. Fisher's product lineup was eventually re-branded as Panasonic.


Fisher Studio - Standard FM-2310


Fisher FM-2310

This is one of Fisher's last high-end designs for an AM-FM stereo tuner and was a serious competitor of Marantz brand. The tuner part is similar to what can be found in Fisher's top receiver, the RS-1080. Has an aluminum face panel with simple markings, 3 meters: signal level, the center of channel tuning, and deviation/multipath (switchable) on the front panel. The FM Deviation / Multipath Meter is very unique, different and definitely, I don't see on any other manufacturers. The dial is somewhat reduced in length due to the inclusion of the meters, but still easy to read. Inside has two circuit boards, one for the power supply (which includes the Deviation/Multipath circuitry) and one for the AM-FM IF MPX and audio circuits. The FM RF circuitry is in a separate shielded box along with the AM RF/Osc/Mixer tuning circuits. Has an FM front end with DGMOSFET RF amplifier stage, separate mixer, and oscillator circuits and a 5-gang mechanical tuning capacitor. It has a total of 4 ceramic IF filters (all of which are plugged into sockets) that are all 280kHz bandwidth. Since the 3-leg filters plugin, they can easily be changed to narrower bandwidth filters if desired for DX work. The LA1230 quadrature detector and LA3350 MPX ICs are also factory socket-mounted!

General information:

  • Manufactured at 1977 by Fisher (Sanyo) in Japan
  • 2 band analog superheterodyne receiver, MW and FM
  • Coverage: MW 525kHz - 1.605MHz, FM 88.0MHz - 108.0MHz
  • Antenna input impedance for FM: 300 ohms balanced and 75 ohms unbalanced,
  • No preset memory for FM
  • Usable sensitivity: 1.7 uV on FM mono and 4.3 uV (!) for stereo; 280uV/m on AM
  • Intermediate frequencies: 455kHz for AM, and 10.7MHz for FM
  • Used ICs: FM IF amplifier LA1222; FM IF detector LA1230; MPX decoder LA3350; AM IF detector HA1138; output amplifier LA3122 and for deviation/multipath CD894A and TA7120
  • Signal to noise ratio: mono 80dB, stereo 75dB for FM
  • Harmonic distortion: mono 0.10%, stereo 0.15% for FM
  • Output frequency range on FM: 20Hz - 15kHz (+0.5...-1.5dB)
  • Stereo separation (1kHz/10kHz): 50/36 dB
  • Power: 110V/220V 50Hz, consumption 16W
  • Dimensions: 440x140x315 mm, 10.5 kg.
  • Selling price at that time of a new unit: 1089DM
Good things:
  • Has a very clean sound with bright bass, low noise, good channel separation
  • Has a separate operational amplifier IC (LA3122) at output instead of direct signal from MPX IC
  • Very good sensitivity on FM
  • Has an extra meter for deviation and multipath: deviation act almost as a VU meter, and multipath makes it possible to adjust the tuner more precisely on station (when shows 0%)
  • Has an additional adjustable output, adjusted from the front panel
  • High Blend function: during the reception of stereo broadcast, noise possibility caused in both channels are reversed in phase to each other. With high-blend switched on, the separation in the audio high-frequency band becomes a little decreased.
  • Air check calibration circuit: this circuit is to make appropriate the recording level in advance when recording FM broadcast into the tape recorder. This circuit is an RC type oscillator to be used for air check calibration with approximately 400Hz frequency. In the case of AM signal, the air check calibration is not functioning.
Difficult, problematic items:
  • Lower scale width regarding 3 meters on front
  • Has 4 pcs 280kHz wide-bandwidth ceramic filters (in sockets!) - is recommended to be changed with low loss 150kHz models, all carefully paired.
With more than 40 years, is one of the best sounding FM tuner that I have. Was necessary to change all electrolytic capacitors. Unfortunately, on my set, the ferrite antenna is missing, I cannot test the AM. Probably, when I will have more time, I will make one (I know, will never be the same as the original).
Its sensibility outperforms some tuner with better specifications.
It retailed for about $250 back in 1977, which in today's dollars is roughly $890!



General Radio Co.


On June 14, 1915, a small group of investors started General Radio Company in Cambridge, Massachusetts, near Massachusetts Institute of Technology. During the 1950s, the company moved to West Concord, Massachusetts, where it became a major player in the automatic test equipment (ATE) business. It also produced extensive lines of electrical component measuring equipment, sound and vibration measurement and RLC standards. In 1975, the company name was changed to GenRad. In 1991, a startup QuadTech was founded as spinoff of GenRad's Instrumentation division and Precision Product lines, as well as the rights to use the "GenRad" and "General Radio" names. In 2000, IET Labs acquired QuadTech.


419-A Rectifier Type Wave Meter

419-A Rectifier Type Wave Meter

The oldest piece of my "museum" is not exactly a receiver, just the method used in it is similar, is a detector radio used for frequency measurement.

General information:

  • Manufactured at 1929 by General Radio Co., Cambridge A, Massachusetts
  • Measurement method: absorption - placed in vicinity of source
  • 4 ranges with 4 interchangeable inductors: 20-40MHz, 40-75MHz, 75-150MHz and 150-300MHz - all based on amplitude modulation.
  • Calibration: 4 separate charts given for each range/inductor.
  • Accuracy: within 1%
  • Rectifier: one RCA 1G4-G triode, with 1-1.2V/40mA filament voltage (from battery)
  • Power supply: 1.5V A type battery
  • Serial number: 211
Condition: the tube is out of order, now without any modification in tube socket are inserted one Schottky diode and operates well (cannot be received radio programs, tested just via AM signal generator).



Grundig


Grundig began in 1945 with the establishment of a store named Fürth, Grundig & Wurzer (RVF), which sold radios and was headquartered in Fürth, northern Bavaria. After the Second World War, Max Grundig recognized the need for radios in Germany, and in 1947 produced a kit, while a factory and administration center was built at Fürth. In 1951, the first television sets were manufactured at the new facility. At the time Grundig was the largest radio manufacturer in Europe. It grew to become one of the leading radio, TV, recorder, and other electronics goods manufacturers of Europe in the following decades of the 20 centuries. In the 1970s, Philips began acquiring Grundig AG's shares, leading to complete control in 1993. In 1998, Philips divested Grundig. In 2007, Koç Holding bought Grundig and put the brand under its home appliances subsidiary Arcelik A.S.


Grundig T7500

Grundig T7500

This is an excellent tuner, a combination of good reception and very good sound with useful features offered at an excellent price point (German magazines of the time compared the T7500 to a Revox costing almost three times as much). The tuning section is the equivalent of a typical 4-gang tuner while the PLL demodulator uses a Philips TDA1576 chip for scan tuning and on-frequency recognition and a TDA1578 for MPX. Tuning to radio stations can be achieved via manual tuning (step by step or fast search) or automatic search (with adjustable threshold. With the help of the TUNOSCOPE you can find the exact frequency position of the transmitter while an 8-LED meter will show you the signal strength. A mixed selection of FM, AM and LW radio programs can be stored in a 15 presets RAM - nonvolatile memory. You can select the stored radio stations directly via the 15 numeric keypad or with an up/down memory selector. A series of additional symbols on the display will show you the type of tuning you use (HA=manual, AS=automatic), FM-Stereo/Mono/Muting, preset number, "NEW" for a radio station that is not stored, "FREE" for an unoccupied preset or "FULL" for no more presets available. Additionally, every preset can be manually named so that a 4-character station name will be displayed on the Alphanumeric Display. At the back can be found the connectors for 300ohm or 75ohm FM antenna and two output connectors with level control.

General information:

  • Manufactured between 1984-86 by Grundig Portugal
  • 3 bands: FM 87.5 - 108 MHz, LW 155 - 353 kHz, MW 522 - 1611 kHz
  • Tuning steps: FM: 25kHz, LW and MW 1 or 9 kHz, SW 1 or 5kHz
  • Sensitivity: 0.5uV on FM Mono, 20uV on FM stereo; 9.5uV for MW and 12uV for LW
  • Self seek trechhold: on FM 3uV...2mV (75 ohm), on AM 100uV...10mV and on LW 200uV...20mV (both on 75 ohm)
  • Preset memory: 15, and can be mixed between FM, MW and LW
  • Intermediate frequencies: for FM 10.7MHz, for AM 455kHz
  • IF bandwidth: on FM 130kHz, on AM 4kHz
  • IF rejection ratio: for FM higher than 120dB, for AM higher than 40dB
  • AM suppression: higher than 54dB at 1kHz
  • Image rejection: on FM better than 120dB, on MW better than 43dB and on LW better than 63dB
  • Antennas: for FM balanced 75 ohm, for LW and MW external aerial
  • Capture ratio: less than 1.5dB
  • Signal to noise ratio (weighted): 76dB rms
  • FM stereo frequesncy response: 10 - 16.8kHz for -3dB, and 20 - 15kHz for -1dB
  • THD: FM mono less than 0.09%, FM stereo less than 0.15% for 1kHz and 40kHz deviation
  • Dynamic selectivity: mono higher than 80dB
  • FM crosstalk: higher than 47dB at 10kHz, and higher than 48dB at 1kHz
  • Pilot tone rejection: higher than 63dB for 19kHz, and higher tan 80dB for 38kHz
  • Output: AF output 175mV - 1500mV, Level control range: -13 - +5.5dB compared to centre setting (800mV). DIN record level: 0.87mV/kohm
  • Used integrated circuits: FM IF TDA1576, AM IF TDA1072 and TDA1576, MPX decoder TDA1578, synthesizer DS8906N, microcomputer SC86012, display driver COP470N 3 pcs, memory MCM2802, SO459 tunoscope, signal meter UAA180, loop filter CA3140 and HEF4016, voltage regulators MC78M05
  • Power consumption: 15W
  • External dimensions: 450 x 80 x 330 mm (WxHxD)
  • Weight:
  • Price: 798DM at 1984

    • Good things:

    • Manual and automatic station scan via separate buttons
    • Memory scan (manual dialing through stored stations)
    • Comp function: Check whether set frequency already exists in station memory
    • Tuning display and field strength display with LEDs
    • Station short name (4-digit alphanumeric display) can be stored for each fixed station
    • RAM memory (non-volatile memory) for station settings
    • High selectivity on FM - 0.5uV!

    Difficult, problematic items:

    • Usage of special antenna connector for AM
    • Without ferrite rod and with special AM antenna socket the listeing of AM (MW and LW) is difficult

    The models of the Grundig series T6500, T7500, T7500a came on the market one after the other in the mid 80s. They do not differ in circuitry, only the case designs and front panels as well as the display colors (first green, later bluish) are different. Inspite of alumina front panel, the plastic buttons gives a cheap expressions. From circuit point of view, is a very correct tuner, and was the predeccesor of T9000 and T9009.
    Received an EMI filter, connected between main switch and transformer formed from 0.47uF/275Vac+2.2nF/3kV+2x11mH+0.47uF/275Vac+2.2nF/3kV. A revision of the built-in power supply is absolutely necessary, the selenium rectifier and the "thick" electrolytic capacitors have to be checked and replaced .




    Grundig Yacht Boy 360

    Grundig YB 360

    This radio is a cheaper version of the Yacht Boy 400, but with a modern chassis design. The electronic part is almost the same, without SSB, and no external antenna connection. Has a dual IF conversion for AM, borrowed from Sony, 2 times settings, a snooze function and alarm with several possibilities, scan (up and down) and auto, 40 random memory locations, buttons for scrolling the memorized stations, direct SW band selection input. Stereo is just via headphones, tone can be selected just via switch (High/Low), and light button for display illumination.

    General information:

    • Manufactured between 1995-97 by Grundig probably in Far East (China?)
    • 4 bands: FM 87.5 - 108 MHz, LW 144 - 353 kHz, MW 522 - 1710 kHz, SW 1.711 - 30 MHz in total 20 SW bands (the tunning is continuous with steps)
    • Shortwave bands by lengths for SW (20 bands):
      • 90m: 3200 - 3400 kHz tropical
      • 80m: 3500 - 3800 kHz amateur
      • 75m: 3900 - 4000 kHz
      • 60m: 4750 - 5060 kHz tropical
      • 49m: 5950 - 6200 kHz
      • 41m: 7100 - 7300 kHz
      • 40m: 7000 - 7100 kHz amateur
      • 31m: 9500 - 9900 kHz
      • 30m: 10100 - 10150 kHz amateur
      • 25m: 11650 - 12050 kHz
      • 22m: 13600 - 13800 kHz
      • 20m: 14000 - 14350 kHz amateur
      • 19m: 15100 - 15600 kHz
      • 17m: 17065 - 17170 kHz amateur
      • 16m: 17550 - 17900 kHz
      • 15m: 21000 - 21449 kHz amateur
      • 13m: 21450 - 21850 kHz
      • 12m: 24890 - 24990 kHz
      • 11m: 25650 - 26100 kHz
      • 10m: 28000 - 29700 kHz amateur
    • Tuning steps: FM: 50kHz, LW and MW 1 or 9 kHz, SW 1 or 5kHz
    • Preset memory: 40 random memory locations
    • Intermediate frequencies: for FM 10.7MHz, for AM 55.85MHz and 450kHz
    • Antennas: for FM and SW a telescopic aerial, for LW and MW a built-in ferrite rod
    • Output power: 320mW via a built-in 32 ohm loudspeaker
    • Used integrated circuits: FM frontend LA1185, AM/FM IF LA1205, MPX decoder LA3335, stereo power amplifier LA4550, PLL sintheser LC7216, controller and display driver LC5863H, voltage regulators LA5005M, RH5VA50AA, RH5VA45AA, comparator LA6393M
    • Stereo: just via headphones
    • Power supply: 9 V by 6 pcs of AA-type batteries or 9 V DC external power supply (negative at the center of the connector!)
    • External dimensions: 178 x 120 x 39 mm (WxHxD)
    • Weight:590 g (without batteries)
    • No more technical parameters are available about this radio

      • Good things:

      • High selectivity (excepting LW)
      • Scan up and down
      • Good sound despite of the small speaker diameter
      • Signal level, band, and clock indication on the display

      Difficult, problematic items:

      • No tuning knob, just up/down tuning buttons
      • Heavy regarding 6 pcs of AA batteries
      • No external antenna connectivity
      • No SBB reception possibility, for this reason, cannot be used efficiently the whole SW band
      • Different output capacitor values at the output of power amplifier: 470uF for speaker and right headphone, and for the left headphone 220uF (via 47ohm resistor for both headphone outputs).

      The radio's PCB is not the same as the YB400 model, the PCB is double-layer with soldered vias. The components notation on the PCB is not marked, just the polarities and perimeter of components - difficult to identify them without a detailed service manual. The technology used for soldering: glues SMD with TH components, all wave soldered.
      Modifications: over 27 years, and because the used capacitors are low voltage types, their degradation level requires to be changed - but some of them were in exceptionally good condition. I used mostly solid electrolytics. The power of MPX decoder was increased from 10uF to 47uF, now both power audio output capacitors are the same, 470uF/16V, and the memory capacitor from 0.047F now is 0.22F (just, because this was what I had, and fits in place).
      In general is a good radio, with very good sensibility and selectivity on FM, MW, and SW. The LW is weak. If you have the possibility, is better if you purchase the YB400, which has the SSB reception possibility, because with that you can listen the amateur bands' message. This radio is much better than the YB-P 2000!


    Grundig Yacht Boy - Porsche 2000 (YB-P 2000)

    Grundig YB-P 2000

    The timeless elegance of this radio was inspired by the legendary Porsche 911, exhibits the same purity of line that has made the 911, a timeless classic. The genuine leather case embodies the meticulously crafted control panel with its smooth, recessed speaker grille and deeply sculptured buttons that highlight this design. Has scan and manual tuning, preset-memories, direct keypad entry, dual-alarm clock, sleep timer, headphone connection, etc., like an ideal traveling partner.

    General information:

    • Manufactured between 1997-98 by Grundig in Portugal (that time part of Philips)
    • 4 bands: FM 87.5 - 108 MHz, MW 520 - 1710 kHz with 10kHz steps for America, and 522 - 1620 kHz for the rest of the World, SW1 2.30 - 7.40 MHz and SW2 9.40 - 26.10 MHz, in total 13 SW bands
    • Shortwave bands by lengths for SW1 (6 bands):
      • 120m: 2300 - 2550 kHz
      • 90m: 3150 - 3450 kHz
      • 75m: 3850 - 4050 kHz
      • 60m: 4700 - 5150 kHz
      • 49m: 5750 - 6300 kHz
      • 41m: 7050 - 7400 kHz
    • Shortwave bands by lengths for SW2 (7 bands):
      • 31m: 9400 - 10050 kHz
      • 25m: 11500 - 12200 kHz
      • 22m: 13500 - 13900 kHz
      • 19m: 14950 - 15700 kHz
      • 16m: 17400 - 18000 kHz
      • 13m: 21300 - 21950 kHz
      • 11m: 25600 - 26100 kHz
    • Tuning steps: FM: 50kHz, MW 9/10 kHz, SW 5kHz
    • Preset memory: in total 20 - 5 for FM and, 5-5 for AM (5 for MW, 5 for SW1, and 5 for SW2)
    • Intermediate frequencies: for FM 10.7MHz, for AM 450kHz
    • Antennas: for FM and SW a telescopic aerial, for MW a built-in ferrite rod
    • Output power: 250mW
    • Used integrated circuits: FM frontend TA7358, AM/FM IF and MPX decoder TA8132, stereo power amplifier TA7376, controller and display driver TC9316F, voltage regulators LA5002M, RH5VA20C, RH5RL25AA
    • Stereo: just via headphones (the impedance of delivered headphone was 32 ohms)
    • Power supply: 4.5V by 3 pcs of AA type batteries or 4.5V DC external power supply
    • External dimensions: 142 x 92 x 35 mm (WxHxD)
    • Weight: 330 g
    • Sales price in 1998 was 220 DM.
    • No more technical parameters are available about this radio

      • Good things:

      • Very beautiful design, easy operation, all buttons deepened, but easy to be pushed
      • Is a stereo radio via headphone
      • Nice snap-on leader case. When is closed, the speaker, the antenna, and the power button are free. The case can be folded back and became a support for the tilted radio
      • Direct digital keypad tuning
      • Can be selected the required SW band by name of band wavelength/meter
      • Has a Lock switch, protecting during travel or by mistake and powering on

      Difficult, problematic items:

      • Low preset memory, just 5-5 locations for FM, MW, SW1, and SW2
      • No continuous tuning, in Continuous mode the radio jumping from the end of one of commercial bands to the beginning of the next commercial band (ex from end of 120m band, 2550kHz will jump to beginning of 90m band, to 3150kHz) - means the tuning is not really continuous.
      • The display lamp is activated just till the Lamp button is pressed, no temporization
      • The selectivity on FM is good, on MW is acceptable (internally has a very small ferrite rod), but on the SW band is very low
      • In AM mode has just a single conversion IF, which means on the AM the reception is very noisy
      • The tuned indicator on the display shows just the radio is tuned to the station frequency, if we are near, no help in which direction we should go

      This radio has very good marketing in its time, in several magazines with high reputation was named World Receiver, but the radio part is very weak, I did not recommend it to any DX activity. The problem: has no any front-end circuit, which can increase its sensiblity. Still, the Sony ICF-SW11 is much better, which is also a single IF radio. In some radioamateur portals are highlighted its poor SW reception capability - and this is true.
      This radio later was produced by Eton Co. as Grundig G2000A - is a completely same radio.
      Modifications: over 20 years, and because the used capacitors are low voltage types, their degradation level require to be changed. I recommend solid electrolytic capacitors (or tantalum in the RF part). In position C47 instead of 470uF/10V I soldered 1000uF/6.3V OSCON type, C12 instead 22uF received 47uF, C52 was changed from 22uF to 100uF, and C51 from 100uF to 220uF, the rest of the capacitors were changed with the same values.
      The keyboard rubber is fixed to PCB very ingeniously - via small rubber legs, which need to be inserted in PCB to keep their position. For reinsertion you can use component legs, pushing the wire from the opposite side of the rubber into the hole on the PCB - and for this, the legs have a cylindrical hole made for this purpose! Another thing that impressed me was the output capacitor value and is the same for both channels: 470uF/10V, which gives a nice color for music especially via headphones.



    Harman Kardon


    In the early 1950s, Sidney Harman was the general manager of the David Bogen Company, a manufacturer of public address systems at the time. Bernard Kardon was the chief engineer at Bogen. Due to management changes at Bogen in the early 1950s, both men resigned, and Sidney Harman and Bernard Kardon founded the Harman Kardon Company in 1953. By 1956, Bernard Kardon decided to retire and sold his interest in the company to Sidney Harman. As the sole head of Harman Kardon, Harman continued to make the company a technical leader in Hi-Fi products. Sidney Harman would change the company's name to Harman International, but the receivers, tuners and amplifiers were still branded Harman Kardon. The products continue to be branded as Harman Kardon to the present day. In 1969 Harman bought the major speaker manufacturer JBL. Harman Kardon's design goal is to have the highest possible design quality for the price, rather than unnecessary features. On March 11, 2017, Samsung Electronics announced the acquisition of Harman.


    Harman Kardon TU-9600

    Harman Kardon TU-9600

    Was the flagship of Harman Kardon's tuner series in 1991. Has a very good sensitivity on FM, with a very good station separation due to "Active Tracking" circuitry and "Digital Fine Tuning".

    General information:

    • Manufactured by Harman Kardon in USA at 1991
    • Digital 2 bands (MW-FM) PLL radio,
    • 24 memory presets, which can be mixed between AM and FM
    • Coverage: MW 520kHz - 1.710MHz, FM 87.5MHz - 108.0MHz
    • Usable sensitivity: 20uV on AM, 1.0uV on FM (mono) and 17.7uV for stereo - via a very sensitive JFET FM tuner
    • FM IF IC: LA1235, AM tuner IC: LA1245, stereo decoder: LA3450, PLL with prescaller: TC9227P, uController: TC9301AN, interface for I/O port: TC9173P, LED driver for signal strength: BA6124, FL tube display driver: TB2104F
    • Output frequency range: 20Hz - 15kHz (-1...+0.5dB)
    • Signal/noise ratio: AM 53dB, FM 82dB mono, 78dB stereo
    • THD: on FM 0.06% for mono, and 0.08% for stereo
    • Stereo separation: 50dB
    • Alternate Channel Selectivity (FM): 80dB with Active tracking mode
    • Adjacent Channel Selectivity: on FM 30dB with Active tracking mode, on AM 55dB
    • Line output impedance: 10 kohm
    • Line output levels: 440mV in AM mode, 1.1 V in FM mode
    • Antenna input impedance for FM: 75 ohms for both. Selection of input via relay
    • Power: 230V/50Hz, Consumption: 9W
    • Dimensions: 443x73x328mm, 3.4kg

    Good things:

    • Has a very clean sound, low noise, good channel separation, good readable FL display, and good "Active Tracking" which has a function of "narrow" IF.
    • Has 2 FM antenna inputs, selectable from the front panel
    • Discrete output amplifier instead of an operational amplifier IC
    • Is impressive the quality of electrical parts used, especially in case of solid capacitors

    Difficult, problematic items:

    • Memory is organized like 3 x 8 = 24 positions (A:1-8, B:1-8, C:1-8). Should be more natural 3x10 = 30.
    • Has no RDS (in 1991 was not so common).
    • In the case of tracking/fine-tuning, the display does not show the base frequency modification in numbers, just with arrows in +/-2 marks.
    Active Tracking/Fine Tuning: these features are designed to reduce signal interference that can occur when we tune into a weak FM station adjacent to a stronger station. With Fine Tunning, we can shift the receiving frequency away from the stronger station.
    Generally: is a very good tuner for high-quality FM DX audio program listening with 2 selectable antenna inputs.



    Hitachi


    Hitachi is a Japanese multinational conglomerate in Chiyoda, Tokyo, Japan. Was founded in 1910 by electrical engineer Namihei Odara in Hitachi, Ibaraki Prefecture. The first products were 4kW inductor motors used in copper mining. Odaira moved headquarters to Tokyo in 1918. Odaira coined the company's toponymic name by superimposing two kanji characters: hi meaning "sun" and tachi meaning "rise". World War II had a significant impact on the company with many of its factories being destroyed by Allied bombing raids, and discord after the war. At 1958 made its first 6-transistor miniature portable radio. From 1968 start its semiconductor business with LSI hybrid ICs. 1969 color TV sets, from 1984 256kbit DRAM production, 1987 large color LCD displays, in 1990 TFT color LCD display, 1994 32bit RISC processor family and 1Gbit DRAM, 1997 4.7Gbyte DVD-RAM,...


    Hitachi FT-3500

    Hitachi FT-3500

    Is a very fine slimline tuner from the bottom line of Hitachi (middle line from that era was the FT-4500 and FT-5500, but both are with a digital scale, better distortion and SN factors, but same sensibility - 1.0uV on FM; and the top tuner was the FT-8000). Based on advertisements from its era "has a very advanced Hitachi electronics, ..., and has a three-LED vector-tuning cursor to ensure accurate alignment to transmitter frequencies,...". This means the tunning indicator is on the cursor, and the lateral LED from both sides and their intensity helps the user to center the frequency exactly on the radio station used one. The power switch illuminates when the unit is operating.

    General information:

    • Manufactured by Hitachi Ltd., Tokyo, Japan at 1981
    • Analog 2 bands (MW-FM) superheterodyne radio (FT-3500L are with 3 bands, including the LW),
    • No memory presets
    • Coverage: MW 530kHz - 1.605MHz, FM 88.0MHz - 108.0MHz
    • Usable sensitivity: 15uV on MW and 1.0uV on FM mono and 23uV for FM stereo - via a very sensitive MOSFET FM tuner
    • FM IF IC: HA12412, AM tuner IC and IF amplifier: AN217, stereo decoder: HA1196
    • Output frequency range: 20Hz - 12kHz (+2.0dB...-2.0dB)
    • Signal/noise ratio: FM 77dB for mono, 70dB for stereo
    • THD: on FM 0.1% for mono, and 0.25% for stereo
    • Stereo separation: 45dB
    • Alternate Channel Selectivity (FM): 50dB
    • Line output impedance and level: 6.8 kohm/550mV
    • Antenna input impedance for FM: 75 ohms unbalanced or 300 ohms balanced
    • Power: 220-240V 50/60Hz, Consumption: 6W
    • Dimensions: 435x83x253mm (WxHxD), 3.4kg

    Good things:

    • Good sensibility on FM, clean sound, low noise
    • The scale is shown by a rectangular red LED
    • Very easy operation

    Difficult, problematic items:

    • No signal strength indicator, just the 2 lateral LEDs light intensity can be used from the cursor
    • The output frequency range seems to be narrow, just 30-12kHz with high deviation, but the sound is pleasant
    • Has no scale light, which means in dark you cannot see where are you on the scale
    When I bought it as a defective one, the R802 resistor was burned, instead of 39 ohms resistance its value was 1027 ohm. After changing it the radio wakes up. The tuner's ceramic filters are with blue dot, means their center frequency is 10.67MHz with 230kHz bandwidth. The power button bulb was changed with warm white LED (with 1.5kohm + 1N4148 connected to 24Vac). C315/C316 changed with 4.7uF/63V polypropylene foil caps. In the power line, C803 changed to 1000uF/50V, C301 and C804 with 470uF/35V. Rest of electrolytes with same values, below 4.7uF with foil capacitors.
    The power line received an EMI filter: 2.2nF/3kV + 2x35mH noise suppressor coil and 1uF/500V PP capacitor.


    Hitachi FT-8000

    Hitachi FT-8000

    The FT-8000 was the top of the slimline tuners of Hitachi in 1979 and has just one band: the FM. Is a digital synthesized tuner featuring a super stable quartz crystal frequency base, programable 6 station memory preset, highly sensitive all electronic front end with dual gate MOSFET, has automatic or manual stepped tuning, LED signal strength indicator and preset tuning, and record level oscillator for accurate FM recordings. Other important features: a high blend switch to reduce high-frequency noise in difficult reception conditions, a muting function to suppress interstation noise by more than 85 dB when tuning, the multipath switch that lets you audibly detect multipath interference. Use battery supply (2 pcs of UM6 or AA) to retain the preset memory when power is disconnected. This tuner was sold also as FT-8000 DB, but that means just the color of the front panel: dark brown, not silver.

    General information:

    • Manufactured by Hitachi Ltd., Tokyo, Japan between 1978-1981
    • Digital one band FM tuner,
    • 6 memory presets
    • Coverage: 88.0MHz - 108.0MHz
    • Usable sensitivity: 0.9uV on FM mono (no level mentioned for FM stereo) - via a very sensitive MOSFET FM tuner
    • FM IF IC: HA11211, FM IF amplifier HA1211, MPX stereo decoder: HA11223, audio output buffer amp HA1452, prescaller TD6102, crystal osc and counter TC9123, controller TC9124, decoder TC5022 and display driver TC5066 (2 pcs),
    • Output frequency range: 10Hz - 15kHz (+1.0dB...-1.5dB)
    • Signal/noise ratio: FM 75dB for mono, 72dB for stereo
    • THD: on FM 0.12% for mono, and 0.15% for stereo
    • Stereo separation: 50dB
    • Image rejection ratio: 70dB
    • IF rejection ratio: 85dB
    • Alternate Channel Selectivity (FM): 70dB
    • Line output impedance and level: 600 ohms, level not known
    • Antenna input impedance for FM: 75 ohms unbalanced (DIN and wire) or 300 ohms balanced
    • Power: 220-240V 50/60Hz, Consumption: 19W
    • Dimensions: 435x78x369mm (WxHxD), 6,1kg
    • Price in 1981: 798 DM

    Good things:

    • Good sensibility, clear sound, low noise
    • Has an attenuator for very strong local stations
    • Easy operation, clear VFD display
    • Has 2 independent power systems: one for the analog tuner section, and one for the digital section, both with 1-1 transformer.

    Difficult, problematic items:

    • No tunning indicator, but the stations are precisely found on the transmission frequency
    • The input signal attenuation switch is on the backside - is uncommon to switch it on or off during DX-listening.
    • Nowadays 6 preset stations are not enough
    In Japan the tuner name is Lo-D FT-8000, with their FM frequency range: 76 MHz - 96 MHz.
    When I purchase it, the cover was with lack of paint, with bubblies, and missing tunning buttons alumina cover. After repainting and making 2 disks for buttons from outdated coins, start to look better. The front also has scratches - which cannot be removed, just cleaned. The front panel is formed from 2 plates screwed together, with glued push mechanisms for switches. The preset button forms a separate unit mounted in a plastic case cover, seems screwed, but is fixed with double side tape together and to the front panel. Inside the tuner has 3 PCBs: on the rights side close to antenna inputs is the FM front end with a shielded cover. Is interesting, that the top shield with adjusting holes is screwed, not just pressed together with the lateral shield. The other 2 big PCBs are the tuner with power supplies on the left side and the digital synthesizer with display drivers on the right side. The Q809 transistor is the most important heat generator including its heatsink.
    On the net, I did not find the complete service manual, just the block diagram of the complete tuner and the analog part's schematic, with the tuner part and their PCB drawing - nothing about the digital part. This can be reconstructed from the datasheet of TC9124 controllers datasheet.
    Modifications:
    Just in electrolytic capacitors. All audio-signal-related coupling capacitors were changed to 22uF/50V Nichicon Fine Gold. Below 3.3uF and less were changed with foil capacitors and the rest with solid electrolytes and normal ones.
    Sound: clear, smooth, and warm - this is exactly what I expected. The sonics is well balanced and not lacking in the high frequencies. Has a very analog sound, which can be listened to for a long time (that cannot be made in case of new, completely digital tuners). I think, is a very downrated tuner, which refurbished can compete with the best ones.



    JVC


    The Japan Victor Company, is a Japanese international professional and consumer electronics corporation based in Yokohama. Founded in 1927, the company is best known for introducing Japan's first televisions and for developing the Video Home System (VHS) video recorder. From 1953 to 2008, the Matsushita Electric Industrial Co. was the majority stockholder in JVC. In 2008, JVC merged with Kenwood Corporation to create JVCKenwood. JVC sold their electronic products in their home market of Japan under the "Victor" name with the His Master's Voice logo, but used the name JVC or Nivico (for "Nippon Victor Company") in the past for export due to differing ownership of the His Master's Voice logo and the ownership of the "Victor" name from successors of the Victor Talking Machine Company. In 2011, the Victor brand for electronics in Japan was replaced by the global JVC brand. However, the previous "Victor" name and logo is retained by JVC Kenwood Victor Entertainment, and is used as JVCKenwood's luxury HiFi marque.


    JVC T-X1L

    JVC T-X1L

    General information:

    • Manufactured at 1980 by JVC - Victor Company of Japan Ltd. at Yokohama
    • 3 band analog superheterodyne tuner LW, MW and FM
    • Coverage: LW 150 kHz - 360 kHz, MW 520kHz - 1.710MHz, FM 87.5MHz - 108.0MHz
    • Antenna input impedance for FM: 300 ohms balanced, 75 ohms unbalanced,
    • No preset memory for FM
    • Usable sensitivity: 80uV on LW (external aerial), 50uV on MW (ferrite bar), 0.9 uV on FM mono and 22.5 uV for FM stereo
    • Intermediate frequencies: 450kHz for AM, and 10.7MHz (exactly 10.67MHz, blue marked filter) for FM
    • AM/FM ICs: HA1197 AM tuner IC, HA11225 FM IF system, uPC1161C MPX decoder IC and LB1416S as a signal indicator.
    • Output frequency range: 40Hz - 15kHz (-0.5...+0.5dB)
    • Power: ~220V/50Hz, consumption 12W
    • Output power: 600mV/3.3kohm
    • Dimensions: 420x108x313mm, 4 kg.
    Is an old, good tuner with a warm sound, selectivity is very good, and can drive directly my 600 ohm headphones without any problem.
    Is very interesting the scale: can be seen just the selected band ones. Consist of two transparent plexiglass with engraved scale, one for FM and one for AM (MW and LW) and are separately lighted just the used one. From the exterior can be seen just one scale, just the selected/lighted one (like on the picture).
    Just some out of order electrolytic capacitors were changed in the power line.


    JVC T-K10L

    JVC T-K10L

    Is a low end tuner with surprisingly good sensitivity and sound. Cannot be found much information on the net about this model. Its upper model is the T-K20/L.

    General information:

    • Manufactured between 1982 - 1984 by Victor Company of Japan
    • 3 band analog PLL tuner LW, MW, and FM
    • Coverage: LW 150 - 350 kHz, MW 525 - 1605 kHz, FM 88 - 108 MHz
    • Antenna input impedance for FM: 300 ohms balanced, 75 ohms unbalanced,
    • No preset memory for FM
    • Usable sensitivity: 30uV on MW, 100uV on LW, and 0.9 uV on FM (mono) and 44 uV for stereo
    • Intermediate frequencies: 450kHz for AM, and 10.7MHz for FM
    • AM tuner IC: LA1245 amp, osc, IF and det; FM det. HA1137W; stereo decoder (MPX) uPC1161C3; signal indicator LB1416
    • Output frequency range: 30Hz - 15kHz (+0.5dB...-0.8dB)
    • Signal/noise ratio: AM 50 dB, FM 74dB mono, 67dB stereo
    • THD: 0.2% in FM mono, and 0.3% in stereo at 1kHz; 0.3% on AM
    • Stereo separation: 37dB at 1kHz
    • Channel balance: no data
    • Power: ~220V/50Hz, consumption 7W
    • Output power: 800mV/3.3kohm
    • Dimensions: 435(W) x 77(H) x 299mm (D), 2.9 kg.
    Some resistors are printed on the board, and this is the weakness of this tuner. I buy it for 10$ as defective with a very low output audio level, and the problem was one of such resistors.
    The sensibility and the stereo signal capturing outperform the specification - means at very low signal level still can receive the stereo transmission without any sizzling noise.
    The scale has no backlight, just the cursor, which is made from a wide transparent plexiglass and is illuminated by bulbs separately: for AM with very light green, for FM with very light blue lights (now the miniature bulbs were changed with warm white miniature LEDs, using the colored rubber caps from miniature bulbs).
    The power transformer are constantly connected to line without fuse, and the power switch connect the low voltage to tuner. During long operation the transformer remains cool. Received an EMI filter at power line input.
    The RC network (10kohms in serial connection with 10uF) are not mounted on pins 4 and 5 of MPX decoder (uPC1161C3), the audio signal goes trough a low pass and band stop filter (set for 37.5kHz).



    Kenwood


    The company was established in 1946 as the Kasuga Radio Co. Ltd. in Komagane City, Nagano Prefecture, Japan. In 1960, the company was renamed Trio Corporation. An importer of Japanese-made electronics, A&A Trading Co for RadioShack, and a manager from there, William "Bill" Kasuga partnered with George Aratani and Yoichi Nakase decided to establish a company that would be the exclusive importer of Trio products. The name Kenwood was invented by Kasuga as being the combination of "Ken", a common name in Japan and North America that had been tested and proven acceptable to American consumers in the name of Kenmore appliances, and "Wood", referring to the durable substance as well as suggesting a relation to Hollywood, California. The brand recognition of Kenwood eventually surpassed that of Trio, and in 1986 Trio bought Kenwood and renamed itself Kenwood. George Aratani was the first chairman of Kenwood USA Corporation and succeeded by Kasuga. In October 2008, Kenwood merged with JVC to form a new holding company, named as JVCKenwood.


    Kenwood KT-815

    Kenwood KT-815

    This tuner has a Trio trademark: the Pulse-Count Detector. In an FM tuner the conversion of frequency modulation into the original audio signal takes place in a detector that is fundamentally immune to distortion and practically ignores noise. Has IF selectivity switch: Wide and Narrow; MPX filter switch on/off possibility; Auto/mono mode selection; Servo lock/Muting switch on/off. It has servo lock tuning for drift-free RF performance, and de-emphasis (50/75uS) switch on rear cover.

    General information:

    • Manufactured at 1979-1981 by Trio-Kenwood Co., Meguro-ki, Tokyo, Japan
    • 2 band analog superheterodyne tuner, MW and FM
    • Coverage: MW 510kHz - 1.640MHz, FM 87.5MHz - 108.0MHz
    • Antenna input impedance for FM: 300 ohms balanced and 75 ohms unbalanced,
    • No preset memory for FM and AM
    • Usable sensitivity: 0.8 uV on FM mono, 25uV on FM stereo; 9uV on AM
    • Intermediate frequencies: 455kHz for AM, and 10.68MHz
    • Used ICs: AM tuner HA1197, FM IF amplifier LA1222 and TA7060P, FM IF system HA1137, balanced modulator MC1496, pulse count detector TR4010A, PLL stereo demodulator HA11223W, op. amplifiers HA1457.
    • Signal to noise ratio: mono 84dB, stereo 80dB for FM, and 55dB for AM
    • Harmonic distortion: mono 0.05%, stereo 0.07% for FM, and 0.5% for AM
    • Output frequency range: 30Hz - 15kHz (-0.3...-0-5dB)
    • Power: ~110-120/220-240V/50Hz, consumption 20W
    • Output: fix 0.75V/2.5kohm or variable 0-1.3V/1.5kohms; multipath output: vertical 0.02V/1kohm and horizontal 0.35V/10kohm
    • Dimensions: 440x153x402mm, 7.6 kg.

    Good things:

    • Extremely clear sound
    • High sensibility and selectivity on FM, but also the AM is very good
    • Nice adjustment using the 2 instruments
    • Variable output signal level, adjusted from front panel

    Problematic things:

    • Instruments illumination is very weak
    • Lack of bass
    • No any data can be found about TR4010A pulse count circuit, made for Trio-Kenwood
    Is same as KT-8155 model.

    Modifications
    General: all electrolytic capacitors were changed with new ones, and from below 4.7uF with foil-type (mostly WIMA), rarely with TA. Originally the power cord was for 110Vac network, I change it.
    This radio on several portals is mentioned as "the KT-815 is capable of excellent RF performance but its sound quality has been criticized for being "thin" and "too dry". For that reason, mostly based on Tuner Information Center recommendation, I implement some modifications in the signal path and power supply, and the result is impressive! I highly recommend it to every owner!
    Power supply (mentioned just those components, which value were changed): C15, C28, C46, C47, C49, C55, C63 47uF->100uF/63V Rubycon; C33 33uF/16V->100uF/63V Rubycon; C64 470uF/16V->1000uF/35V; C106, C107, C112, C113 1000uF/25V->2200uF/25V Rubycon; C78 220uF->1000uF/35V Rubycon; C92, C102, C103 47uF/16V->470uF/35V Nichicon; C99 33uF/16V->470uF/35V Nichicon; C108 100uF/25V->470uF/35V Nichicon; C110 100uF/10V->390uF/35V Rubycon; C23 200uF/16V->390uF/35V Rubycon. D29 RB-151 changed to 4 pcs UF4007 diodes. R170 100 ohms received in series one 2.2uH coil. In power section any high value capacitor received in parallel a 0.22-0.33uF/50V MKT. Mounted an AC filter after power cord (2.2nF/3kV + 2x7.8mH + 1uF/500V, but the 1uF was mounted after power switch).
    Signal: C95, C96 10uF/16V->100uF/35V Nichicon Fine Gold; C100, C101 3.3uF/50V-> 10uF/63V MFT ROE; C104, C105 10uF/16V-> 22uF/100V MKT Vishay; C90, C91 0.22uF/50V->1uF/63V MPT; C72 270pF ceramic changed to same value PP; C77 0.047uF-> 0.47uF/50V MKT Wima; C84 received in parallel a 39pF NPO type.
    Other recommended changes (not made yet): FM IF ceramic filters to be changed to low loss and narrow ones (ex. +-150kHz). Must be noted: all ceramic filters are blue dot type, which means 10.68MHz, not 10.7MHz! The output operational amplifiers is recommended to be changed with modern low noise types (MC34081, OPA2604, OPA2132 or AD845 are recommended, and can be tested other types), but a SIP8 to DIP8 adaptor is required (I made myself). Is also recommended to be changed the power line path, or take out the balun transformers at the FM antenna input (this can increase the sensibility with +3dB), or take out the FL6 and FL7 filters from the audio output.
    In general, is a remarkably good tuner with a lot of upgrade possibilities!



    Kenwood KT-80

    Kenwood KT-80

    As part of the slim-line series, was designed for KA-80 High Speed DC integrated amplifier. Is just an FM tuner with a servo-lock which eliminates the need for a tunning meter, based on Kenwood advertisement from '80. The signal level meter is made with 5 LEDs. Use the Kenwoods Pulse Count Detector, which virtually banishes FM noise and half the distortion. Has a Record Calibration Control for studio-quality off-the-air recordings, and an exceptional signal to noise ratio: in mono is 83dB, and 80dB for stereo mode.

    General information:

    • Manufactured by Trio-Kenwood Corp., in Japan between 1980-82
    • Analog, just FM band tuner with 4 gangs
    • No memory presets
    • Coverage: 87.5MHz - 108.0MHz
    • Usable sensitivity on 75ohm antenna input: 0,6uV on FM mono and 22uV for FM stereo
    • Used ICs (in total 9): SC114 as an oscillator and mixed in tuner section; TA7060 opamp as IF signal amplifier; HA1137W as FM IF system; AN610 balanced modulator circuit; TR4010A pulse count detector; AN6135 pop-noise canceller; HA12016 FM MPX decoder, AN6551 opamp as record signal calibrator and AFC; M51903L as signal level indicator for LEDs.
    • Output frequency range: 30Hz - 15kHz (+0.2dB...-0.8dB)
    • Signal/noise ratio: FM mono 83dB, FM stereo 80dB
    • THD: on FM 0.07% for mono, and 0.12% for stereo
    • Stereo separation: 47dB
    • Channel balance: 1.5dB
    • Alternate Channel Selectivity (FM): 75dB
    • Line output impedance and level: 3.3 kohms/300mV
    • Antenna input impedance for FM: 75 ohms or 300 ohms
    • Power: 220V/50Hz, Consumption: 11W
    • Dimensions: 440x78x333mm, 4.5kg

    Good things:

    • Very clean sound with low distortion, and has a high signal to noise level ratio (thank to pulse count detector)
    • Good sensibility
    • Two 75ohms antenna inputs: for coaxial cable and wire
    • Has a Postdetection Filter to eliminate HD FM radio noise (used in America)

Difficult, problematic items:

  • No tunning meter, just the servo lock - in the case of stations with low a signal is difficult to adjust using just one Tuned/Lock LED as feedback.
  • The scale is not so easy to read in the dark
  • No narrow/wide IF filter selector
Was available also in black, marked as KT-80B. The FM sections are similar to the earlier KT-615 and later KT-900 models, being simplified the FM tuner part. The IF path (almost the same as KT900) uses a total of three 3-pin ceramic filters with IF amps (discrete and TA7060P) in between, with two different (presumably matched) filter sets: SFE10.7M (+-230kHz) and two SFE10.7MS3 (+-180kHz).
In some forums are mentioned changes to improve the sound shortening its path on the PCB or components: taking out the calibration tone generator, and the signal can go from C40 to C33 using one capacitor, or taking out the R39-R40, C51-C52 (bypassing the last 2), etc.

Modifications:
All electrolytic capacitors changed. Below 4.7uF anywhere, and below 10uF in the signal path with foil capacitors. In the next will be mentioned were I changed or added new components.
Power path: C13, C57, C66 were replaced with 100uF/63V Nichicon, C83 with 2200uF/25V Rubycon, C63, C86 and C88 all replaced with 390uF/35V Rubycon, C27 and C74 replaced with 1000uF/35V Rubycon. Jumper J9 was replaced with a 220ohms resistor (is the power line of IC3/AN610), and in parallel with C16 was mounted a 270uF/16V OSCON with 100pF. On power transformer primer coil after power switch received in parallel one 470nF/275Vac pp, and on secondary, on both outputs one-one 470nF/275Vac pp foil capacitors.
Signal path: C22, C29 and C31 instead of 0.047uF all were replaced with 1uF/63V pp, C35 changed to 47nF/100V pp, C34 received in parallel 47pF C0G MLCC, between pin 5-6 of HA12016 one 100pF C0G. R18 changed from 1.8kohms to 1kohms. In parallel with C38 on pin 12 of HA12016 inserted one 10nF C0G, same with C61 on pin 13 of HA1137W received 10nF C0G. C39 replaced with 2.2uF/63V pp. C41 and C42 were replaced with the same value, 47uF/63V Nichicon Fine Gold type. R39-R40 changed from 3.3kohms to 5.6kohms. Basis of changes - Kenwood KT-L01T model.
The VCO of HA12016 is difficult to adjust, can be measured the 76kHz signal just between VR1 and R28. After changing all electrolytes needs to be readjusted.
On the PCB of the tuner, around HA12016 can be found the positions of components for 75us de-emphasis, but are omitted including with de-emphasis selection switch in my European version. The most often linked service manual on the net has an error: the output audio signal comes from the negative input of the output buffer amplifier of IC5/HA12016, but correctly comes out from the real output - pins 4 and 7.
Upgrade: (idea implemented from KT-615) at the gate of Q1 R1 instead of direct ground connection is better to be connected to ground via 10kohms, and this point to be connected to the power supply via one 470kohms resistor. This will increase a bit the sensibility of the tuner.
With improved capacitors in the signal path, improved power lines and all other modifications result is a detailed and clear sound.


Kenwood Basic T2

Technics ST-G5

Is the successor of the Basic T1 tuner, equipped with Direct Linear Loop Detector (DLLD) which gives ultra-low distortion for FM detection with distortion correcting circuit, achieving 0.0095% FM THD at 1kHz in wide IF mode. The T2 appears to be the first Kenwood tuner to use the DLLD. Has an advanced low-noise synthesizer circuit with high interference rejection, wide/narrow IF band selector, automatic seek tuning up or down, 8 FM and 8 AM preset memory, 2 stations automatic pre-program memory, and a special circuit: variable AM IF band control to optimized AM broadcast.
In Japan was sold as Kenwood KT-1010 II or under the brand name Trio KT-1010.

General information:

  • Manufactured by Trio-Kenwood Corporation in Japan between 1984-1985
  • Digital 2 bands (MW-FM) PLL radio,
  • 16 memory presets:8 for FM and 8 for AM
  • Coverage: MW 522kHz - 1.611MHz; FM 87.5MHz - 108.0MHz
  • Adjusting steps: MW 9 kHz; FM 50 kHz for EU version
  • Usable sensitivity: 10uV on MW, 0.7uV (in some catalogs 0.95uV) on FM mono and 28uV for FM stereo
  • FM IF system IC: LA1231NS; AM tuner IC: LA1245; MPX decoder uPC1223C; Prescaler: TD6104P; PLL controller TC9157P; FL display driver: TD6301AP; FM IF amplifier: uPC1163H; pop-noise canceller AN6135; signal level LED driver AN6882; analog multiplier NJM4200D; operational amplifiers NJM4558D, NJM45600-N; voltage regulator uPC78M05H
  • Output frequency range: 20Hz - 15kHz (0.0dB...-+0.5dB)
  • Signal/noise ratio: AM 52dB, FM 88dB mono, 76dB stereo
  • THD: on FM in Wide mode 0.004% for mono and 0.008% for stereo, and in narrow mode 0.02% for mono, and 0.04% for stereo at 1 kHz
  • Stereo separation: 55dB on audio band (50 Hz ... 10kHz), and 70 dB at 1 kHz
  • Line output level: on FM 0.6V/ 1.8kohms, on AM 180 mV/ 1.8kohms
  • Antenna input impedance for FM: 75 ohms unbalanced
  • Power: 120/220V 50/60Hz (selectable at plug-in cable with a cover), Consumption: 19 W
  • Dimensions: 440x64x317mm, 3.8kg

Good things:

  • High-quality electrical parts used
  • Very good selectivity and sensitivity on AM (10uV), excellent AM section, very immune to interference/static
  • Variable AM IF band control
  • Dual transformer for circuits isolation
  • Very low distortion on FM (0.004% in stereo wide mode), good stereo separation (68dB) and high signal/noise ratio (88dB)
  • Has a Postdetection Filter to eliminate HD FM radio noise (used in America)

Difficult, problematic items:

  • In stereo mode, once the stereo signal is lost, the unit automatically mutes the audio instead of defaulting to mono which can be annoying.
  • In AM mode is better if you switch to Mono mode (no mute), because the station sound intermittently is broken in case of the weak signal.
I have the European version - means is not mounted the AM step selector (CN3 connector and the S18 switch), and the deemphasis circuit is missing (CN11 connector, the selector switch S17 and C107/C108 capacitors for 75us). Capacitors were in the wrong shape (almost 40 years old), and I changed all electrolytics. In the case of used ones in the sound signal path into pp (till 10uF), the rest with high-quality electrolytics, and received an EMI filter at AC input.
The frequency display is shifted with 50kHz, I did not find how can be adjusted correctly, but with this deviation, the signal is on max value, the stereo decoder works correctly. At AM the sensibility is exceptional: I have never seen such sensibility with the loop antenna, no ferrite bar inside.
The original price was 798DM at 1984.
Modifications:
Basically, because is a well-made tuner, just the power line can be improved. Compared to all datasheets of used ICs, just one significant item I found: the pin 18 of uPC1223 stereo decoder is decoupled with 820pF to the ground.
Modification of power lines: C27, C95 1000uF/35V; C60, C85, C91, C113, C151, C154, C177, C184 390uF/35V; C73, C89, C95, C110, C119, C161, C163, C169, C173 100uF/63V; C146 2200uF/25V; C159 560uF/35V. Additionally was inserted coils in power lines, to decrease the noise between units: in tuner section, J145 jumper was replaced with 10uH/0.2 ohm coil; in IF demodulator section, with R54 in series was inserted 22uH/0.3 ohm coil; in stereo demodulator section, J68 was replaced with 47uH/0.6 ohm; in the power circuit of PLL controller J172 jumper was replaced with 10uH/0.2 ohm.


Kenwood KT-880DL

Kenwood KT-880DL

Is a quartz-synthesizer 3 band stereo tuner with DLRC (Direct Linear Reception Circuit), Pentacle Power System, Computer controlled tuning system, automatic tuning, and FM IF-bandwidth selector. Has a 20 stations random access preset memory and a large FL display. Is very sensitive, in some catalogs are mentioned 0.7uV as FM sensitivity. Funs like it for reception capability and sound.

General information:

  • Manufactured by Kenwood in Japan between 1987 to 1990
  • Digital 3 bands (MW-FM) PLL radio without RDS capability,
  • 20 random access memory presets, organized in 10+10
  • Coverage: LW 153kHz - 281kHz, MW 531kHz - 1.602MHz, FM 87.5MHz - 108.0MHz
  • Channel space: 1kHz for LW, 9kHz for MW, and 50kHz for FM
  • Intermediate frequency: 450kHz for AM and 10.7MHz for FM
  • Usable sensitivity: 10uV or 350uV/m on AM, 0.95uV on FM mono, and 25uV for FM stereo
  • Integrated circuits: FM IF amplifiers BA401 (2 pcs), FM IF IC: LA1235, AM IF IC: LA1245; stereo decoder: LA3401, PLL freq. synthesizer: LM7001, electronic tuning controller: uPD7538AC-045; FL display driver: LB1241, signal level LB1493, 3 terminal power regulators: AN7805F, uPC78L10J (2pcs), Operational amplifiers: M5223P (3 pcs), M5218P, NJM2901N, band selector LA7910, digital IC: uPD4013 D-flip-flop for switches, and uPD4069UBC inverter
  • Output frequency response on FM: 20Hz - 15kHz (+0.5...-0.5dB)
  • Signal/noise ratio: AM 52dB, FM 88dB mono, 76dB stereo
  • THD: on FM 0.1% for mono, 0.12% for stereo at 50...10kHz, on AM 0.3%
  • Stereo separation: 55dB at 1kHz, 40dB at 50...10kHz
  • Alternate channel selectivity: 60dB on Wide, 90dB on Narrow
  • Antenna input impedance for FM: unbalanced 75 ohms, for AM: loop antenna connector and an external antenna connection possibility
  • Output signal level/impedance: 0.18V on AM on 400Hz, and 0.6 V on FM at 1kHz, 3.3kohm
  • Power: 220V/50-60Hz, consumption: 13W
  • Dimensions: 440x78x317mm, 3.5kg

Good things:

  • Has a very clean sound with an extremely low noise level, low distortion,
  • Big FL display
  • Wide and narrow IF filters selection possibility for FM

Difficult, problematic items:

  • No mono/stereo switch - is automatically activated via manual/auto-scanning
  • No fuse on primer circuit of transformer - recommended being additionally inserted. Has just thermal protection
Is a 4 gang tuner on FM, and 2-2 for MW/LW. The schematic is very similar to KT5020 (differences: additional 3 terminal power rectifier for FM oscillator, different FM-IF circuit with LA1266 quadrature, and has one NJM4560 operational amplifier after LA3401 stereo decoder as output buffer).

Modification (based on FM TunerInfo, posted by JohnC, modified to my components):
Old electrolytics were ELNA type in average shape: some of them were OK (50% of 10uF/35V), but those with high capacitance and low voltage, like 100uF/10V or 220uF/6.3V were in poor condition. All were changed.
Power line: C137 changed to 4700uF/25V; C138 and C150 to 680uF/50V; C142, C151, C152 to 1000uF/35V; C32, C51, C65, C108, C120, C132, C133, C135, C148, C165, C181, C194 to 100uF/63V; C54 to 390uF/35V; C193 to 3300uF/16V; C128 to 22uF/50V. At AC power input received an EMI filter circuit formed by 2.2nF/2kV ceramic capacitor, a 2x6.7mH filter coil, and after in parallel with the primer coil of transformer one 0.68uF/275Vac pp foil capacitor.
Audio output: all capacitors were changed with polypropylene type. Instead of 10uF I use 2 pcs of 4.7uF in parallel. Capacitors changed: C54, C60, C64, C78, C79, C82, C83.
All other electrolytics below 4.7uF changed to foil type.
Other recommended modifications: rectifier diodes to be changed into Schottky type, and insert an operational amplifier as audio buffer on output after LA3401 filters, like in KT5020 model.
Now has good stable image, wide soundstage, midrange is pretty good, nice tight bass and fairly deep, and the treble is clear.


Kenwood KT-5020L

Kenwood KT-5020L

Is a 3 band stereo tuner with DLRC (Direct Linear Reception Circuit), DLLD (Direct Linear Loop Detector, designed to significantly widen the dynamic range the tuner can handle without distortion), distortion correction circuit (DCC) at outputs, automatic-quieting (mute inter-station noise while still allowing reception of weaker station), Pentacle Power System (eliminate interference between tuner circuits which can arise if they share a common power supply line) and Flex-On Printed Circuit Board for better sound (a special suspension system that helps dampen frame and external vibrations which could interfere with the accurate operation of electronic components). Has automatic searching and tunning function, an FM IF-bandwidth selector, 20 stations random access preset memory, and a large FL display. Is very sensitive, 0.7uV as FM sensitivity.
Other family members: KT-1020L, KT-2020L and KT-7020.
It is ranked as 7th best tuner, as sensibility and audio quality. Interesting: the top Kenwood (and other) tuners, like KT-990D, L-1000T, KT-917, KT-1100, KT-3300D, KT-8300, Pioneer F-90 and Onkyo T-9090II and KT-7020 are behind this, exactly in this order. (contest published by fmtunerinfo.com, shouts #68 to 81 from 20 Apr 2004 till 12 Dec 2006, comparison made with 84 tuners)

General information:

  • Manufactured by Kenwood Corporation in Japan between 1989 to 1990
  • Digital 3 bands (MW-FM) PLL radio without RDS capability,
  • 20 random access memory presets, organized in 10+10 (A and B page)
  • Coverage: LW 153kHz - 281kHz, MW 531kHz - 1.602MHz, FM 87.5MHz - 108.0MHz
  • Channel space: 1kHz for LW, 9kHz for MW, and 50kHz for FM
  • Intermediate frequency: 450kHz for AM and 10.7MHz for FM
  • Usable sensitivity: 10uV or 350uV/m on MW, 10uV or 600uV/m on LW, 0.7uV on FM mono, and 25uV for FM stereo
  • Integrated circuits: FM IF amplifiers BA401 (2 pcs), FM/AM IF control and detection: LA1266, AM/FM power selector: LA7910, PLL synthesizer: LA7001, mute control: uPD4069, narrow/wide switch and driver: uPD4013 and M5223, signal check: M5218, T-meter comparator: M5218, FM IF amplifier/buffer: uPC1163, stereo MPX decoder: LA3401, output buffer: NJM4560D, microcontroller: uPD7538AC-045; FL display driver: LB1241, signal meter driver: LB1433N, 3 terminal power regulators: uPC7805HF, uPC78L10J (4pcs)
  • Output frequency response on FM: 20Hz - 15kHz (+0.5...-0.5dB)
  • Signal/noise ratio: MW 52dB, LW 50dB, FM 78dB mono and 67dB stereo
  • THD: on FM 0.07% for mono, 0.2% for stereo at 50...10kHz, on AM 0.3%
  • Stereo separation: 52dB at 1kHz, and 42dB at 6.3kHz
  • Alternate channel selectivity: 75dB on Narrow
  • Image rejection ration: 82dB at 98MHz
  • IF rejection ratio: 110dB at 98MHz
  • Antenna input impedance for FM: unbalanced 75 ohms, for AM: loop antenna connector and an external antenna connection possibility
  • Output signal level/impedance: 0.18V on AM on 400Hz, and 0.6 V on FM at 1kHz, 3.3kohm
  • Power: 220V/50-60Hz, consumption: 15W
  • Dimensions: 440x98x318mm, 4.3kg
  • Price at 1989: 495DM

Good things:

  • Has a very clean sound with an extremely low noise level, low distortion,
  • Big FL display
  • Has output buffer after MPX circuit
  • Wide and narrow IF filters selection possibility for FM

Difficult, problematic items:

  • No mono/stereo switch - is automatically activated via manual/auto-scanning
  • No fuse on primer circuit of transformer - recommended being additionally inserted. Has just thermal protection. The radio is switched ON from the secondary side of the transformer.
Is a 4 gang tuner on FM with 3 ceramic filters in IF, and 2-2 for MW/LW. The schematic is very similar to KT880DL. In my set the System Control (E7) and its components are not mounted, also the De-emphasis switch (S22), and the tunning step selector (S21) are missing - is a set made for Europe.
Modification (based on FM TunerInfo, posted by Jim, modified to my components):
All electrolyte capacitors were ELNA type, which at that time were good, but their degradation is fast. I measured all of them, and some of them have high ESR (above 6 ohms), high loss (higher than 20%). For this reason, I changed all of them (with pp below 4.7uF and solid electrolyte types, exception just above 330uF).
In the audio part, all 7 pcs of 10uF/35V Elna (C90, C101, C102, C107, C108, C111 and C112) were changed into 10uF/50V bipolar Nichicon Fine Gold capacitors.
Received a power line filter: 2x1uF/275Vac, 2x12mH noise-canceling coil, and one 2.2nF/2kV ceramic capacitor.
Now has a good stable image, wide soundstage, the midrange is pretty good, nice tight bass and fairly deep, and the treble is clear.
Other recommended modifications (not made yet): rectifier diodes to be changed into Schottky type, change the actual audio buffer, mount a socket, and insert a better OPA, like OPA2132.


Kenwood KT-1050L

Kenwood KT1050L

Is the smallest model from 1992-1993 (behind KT2050 and KT3050). Radio quality (and radio part schematic) is the same as the model KT2050, excepting the memory of previously listened to station and automatic synchronization.

General information:

  • Manufactured by Kenwood Portugal at 1992-1993
  • Digital 3 bands (LW-MW-FM) PLL radio,
  • 30 memory presets, which can be mixed between AM and FM
  • Coverage: LW 153 - 281kHz, MW 520kHz - 1.710MHz, FM 87.5MHz - 108.0MHz
  • Usable sensitivity: 22uV on LW, 13uV on MW (400uV/m), and 0.7uV on FM (mono) and 22uV for stereo - via a very sensitive JFET FM tuner
  • AM/FM Tuner System IC: LA1266, stereo decoder: AN7470, direct PLL frequency Synthesizer IC: LM7001, uController and FL tube driver: CXP5014, LED driver for signal strength: LB1433N, + M5223 and XRA10393 opamps.
  • Output frequency range: 30Hz - 15kHz (+0.5...-2dB)
  • Signal/noise ratio: LW 47dB, MW 50dB, FM 68dB mono, 63dB stereo
  • THD: on FM 0.15% for mono, and 0.4% for stereo, on AM 0.5%
  • Stereo separation: 48dB
  • Line output impedance: 3.3 kohm
  • Line output levels: 180 mV in AM mode, 0.6 V in FM mode
  • Antenna input impedance for FM: 75 ohm
  • Power: 230V/50Hz, Consumption: 10W
  • Dimensions: 440 x 79 x 264 mm, 2.6 kg

Good things:

  • Very good sensitivity on FM (0.7uV) and AM: 13uV on MW and 22uV on LW
  • Used components were good quality (at that time).

Difficult, problematic items:

  • Memory is organized like 3 x 10 = 30 positions, but from first position cannot be selected just 9 (the 0 button can be used just with 1, 2 or3). With this, I can say just 9 stations can be selected directly on the first page.
  • The display is situated too deep, cannot be seen just from a narrow-angle from the front side.
  • The transformer is always connected, and the radio is switched electronically with push-button or via remote controller -> extra consumption.
  • The mainboard is difficult to be taken out for repair/modification, because of short deepness (just 264mm): connectors are mounted on PCB and screwed to the rear panel, and the FL display on the front, mounted also on PCB are too deep in the front cover. To remove it is necessary to remove the back or the front of the tuner.
  • No narrow or wide FM IF selection possibility.
Generally: is a very good, sensible tuner for FM DX audio program listening with good selectivity. Has no any functions which can be found in higher family models (KT-2050L, KT-3050L and KT-6040): DLRC, DLLD, DCC, RDS, Pentacle system, timer, active reception control and IF rejection.
As usual, was necessary to change all electrolytic capacitors. In RF parts received tantalum type capacitors, in other areas, below 4.7uF film capacitors, in audio part Nichicon Fine Gold, in the power line, above 22uF Nichicon or Rubycon capacitors.



Luxman


Lux Corporation was founded in Japan in June 1925, by T. Hayakawa and his brother K. Yoshikawa. The company began as the radio equipment department of Kinsuido Picture Frame Store in Osaka, until then only an importer of picture frames, and was founded just ahead of the first radio broadcast that year.
At the time, Japanese radio listeners were dependent on technology originating in the United States and Europe. Importing radio equipment and parts was a very forward-looking enterprise for Lux, and passersby often crowded the store to hear the inviting sounds of the radios on display. Lux Corporation later decided that to compete effectively as a supplier, it had to not only sell equipment but manufacture parts in-house to reduce the costs of importing, beginning the creation of the Luxman brand. As a result of this pursuit, Luxman became famous for the output of various quality transformers and switches in Japan, and today is one of the oldest manufacturers in Japan of electronic components, which is reflected in the company's tagline "Ultimate Fidelity since 1925". In the mid-1970s and early 1980s, Luxman rose to prominence in the world hi-fi community, owed to the quality sound produced by its equipment. Luxman was primarily a specialist in making vacuum tube amplifiers of the highest caliber. One of the traits of Luxman equipment from this era is the quality and warmth of vacuum tube sound, paired with powerful solid-state electronics and often beautiful, minimalist aesthetic designs.
An engineer by the name of Atsushi Miura married Mari Yoshikawa (Mr. K. Yoshikawa's eldest daughter) and became a part of the founding 'Luxman' family. Atsushi Miura's father was an audio engineer and was head of Luxman for many years in Japan. In the early 1980s, Atsushi took over the reins from his father to run Luxman. Sensing the Japanese audio industry was heading towards cheaper mass-produced components and against the founding philosophy of Luxman, Atsushi sold Luxman to Alpine in 1984, before starting the Airtight audio brand. Alpine, wishing to merge their home hi-fi divisions and Alpine brand with Luxman gear, took corporate actions which nearly bankrupted Luxman. The first of these corporate mistakes was getting Luxman involved in a hi-fi market share war with rival consumer electronics brand Yamaha. Up to the point of the merge, Luxman was revered as a prestigious audio brand; one that sold its equipment in specialist independent hi-fi shops. Post-merge, Luxman looked to sell their products to companies such as Costco (United States) and Richer Sounds (UK) to compete with Yamaha. This plan resulted in much confusion amongst consumers, as well as their perception of the brand's values. Where Luxman's reputation was in high-end and often expensive markets, its new distributors had reputations for selling in budget and low-value markets, causing problems for existing dealers and consumers loyal to Luxman's values. The second corporate mistake by Alpine was problems with product branding and poor product planning. While Alpine equipment was seen as "okay" and "acceptable" in most consumers' eyes, Luxman was seen as a perfectionist and even elitist brand. The co-branding of cheap and inferior plastic Alpine products with expensive Luxman gear (Luxman equipment was badged Alpine/Luxman) in both Alpine and Luxman factories caused further confusion amongst consumers. This move totally destroyed the image and, ultimately, the sales of Luxman equipment, and the company ended up retreating from all its sales network worldwide except Japan.
Alpine, due to all the troubles it experienced with the Luxman brand, sold it off in 1994. In 2009, Luxman Corporation was acquired by the International Audio Group Ltd. IAG.


Luxman T-4

Luxman T-4

This tuner, part of Studio Standard Series, was made in 1978 are equipped with Accutouch Closed Loop Lock(ACLL), which offers perfect accuracy and unconditional stability in FM tuning, which interacts with the Accutouch system to provide a mechanical lock on the tuning knob when the station is precisely tuned in. The front has a clean minimalist design: AM/FM band selector, Mode switch (Mono/Stereo), FM IF Bandwidth Selector (Wide/Narrow), FM Muting level adjuster, tuning know and power switch. On backside has an additional DIN FM antenna connector.

General information:

  • Manufactured between 1978-1979 by Lux Corporation in Japan
  • 2 band analog superheterodyne receiver, MW and FM
  • Coverage: MW 525kHz - 1.605MHz, FM 87.5MHz - 108.0MHz
  • Antenna input impedance for FM: 300 ohms balanced and 75 ohms unbalanced (terminal and also with DIN connector),
  • No preset memory for FM
  • Usable sensitivity: 0.9 uV on FM mono and 22 uV for stereo; 250uV/m on AM
  • Intermediate frequencies: 450kHz for AM, and 10.73MHz for FM
  • Used ICs: FM IF system LA1231; AM tuner: HA1197; MPX decoder uPC1173C; signal level LED driver BA656, operational amplifiers for CLL and audio output buffer NJM4558D
  • Signal to noise ratio: mono 75dB, for stereo no specified FM
  • Muting threshold: 5-300uV
  • Harmonic distortion: mono 0.08%, stereo 0.15% for FM at 1kHz
  • Output frequency range on FM: 30Hz - 15kHz (+1...-1dB)
  • Output voltage and impedance: 1 V on FM and 0.3V on AM / 100 ohms
  • Stereo separation: 48dB at 1kHz
  • Power: ~220V/50Hz, consumption 10W
  • Dimensions: 438 (W) x 84 (H) x 331 (D) mm, 6.5 kg.

Good things:

  • Beautiful minimalist front panel, warm and very clear sound
  • Closed Loop Lock, which makes it easy to tune exactly on station the tuner

Problematic things:

  • The signal-LEDs are deep in panel, can be seen just from certain angles
  • No tune indicator, just the signal strength
Interesting parts: some modules are separated with capacitor-multiplier circuits in the power line, like the FM oscillator and FM tuner, the audio output buffer, and the CCL circuit decreasing the noise of which comes from the power line to those units.
The oil-paper capacitors from the main switch were cracked, and the epoxy cover starts to peel off. Both were replaced with 2.2nF/3kV ceramic disk capacitors.
Power section: C103 and C168 now is 100uF/25V solid electrolyte capacitor (was necessary to decrease the value of R202 from 47k to 15k), C175 now is 3300uF/25V, C176 is 2200uF/25V, C147, C169, C172, C173, C216, C311, C312, C313 now are 470uF/35V, C163 is 10uF/35V.
In signal path C158 and C159 now are 3.3uF/100V pp, C161 and C162 now are 0.47uF/63V pp, rest below 4.7uF all pp.




Marantz


Marantz is a company that develops and sells high-end audio products. The company was founded in New York, but is now based in Japan. The first Marantz audio product was designed and built by Saul Marantz in his home in Kew Gardens, New York. The company had a major influence in the development of high-fidelity audio systems, and reached the high point of their success in the mid to late 1970s. During the 1980s, while owned by Philips, a pioneer in compact disc technology, Marantz sold some very well received CD players, but other products in the line were not as successful as in the past. Beginning in the early 1990s, Marantz focused on higher-end components. In 2001, Marantz Japan acquired the brand from Philips and owned all overseas sales subsidiaries. 2002 merged Marantz with competitor Denon into D&M Holdings Inc., later named in D+M Group. On March 1, 2017, Sound United LLC completed the acquisition of D+M Holdings.


Marantz ST 450

Marantz ST-450

Is a very fine tuner with the second-best selectivity on MW I ever meet on tuners, 10uV (behind Kenwood Basic T2 tuner)! Also, the FM selectivity is good: 0.9uV. Inside is full analog, just the display is digital. Has a 4 stage FM tuning capacitor, a precision tuning system with digital readout and servo lock, pilot frequency rejection circuit, FM muting.

General information:

  • Manufactured by Marantz in Japan between at 1979-1982
  • Digital 2 bands (MW-FM) PLL radio (exist also a 3 band version, with LW named ST 450L),
  • No preset memory
  • Coverage: MW 531kHz - 1.602MHz, FM 87.5MHz - 108.0MHz
  • Usable sensitivity: 10uV(!) on MW and 0.9uV on FM mono and 20uV for FM stereo - via a very sensitive MOSFET FM tuner
  • FM IF IC: LA1231N, AM tuner IC: LA1240, stereo decoder: HA11223, uController and display driver: LC7258, prescaller: DS8629, signal level indicator LB1415
  • Output frequency range: 30Hz - 15kHz (+0dB...-1.0dB)
  • Signal/noise ratio: AM 55dB, FM 76dB mono, 70dB stereo
  • THD: on FM 0.17% for mono, and 0.2% for stereo
  • Stereo separation: 45dB
  • Channel balance: 0.2dB
  • Alternate Channel Selectivity (FM): 70dB
  • Line output impedance and level: 1.8 kohm/700mV
  • Antenna input impedance for FM: 75 ohms or 300 ohms
  • Power: 220-240V/50Hz, Consumption: 14W
  • Dimensions: 416x73x194mm, 3.2kg

Good things:

  • Has a very clean sound, low noise, good channel separation
  • Discrete output amplifier instead of an operational amplifier IC
  • Very good sensitivity on MW (10uV) with its own frame antenna, and 0.9uV on FM
  • High quality of electrical parts used, especially in case of solid capacitors, coils
  • Has a very fine tuning mechanism called Gyro Touch, smooth running, but easy and fast you can slide from one end to another one of scale

Difficult, problematic items:

  • No memory preset possibility
In the case of such old tuners was necessary to change all electrolytic capacitors (originally all were ELNA brand). In the audio part, I use audio grade capacitors also in the power line (Nichicon Fine Gold, etc). In the RF part power line I use tantalum capacitors and in the display part tantalum and OSCON. Used IF filters: for AM CFM2-455B, and for FM SFE10.7MS3G, SFE10.7MD1. Their central frequency is 10.73MHz. Crystal: 4.000MHz.



Marantz ST 530

Marantz ST-530

Is a very good FM tuner with dual gate MOSFET front end with twin varactor type tuning stage. FM sensitivity is 0.7uV. Inside has a digital synthesizer. Record programable: up to 6 stations can be recorded alternatively via the original Marantz Bus system, last station memory, and multiplex pilot canceler. At the backside has a switch to select the steps for AM and FM: 9/10kHz for AM, and 50/100kHz for FM (European and American radio standard).

General information:

  • Manufactured by Marantz in Japan between at 1983-1984
  • Digital 2 bands (MW-FM) PLL radio (exist also a 3 band version, with LW named ST 530L),
  • 8+8 preset memories, 8 for FM and 8 for AM
  • Coverage: MW 522kHz - 1.611MHz, FM 87.5MHz - 108.0MHz (LW 153 - 353 kHz)
  • Usable sensitivity: 6uV (in the user manual is written 350uV) on MW and 0.7uV on FM mono and 22uV for FM stereo
  • FM IF IC: HA11225; AM tuner IC: LA1245; stereo decoder: HA11223; uController and display driver including the signal level indicator: uPD1704C-544; prescaller: uPB553AC
  • Output frequency range: 30Hz - 15kHz (+0dB...-1.05B)
  • Signal/noise ratio: AM 54dB, FM 80dB mono, 72dB stereo
  • THD: on FM 0.1% for mono, and 0.2% for stereo
  • Stereo separation: 50dB
  • Channel balance: 0.2dB
  • Alternate Channel Selectivity (FM): 70dB
  • Line output impedance and level: 1.8 kohm/150mV
  • Antenna input impedance for FM: 75 ohms or 300 ohms
  • Power: 110-120/220-240V and 50/60Hz, Consumption: 12W
  • Dimensions: 416x55x300mm, 2.9kg

Good things:

  • Has a very clean sound, low noise, good channel separation
  • Discrete output amplifier instead of operational amplifier IC or direct output from the stereo decoder
  • Very good sensitivity on FM: 0.7uV
  • High quality of electrical parts used, especially in case of foil or ceramic capacitors, coils
  • Has very sensible switches, operates smoothly

Difficult, problematic items:

  • On MW is not as sensible as are mentioned in brochures (6uV on MW), I think is closer to 350uV which is written in the service manual. The sensitivity on MW is much lower compared with Marantz ST450, which on MW has a real 10uV with its frame antenna.
All electrolytic capacitors (originally all were ELNA brand). were changed. In the audio part, I use audio grade capacitors (Nichicon Fine Gold, etc.), in power line Rubycons. In the RF part power line and for the microcontroller I use tantalum capacitors Used IF filters: for AM SFP-450H, and for FM SFE10.7MD-1, SFE10.7MS3G. Their central frequency is 10.70MHz. Crystal: 4.500MHz.


Marantz ST-64L

Marantz ST-64L

Is a state-of-the-art digitally synthesized tuner with preset convenience and connections for BUS remote control. Has quartz synthesized tuning for drift-free reception and autotune possibility. The high sensitivity front end with low noise and low distortion makes the best out of the high-quality broadcast. Has also a switchable IF bandwidth to pick out the stations under difficult reception conditions or to achieve the best possible stereo separation and lowest crowded bands. Despite its excellent parameters, its exterior looks horrible - I think is a worst design ever made by Marantz.

General information:

  • Manufactured by Marantz in Japan between at 1985-1987
  • Digital 3 bands (LM-MW-FM) PLL radio,
  • 24 memory presets:16 for FM and 8 for AM
  • Coverage: LW 153kHz - 281kHz; MW 531kHz - 1.602MHz, FM 87.5MHz - 108.0MHz
  • Usable sensitivity: 800uV on LW, 350uV on MW and 0.7uV on FM mono and 20uV for FM stereo - via a very sensitive MOSFET FM tuner
  • FM IF IC: LA1231 and uPC1136H, AM tuner IC: LA1245, stereo decoder: KB4437, uController: uPD1704C-552, prescaller: uPB553AC, display driver: uPD6320G; signal level indicator AN6876
  • Output frequency range: 20Hz - 15kHz (+0.5dB...-1.5dB)
  • Signal/noise ratio: AM 54dB, FM 85dB mono, 76dB stereo
  • THD: on FM 0.05% for mono, and 0.08% for stereo
  • Stereo separation: 55dB
  • Channel balance: 0.2dB
  • Alternate Channel Selectivity (FM): 75dB
  • Line output impedance: 10 kohm
  • Antenna input impedance for FM: 75 ohms or 300 ohms
  • Power: 220-240V/50Hz, Consumption: 12W
  • Dimensions: 416x73x295mm, 3.4kg

Good things:

  • Has a very clean sound, low noise, good channel separation
  • Discrete output amplifier instead of an operational amplifier IC
  • Very high sensitivity: 0.7uV on FM!
  • Program records allow the tuner to switch between 6 stations for unattended recording
  • Last station memory - tuner switches on with the last station listened (at that time was a new thing)
  • High quality of electrical parts used, especially in case of solid capacitors, coils

Difficult, problematic items:

  • Memory is organized like 3 x 8 = 24 positions (A:1-8, B:1-8, C:1-8). Should be more natural 3x10 = 30.
  • Has only 1 antenna input. Some tuners have 2, and for DXing could be more suitable...
  • Has a very poor design, and the display is mounted too deep
In the case of such old tuners, all electrolytic capacitors should be changed. In the audio part are recommended to use audio grade capacitors also in power line (Elna SilmicII or Nichicon MUSE etc.). In RF part power line I use tantalum capacitors. This tuner uses 5 lamps, all 8V/50mA -> can be replaced easily with green LEDs, increasing just their serial resistor from 10 ohms to 270 ohms. The polarity can be determined via schematics and PCB drawing from the service manual. Used IF filters: for AM SFP450H, and for FM SFE10.7MS3G, SFE10.7MA8-A. Crystal: 4.500MHz


Marantz ST-6000

Marantz ST-6000

The Marantz ST 6000 is a reasonably well built 4 gang equivalent, 4 filters, dual bandwidth, AM/FM tuner manufactured in China. Has a dual-gate MOSFET front-end, quartz-locked digital tuning with low noise, drift-free reception of stereo FM, Wide/narrow switchable IF bandwidth, 60 preset memory, D-Bus connector for system remote control (via amplifier), and has a beautiful solid aluminum front panel with minimalist and modern design.

General information:

  • Manufactured by Marantz in China (!) between 1999-2004
  • Digital 3 bands (LM-MW-FM) PLL radio,
  • 60 memory presets:30 for FM and 30 for AM
  • Coverage: LW 146kHz - 290kHz (1 kHz step); MW 522kHz - 1.622MHz (9 kHz step), FM 87.5MHz - 108.0MHz (50 kHz step, or 10 kHz in Fine step mode within +-50kHz range)
  • Usable sensitivity: 50dBuV/m on MW, 57dBuV/m on LW and 1.2uV on FM mono
  • FM IF IC: LA1235, FM IF amplifier: TA7060AP, AM tuner IC: LA1135, stereo decoder: LÁ3401, uController and FL display driver: ANAM1288T/TMP87PM78F, RDS decoder: TDA7330BD, PLL LC72131M, output buffer: MC4558S, stabilizer KA7815ZA and KA7805ZA
  • Output frequency range: 20Hz - 15kHz (+1.0dB...-3.0dB)
  • Signal/noise ratio (1 kHz): LW 45dB, MW 50dB, FM 80dB mono, 75dB stereo
  • Selectivity (+-400 kHz): in Wide mode 65 dB, in Narrow mode 80 dB
  • THD: on FM 0.08% for mono, and 0.15% for stereo, on AM 1.0%
  • Stereo separation (1 kHz): 50dB
  • Channel balance: 0.5dB
  • Line output impedance: 2 kohms
  • Antenna input impedance for FM 75 ohms unbalanced, 2 selectable inputs: A & B, indoor loop antenna for AM
  • Power: 230V/50Hz, Consumption: 7.6 W
  • Dimensions and weight (net): 440 x 96 x 307 mm (WxHxD), 3.8kg
  • Selling prices were around 279$ in 2001

Good things:

  • Has a very clean and warm sound, low noise, good channel separation
  • Use operational output amplifier after stereo decoder
  • Timer function: used for presetting the time when the system is turned on and off every day at a specified time (needs a Marantz amplifier which can communicate with this tuner)
  • Signal level indicator
  • 2 selectable antenna inputs for FM
  • Automatic scan and storage operation
  • RDS capability: PTY, PS, RT, CT, TA
  • "Anti-birdie filter" installed after MPX decoder, no any pilot tone or subcarrier suppressor mentioned, but the output is quite clean

Difficult, problematic items:

  • Low quality of electrolytic capacitors used (Daewoo)
  • Medium selectivity, nothing special
  • The FL display has low intensity, in a bright environment is difficult to be read
  • The two voltage regulator IC after one hour of operation is very hot, and that temperature change is not good for ceramic filters
  • The built-in clock loses time if the tuner is unplugged or the power goes out (but the stored stations are kept). When the power comes back, and we start to listen to a station with RDS, automatically will be adjusted
When I purchased this tuner and the first time I listen to it, I was completely disappointed. Regarding excessive marketing, in any magazine in its time was mentioned the ST-6000 as one of the best tuners. In reality: average sensibility. The 2 filters Wide and 4 filters Narrow IF employs a single TA7060 IF operational amplifier feeding a LA1235 FM IC. No extra feature compared to other top tuners from that era (ex. Denon TU-1500RD), and additionally was made with the worst electrolytic capacitors inside what I ever see from a market leader company (they use in my set Daewoo RM), and just after 19 years from manufacturing some of them were completely dried - ex. a 220uF/25V Daewoo RM capacitor measured: 88uF, 1.5 ohms ESR and 21% loss!
In several forums are mentioned just as a good sounding tuner, and are recommended several modifications: not just increasing in some positions the values of the capacitors or replacing them with a higher grade, changing rectifier diodes to Schottky type, but also changing the operational amplifier type from the output (the audio buffer is a Fairchild KA4558s SIP-9 IC), modification of audio feedback network, and in my opinion, also the voltage regulator ICs are better to be mounted on the back of chassis to transfer the dissipated heat outside from the body, or to change into a less noisy LM317 plus some additional components. Although there is no bottom plate in the steel chassis, board removal is very easy regarding the connectors used on it.
In general is a good tuner, especially when the signal is enough strong - the sound is full with warm bass. It has a slight loudness-like response, tending to accent the bass a little in comparison with the treble, but this could just as well be very linear low range and slightly depressed high range, caused by the need to filter out the pilot tone. Nevertheless, this is an extremely listenable sound, with a bit more warmth than is needed.
I did not recommend it for DX or for the countryside, where some stations have a low signal level, but if you live in a well covered area, this tuner has a magnific sound!



NAD


The NAD Electronics (NAD Electronics) company was founded in London, England, in 1972 by Dr. Martin L. Borish, an electrical engineer with a PhD in physics. Its most famous product is the late-1970s NAD 3020, an integrated amplifier designed by Bjřrn Erik Edvardsen, which was highly regarded by various magazines in Britain. NAD's philosophy is to include only genuinely useful features for aesthetically understated designs when compared to other competitors' products. NAD was one of the first audio manufacturers to outsource the manufacturing of its products to electronics factories in east Asia. NAD was acquired by the Danish firm AudioNord in 1991 and subsequently sold in 1999 to the Lenbrook Group of Pickering, Ontario, Canada.



NAD 4220

NAD 4220

As part of the new series from 1987, is one of the best tuner of NAD. Has ultra-linear IF filters, a switchable blend circuit, a high SN ratio (>75dB), and 10 random preset memories.

General information:

  • Manufactured in Taiwan, NAD Electronics, Inc Boston/London in 1987
  • Digital PLL analog 2 bands (MW-FM) superheterodyne radio,
  • 10 random memory preset, 5 for FM and 5 for AM
  • Coverage: MW 522kHz - 1.611MHz, FM 87.5MHz - 108.0MHz
  • Usable sensitivity: 5uV(!) on MW and 2.0uV on FM mono and 37uV for FM stereo
  • AM/FM IF IC: LA1265, stereo MPX decoder: LA3401, uController: TC9147P, LED display driver: TD6301AP, prescaller: TD6104P, tuning level indicator LB1450, power supply regulator: L78M12
  • Output frequency range: 30Hz - 15kHz (+0.5dB...-0.5.0dB)
  • Signal/noise ratio: FM mono 80dB, FM stereo 75dBdB, on AM 45dB
  • THD: on FM 0.09% for mono, and 0.09% for stereo at 1kHz, 0.3% on AM
  • Stereo separation: 50dB at 1kHz
  • IF rejection: on FM 100dB, on AM 35dB
  • RF intermodulation: 65dB
  • Subcarrier suppression (19 & 38kHz): 60bB
  • Channel balance: 0.2dB
  • Alternate Channel Selectivity (FM): 65dB
  • Line output impedance and level: 600 ohm/700mV
  • Antenna input impedance for FM: 75 ohms or 300 ohms
  • Power: 220V/50Hz, Consumption: 10W
  • Dimensions: 420x76.2x250mm, 3.2kg

Good things:

  • Has a very clean sound, low noise, good channel separation
  • Very simple front panel with LED display
  • No any lights when is switched off
  • Clever ground trace on the PCB
  • I have the European version, but the transformer has 2x110V coils on the primer side

Difficult, problematic items:

  • Just average sensibility on FM, on AM is less
  • The power regulators (Q501L78M12, the Q502/2SA796Y), and the R502/56ohms and 1W) generate a lot of heat, heating the power filtering capacitors
  • The heatsink screwed on Q501 and Q502 are made from iron, not copper or alumina - give an impression of a very cheap model
  • The PCB is a low grade, parts which we would like to remove/changed, should be made very carefully, to avoid piling of the pattern
  • The main RF and audio ICs has no buffer capacitor on their power supply line, just 22nF ceramic type
Is a predecessor of the more common NAD 4225, which has 2x7 preset memory, but completely same schematic (excepting this additional memory selection).
Modifications:
Power: both heat generators (Q501 and Q502) were mounted on the internal stiffener plate. Is still made from iron, and is situated in the radio, but the heat now was taken out from the neat of the capacitors
The power line input received an EMI filter, and related filtering capacitors were changed and/or increased their values. C510 390uF/35V, C515 and C519 330uF/50V, C516 and C522 100uF/63V, C518 and C520 47uF/35V solid electrolyte. C143 received in parallel a 100uF/16V and C117 replace with 100uF/16V, both solid electrolyte capacitors. C904 received in parallel an additional ceramic capacitor, 4.7uF/35V.
This tuner has a musicality, very listenable - but different from Marantz or Technics. Like a tuner with a clear character, a different identity.



Nokia


Nokia Corporation (natively Nokia Oyj in Finnish, referred to as Nokia) is a Finnish multinational telecommunications, information technology, and consumer electronics corporation, established in 1865, when Finnish-Swede mining engineer Fredrik Idestam established a pulp mill on the shores of the Tammerkoski rapids near the town of Tampere, Finland. In 1922, in a now independent Finland, Nokia Ab entered into a partnership with Finnish Rubber Works and Kaapelitehdas (the Cable Factory). The rubber company grew rapidly when it moved to the Nokia region in the 1930s to take advantage of the electricity supply, and the cable company soon did too. In 1967, the three companies - Nokia, Kaapelitehdas, and Finnish Rubber Works - merged to create a new Nokia Corporation, restructured into four major businesses: forestry, cable, rubber, and electronics. In the early 1970s, it entered the networking and radio industries. Nokia started making military equipment for Finland's defence forces. In 1977, Kari Kairamo became CEO and transformed the company's businesses. By this time, Finland was becoming what has been called "Nordic Japan". Under his leadership, Nokia acquired many companies, including television maker Salora in 1984, followed by Swedish electronics and computer maker Luxor AB in 1985, and French television maker Oceanic in 1987. This made Nokia the third-largest television manufacturer of Europe (behind Philips and Thomson). In 1987, Nokia acquired Schaub-Lorenz, the consumer operations of Germany's Standard Elektrik Lorenz (SEL), which included its "Schaub-Lorenz" and "Graetz" brands. It was originally part of American conglomerate International Telephone & Telegraph (ITT), and after the acquisition products were sold under the "ITT Nokia" brand, despite SEL's sale to Compagnie Générale d'Electricité (CGE), the predecessor of Alcatel, in 1986. After 1990 started the computer, mobile and network business with a deep restructuring of company profile. On 12 June 1996, Nokia announced the sale of its television business to Canada/Hong Kong-based Semi-Tech Corporation. The television manufacturing plant in Germany closed down in September 1996. The sale included a factory in Turku, and the rights to use the Nokia, Finlux, Luxor, Salora, Schaub-Lorenz and Oceanic brands until the end of 1999. Some of these brands were later sold to other companies.



Nokia RP-9160

Nokia RP-91600

This radio, which was manufactured by Sangean and was marketed under the name Nokia, is internally identical to their ATS-808 model; the display and keypad panel, however, have slightly different button layouts. Sangean offered this design under various names, including Siemens RK661/761, Uher 808, Roberts 808, AIWA WR-D1000, and Radio Shack Realistic DX-390, among others. Is a small double conversion radio that can fit within a pocketbook that is microprocessor operated and uses PLL frequency synthesis hardware to span the whole commercial AM and FM range. The numeric keypad can be used to enter the frequency directly; alternatively, the UP/DOWN buttons or the tuning knob with two tuning speeds can be used. The set lacks a BFO for single sideband transmission reception. Additional features: Signal/Battery Indicator, Tone switch, Keypad, Sleep and Clock-Timer, 45 Memories, Manual Local-DX Switch, 9/10 kHz MW Step, Narrow/Wide AM selectivity switch, External Antenna Jack, Lock.

General information:

  • Manufactured by Nokia, Unterhaltungselektronik GmbH (Graetz), Pforzheim, but was made by Sangean in Taiwan (like several models of Siemens or Realistic) between 1993-1996
  • Is a digital controlled 4 bands analog receiver (MW-LW-SW-FM) superheterodyne radio,
  • In total 45 memory presets for all bands
  • Coverage: LW 150kHz - 519kHz, MW 520kHz - 1.710MHz, FM 87.5MHz - 108.0MHz and the SW 1.711 MHz - 29.999MHZ is divided in 13 bands,
      • Shortwave bands - can be selected also by meters/wave length, and any frequency can be selected also between bands:
    • SW1: 2300 - 2495 kHz, 120 m
    • SW2: 3200 - 3400 kHz, 90 m
    • SW3: 3900 - 4000 kHz, 75 m
    • SW4: 4750 - 5060 kHz, 60 m
    • SW5: 5900 - 6200 kHz, 49 m
    • SW6: 7100 - 7350 kHz, 41 m
    • SW7: 9400 - 9990 kHz, 31 m
      • 55845
    • SW8: 11600 - 12100 kHz, 25 m
    • SW9: 13570 - 13870 kHz, 21 m
    • SW10: 15100 - 15800 kHz, 19 m
    • SW11: 17480 - 17900 kHz, 16 m
    • SW12: 21450 - 21750 kHz, 13 m
    • SW13: 25600 - 26100 kHz, 11 m
  • Tunning steps (fast and slow): LW 5/1kHz, MW 9 or 10/1kHz, SW 5/1kHz, FM 100/50kHz
  • Usable sensitivity: LW 1000uV/m, MW 400uV/m, SW 4uV, FM 4uV - all better than limit values specified
  • IF frequencies: for AM 55.845MHz and 450kHz (+-1kHz), for FM 10.7MHz (+-0.05MHz)
  • FM/AM IF IC: TA7758, stereo decoder: AN7415S, voltage regulator: LA5003, uController and display driver: uPD75308GF, prescaller: CXD1118, signal level TA75339 2pcs, digital TC40H148F, audio output amplifier AN7117 2pcs
  • IF rejection: 60dB
  • Image rejection: 40dB
  • AM suppression: minim 30dB
  • Output frequency range: not specified
  • Signal/noise ratio: 50dB on FM, 24dB on AM
  • THD: on FM 2%
  • Stereo separation: 25dB
  • Tone action/upper cutting freq 6.3kHz: 5dB
  • Alternate Channel Selectivity (FM): 50dB
  • Output impedance and power: 8ohm/440mW
  • Antenna: for LW/MW built-in ferrite bar, for SW and FM telescopic antenna, for SW external ant. socket
  • Power: 4x1.5V AA (UM3) or external 6V/300mA (minus is on center!) and 2x1.5V AA (UM3) for clock and presets
  • Dimensions and weight: 196(L)x125(H)x36(T)mm, 600g without batteries
  • Price: 249USD in 1993

Good things:

  • Has a very clean sound, low noise, good channel separation also in SW
  • Signal strength bar
  • Very good sensibility
  • Wide/Narrow Selectivity, using two AM IF bandwidth filters, (6 and 2.7 kHz wide (-6dB), both with a fair shape factor for a receiver of this type
  • Stereo reception on FM through headphones. The radio "switch" in stereo mode just if the headphone is pluged-in and the FM mode switch is in stereo position. Just in this case the stereo reception will appear on the display.

Difficult, problematic items:

  • No light for display. Night time is difficult to operate.
  • Lack of SSB reception. This is someway compensated for comercial programs by the switchable AM bandwidth filters, but is not usable for DX/HAM
  • The radio offers 45 memory channels, nine each on LW, MW, FM, and 18 on SW. The first bank of 9 is selected by pressing a number of the keyboard. The next 9 are selected by pushing the "0" button first, then the chosen number. This is not written in the manual.
Modifications: The diode was added as a tweak to guard against reverse polarity; it was previously located on the PCB but was not mounted. When compared to the audio IC's datasheet, an optimization in component usage, particularly in the audio part, can be seen: the output capacitor for the headphone part was 100uF, which is too low for a 16 ohm headphone impedance, or the additional ripple rejection capacitors on the power amp used only for headphones have higher capacitance (datasheet recommends 33uF in NFB position, mounted value is 47uF, used already in several position in the radio part) to reduce the values-diversity. The ripple rejection in both case was 220uF, respectively 100uF instead of 330uF. Now all capacitor in both channels are the same as recommended in the datasheet. It is advised to replace all electrolytics in this 30-year-old set, especially those with high capacitance.



Nordmende


Nordmende comes from Norddeutsche Mende-Rundfunk GmbH, a radio company founded in 1923 by Otto Hermann Mende in Dresden, and was rebuilt after WWII in Bremen in 1947. In the 1980s, the factories in Bremen were closed, Nordmende becoming purely a Thomson trademark (sold by family). This means this radio was made in the transition era, but Nordmende already was a Thomson affiliate.



Nordmende TU-1300

Nordmende TU-1300

Is a very fine tuner with the best selectivity on FM, 0.9uV, outperforming other tuners with the same official sensibility! Is a full analog tuner, with a digital display, but on FM tunning are made via varicap diodes. The tuner complete name: Hifi Tuner Philharmonic TU-1300 981.143H

General information:

  • Manufactured by Nordmende, Norddeutsche Mende-Rundfunk GmbH (Sterling), Bremen-Hemelingen at 1981
  • Analog 3 bands (MW-LW-FM) superheterodyne radio,
  • 6 memory preset for FM
  • Coverage: MW 520kHz - 1.620MHz, LW 150kHz - 350kHz, FM 87.5MHz - 108.0MHz
  • Usable sensitivity: 10uV(!) on MW and 0.9uV on FM mono and 23uV for FM stereo - via a very sensitive MOSFET FM tuner
  • FM IF IC: HA11225, AM tuner IC: LA1245, stereo decoder: uPC1161C, adjusting voltage stabilizer: HA17723G, uController and display driver: LC7258, prescaller: MSL2312RS, signal level indicator LB1405
  • Output frequency range: 20Hz - 15kHz (+0dB...-1.0dB)
  • Signal/noise ratio: FM 68dB
  • THD: on FM 0.1% for mono, and 0.2% for stereo
  • Stereo separation: 47dB
  • Channel balance: 0.2dB
  • Alternate Channel Selectivity (FM): 50dB
  • Line output impedance and level: 1.8 kohm/700mV
  • Antenna input impedance for FM: 75 ohms or 300 ohms
  • Power: 220V/50Hz, Consumption: 13W
  • Dimensions: 440x108x289mm, 4.2kg

Good things:

  • Has a very clean sound, low noise, good channel separation
  • Very good sensitivity on MW (10uV) with its ferrite antenna, and 0.9uV on FM

Difficult, problematic items:

  • Memory preset possibility just for FM
  • The audio band starts from 20Hz, has less bass than Technics SA5370 or Marantz ST450
In the case of such old tuners was necessary to change all electrolytic capacitors (originally all were ELNA brand). In the audio part, I use audio grade capacitors also in the power line (Nichicon Fine Gold, etc.). In the RF part power line and in the display part I used tantalum capacitors.



Onkyo


Onkyo Corporation is a Japanese consumer electronics manufacturer, specializing in premium home cinema, and audio equipment, including AV receivers, surround sound speakers and portable devices. The company started under the name of Osaka Denki Onkyo K.K in 1946. The word Onkyo translates as "sound resonance". The current Onkyo Corporation umbrella includes the Integra and Integra Research divisions as well as the main Onkyo brand. In March 2015, Onkyo purchased Pioneer Corporation's Home Electronics Corporation. In return, Pioneer took a 14.95% stake in Onkyo.


Onkyo TX-2500

Onkyo TX-2500

This is a nice Onkyo receiver from 1976, a younger brother of TX-4500. Has a very conservative front, frontend with FET, PLL MPX decoder, tuning servo-locking, Loudness, High-filter (from 6kHz -12dB/octave), tape 1 & 2 monitor, and "accutouch" tuning knob (temporarily inhibits the locking circuits for manual, large-scale tuning: hands-on; when released, hands-off, the locking function clicks back in and fine-tunes on its own the locked station until the tuned indicator lights up). Has the possibility to connect Dolby FM adaptor for Dolby FM broadcasts. Its successor was the TX-2500 MKII with a bit better specification for preamp and tuner section, and quite a bit more power, too.

General information:

  • Manufactured between 1976-1978 by Onkyo Co., in Japan. On the net I found sources, where is mentioned this receiver was manufactured from 1975, on other sites 1977.
  • 2 band analog superheterodyne receiver, MW and FM
  • Coverage: MW 530kHz - 1.605MHz, FM 87.5MHz - 108.0MHz
  • Antenna input impedance for FM: 300 ohms balanced,
  • Antenna for AM: build in ferrite core and external terminal
  • No preset memory for FM
  • Usable sensitivity: 1.6 uV on FM mono and 4 uV (!) for stereo; 25uV on AM
  • Intermediate frequencies: 455kHz for AM, and 10.7MHz for FM
  • Used ICs: FM IF system: HA1137; AM radio receiver: HA1151; MPX decoder LA3350; operational amplifiers TA7136, TA7504
  • Signal to noise ratio: FM mono 65dB, FM stereo 60dB, AM 40dB
  • Output frequency range on FM: 30Hz - 15kHz (+0.5...-2dB)
  • Stereo separation (1kHz/10kHz): 37/30 dB
  • THD: 0.2% for FM mono, 0.4% FM stereo, 0.8% for AM
  • Power output: 27W/8 ohms, 2-60kHz within +-1dB, with 0.5% THM; 34W/4 ohms
  • Damping factor: 40 at 8 ohms, 1 kHz, 10W
  • Phono sensitivity/impedance: 2.5mV/50kohms
  • Phono Overload: 150mV RMS 1kHz 0.5% THD
  • RIAA curve deviation: +-0.2dB, 30...15kHz
  • Tape Play/Rec and Dolby Out: 150mV/50kohms
  • Dolby In: 580mV/50kohms
  • Bass control: +-10dB at 100 Hz
  • Treble control: +-10dB at 10 kHz
  • High Filter: 6kHz
  • Loudness: +5dB at 100 Hz and 10 kHz
  • Signal to noise ratio: Phono 65dB, Tape 80dB
  • Power: 110V/120/220/240V 50/60Hz, consumption max. 320W
  • Dimensions: 488x163x400 mm, 12 kg.

Good things:

  • Has a very clean sound, with an exceptional stereo feeling
  • Has a separate transistor buffer at output instead of direct signal from MPX IC or via operational amplifier
  • Very good sensitivity and selectivity on FM
  • Has analog signal strength and center tuning meters
  • Accutoutch sensibility can be adjusted with a 3 position switch found on rear panel of radio

Difficult, problematic items:

  • Has a FET input FM tuner (MKII version has a mosfet one), but the sensitivity is quite good
  • Some components are missing, like R154 100k semi-adjustable potmeter was replaced with 22 kohm resistor, but the whole radio works very well
With more than 44 years, is a receiver with a very pleasant sound. Was necessary to change all electrolytic capacitors, all bulbs. The scale pointer, Stereo, Tuned, and Locked indicators were changed with LEDs, just for the pointer LED was necessary to insert additionally one diode and 22uF/16V capacitor, because this was the only bulb powered from AC. Also was built in an EMI filter after AC input.
The radio part has 2 versions: NAIMX-345, a simpler, and NAIMS-345, a more complex one (S means Super?), this last one is a better version, seems more similar with MKII (looks like a transition between them). I have the version NAIMX-345, but on the PCB can be seen position of components from NAIMS-345, but not all of them. Ex. position of T102 was shunted, and I replaced with the right C-L components, or in L101 position was mounted a 100ohms resistor (like in MKII), I replaced it with 3.3uH inductor.
Its sensibility outperforms some tuners with better specifications.
The TX-2500 on AM are with 2 gangs, on FM are with a 3-gangs variable capacitor, two IF amp stages, 2 pcs of 10.7MHz ceramic filters, and an Onkyo-made low-pass filter (NMC-8-7). Recommended to be improved: the audio stage separation from common radio power with a 56 ohms resistor followed by a puffer capacitor 470uF/25V. In the RIAA feedback network, is recommended to be changed the C304/C404 from 3.9nF to 3.6nF+220pF - but to be identical, PP capacitors from same type and same manufacturer. I added 1-1 uF/100V in parallel with C905/C906 4700uF/80V Nichicon capacitors in main power supply.


Onkyo T-3100

Is a rare unit. Seems a predecessor of T-5000. Has a very simple design, clear scale with 2 bulbs at 2 ends, and 2 analog instruments showing the signal strengths and the tunning. The front contains just 3 switches (power, stereo with muting/mono, and FM/AM selector), and one tuning knob - nothing else. On the backside, you can find the power voltage selector, the power cord socket, the adjustable ferrite rod antenna (can be pulled in or out, and some rotation in the horizontal plane), the FM antenna connection screws, and the De-emphasis selector switch (50/75us).

General information:

  • Manufactured by Onkyo in Japan at 1978
  • Analog 2 bands (MW-FM) superheterodyne
  • No memory presets
  • Coverage: MW 525kHz - 1.605MHz, FM 87.5MHz - 108.0MHz
  • Usable sensitivity: 40uV on AM, 1.7uV on FM (mono) and 40uV for stereo
  • FM IF: HA1137W, stereo decoder: HA1196
  • Intermediate frequency: 10.7MHz for FM, 455kHz for AM
  • Output frequency range: 30Hz - 15kHz (+1dB...-3dB)
  • Signal/noise ratio: AM 33dB; FM 60dB mono, 55dB stereo
  • THD: on FM 0.3% for mono, no data for stereo; on AM 0.8%
  • Stereo separation: 37dB at 1kHz, 30dB at 100 - 10000Hz
  • Image rejection: on FM 35dB, on AM 40dB
  • IF rejection ratio: FM 80dB, AM 30dB
  • Line output level: 600mV on FM, 200mV on AM
  • Antenna input impedance for FM: balanced 300 ohms, unbalanced 75 ohm; for AM built-in ferrite rod and external terminal
  • Power: 110/120/220/240V and 50/60Hz, consumption: 11W
  • Dimensions: 418x149x309mm, 4.5kg

Good things:

  • Has a nice, musical sound, average channel separation, good readable big display.
  • Ferrite antenna is easy to move in/out from the body, and can be rotated in the horizontal plane
Difficult, problematic items:
  • The AM section is weak.
  • The bottom plate is very thin, easily can be deformed if you are not careful during handling
  • The top of the backplate is not so stable, is not fixed to the cover plate.
Not so much info can be found about this tuner on the net. The numbering in the case of Onkyo seems very random, you cannot be sure which are the top tuner of the family. Inside is very similar to T-5000, which has almost the same circuit, with very few differences: in FM tuner has feedback to eliminate the distortion caused by local stations, lightly improved AM circuit, and has a separate output buffer made from 1-1 transistor with adjustable output signal level.
Modifications: excepting output buffer, all improvements from T-5000 were built into this tuner, and received an EMI filter at power AC input. The scale lighting was changed to LEDs (4 warm light LEDs/side), and also the stereo bulb now is a red LED.


Onkyo T-9060

The very rare T-9060 just FM tuner. Has seven presets, buttons for IF bandwidth (Normal and Wide), auto hi-blend, muting/mode, de-emphasis, signal strength/deviation meter and auto tuning, super-servo circuit in AF amp, De-emphasis switch for Dolby FM. Is a 5 gang tuner with dual-gate mosfets, with 5 IF ceramic filters.

General information:

  • Manufactured by Onkyo Corporation in Japan between 1981 - 1984
  • Digital only FM PLL tuner,
  • Memory: 7 memory presets
  • Coverage: FM 87.5MHz - 108.0MHz with 50kHz steps
  • Antenna: 300 ohm balanced, 75 ohm unbalanced
  • Usable sensitivity: 0.7uV on FM (mono) and 25uV for stereo - via a very sensitive MOSFET FM tuner
  • Antenna input impedance: 75 ohm
  • FM tuner IC: HA11225, stereo decoder: HA12016, IF amplifiers LA1222 and uPC555H, deviation indicator TA7316, signal meter uPC1198H, output indicator IR2433, prescaler uPB533P, uController and display driver uPD1703C-016, control buttons TC9130P 2 pcs, preset display 74LS42, and output audio opa NJM4558D 2pcs, voltage regulator 7812
  • Capture ratio: 1.0dB
  • Signal/noise ratio: FM 81dB mono, 73dB stereo
  • THD: on FM 0.05% for mono, 0.13% for stereo in IF Wide mode
  • Stereo separation: 45dB at 1kHz, 33dB at 70-10000Hz in IF Wide mode
  • Alternate channel separation: 50dB
  • Selectivity: 70dB (+-300kHz with 40kHz deviation, IF in Normal position)
  • Image rejection: 100dB
  • IF rejection ratio: 100dB
  • AM suppression ratio: 55dB
  • Output frequency range: 30Hz - 15kHz (+0.5dB -1.5dB)
  • Line output voltage: 0 - 1.5V, adjustable
  • Power: 220V/50Hz, consumption: 27W
  • Dimensions: 450x74x355mm, 5.6kg
  • Price in 1981: 490$

Good things:

  • Very high sensibility, 0.7uV
  • Automatic hi-blend function
  • The signal and deviation meter has 9 distinct levels
  • Dedicated output audio amplifier with servo
Difficult, problematic items:
  • Just 7 preset memories
The front, with its backlight, is stunning. It's worth noting that all five 10.7MHz ceramic filters have +-280kHz band (2 pcs of 10.7MX, 3pcs of 10.7M type, all have blue body, red dot at top left side, manufactured by Murata) for Normal and Wide mode - this is most likely why they were chosen. On the bottom of the international version, there should be a switch to select the tuning stept 50/200kHz - this is not placed on my set (I have the G version). A potectiometer on the rear can be used to set the audio output level. The Muting switch also serves as a mode switch: ON is stereo, OFF is Mono mode. For memory storage, the bottom side features a battery storage (2 AA type) that can be simply opened without the use of any other equipment (such as a screwdriver).
Modifications
Because the transformer was noisy, I added a 3mm thick rubber under it. Now is perfectly silent. The 7812 regulatros - which produces a lot of heat (the power line voltage is 240V instead of 220V) - was installed on the backside plate. All electrolytics with 6.3V nominal voltage (usually 100uF, 330uF, and 1000uF) were out of order, I recommend to be changed to solide electrolyte type. Audio signal path capacitors changed to Elna bipolar 47uF. The sound is really nice and detailed, especially when the output capacitors were changed. Because the NJM4558 is not a high-end model, I recommend replacing the opa with a better one.


Onkyo T-4210R

Is a rare unit with RDS. Has a blue, bright and saturated, and even something 2 color fluorescent display with an APR (Automatic Precision Reception) unit, choosing between mono/stereo, DX and Local in the function of signal strengths. Has Scan function, which scans and memorizes the strongest 20 stations at the touch of the Scan button. Is equipped with signal strengths meter, selectable display character input, battery-free memory (0.1F supercapacitor are used), AM loop antenna, and is RI remote system compatible.

General information:

  • Manufactured by Onkyo in Japan between 1991 - 1996
  • Digital 2 bands (MW-FM) PLL radio with RDS+EON capability,
  • 30 memory presets, organized in 3x10 groups
  • Coverage: MW 531kHz - 1.602MHz with 9kHz steps, FM 87.5MHz - 108.0MHz with 50kHz steps
  • Usable sensitivity: 25uV on AM, 1.0uV on FM (mono) and 20uV for stereo - via a very sensitive MOSFET FM tuner
  • FM/AM tuner IC: LA1266, stereo decoder: AN7470, PLL freq. synthetizer: LC7001, uController and dot matrix VFD display driver uPD78044A, RDS decoder: uPC1346CS
  • Output frequency range: 30Hz - 15kHz (+-1.5dB)
  • Signal/noise ratio: AM 40dB; FM 73dB mono, 66dB stereo
  • THD: on FM 0.1% for mono, 0.2% for stereo; on AM 0.8%
  • Stereo separation: 40dB
  • Image rejection: on FM 80dB, on AM 40dB
  • IF rejection ratio: FM 90dB, AM 40dB
  • Line output impedance: 100 ohm
  • Antenna input impedance for FM: 75 ohm
  • Power: 230V/50Hz, consumption: 9W
  • Dimensions: 455x90x309mm, 3.7kg

Good things:

  • Has a very clean sound, low noise, average channel separation, good readable big display.
  • Automatic RF-attenuation for strong stations thanks to APR.
  • Has Radio Text - RDS EOS with PTY and TP. In 1991 this feature was rare
Difficult, problematic items:
  • Has a sound with leak bass.
I did not found on the net the schematic of T-4210R, but the radio part is the same as T-4210 (from 1986), and the RDS part with T-4310R (1993?) - combining them, you can have a detailed picture.
Modifications
All modifications covers the power lines, noise reduction and sound improvements. On Power line: C002 100uF/16V replaced with 390uF/35V, C114 22uF/16 replaced with 100uF/63V, C205 470uF/16V replaced with 1000uF/35V, C220 47uF/16V replaced with 100uF/63V, C706 220uF/6.3V replaced with 390uF/35V, power cap of RDS 10uF/16V replaced with 100uF/63V, C902 2200uF/25V with 3300uF/25V, C904 470uF/16V replaced with 1000uF/35V, C905 10uF/50V with 100uF/63V, C907 47uF/16V with 100uF/63V, C913 47uF with 100uF/63V, C914 220uF/35V with 390uF/35V, C915 220uF/35V with 390uF/35V, C919&C920 with 390uF/35V. Received an AC power line filter: 2.2nF/2kV, 2x7.8mH and 0.68uF/275Vac.
Other changes: C117 1uF/50V to 3.3uF/100V PP, C169 10uF/35V to 4.7uF/63V PP, jumper J109 replaced with 3.3uH coil, C202 22uF/16V with 4.7uF/63 PP (based on input impedance was not justified to increase above 4.7uF), C211&C212 22uF/16V with 10uF/63V PP (that can be increased, depends by the input impedance of preamplifier. The best solution should be a separate buffer on the end of MPX decoder).


Onkyo T-4211

Constitutes the sibling pair of T-4511. Concurrently observed with T-4040, albeit exhibiting a full RDS. Produced in two distinct hues: silver or black alumina front, with minimalist, classic design. Indide, with the exception of a software-related issue that has been executed more frequently, remains unchanged compared with T-4210R model. The display is entirely moncrome orange and the text is crystal clear. System connectivity is possible via Onkyo's RI system. Has 2-mode APR (Automatic Precision Reception) with exceptional sensitivity and superb selectivity (according to Onkyo's marketing at the time, with manual station name setting up to eight characters ), automatic preset scan and signal-strength meter.

General information:

  • Manufactured by Onkyo in Malaysia between 1997 - 2007
  • Digital 2 bands (MW-FM) PLL radio with RDS+EON capability,
  • 30 random memory presets for FM/AM, organized in 3x10 groups (A, B, and C)
  • Coverage: MW 522kHz - 1.611MHz with 9kHz steps, FM 87.5MHz - 108.0MHz with 50kHz steps
  • Usable sensitivity: 25uV on AM, 0.9uV on FM (mono) and 20uV for stereo - via a very sensitive MOSFET FM tuner
  • Antenna input impedance for FM: 75 ohm
  • FM/AM tuner IC: LA1266, stereo decoder: AN7470, PLL freq. synthetizer: LC7001, uController and dot matrix VFD display driver uPD78044A, RDS decoder: BU1923
  • Capture ratio: 1.5dB
  • Signal/noise ratio: AM 40dB; FM 73dB mono, 66dB stereo
  • THD: on FM 0.1% for mono, 0.2% for stereo; on AM 0.8%
  • Stereo separation: 40dB at 1kHz, 30dB at 70-10000Hz
  • Alternate channel separation: 50dB
  • Selectivity: 55dB (+-300kHz with 40kHz deviation
  • Image rejection: on FM 80dB, on AM 40dB
  • IF rejection ratio: FM 90dB, AM 40dB
  • AM suppression ratio: 50dB
  • Output frequency range: 30Hz - 15kHz (+-1.5dB)
  • Line output voltage and impedance: 0.75V on FM and 0.15V on AM, 100 ohm
  • RDS function: yest, with PTY, TP, RT, CT and PS
  • Power: 230V/50-60Hz, consumption: 9W
  • Dimensions: 435x91x305mm, 3.6kg
  • Price in 2000: 340DM

Good things:

  • Its sound is better than of T-4210R
  • Automatic RF-attenuation for strong stations thanks to APR (automatic switch between Local and DX).
  • Has Radio Text - RDS EOS with PTY and TP
Difficult, problematic items:
  • Has a sound with leak bass.
Is a 4 gang FM tuner with 3 IF ceramic filters with 2 one-transistor IF amplifiers between them.
Modifications
All modifications covers the power lines, noise reduction and sound improvements. On Power line: all capacitors changes, for tuner, RDS and IF with solid electrolyte capacitors. Tuner supplying go through a ferrite bear. Received an AC power line filter: 2.2nF/2kV, 2x5.9mH and 0.47uF/275Vac.
In audio path: MPX input and audion outputs 47uF/25V ELNA bipolar. The best solution should be a separate buffer on the end of MPX decoder). This increased the lower range of output, now seems more equilibrated the whole audio.



Panasonic


Panasonic Corporation, (Panasoniku kabushiki gaisha) formerly Matsushita Electric Industrial Co., Ltd. is a major Japanese multinational electronics company, headquartered in Kadoma, Osaka. It was founded by Konosuke Matsushita in 1918 as a lightbulb socket manufacturer. In 1927, Matsushita adopted the brand name "National" for a new lamp product. In 1955, the company began branding audio speakers and lamps for markets outside Japan as "PanaSonic", which was the first time it used the "Panasonic" brand name. The company began to use the brand name "Technics" in 1965 for high fidelity audio equipment. Throughout the 1970s and early 1980s, Matsushita continued to produce high-quality specialized electronics for niche markets, such as shortwave radios, and developed its successful line of stereo receivers, CD players, and other components. The use of multiple brands lasted for some decades. While 'National' had been the premier brand on most Matsushita products, including audio and video, 'National' and 'Panasonic' were combined in 1988 as National Panasonic after the worldwide success of the Panasonic name.
Matsushita's brother-in-law, Toshio Iue, founded Sanyo as a subcontractor for components after World War II. Sanyo grew to become a competitor to Matsushita but was later acquired by Panasonic in December 2009.
Since that time, Panasonic closes its plasma (2011) and LCD (2021) displays manufacturing, solar panels (2021), and semiconductors (2019) manufacturing business.


Panasonic RF-9L

Panasonic RF-9L

The Panasonic RF-9L is one of the smallest shortwave travel radio radios that really fits into a shirtpocket. It's a single conversion superhet with the longwave band in European version. The tiny black - golden cabinet gives a very elegant appearence to the set and the leatherette cover even improves this. Has a 5cm speaker, LED as signal strength indicator, just below the AM/FM modes switch, a tone and the power switch.

General information:

  • Analog shortwave portable with single IF conversion: for AM 455 kHz; for FM: 10.7 MHz
  • Coverage: LW 150-285 kHz, MW 520-1610 kHz, FM 87.5MHz - 108MHz, and 6 SW bands
      • Shortwave bands:
    • SW1: 5950 - 6200 kHz, 49 m
    • SW2: 7100 - 7300 kHz, 41 m
    • SW3: 9500 - 9800 kHz, 31 m
    • SW4: 11700 - 12000 kHz, 25 m
    • SW5: 15100 - 15450 kHz, 19 m
    • SW6: 17700 - 17900 kHz, 16 m
  • Sensitivity: 7uV on FM, 159uV/m on LW, 71uV/m on MW, 2.2uV on SW1 and SW6, 1.3uV on SW2 and SW3, 1.8uV on SW4 and SW5 - all for 50mW output
  • Antenna: for LW and MW internal ferrite rod, for SW and FM telescopic antena. No jack for external antena connection
  • Used ICs: AN7216 FM RF and mixer, AN7226S AM osc, mixer, AM & FM IF and detector
  • Output: 200 mW RMS Max., on an 5 cm 4 ohm speaker
  • Power: 3V - 2 AA size batteries or DC IN jack (- in interior!)
  • Dimensions/weight: 136 x 74 x 26 mm, 200 g (without batteries)
  • Produced: between 1984 - 1993

Good things:

  • Small, light and elegant
  • Good selectivity, especially on FM and LW.

Problems:

  • Signal/tunning level indicator - just via one LED
  • Its sound is very sharp regarding small speaker, but via headphone is quite good
  • The radio is just mono, including the headphone jack. With stereo headphones, the radio can listen just on the left side.
After 38 year, the electrolyte capacitors were out or order: high dissipation (>5%) and high ESR (in some case above 3 ohms), all Matsushita type, with low voltage (100uF/4V, 220uF/4V,...). All changed to solid electrolytic types. The C85 changed to 1000uF/6.3V, C96 to 330uF/6.3V, for the rest I used same values. If you are looking for a high tech receiver with digital frequency display, the much more recent Sony ICF-SW1 might be Your choice, but if you look for a really miniature multiband radio with above average finish, then look for a used Panasonic and leave these Chinese cheepish sets on the shelves at the discounter.


Panasonic RF-B20L

Panasonic RF-B20L

The Panasonic RF-20L was the first analod double conversion portable radio made by Panasonic at 1986. Use the same frequencies as the RF-9L model - 9 bands, and is a step up model from B10L, but with a more modern schematics. Has a 6.6cm speaker, LED as signal strength indicator, just nearby the SW band selector switch, band selection is electronic via push-buttons - the band selectors (FM, MW LW and SM are used to swith on the set, and has a separate button for power Off. At back side can be found the DX-Local switch (has effect just for AM), and on top the Hold switch to keep the radio from being accidentally switched on when it's packed away. A tone control potentiometer are on the lateral (which was a rarity at that time on such small sets) side above power- (4.5Vdc) and headphone connector (3.5mm, mono), and on the oposite side is the tunning knob and volume adjusting potentiometer. It's competitor from that time, was the Sony ICF-4900/4910 or ICF-4920/ICF-5100.

General information:

  • Analog shortwave portable with double IF conversion: for AM 455 kHz and 10.7MHz (already known from Sony); for FM: 10.7 MHz
  • Coverage: LW 150-285 kHz, MW 530-1610 kHz, FM 87.5MHz - 108MHz, and 6 SW bands
      • Shortwave bands:
    • SW1: 5950 - 6200 kHz, 49 m
    • SW2: 7100 - 7300 kHz, 41 m
    • SW3: 9500 - 9800 kHz, 31 m
    • SW4: 11650 - 12050 kHz, 25 m
    • SW5: 15100 - 15600 kHz, 19 m
    • SW6: 17550 - 17900 kHz, 16 m
  • Sensitivity: 2uV on FM, 126uV/m on LW, 100uV/m on MW, 1.8uV on SW1, 1.3uV on SW2, SW4 and SW5, 1.4uV on SW3 and SW6 - all measured at 50mW output
  • Antenna: for LW and MW internal ferrite rod (12 cm long), for SW and FM telescopic antena. No jack for external antena connection
  • Used ICs: FM osc an mixer TA7358P, FM/AM IF amp, det, AM osc, AF amp AN7236S, band swith circuit MN4043 RS latch and 3 pcs of MN4072 OR gates
  • Output: 400 mW RMS Max., on a 6.6 cm 8 ohm speaker
  • Power: 4.5V - 3 AA size batteries or DC IN jack (- in interior!)
  • Dimensions/weight: 165 x 92 x 29 mm, 320 g (without batteries)
  • Produced: between 1986 - 1988
  • Price at 1984: 140$

Good things:

  • Clear, elegant design with good sound compared with its size, good tonal balance
  • Good sensitivity, especially on FM, SW, and LW.
  • DX-Local switch

Problems:

  • Signal/tunning level indicator - just via one LED
  • Shortwave selectivity is mediocre
  • No back stand, which can give a more stable and easy operation
  • The radio is just mono, including the headphone jack. Using a stereo headphones, the radio can listen just on the left side.
  • No programmable channel memories
After 36 year, the electrolyte capacitors were close to be out or order: high dissipation (>3%) and high ESR (in some case above 3 ohms), all Matsushita type, with low voltage (6.3V). All changed to solid electrolytic types.
Deviation in original set compared to service manual: instead of C71 an C72, both should be 470uF/6.3V, was mounted just in C72 position one capacitor with 1000uF/6.3V. C69, instead of 1000uF/6.3V was mounted 470uF/6.3V, and C64 on schematis should be 22uF/50V, in the set was mounted 2.2uF/50V.
Changes and modifications: C69 was changed back to 1000uF/6V, C64 now is 3.3uF/50V, C71 and C72 changed back to 2 pcs of 470uF/6.3V dry electrolyte capacitors, C54 instead of 220uF/6.3V now is 270uF/6.3V dry electrolyte type. All other capacitors changes with dry electrolyte, excepting 2 pcs of 47uF/6.3, now they are tantalum type. The highest effect has the audio output capacitor - is not an audio grade, but the sound has more bass (taking in consideration the size of the speaker and the old capacitor).
The RF-B20 makes a decent travel companion if you can live without 22m coverage.


Panasonic RF-B45

Panasonic RF-B45

Is a travel shortwave radio with SSB capabilities built at 1991, is the "little brother" of the RF-B65, very similar to Sony's legendary ICF-7600D

General information:

  • Digital shortwave portable (dual conversion):1st IF: 55.845 MHz; 2nd IF: 459 kHz; for FM: 10.7 MHz
  • Coverage: AM 144kHz - 29.995MHz (selected bands LM, MW, and 13 SW), FM 87.5MHz - 108MHz, continuous on the whole SW band (1622-29995 kHz in 5 kHz steps),
      • Shortwave bands - can be selected also by meters/wave length:
    • SW1: 2300 - 2495 kHz, 120 m
    • SW2: 3200 - 3400 kHz, 90 m
    • SW3: 3900 - 4000 kHz, 75 m
    • SW4: 4750 - 5060 kHz, 60 m
    • SW5: 5950 - 6200 kHz, 49 m
    • SW6: 7100 - 7300 kHz, 41 m
    • SW7: 9500 - 9775 kHz, 31 m
    • SW8: 11650 - 12050 kHz, 25 m
    • SW9: 13600 - 13800 kHz, 21 m
    • SW10: 15100 - 15600 kHz, 19 m
    • SW11: 17550 - 17900 kHz, 16 m
    • SW12: 21450 - 21850 kHz, 13 m
    • SW13: 25670 - 26100 kHz, 11 m
  • 9/10 kHz steps on LW/MW, 5 kHz steps on SW, and 50 kHz steps on FM
  • Synchronous detection
  • Sensitivity: FM 4uV/50mW output; LW 600uV/m 50mW output; MW 180uV/m 50mW output; SW 10uV/m at 50mW output
  • Possibility of SSB reception, but cannot be selected the LSB and USB
  • Fine tuning for AM SSB (is not followed by frequency meter) approx +-5kHz
  • Has just 18 presets: 9 for FM, and 9 for AM/SW. The 0 button make a scroll of preset stations
  • External antenna jack for LW, MW and SW
  • Alarm and sleep functions
  • Frequency synthesizer / microcontroller: µPD1724GB561
  • Output: 600 mW RMS Max., on an 7 cm (in some catalog mentioned 8 cm) 8 ohm speaker
  • Power: 6V - 4 AA size batteries or DC IN jack (- in interior!)
  • Dimensions/weight: 204 x 119 x 37 mm, 620 g (without batteries)
  • Produced: between 1991 - 1993

Good things:

  • Entering and recalling frequencies is pretty simple
  • Good selectivity, especially on FM (better than all Sony ICF-SW7600XX models).
  • Signal level indicator - 3 levels
  • Its sound is very clear, on FM is better than Sony's

Problems:

  • Not enough memory to store stations (just 9 for FM and 9 for whole AM)
  • The power-on button is on the lower right side - incommode to operate
  • The volume potentiometer adjusting is reversed: you should rotate it from top to bottom to increase the volume
  • The Power button has a green backlight LED, which is switched on continuously during operation. In nighttime listening, this green light is too bright and useless.
  • The radio is just mono, including the headphone jack. With stereo headphones, the radio can listen just on the left side.
  • The sound has lack of bass, probably regarding the output capacitor of the power amplifier
  • The Auto-Tunning runs just forward, but in a short time very precisely set the center frequency of stations
In general, is a good travel radio, not as performant as Sony's ICF-SW7600 family, but its sensibility on FM can compensate for that. On the net scrolling on reviews, sometimes are mentioned as same, or rarely better than the Sony ICF-SW7600xx series.
Recommendation: I changed the CFX3 and CFX2 10.7Mhz (Murata type with 280kHz BW and 6-7dB loss) ceramic filters with a Murata 150kHz BW, 4-5 dB loss filters. Sensitivity lightly increased on FM, and no adjacent programs can be heard, and easily can be found the real transmission frequency of FM radio station.
The sound is very clear, especially on midrange and treble, but with less bass. This can be improved by changing the output capacitor from 220uF/6.3V to 470uF/6.3 solid electrolyte type.
Next step for improvement: to change the headphone jack into a stereo one, and to move the power button LED to backlight the LCD (more useful).


Panasonic RF-U350

Panasonic RF-U350

The RF-U350 is a digital FM table-radio with 10 station memories and dot-matrix display which can show the current station name via the RDS function and the Radio Text information of transmitted program. The stations can be stored using the automatic station search. The sleep timer is particularly convenient, with which the radio switches off automatically after the preset time. Has 4 preprogrammed equalizer settings and a unique function called Slow speech, which uses the silent part between words to slow down the speech. Depending on the content of the broadcast, such as a music program, the effect of slow playback may not be obtained. Based on Panasonic, is the successor of RF-3700, and was replaced by RF-D10 and RF-D30 models.

General information:

  • Produced: between 2008 - 2018 by Panasonic AVC Networks in Malaysia
  • Digital FM table radio with RDS and Radio Text
  • Intermediate frequency: 10.7 MHz
  • Coverage: FM 87.5MHz - 108MHz with 50kHz tunning steps
  • Sensitivity: no data in the specification
  • Has just 10 presets: 2x5 stations
  • No external antenna connection possibility
  • Timer and sleep functions
  • Used circuits cannot be identified: FM tuner: C1BB00001070, sound processor BD3871FS, audio power amplifier LA4627N, control unit and dot display driver C2CBHG000236, RDS decoder C1AB00002751, speech speed controller C1AB00002762
  • Output: 1 W RMS Max., on a 10 cm wide range 8 ohms speaker, or headphone 3.5mm jack (8-16ohmS9
  • Power: 9V from 6 pcs R14/LR14 size batteries or via 230Vac/50Hz
  • Power consumption: 6W, 0.9W in stand-by
  • Dimensions/weight: 270 x 152 x 92.5 mm, 1290 g (without batteries), 1.7kg with batteries
  • Original price: 250$

Good things:

  • Slow speech function is very ingenious
  • Good selectivity
  • Very fast RDS and Radio Text
  • Its sound is very clear regarding its wide range speaker

Problems:

  • No radio signal level indicator
  • No back-light display, for this reason if the display is is shadow, cannot be read.
  • In case of power off, the clock loses its setting
  • No auto clock setting from RDS data
  • No stereo decoder, also via headphones you can listen to the programs just in mono
  • The Auto station search runs just forward, but in a short time very precisely set the center frequency of stations
  • Cannot charge batteries
On the net can be found several versions, with or without AM band, or Japanese version additionally can receive both Type 1 and Type 2 emergency warning broadcasts.
Recommendation: I changed all electrolytics. All 6.3V types were in poor condition.
Considering the all hardware inserted into this radio is not clear why Panasonic does not exploit their possibilities, like stereo listening via headphones, clock auto setting from RDS, or switchable backlight for the display.
The sound is very clear, regarding its full range 10cm speaker. For daily use in the office, or for kitchen-radio is a perfect choice. Personally, I did not like its sound. Is not smooth, or is not a long time listenable radio. Is difficult to express it in words, but I feel its sound in some way without life.



Philips


The Philips Company was founded in 1891, by Gerard Philips and his father Frederik Philips. Frederik, a banker based in Zaltbommel, financed the purchase and setup of an empty factory building in Eindhoven, where the company started the production of carbon-filament lamps and other electro-technical products in 1892. In the 1920s, the company started to manufacture other products, such as vacuum tubes. In 1927, Philips began producing radios.
In 1980, Dutch Philips Group bought the Marantz (in 2001 Marantz Japan acquired the brand back from Philips), and in 1984 bought out nearly a one-third share and took over the management of German company Grundig.
On 29 January 2013, it was announced that Philips had agreed to sell its audio and video operations to the Japan-based Funai Electric.


Philips L1W35T

Philips L1W35T

General information:

  • Manufactured at 1964 by Philips in Eindhoven
  • Just one band MW (AM) superheterodyne pocket radio with build in earphone, placed near the battery case (via one switch can be selected the speaker or the earphone)
  • Coverage: 525kHz -1622kHz (185m - 571m wavelength)
  • Intermediate frequency: 452kHz, 5 RF circuits
  • Power: 6V (4 pcs of AA batteries)
  • Power consumption without signal: 12mA
  • Output power: 120mW
  • Dimensions: 142x92x35mm, 300 gr.
This is my second oldest radio with transistors (6 transistors: 3 pcs of AF127 for mixer-oscillator and IF (2), 3 pcs of AC132 for the preamp and power amp (2), and one OA70 diode for detector - all Germanium type). Sensibility is average, the volume potentiometer is scratching, but the whole radio is still working quite well.


Philips FT980

Philips FT980

This tuner was the top tuner of Philips, but this Philips FT980 basically is a Grundig development from Fürth (when Grundig and Marantz were already part of Philips) and was only plugged into a different housing by Philips for its brand and got a different device number. Technically almost or largely identical RF part (except for external design/housing and used microcontroller) are Grundig T-5200, T-5500, T8200 MKII, T-304, T4, Fine Arts T-904 or Marantz ST72L. Several webpages highlight its pleasant sound, very good reception quality, and also recommend it for DX.

General information:

  • Manufactured by Philips Portugal at 1990-1992
  • Digital 3 bands (LW-MW-FM) PLL radio,
  • 30 memory presets, which can be mixed between AM and FM
  • Coverage: LW 150 - 283kHz, MW 528kHz - 1.605MHz, FM 87.5MHz - 108.0MHz
  • 9/1 kHz steps on AM, 50/25kHz on FM - (auto/manual search)
  • Usable sensitivity: 200uV/m on LW, 200uV/m on MW (400uV/m), and 0.85uV on FM (mono) and 23uV for stereo - via a very sensitive MOSFET FM tuner
  • AM/FM Tuner System IC: LA1266, stereo decoder: LA3401, direct PLL frequency Synthesizer IC: LC7217, uController MC68HC11, FL tube driver: uPD7537A, RDS decoder LA2231, reset IC: M51957A, TA7061AP IF amplifier and RC4560 RDS filter opa.
  • Output frequency range: 10Hz - 15kHz (+0.5...+1.5dB)
  • Signal/noise ratio: LW 55dB, MW 55dB, FM 86dB mono, 78dB stereo
  • THD: on FM 0.08% for mono, and 0.12% for stereo, on AM 0.5%
  • Stereo separation: 50dB
  • Line output impedance: 3.3 kohm
  • Line output levels: 400 mV in AM mode, 370 mV in FM mode
  • Antenna input impedance for FM: 2 x 75 ohms (one for local, one for DX)
  • Power: 230V/50Hz, Consumption: 10W
  • Dimensions: 420 x 86 x 334 mm, 2.6 kg

Good things:

  • Very good sensitivity on FM (0.85uV),
  • Narrow and wide IF band selection possibility, with 5 ceramic filters! - 3 for wide, and +2 for narrow IF band,
  • 2 selectable FM antenna inputs: one for local, and one for DX,
  • Sensible RDS,
  • Used components were good quality (at that time).

Difficult, problematic items:

  • The RDS display just the radio station name, no Radio Text
  • The transformer is always connected to power line, and with the 2 regulator ICs heatsink generate a lot of heat,
  • Behind FL display were also components (electrolytic capacitors, resonator, resistors, etc) -> all capacitors were removed and mounted on the backside of PCB for easy access in future,
  • Has some timer possibility, but without the user manual, is difficult to use it
  • FM IF is 10.73MHz (ceramic filters with an orange dot), which means is difficult to upgrade them.

Generally: is a very good tuner with high sensibility and selectivity for FM DX audio program listening.
As usual for its age, was necessary to change all electrolytic capacitors. In RF parts received tantalum type capacitors, in other areas, below 4.7uF film capacitors, in audio part Nichicon Fine Gold, in the power line, above 22uF Nichicon or Rubycon capacitors.
On some portals are recommended to be changed the C311 adjustable capacitor with a teflon type, but in my one, I did not see any reason to change it. After comparing the schematics and specifications of the above-mentioned tuners, I decided to upgrade the tuner with component values used in Grundig Fine Arts T4 and/or Marantz ST72, changing R105 4.7k into 3.6k, R145 10 ohm into 4.7 ohms, R187 10k into 6.8k, R315 120k into 56k, and insert a 3.3uH (L11) coil in the power line of FM-IF operational amplifier. To my surprise, those were originally changed/inserted by manufacturer -> means the Philips FT980 RF parts differ from its service manual and are same with the RF parts used in Grundig Fine Arts T4. Marantz ST72 has additionally other values in the case of some components, like in FM oscillator or in FM tuner output amplifier, but I considered risky their changes regarding surrounded RF circuits.
List of other differences between Philips FT980 and Marantz ST72L: R16 8.2k/100, R165 1.2k/1k, R181 47/220, R301 31/390, R309 330/68k, R311 220k/68k, R322 3.9k/5.6k, C112 10n/47n, C113 10u/no, C145 4.7n/390p, L11 no/3.3u. The RF coils cannot be compared, because in both manuals has a different notation (looks like Philips and Marantz used a different notation system), but their position-number, appearance, and the capacitors from the circuit are the same.



Pioneer


Pioneer Corporation (Paionia Kabushiki-gaisha) commonly referred to as Pioneer, is a Japanese multinational corporation based in Tokyo, Japan, that specializes in digital entertainment products. In 1937: Pioneer's founder, Nozomu Matsumoto develops the A-8 dynamic speaker, and one year later, in 1938 Fukuin Shokai Denki Seisakusho (precursor of Pioneer) is founded in Tokyo as a radio and speaker repair shop. In May 1947 Fukuin Denki is incorporated, and in June 1961 company name changed to Pioneer Electronic Corporation. Pioneer played a role in the development of interactive cable TV, the Laser Disc player, the first automotive Compact Disc player, the first detachable face car stereo, Supertuner technology, DVD and DVD recording, the first AV receiver with Dolby Digital, plasma display and Organic LED display (OLED). In March 2010, Pioneer stopped producing televisions as announced on 12 February 2009. On June 25, 2009, Sharp Corporation agreed to form a joint venture on their optical business to be called Pioneer Digital Design and Manufacturing Corporation. In September 2014, Pioneer agreed to sell Pioneer Home Electronics (Home A/V) to Onkyo. In June 2021, Voxx International announced that it had finalized a licensing agreement with the Pioneer and Pioneer Elite brands "for all markets, except China" as part of their acquisition of Onkyo.


Pioneer F-90

Pioneer F-90

The Pioneer F-90 (for the Japanese market is F120, absolutely the same, except the FM range) is a high-performance AM/FM tuner made by Pioneer (after F99X). Features a 4 gang FM tuner with DMOS first stage, a balanced mixer, three narrow-IF filters, a pulse-count detector called Digital Direct Decoder, and a novel switched-sinewave stereo decoder. The stereo demodulation capability is superior to the switching MPX circuits used by other companies, and high channel separation has been obtained. It has good sensitivity, excellent overload resistance, excellent immunity to spurious composite signals, very high AM suppression, very high S/N, and extremely low distortion. Has a Record level check for easy recording level adjustment.

General information:

  • Manufactured by Pioneer in Japan between 1982-85
  • Digital 2 bands (MW-FM) PLL radio,
  • 8+8 memory presets, 8 for AM and 8 for FM
  • Coverage: MW 522kHz - 1.611MHz, FM 87.5MHz - 108.0MHz, EU version
  • 9 kHz steps on AM, 50 kHz on FM - (auto/manual search)
  • Usable sensitivity: 150uV/m on MW, and 0.75uV on FM (mono) and 22uV for stereo
  • FM IF amp IC: 2 pcs uPC1163H, FM IF amp and detector: PA3007A, pulse count circuit: PA5006, stereo decoder: PA5007, AM dem and IF: LA1247, direct PLL Frequency Synthesizer and control IC: TC9147P, led display driver: TD6301AP, FM prescaller: TD6104P and M5218P opa.
  • Output frequency range: 20Hz - 15kHz (+0.2...-0.8dB)
  • Signal/noise ratio: MW 50dB, FM 93dB mono, 86dB stereo
  • THD: on FM 0.01% for mono, and 0.02% for stereo measured at 1kHz in Wide mode, and 0.1°for mono, 0.5% for stereo in Narrow mode
  • Capture ratio: 0.8dB in Wide mode
  • Alternate Channel Selectivity: 85dB in Narrow mode
  • Output frequency response on FM: 20Hz - 15kHz (-0.5...+0.5dB)
  • Stereo separation: 65dB in Wide mode, 40dB in Narrow mode at 1 kHz
  • Line output impedance: 900 ohm
  • Line output levels: 150 mV in AM mode, 650 mV in FM mode
  • Antenna input impedance for FM: 75 ohms unbalanced, and 300 ohms balanced, for AM loop antenna
  • Power: 220V, 50/60Hz, Consumption: 14W
  • Dimensions: 420 x 61 x 317 mm (WxHxD), Weight 4.5 kg
  • Selling price in 1983: 650DM

Good things:

  • Very simple, clear front panel
  • Extremely high S/N ration of FM: 93dB in mono, and very low distortion: 0,0095% in mono at 1kHz
  • Extremely clear sound regarding Digital Direct Decoder and switched-sinewave stereo decoder
  • Very musical sound, highly recommended as the tuner in Hifi systems

Difficult, problematic items:

  • Just 8 memories for each band
  • The transformer is always connected to the power line, and the 2 regulator transistors on the heatsink generate a lot of heat to upset a careful alignment,
  • Has no signal-strength indicator
  • The IF bandwidth and mono/stereo settings are not saved in the device's memory when the station is saved.
  • The mainboard must be unbolted and awkwardly tilted to the power side for modification because there is no bottom access to the soldering side (U shape base plate).
  • The memory pushbuttons often don't work due to the deterioration of foam between the front panel and switches
  • The soldering of connection multiwire cables and the display driver TD6301AR pins to PCB are very weak and can make connection problems, is better if you resolder all solder joints on PCB.

The tuner is very similar to the latest and famous F99X model, excepting the 2 IF amplifier stages, separate for Wide and Narrow IF circuits, for better selectivity. The F90 is a simple but good-sounding tuner, and can be asked, how this tuner gets this sensational data of 0.01% (mono) or 0.02% (stereo) distortion; a crosstalk attenuation of 65dB; and a massive 93dB signal-to-noise ratio (mono) and 85dB selectivity (400kHz, narrow IF)? The answer is simple: via the 2nd IF stage and its patented DDD (Digital Direct Decoder) which uses two proprietary ICs (PLL muting PA5007, and a DDD with pulse-count detector PA5006). The IF signal with its maximum frequency deviation is doubled via Q110 and Q111 to get the 21.4 MHz with maximum frequency deviation +-150kHz - and this is mixed with the second local oscillator (20.14MHz) to get the 2nd IF signal of 1.26 MHz (Q305) with max. freq. deviation of +-150kHz. This method improves significantly the decoding efficiency and the signal-to-noise ratio. This 2nd IF signal is applied to DDD IC. The signal is converted into digital pulse series by a pulse converter and processed further. The conversion back into an analog signal only takes place in the multiplex decoder, which breaks down the digital signals into the components of the two channels by adding a 38kHz sine wave subcarrier. There is thus complete immunity to noise and distortion. Since this method also eliminates the need for an anti-birdie filter, there are no negative effects on the sound quality. In addition, a sine wave can be used as the 38kHz subcarrier, which means that the subcarrier signal does not introduce any harmonics (distortion) either.
The AM section uses a Sanyo LA1247, which has an improved subchannel signal/noise ratio as compared with the LA1245, and has an auto search stop signal.
As usual for such old tuners (almost 40 years old!), was necessary to change all electrolytic capacitors.
Modifications:
Power supply: the power supply pass transistors (Q403 and Q405) originally are mounted on two heatsinks. They generate enough heat to significantly raise the internal temperature of the tuner, which can degrade the tuner's alignment, especially of ceramic filters. For this reason, both transistors must be mounted on the rear panel, electrically isolated, to dissipate the heat outside (fortunately this was made by the previous owner). Changed values: C374, C403 100uF/25V solid elcap; C406 and C410 330uF/50V Capxon; C412, C335, C513 220uF625V Rubycon; C368, C405 1000uF/35V Capxon; C23, C212 390uF/35V Rubycon; C325, C376, C404 changed to 2200uF/25V Rubycon. Inductances inserted into power lines to decrease spurious interferences and noise between units: 100uH before C513 for TC9147P (PLL + control), 33uH for TD6104 (prescaller) after R501, 33uH for TD6301 (LED driver).
Signal: for this, I considered the F99X schematic:
AM: R506 replaced with 2 pcs of 1N4148, C217 removed (extends the high end response), C356 changed to 0.47uF foil Wima (improves the bass). C216 was removed from before C215 and moved after it.
FM: at frequency-doubler Q110 and Q111 have the same emitter circuit: is better to be separated adding one more 560 ohms and 1000pF styro. R309 was removed, L301 and L303 changed between each other. C336+C337 and C341+C342 were replaced with 1-1 of 3.3uF foilcap. R331 and R332 were replaced with 31.6kohms, C334 and C339 changed from 1.5nF to 2.2nF styrocap type.
Other recommended changes: changing the narrow circuit filters with low loss +-150kHz type (must be paired!), readjusting the stereo decoding matrix's R306 68kohms, replacing with a 100kohm trimpot, and should be adjusted for maximum separation.
The full potential of this tuner is most evident where the most unfavorable conditions exist: on the one hand in metropolitan areas with densely occupied FM bands by strongly incident transmitters and multiple interferences and multipath reception problems, on the other hand in remote peripheral areas where it applies, despite low transmitter field strengths to enable good reception.
Is a good tuner, a fine basis for improvements, and has a very good, pleasant sound on FM and also on AM. Is not as sensible, as comes out from the specification (0.75uV in mono on FM), which means is not a DX tuner (with a good antenna can be), but has a very musical sound, and I like it.


Pioneer F-77

Pioneer F-77

The Pioneer F-77 is a middle-of-the-line model of Pioneer from 1986. Its circuitry, apart from the dual bandwidth, comes from F-99X (follower of F-90 presented above). Has a 3 point signal strength indicator and stereo indicator. Features a 3 gang FM tuner, and 2 ceramic IF filters. It has good sensitivity and excellent overload resistance. The front panel has an Auto search ON/OFF button, which works on AM and FM, Mutting ON/OFF, in case of OFF, the tuner will be in mono mode, and a switch to change between memory banks 1-8/9-16.

General information:

  • Manufactured by Pioneer in Japan between 1985-88
  • Digital 2 bands (MW-FM) PLL radio,
  • 8+8 memory presets, random presets (can be mixed AM/FM)
  • Coverage: MW 522kHz - 1.611MHz, FM 87.5MHz - 108.0MHz
  • 9 kHz steps on AM, 50 kHz on FM - (auto/manual search)
  • Usable sensitivity: 150uV/m on MW, and 0.95uV on FM (mono) and 23uV for stereo
  • FM IF amp IC: uPC1163H, FM IF amp and detector: PA5008, stereo decoder: PA5007, AM dem and IF: LA1247, direct PLL Frequency Synthesizer and control IC: TC9157P, display driver: TD6301AP, FM prescaller: TD6104P, voltage regulator 78M12.
  • Output frequency range: 20Hz - 15kHz (+0.5...-1.0dB)
  • Signal/noise ratio: MW 50dB, FM 93dB mono, 86dB stereo
  • THD: on FM 0.01% for mono, and 0.02% for stereo measured at 1kHz in Wide mode, and 0.1°for mono, 0.5% for stereo in Narrow mode
  • Capture ratio: no data
  • Alternate Channel Selectivity: no data
  • Output frequency response on FM: 20Hz - 15kHz (-0.5...+0.5dB)
  • Stereo separation: no data
  • Line output impedance: no data
  • Line output levels: 150 mV in AM mode, 650 mV in FM mode
  • Antenna input impedance for FM: 75 ohms unbalanced, was produced also with 300 ohms balanced input, and input for AM loop antenna
  • Power: 220V, 50/60Hz, Consumption: 9W
  • Dimensions: 420 x 61 x 221 mm (WxHxD), Weight 2.5 kg
  • Selling price in 1986: 500DM

Good things:

  • Simple front panel
  • Clear sound

Difficult, problematic items:

  • The transformer is always connected to the power line, and the voltage regulator on the heatsink generates a lot of heat to upset a careful alignment,
  • The signal-strength indicator has just 3 level
  • The mainboard must be unbolted for modification because there is no bottom access to the soldering side (U shape base plate).
  • The soldering of connection multiwire cables and the display driver TD6301AR pins to PCB are very weak and can make connection problems, is better if you resolder all solder joints on PCB (like in the case of F-90 model).

I meet till now 2 versions of this tuner: one with noise canceling filter-coil before the power transformer, which has a separate tuner PCB mounted on the mainboard, and the FM unbalanced connector is mounted separately on the rear cover and has no 300 ohm FM antenna input. The second one has no filter before the power transformer, all parts are mounted on the main board and the FM tuner is shielded, but has balanced and unbalanced FM input, and all of them with AM antennas are molded together and screwed to the chassis. I have the first version.
Deviation from the service manual: at audio output additionally has a 2.2uH coil in the signal path, followed by a 22pF capacitor to the ground on both channels. Unfortunately the service manual is incomplete, I did not found the whole specification of this tuner.
The tuner is very similar to the latest and famous F99X model, excepting the 2 IF amplifier stages, separate for Wide and Narrow IF circuits, for better selectivity.
The AM section uses a Sanyo LA1247, which has an improved subchannel signal/noise ratio as compared with the LA1245, and has an auto search stop signal.
Modifications:
Power supply: the power supply regulator originally was mounted on a heatsink, and generates enough heat to significantly raise the internal temperature of the tuner, which can degrade the tuner's alignment, especially of ceramic filters. For this reason, the regulator was mounted on the rear panel, electrically isolated (has the same potential, but to avoid any ground loop, I decided to isolate it), to dissipate the heat outside. The filter coil before the transformer was extended with 2+2 capacitors: 2x0.47uF/275Vac foil, and 2x2.2nF/2kV ceramic.
Changed values: C21 270uF/16V, C109 100uF/16V, C207 2200uF/25V Rubycon, C221 1000uF/25V Yageo, C319 100uF/16V, C322 47uF/16V, C415 received one more 2200uF/25V in parallel (location was already made on the PCB), C433 33uF/25V, R104 and R107 270ohms, R207 and R226 390k, 2.2uF mounted in parallel with R226, 10nF mounted in parallel with R103. Inductances inserted into power lines to decrease spurious interferences and noise between units: 100uH after C221, followed by a 270uF/16V, in the power line of TD6104 2.2uF, in the power line of uPD1163 2.2uH, and 10uH at the cathode of D425 and D416 for TC9147P (PLL + control).
Signal: for this, I considered the F99X schematic:
AM: C210 and C223 to 0.1uF foil Wima (improves the bass).
FM: R212 and R213 31.6k, R222 and R223 1.3k, R224 and R225 2.7k.
Other recommended changes: changing the ceramic IF filters (now have 2 same Murata with a blue body, red line mark on the top, and marking E10.7P) with low loss +-150kHz type (must be paired!).
Is a good tuner, recommended for improvements, and has a good, pleasant sound on FM and also on AM. Has a very musical sound!



ReVox


ReVox is a brand name, registered by Studer on 27 March 1951 for Swiss audio equipment for amateur recorders, while the professional machines retained the Studer name. The company moved to Löffingen, West Germany, in 1966, due to labour issues in Switzerland, but the building of a second factory was started in Regensdorf, Switzerland in 1967 - to open in 1968. In 1967 the 36-series tape recorders ended with the G36, and were superseded by the transistorised A77 with a servo-controlled direct drive capstan. Over 80,000 36-series recorders had been manufactured. The A77, of which more than 460,000 were built, was complemented by an integrated amplifier (A78) and FM tuner (A76). The start of the 1980s saw the introduction of the "B7xx" series of high fidelity components, which was in turn replaced by the B2xx series in the mid 1980s. The B2xx series was versatile and feature-rich, all components containing microprocessors. In 1990 Willi Studer sold the Studer Revox Group to Motor-Columbus AG, including all subsidiary companies. In 1991, Motor-Columbus split the Studer Revox Group into Studer (Pro), Revox (HiFi) and a Manufacturing-division. Motor-Columbus sold several subsidiaries and plants. The extensive reorganization culminated in the sale of the Studer Group to Harman International Inc., in March 1994. The Revox Group was excluded and sold to private investors. On 17 March 1994 Harman International Industries completed its acquisition and acquired from Motor-Columbus AG 100% of Studer Revox AG. Harman paid 100 Swiss Francs (approximately US $70.00) for all of the issued and outstanding stock in Studer Revox. Harman assumed post-acquisition indebtedness of Studer Revox of approximately 23 million Swiss Francs (approximately US $16 million).

ReVox A76

ReVox A76

The Revox A76 is a high-end FM tuner that was built to last, with a sleek and minimalist design that looks great in any vintage setup. But what really sets the A76 apart is its incredible sound quality. Was designed by Ernst Mathys, one of the world's best "FM tuner gurus" (he earned his reputation with this receiver), and the A76 is a completely unconventional receiver. It's known for its ability to pull in weak signals and deliver a warm, detailed sound that's perfect for radio enthusiasts and audiophiles alike. This tuner has a reputation for being incredibly reliable and well-built, with high-quality components that was designed to stand the test of time. Indeed, aside from the typical alignment, this tuner is still in top shape. It's no wonder that the Revox A76 is still sought after by collectors and vintage audio enthusiasts to this day.

General information:

  • Produced: 1968-1971, made by Studer in Regensdorf, Switzerland
  • Tuning Range: 87.5-108MHz
  • Antenna Inputs: 60-75 ohms unbalanced (BNC); 240-300 ohms balanced (DIN)
  • Selectivity: 1.0uV for mono and 10uV for stereo (measured on 60ohm, 30dB S/N, deviation 15kHz)
  • Used semiconductors: 2 dual-gate mosfets (MFE3007), 6 integrated circuits (5 pcs CA3053 and one MC790P), 41 silicon transistors, 27 diodes, and 2 silicon rectifiers
  • Static Selectivity at 300 kHz separation): 60 dB
  • Operational Selectivity (for two signals 100uV and 1 mV, 40kHz dev. at 1kHz, 300kHz separation): 80 dB
  • Spurious Response: 90 dB
  • Image Response: 70 dB
  • Pulse Noise Rejection (signal 100uV and 1 mV peak per 100 kHz pulse noise, 75 kHz deviation): 40 dB
  • IF Filter Bandwidth: 130 kHz
  • Capture ratio: 1 dB
  • Signal to noise ratio (unweighted, 75kHz deviation): 70dB
  • Distortion (40 kHz deviation at 1kHz): 0.2%
  • Stereo Separation: 40dB at 1 kHz
  • Pilot Signal and Subcarrier Suppression: 40dB
  • Frequency response: 30Hz - 15kHz, -1dB
  • Audio output signal level (75kHz deviation; adjustable, low internal impedance): 1000mV, and the signal can come out via DIN or RCA sockets, the output levels are adjustable from backside.
  • Deemphasis: 50us
  • Power Supply: selectable 110, 130, 150, 220, 240, 250 V, 50/60 Hz
  • Power Consumption: 20W
  • Dimension (W x H x D): 415 x 160 x 245mm, 7.8kg
  • Prise at 1969: 1340 DM or 1390 SFr
There are three versions of A76 (1969-1971, ser. nr. 20-1800), A76 MKII (1971-1974, ser. nr. 7013-21055) and A76 MKIII (1974-1978, ser. nr. 21056-34105). The MKII and MKIII input stage is the same, and contains 3 dual-gate mosfets (one more in the mixer stage) and one bipolar transistor.

Because this radio's circuit is unconventional, below you can find a short description of circuit (translated from German from ReVox A76 in der Funkschau and shortened):
The input section features "dual gate" field effect transistors and quadruple variable capacitor tuning.
The FM demodulation is performed in a line demodulator. This consists of a driver stage with the differential amplifier (Q301 & Q303), two coaxial delay cables (with an electrical length of lambda/8 of the intermediate frequency) as load resistor, and a rectifier circuit (D301 & D302). In the arrangement, the frequency-dependent impedance of the line sections, one of which is short-circuited at the end (C308) and the other open, converts the FM into an AM. The line demodulator has the wide bandwidth of 5 MHz with good linearity. In combination with the wideband IF amplifier, a capture ratio of 1 dB is obtained, which gives excellent common mode selection. The operation of the line demodulator is completely uncritical, since RF balancing elements are missing. For AM suppression, only the limiting in the IF amplifier is decisive.
The subcarrier regeneration is characterized by an unusually high effort. The 38 kHz subcarrier is generated by a PLL circuit (phase locked loop). An oscillator with the differential amplifier Q405 and Q406 as active element generates a frequency of 76 kHz. After pulse shaping, this frequency is divided in an IC401 (MC790) integrated frequency divider with a divider ratio of 1:2:4. The resulting frequency of 38 kHz (subcarrier) controls the multiplex switching demodulator. The good symmetry of the switching frequency suppresses the SCA channel (background music, common in the USA) to a high degree even without a special 67 kHz cut filter. The 19kHz frequency passes from the frequency divider to a phase comparison stage (differential amplifier Q403 and Q404). In a broadband filter, the pilot frequency is filtered out of the multiplex signal and also fed to the phase comparison stage via the Q401 & Q402 differential amplifier. The bandpass filter has good phase stability and causes the pilot phase to rotate 90 degrees. Interference components of the pilot tone are kept away from the post-tuning circuit (capacitance diodes D402) of the 76 kHz oscillator by a 15Hz low-pass filter (R409, C408, R410). This arrangement acts as a narrowband pilot filter with a bandwidth of ±15 Hz. The bias voltage for the capacitance diodes is obtained at Z-diode D401. This type of subcarrier generation has the additional advantage that amplitude fluctuations of the pilot tone, caused by multipath interference, do not affect the stability of the subcarrier.
The multiplex decoder operates according to the splitting method. The multiplex signal is split for the main channel in the low-pass network (R508, C504, R509) and for the auxiliary channel in the 38 kHz bandpass (L501, C 501, R502). The auxiliary signal is amplified in stage Q501 and switch demodulated in Q503 and Q504. Switching demodulation was chosen because, in contrast to envelope demodulation, it transposes into the audible range only spurious frequencies that lie in the range of odd-numbered multiples of the auxiliary carrier. The first critical point is thus at 114kHz, which attenuates the deemphasis in the 38 kHz bandpass by 30 dB. Separate deemphasis for the main and auxiliary channels before multiplex demodulation has the advantage of strongly suppressing interference noise, such as whistling and chirping. The signal (L-R) or -(L-R) is generated on the resistors R518 & R519. The residues of the main signal reaching the switching demodulator, since they occur in phase at the working resistors, are eliminated by the common-mode suppression of the differential amplifier Q505 & Q506. This amplifier simultaneously operates as a matrix by forming the L and R signals, respectively, from the main signal amplified in transistor Q502 and the differential signal. Between the matrix output and impedance converters Q507 and Q508 are 15-kHz low-pass filters to suppress multiplex residual voltages. The level of the low impedance outputs is adjustable from 50 mV to 1V (75kHz swing).

The tuner I purchased had a few minor flaws: a missing metallic cover for the tuning knob, an obstructed signal level indicator instrument,one screw from the underside - all had been replaced or repaired. The signal level meter was fabricated using an analog instrument with the exception of the display component, which was retained in its original form. Additionally, the indicator was inclined at a 90-degree angle in order to be utilized in the horizontal position. While maintaining the same current and voltage (12V and 19mA, equivalent to one bulb of 24V/30mA utilized at 12V), the backlight was converted to four pleasant light LEDs.
By connecting the unbalanced input directly to the first stage of the tuner, after the 240 ohm impedance transformer, it is possible to enhance the signal while eliminating a 3 dB loss..
All electrolytics were altered: 50uF/25V was changed to 47uF/25V solide electrolytics for C114, C309 and C310 Oscon, and 47uF to 100uF/25V for C515 Elna SilmikII, C516 and C517, which convert 3.3uF/35V tantalum to 4.7uF/50V foil capacitors, C801 and C802 which apply 1000uF/63V elecrtolytic capacitors in parallel with 0.33uF/100V plastic capacitors.
At the power line input, I installed an EMI filter (Schurter 5500-1-55, comprised of two 560nF/275Vac components positioned before and after the line, as well as one 2.2nF/1kV ceramic component designed to filter a broader range of noise). In parallel with the contacts, two components of 2.2nF/3kV were added to the main power supply in order to eradicate the pop-up noise during switching On/off operation.
Despite this extremely unconventional circuitry, the sound is extremely delightful, warm, clear and detailed. The frontplate is extremely conservative and uncomplicated; with the exception of the original set from Revox/Studer, the A78, it is difficult to locate a system that resembles it.



RFT


The origin of all companies that produced radios in Leipzig was founded in 1925 by the businessman Oswald Ritter and the technician Wilhelm Dietz. The company initially produced transformers, power amplifiers and dynamic loudspeakers under license from the American company Magnavox. From 1932 radio receivers were added to the product range and the company in Körting Radio, Dr. Dietz & Ritter GmbH changed. With the models Cyclo-Super and Hexodensuper, their first superheterodyne receivers, also called superheterodyne receivers, came onto the market. In the course of arming the Wehrmacht, D & R built radio technology for the Air Force under license from Telefunken and Lorenz on behalf of the Reich Aviation Ministry (RLM) from 1935. In 1938 Körting Radio was one of the leading manufacturers in the market. The Leipzig radio equipment manufacturing facility was affiliated to the Berlin Löwe Radio AG in April 1941 as Löwe Radio AG, Leipzig plant. From August 1, 1942, the Löwe branch in Melscher Strasse was called the Leipzig plant, analogous to the parent company Opta Radio AG. With the financial means from the outsourcing of his Wehrmacht production, Ritter continued the radio receiver production as the sole owner of the old factory at Eichstädtstraße 11 (today Untere Eichstädtstraße) under the name "Körting-Radio-Werke Oswald Ritter". The Opta operation in Melscher Strasse was named Opta-Radio AG, Stötteritz plant with the status of a SAG (Soviet state company) and in 1948 became VEB Stern-Radio Leipzig. In 1952, after an internal profile change, the name was changed to VEB Fernmeldewerk Leipzig, which was now mainly dedicated to the production of telecommunications systems, but also z. B. Manufactured microphones. The former Körting Radio Werke Oswald Ritter in Leipzig were initially incorporated into the RFT-Funkwerk Leipzig VEB and in 1964 the VEB Fernmeldewerk Leipzig. With the formation of the Kombinate, this company received the status of the parent company of the VEB RFT Kombinat Fernmeldewerk Leipzig in 1970.

RFT Capri 6401 Stereo

RFT Capri 6401 St       RFT Capros 6401 St

Both of my grandfathers had this type of radio at Alsóbölkény (Beica de Jos) and Marosvásárhely (Neumarkst, Tirgu Mures) - in Transylvania, now part of Romania, and I always was fascinated by their sound. Is a mono receiver with stereo amplifier made in 1963 by RFT (see below).

General information:

  • Principle: AM superheterodyne, with IF=460kHz, 9 RF circuits.
  • For FM: IF=10.7MHz, with 10 RF circuits
  • Manufacturer: RFT (Rundfunk- und Fernsehentechnik) at Goldpfeil Rundfunkgerätewerk Hartmannsdorf from DDR (East or Communist Germany)
  • Bands: in total 7 - LW: 150 - 410 kHz, MW: 510 kHz - 1.630 MHz, 4 SW bands (1.9-5.7Mhz, 5.65-10MHz, 11.5-18.2MHz, 18.1-26.4MHz) and one FM OIRT: 66-73MHz
  • Selectivity: AM 15-20uV/10dB, FM 3uV/30dB
  • Tubes: 10 pcs - ECC85, EF89, ECH81, 2xEBF89, 2xECC83, 2xEL84, EM84, 2 GE diodes: OA646, 1 Si diode: OA910 and 2 Selenium rectifiers: 1/2 B 250/200 - 0.15A
  • Power supply: alternating current, selectable 110-240V, 50Hz, 95W
  • Audio bandwidth: AM 40Hz-6kHz, FM 40Hz-18kHz, 2x4W
  • Speakers: 2 oval 18x25 cm for bass and middle in front and 2 tweeters 9 cm at lateral sides
  • Adjustable bass, treble and balance potentiometers, and 4 sound mode selector switches: speech, solo, jazz and x-bass.
  • Inputs: AM and FM antenna, tape recorder and turntable (crystal cartridge)
  • Dimension: 690x405x275 mm, 19.5 kg
Originally this radio has a possibility for upgrade: later, in the early '70s could be added an FM stereo decoder module made also by RFT with transistors. This radio can be considered as the successor of famous Beethoven radio receiver.
Modification: now has a power line socket with EMI filter + detachable power cable, and on DC filtering parts electrolytic capacitors were chanced with new ones.



Rotel


Rotel is a family-owned Japanese manufacturer of high-end audio and video equipment: home theater, amplifiers, compact disc players, etc. The company was established in 1961. In the early 1980s Rotel joined the B&W Group forming a strategic alliance with Bowers & Wilkins and later adding Classé Audio. The global affiliation between Rotel and the B&W Group dates back to the early 1980s with the establishment of exclusive distribution in North America and several European markets. Over the next 20 years, Rotel appointed virtually all Bowers & Wilkins distributors globally. In 2000 the B&W Group established Rotel Europe in the UK to consolidate all Rotel sales and support activities outside North America. The Classé brand was acquired by Sound United in 2018, breaking the link with B&W. Rotel maintains an exclusive network of specialist hi-fi dealers around the world.


ROTEL RX-850

Rotel RX-850

Is a receiver amplifier with a very warm sound from 1980's with exceptionally good overload characteristics.

General information:

  • Digital 2 bands (MW-FM) PLL radio without RDS capability,
  • 16 memory presets, 8 for FM and 8 for AM
  • Coverage: MW 520kHz - 1.611MHz, FM 87.5MHz - 108.0MHz
  • Channel space: 9kHz for AM and 50kHz for FM
  • Intermediate frequency: 450kHz for AM and 10.7MHz for FM
  • Usable sensitivity: 12uV on AM, 0.95uV on FM mono and 20uV for FM stereo
  • Integrated circuits: FM IF IC: LA1235, stereo decoder: LA3390, PLL freq. synthesizer: TC9147BP, FM prescaller TD6104P, DTS 6-8  display driver TC9158P, NE5532 OPA for RIAA
  • Output frequency response on FM: 30Hz - 15kHz (-1...+1dB)
  • Signal/noise ratio: AM 53dB, FM 82dB mono, 78dB stereo
  • THD: on FM 0.07% for mono, 0.25% for stereo
  • Stereo separation: 43dB
  • Antenna input impedance for FM: 75 and 300 ohm
  • Amplifier part: continuous power on 8 ohm: 30 W / channel, THD 0.03% (20...20000 Hz)
  • Amplifier input sensitivity: PHONO (MM) 2.5mV / 47 kohm; CD, VIDEO and TAPE 150mV / 4.7 kohm;
  • Amplifier input overload level: PHONO 200 mV (MM) and 5 V for other inputs
  • Amplifier frequency response: Phono 20...20000 Hz ±0.3 dB (RIAA STD), 20...30000 Hz +0..-1 dB from other inputs
  • Amplifier tone control: Bass 100Hz ±3.5dB, Treble 10kHz ±3.5dB
  • Amplifier signal to noise ratio (A weightened) 80dB for PHONO, 100dB for other inputs
  • Power: 220V/50-60Hz, consumption: 180W
  • Dimensions: 444x86x346mm, 7.0kg

Good things:

  • Has a very clean sound, beautiful bass, low noise and high FM selectivity
  • Has signal level indicator
  • Has a Postdetection Filter to eliminate HD FM radio noise (used in America)

Difficult, problematic items:

  • 2x8 preset memories are not enough, especially for FM
Considering its age, was necessary to change almost all electrolyte capacitors.



SABA


SABA (Schwarzwälder Apparate-Bau-Anstalt) originally was a German electronics company founded in 1923 at Triberg im Schwarzwald (Black Forest), present-day Baden-Württemberg. SABA started as a clock-making company, then became a radio manufacturer, and a few years later a record label. In 1968, SABA sold the majority of the company to GTE, an American telephone company. In 1980 the company was purchased by Thomson SA and integrated as a separate business unit.


Saba TS2030 RDS

Saba TS2030 RDS

Is an interesting tuner, without too many references on the net. Has RDS capability, a primitive one, with several operational amplifiers to filter the radio signal (57kHz), extract, and decode the RDS information with its own microcontroller (no dedicated integrated circuit are used!). Has remote control possibility, marked as CRC (Computerized Remote Control), and the last channel recall. The RDS data is visualized only on a 4 character display with scrolling characters, and shows just the station name.

General information:

  • Manufactured by Saba in Villingen in Germany in 1985.
  • Digital 3 bands (LW-MW-FM) PLL radio,
  • 29 memory presets on 3 pages for FM and AM
  • Coverage: LW 153kHz - 281kHz; MW 531kHz - 1.602MHz; FM 87.5MHz - 108.0MHz
  • Usable sensitivity: unknown
  • FM IF IC: LA1170, AM tuner IC: TDA1220B, stereo decoder: TEA5580, SAA1057 PLL syntheser IC, uController and display driver: uPD75216ACW/200, U2505B infrared remote control system IC.
  • Output frequency range: 20Hz - 15kHz (+0.5dB...-1.5dB)
  • Signal/noise ratio: unknown
  • THD: unknown
  • Stereo separation: unknown
  • Channel balance: unknown
  • Alternate Channel Selectivity (FM): unknown
  • Line output impedance: 10 kohm
  • Antenna input impedance for FM: 75 ohms
  • Power: 220V/50Hz, Consumption: 10W
  • Dimensions: 440x80x290mm, 2.7kg

Good things:

  • Discrete output amplifier instead of an operational amplifier IC
  • Last station memory - tuner switches on with the last station listened (at that time was a new thing), which is not necessary to be a saved one in memory
  • High quality of electrical parts used, especially in case of solid capacitors, coils

Difficult, problematic items:

  • No ferrite antenna, the AM signal can be captured just via external antenna
  • Has only 1 antenna input.
  • No signal level indicator
  • Everything is plastic, including the front side
The memory are kept via a Lithium battery soldered on control panel (CR2432). All electrolyte capacitors changed.



Sangean


Sangean Electronics, Inc. is a Taiwanese electronics company headquartered in Zhonghe District, New Taipei, Taiwan, with a factory located in Dongguan, China. Apart from products sold under its own brand names, which include Lextronix, Sangean also produces on behalf of other companies -> any of the shortwave radios marketed by Siemens, Panasonic, Braun, Grundig, C.Crane, and Roberts have been and are being developed and produced by Sangean. The organization is globally active with business units in Venlo, The Netherlands for Europe and Santa Fe Springs, California for the Americas. The business units are directly in contact with distributors in relevant areas. It is noted for its shortwave radio receivers and digital radio (HDR and DAB/+) receivers.


Sangean ATS-909

Sangean ATX-909

Sangean released this radio in 1995 (identical to Siemens RK-777, Radio Shark DX-398, Technisat ATS-909, Roberts R861, all manufactured by Sangean) - and instantly became the number 1 competitor of Sony's ICF SW7600 series, which was the most famous portable SW radio at that time. Is a portable shortwave radio about the size of a large printed novel. It tunes from 150 kHz to 29,999 kHz and from 88 to 108 MHz in four bands, in SW can be received all 14 commercial bands. Can receive single-sideband in true LSB/USB, rather than the simple BFO of most portables of its class, though it doesn't offer synchronous detection. Unlike the Sony ICF SW7600G or GR, the Sangean can tune in 40 Hz steps in SSB, but does not display frequencies at that resolution. Has a big screen (the idea comes from Sony ICF SW77?) with a green backlight, priority button, double audio power amplifier for stereo headphones, ATS (auto scan tuning) function (excepting SW), 3 alarms, snooze, external antenna jack (for SW), AM RF gain adjust, sleep mode, clock with 2 timezones, etc.

General information:

  • Manufactured: by Sangean in Taiwan, Chung Ho city from 1996 to 2010. Was replaced by the ATS-909X model in 2011
  • Analog 4 band (LW-MW-SW-FM) with digital PLL radio with RDS capability (just the station name is shown)
  • 306 memory presets on 34 pages + 1: 18 for FM, 9 for LW, 18 for MW, and 261 for SW - each one on pages with 9 presets/page, +1 is a direct button for the favorite station
  • Coverage: LW 153kHz - 519kHz, MW 520kHz - 1.710MHz, SW 1.711MHz - 29.999MHz, and on FM 88MHz (can be set from 76MHz with HW) - 108.0MHz (stereo via headphones)
      • Shortwave bands (directly selectable):
    • SW1: 2300 - 2495 kHz, 120 m
    • SW2: 3200 - 3400 kHz, 90 m
    • SW3: 3900 - 4000 kHz, 75 m
    • SW4: 4750 - 5060 kHz, 60 m
    • SW5: 5900 - 6200 kHz, 49 m
    • SW6: 7100 - 7350 kHz, 41 m
    • SW7: 9400 - 9990 kHz, 31 m
    • SW8: 11600 - 12100 kHz, 25 m
    • SW9: 13500 - 13870 kHz, 21 m
    • SW10: 15100 - 15800 kHz, 19 m
    • SW11: 17480 - 17900 kHz, 16 m
    • SW12: 18900 - 19020 kHz, 15 m
    • SW13: 21450 - 21750 kHz, 13 m
    • SW14: 25600 - 26100 kHz, 11 m
  • Tuning steps (Fast/Slow): FM 100kHz/50kHz, LW 9kHz/1kHz, MW 9 or 10kHz/1kHz, SW 5kHz/1kHz, LSB/USB 1kHz/40Hz,
  • Intermediate frequencies: IF1 450kHz, IF2 55845kHz for AM, 10.7MHz for FM
  • Used ICs: FM front-end TA7358, AM/FM IF system TA7758, MPX decoder AN7415, audio amplifier AN7117 2pcs, preamplifier NJM2100; voltage regulators LA5003, 1.1GHz PLL frequency syntheser MB15A01, SAA6579 RDS demodulator, programable LCD controller/driver uPD7225, 8bit microcontroller uPD78063GF, 8 stage shift register TC4094, 16k 2.5V I2C eeprom 24LC164, voltage regulators
  • Antenna: integrated ferrite for LW and MW, for SW and FW telescopic antenna. External AM antenna connection for SW - received ANT-60 portable SW wire antenna with the radio
  • No other official specifications are available
  • Output power: 1W on a speaker of 3" 8 ohm 3W
  • Power: wall adapter 6V/400mA (Sino-American A40640GR) - center connection is negative, or 4 AA (UM-3/R6) batteries,
  • Dimensions: 215x135x37.5mm, 0.718 kg without batteries
  • Price in the first year of sale (1996): 260$

Good things:

  • Has a 7-bar signal strengths meter (looks like 14 bars, but every 2nd is connected with the previous one),
  • 3 sleep timers
  • Selectivity is very good on FM and LW, good on MW/SW
  • The frequency ranges depending on the model. Some have SW just till 26MHz, and FM starts from 76MHz,
  • Has just simple RDS, but the clock can be synchronized with the transmitted RDS signal's clock content
  • Has a switch for AM 9/10 kHz steps setting
  • Has also a rotary knob for manual tuning, and could be set the tunning steps via the Step button: hold, slow and fast
  • Has a narrow/wide IF filter switch, to overcome any nearby station interference
  • If you use it via external power source (wall-plug), the backlight remain on, but can be also switched off

Difficult, problematic items:

  • The physical dimensions are too big to be used in any pockets.
  • The used speaker, despite of its dimension, has a low quality, no bass, and in my set, the cone with the wire and its supporting cylinder was stuck - some material powder goes between the magnet and coil and does not permit it to move freely, but the coil was not damaged, no eccentricity could be seen
  • The manual is not so explicit, ex. cannot be found how to delete the alarms or sleep timers
  • Relatively high power consumption compared to Sony's similar radios
I bought my set just in 2022 (for 45$), and like in any other case, I search on the net about modifications. Surprisingly numerous improvements can be found for this radio that may be found on plenty of modification websites - most of them repeating the same items.
I did not remove the alarm speaker, not made the anti-chuffing modification, I did not remove the detent in the tuning knob, not made finer tuning for SSB, 40Hz steps are enough for me.
Modifications:
Improving AGC: C57 changed from 22uF to 10uF, C11 changed from 10uF to 4.7uF (as in the service manual), and R181 changed from 100k to 470kohm.
Modification for better audio: the speaker was changed with a speaker of ATS9009X. C80, C93, C94, C106, C107, C132, and C133 changed to 10uF, C110 and C111 to 330uF, C116 and C117 to 1000uF, C130 and C131 to 4.7uF.
Modification in power line: C76 changed to 100uF/16V, C99, C100 and C193 to 470uF/10V, C192 270uF/16V, all dry electrolytes. C95, C184, C189 to 4.7uF/35V X7R SMD MLCC,
All electrolytes in my set were Su'scon SL 85-degree type (the same capacitors are used by Denon in their devices, CD/DVD players, and tuners from the same period). Half of them were still good, others with higher leakage and increased ESR. All were changed with Yageo (in signal path) or solid/dry electrolytic capacitors (in power line). LED backlight was changed with orange LEDs.
Is a good set for modification. Now the sound is much better, but not as of ATS-909X model. Is one of the best portable on LW, MW, and FM, but on SW cannot beet the SONY ICF-SW7600GR or the Panasonic RF45B.


Sangean DT-220

General information:

  • Manufactured: by Sangean in Taiwan, Chung Ho city from 1998 till 2008
  • Digital 3 band (LW-MW-FM) PLL radio with RDS+EON capability, stereo with build in headphone/selectable, time and alarm function, auto scan and traffic info possibility
  • 25 memory presets: 16 for FM and 9 for AM
  • Coverage: LW 153kHz - 279kHz, MW 520kHz - 1.710MHz, FM 87.5MHz - 108.0MHz (stereo with headphones)
  • 9/10 kHz steps on AM (selectable), 50kHz on FM
  • Intermediate frequencies: 450kHz for AM, 10.7MHz for FM
  • AM/FM tuner circuit with stereo decoder: TA2104BFN, RDS decoder: SAA6579T, PLL circuit: TC9418FN, uController: uPD753012A and amplifier: CXA1622M
  • Signal/noise ratio 30dB on AM and 46dB on FM
  • Sensitivity: 60dBuV on LW, 52dBuV on MW, 12dBuV on FM, 18dBuV for stereo and RDS
  • Output power: 100mW in speaker or 2x5mW in headphones, THD 5% on AM and 3% on FM
  • Power: DC in 3V/300mA, or 2 AA (R6) batteries
  • Dimensions: 124x75x25.5mm, 169g without batteries

Problems:

  • Too high power consumption from batteries. A Sony radio with same capability could run 2-3 time longer with same power/batteries
  • The incorporated headphone wires lengths are too short, you cannot put the radio on your trousers pocket and in same time the headphones in your ears. To store the radio on your shorts pocket is very uncommon and heavy.
  • The physical dimensions are too big to be used in any pockets.
  • Selectivity is an average, not better
  • In my radio the LW parts components are not mounted, means cannot be used for LW band reception, but in manual are not described also how to switch to LW band.
  • Has just a simple RDS, cannot display Radio Text messages.
Generally, is a good radio, but a bit overpriced.
At its time was one of the smallest receiver with RDS capability, used for RDS reception checking and signal transmission accuracy/level by Hungarian Radio authorities in 2000-2006.
One weakness is the volume potentiometer: rapidly became unusable giving scratch noise in the speaker. Temporary can be "refurbished" with contact spray, but is better if you change it asap (R-VR 20kA, partnumber: 1312014).
Some parts are also different from schematic: C44 instead of 220uF/6.3V is 470uF/6.3V, CF2 instead of Murata 10.7MS3 is L10.7S Chinese type.
Modifications: ceramic filter changed from L10.7S with a Murata 10.7MJ type, and all electrolytic capacitors, excepting the 2 audio output ones, were changed because of their high loss (>2%) and high ESR (>2 ohms) (after 9 years usage), with same capacitors value TA type (4,7uF/16V; 10uF/16V and 47uF/6.3V).



Sangean DPR-69+

Sangean DPR-69+

Is a low-cost table radio with RDS/radio text on FM and DAB+ capability. From 2018 are sold in Europe under the name TRAVELLER 690.

General information:

  • Made by Sangean between 2010 till 2018
  • Digital 2 bands (FM and DAB+) DSP radio with RDS and Radio Text capability (PS, PTY, CT, and RT),
  • 5+5 memory presets, 5 for each band
  • Coverage: FM 87.5MHz - 108.0MHz, DAP+ (Band III, channels 5A - 13F) 174.928MHz - 239.000MHz
  • Channel space: 50kHz for FM and not known for DAB
  • From the menu can be selected the Local/DX reception
  • Integrated circuits: digital radio module from Frontier Silicon Kino3 FS2027, NJM2100 preamplifier and filter, MC33340 charger, PT2308 headphone amplifier, TPA2005D1 D class amplifier for speaker, Atmel 0726 EEPROM, CD4013 as switch circuit.
  • Stereo just via headphone
  • Built in speaker: 8 ohm/0.3W (in specification are rated 0.5W), with 75mm diameter
  • Power: from 4xLR6 (AA size) batteries or 4xNiMH rechargeable, or from an external power supply 7.5V/800mA (+ at middle) which can charge the NiMH accumulators in selected charging mode.
  • Dimensions: 161 x 106 x 37mm (W x H x D)
  • Weight: 348g without battery
  • The box contains: the radio + user manual + external power supply (PWM)

Good things:

  • Selectable Local or DX mode. Selectivity is quite good.
  • RDS with Ratio text
  • NiMH charging possibility
  • Selectable Auto/Manual searching mode
  • Lock switch

Difficult, problematic items:

  • Just 5 stations presets/band
  • Buttons are rubber-coated with lacquer
  • A bit slow wake-up after turn on
  • High power consumption (less than 25 hours), is better if you use it from an external power supply
  • The antenna doesn't pop out so you can have it vertical while lying the radio on its back
  • The radio's house is very shiny and because I have the black version, any fingerprint can be seen on it.
  • Display's light cannot be swithen on or set it to remain longer time on. Problem appears, when you would like to read the RT send by station during listening
  • No any signal strength meter (bargraph) or visually via one LED
In several advertisements are mentioned has USB B connector on the left side, above the headphone jack, for software (firmware) upgrade, and this is also mentioned on the original user manual received with the radio, but my sets haven't have any USB post. My radio's software version: dab-mmi-FS2027-0000-0050_V4.0.13.27373-5.
Inside the capacitors were manufactured by GD (China), SH7 type, 105C degree. All are in good condition (my set was made at end of 2016).
Not so many articles or reviews can be found about this radio, neither service manual. Look similar to Sangean DPR-67. As a guideline, I used the service manual of Sangean DPR-99 (construction, units are the same, but use different integrated circuits).
Is overpriced, in 2021 the unit is sold for 79-110 Euro, on the used market costs 20-40 Euro.


Sangean ATS-909X

Sangean ATX-909X

Sangean released it in 2011 as an upgrade of ATS-909 (identical with Radio Shack DX-398). Although the model name is similar, the radio received a complete redesign in and outside. Has a new face, big screen with full backlight, DSP, built-in charger, Aux-in jack, priority button, separate built-in headphone amplifier, ATS (auto scan tuning) function (excepting SW), squelch function (background noise level decreasing, works just on AM), alarm, snooze, SSB reception possibility, external antenna jack (for SW), record line out, AM RF gain adjust, etc.

General information:

  • Manufactured: by Sangean in Taiwan, Chung Ho city from 2011 till 2020 (now are replaced by ATS-909X2 model)
  • Digital 4 band (LW-MW-SW-FM) PLL radio with RDS+EON capability, stereo with headphone, time and 3 alarm function,
  • Has auto scan, called ATS: Automatic Tuning System.
  • 406 memory presets: 27 for FM, and 9 for LW, 18 for MW, and 351 for SW - each one on pages with 9 preset/page.
  • Coverage: LW 100kHz - 519kHz, MW 520kHz - 1.710MHz, SW 1.711MHz - 29.999MHz, and on FM 76MHz - 108.0MHz (stereo with headphones)
      • Shortwave bands (directly selectable):
    • SW1: 2300 - 2495 kHz, 120 m
    • SW2: 3200 - 3400 kHz, 90 m
    • SW3: 3900 - 4000 kHz, 75 m
    • SW4: 4750 - 5060 kHz, 60 m
    • SW5: 5900 - 6200 kHz, 49 m
    • SW6: 7100 - 7350 kHz, 41 m
    • SW7: 9400 - 9990 kHz, 31 m
    • SW8: 11600 - 12100 kHz, 25 m
    • SW9: 13500 - 13870 kHz, 21 m
    • SW10: 15100 - 15800 kHz, 19 m
    • SW11: 17480 - 17900 kHz, 16 m
    • SW12: 18900 - 19020 kHz, 15 m
    • SW13: 21450 - 21750 kHz, 13 m
    • SW14: 25600 - 26100 kHz, 11 m
  • Tuning steps (Fast/Slow): FM 100kHz/50kHz, LW 9kHz/1kHz, MW 9 or 10kHz/1kHz, SW 5kHz/1kHz, LSB/USB 1kHz/40Hz,
  • Intermediate frequencies: IF1 450kHz, IF2 55845kHz for AM, 10.7MHz for FM
  • DSP SI4735; AM IF TA7640; aux audio in switch TC4066; headphone amplifier PT2308 (=TDA1308); NJM2073D speaker amplifier; preamplifier NJM2100; battery charge controller MC33340; voltage regulators: XC62AP3002PRN and LD1117AL-Adj; 8bit microcontroller uPD78F0513A; eeprom: 24L32A; keypad interface and display driver AP650; 1.1GHz PLL frequency Synthesizer MB15A01
  • No any other official specifications are available
  • Output power: 1W on a speaker of 3" 8 ohm 3W
  • Power: AC 9V/700mA, or 4 AA (R6) batteries, or 4 NiMH accumulators (automatic charging is selectable in battery compartment via Alkaline/NiMH charging switch)
  • Dimensions: 207x134x41mm, 169g without batteries

Good things:

  • Si4735 DSP that gives good sensitivity and selectivity (on FM is exceptional) with 2 IF bandwidths on MW and SW
  • Good SSB mode with low distortion audio, and separate USB and LSB selections
  • Has a very pleasant sound, especially on FM
  • Has a real 12 bar signal strengths meter,
  • Very good ergonomics, rubber buttons, and easy to view big LCD that also features excellent white backlighting (on full time when operating from external AC adapter)
  • The frequency ranges depend by model. Some has SW just till 26MHz, and FM starts from 87.5MHz,
  • Has a side mounted variable gain (marked as RF Gain) that works well on SW/MW to improve the reception
  • Also in battery compartment is the tunning step switch for AM 9/10 kHz, which during battery insertion easily can be switched by mistake in other position
  • 3 position tone switch for speech, normal, and music setting

Difficult, problematic items:

  • Sensibility is just average on MW, on LW is low
  • Has just a full RDS, but cannot be programmed to display automatically for each station the Radio Text messages, just if you select it. Its sensibility is quite good
  • 3-step battery indicator is only to show something, but is not really useful
    • .
  • The physical dimensions are too big to be used in any pockets.
  • External antenna jack does not work on FM.
  • General audio quality on AM Mode is poor



Sansui


Sansui Electric Co., (Sansui Denki Kabushiki-gaisha) was a Japanese manufacturer of audio and video equipment. The company was founded in Tokyo in 1947 by Kosaku Kikuchi, who had worked for a radio parts distributor in Tokyo before and during World War II. Due to the poor quality of radio parts Kikuchi had to deal with, he decided to start his private radio part manufacturer facility in December 1944 in Yoyogi, Tokyo. He picked transformers as his initial product line. Kikuchi's thought was "Even with higher prices, let's make the higher quality of products." In 1954 manufacturing Pre-Amp, Main-Amp kits, as well as finished amplifiers which used tubes, was started; in 1958 Sansui introduced the first stereo tube Pre- and Main amplifiers. By the 1960s Sansui had developed a reputation for making serious audio components. They were sold in foreign markets through that and the next decade. As the mid-1980s arrived, sales were lost to competitors (Sony, Pioneer, Matsushita's Technics). Sansui began to lose visibility in the United States around 1988 and then focused on manufacturing high-end components in Japan. The company began to manufacture high-end television sets and other video equipment but ceased exportation. Sansui ended its Japanese production of high-end amplifiers sometime between 2002 and 2005 and went out of business in 2014. In Japan, consumer product maker Doshisha has the right to manufacture and sell under the Sansui brand. Outside of Japan, the brand belongs to Nimble Holdings of Hong Kong.


Sansui T-500L

Sansui T-500L

Is a nice tuner from the lowest family of System IS, part of IS-500. Its specification (excepting the quieting sensitivity at 50dB, which is 17.0dBf, compared to 16.5dBf) all specifications are the same with the higher family tuners, the T-700 and T-900. The pointer light's color is the tunning indicator: during searching is red, but if the tuner is rightly on the station, became green. The tunning knobs' blue backlight is phenomenal.

General information:

  • Manufactured at 1980 by Sansui Electric Co. Ltd., 14-t Izumi 2-Chome, Suginami-ku, Tokyo 168, Japan; Made in Japan
  • 3 band analog PLL tuner LW, MW, and FM
  • Coverage: LW 150 - 350 kHz, MW 530 - 1600 kHz, FM 88 - 108 MHz
  • Antenna input impedance for FM: 300 ohms balanced / 75 ohm unbalanced,
  • Usable sensitivity: 398uV/m on MW, 1000uV/m on LW, 0.9 uV on FM (mono), for stereo not specified,
  • Signal to noise ratio: mono 75dB, for stereo 70dB,
  • Distortion at 65dBf at 1000Hz: for mono 0.15%, for stereo 0.2%,
  • Intermediate frequencies: 455kHz for AM, and 10.76MHz for FM,
  • AM tuner IC: LA1240 amp, osc, IF and det; FM det. LA1231; stereo decoder (MPX) BA1332; tunning indicator BA6137,
  • Output frequency range:30Hz - 15kHz (-1.5...+1.0dB),
  • Power: ~220/240Vac, 50/60Hz, consumption 8W,
  • Output level and impedance: 600mV/2.2kohm,
  • Dimensions: 430x78x233mm, 2.5 kg.
Has a pleasant warm sound, selectivity is quite good. Has one problem: the muting level is too high, should be readjusted.
To be considered: no fuses are mounted inside of the tuner (they are shorted with wire). The transformer is continuously connected to the power supply, and the power switch connects only one secondary coil's voltage to the tuner circuit. The mQ1 regulator transistor stabilizes the input DC voltage from 18.5V to 13.5V - and the heatsink remains almost cool after several hours of operation.
Modifications:
Power circuit: mC3 from 470uF/25V to 2200uF/25V, mC4 from 330uF/16V to 470uF/35V, mC5 from 10uF/16V to 390uF/35V, dC36 from 220uF/16V to 470uF/35V, eC24 from 100uF/16V to 330uF/16V.
All electrolytes from the signal line were changed to polypropylene. The audio output capacitors (mC48L and mC48R) value was changed from 0.15uF/100V to 0.47uF/63V. Other below 10uF were changed to solid electrolytes or tantal capacitors.
The tuner is built from modules, like AM IF module, FM IF module, MPX module, signal level meter module, etc, and all are soldered to baseplate - not via sockets! This is a cheap solution but is a nightmare if you would like to repair any of them or to change all electrolytic capacitors. On the base plate are no components, just soldered modules. The straps which connect them are printed on the soldering side, on the top side can be seen a drawing of patterns from the bottom side, making it easy to recognize the trace. Also, the tuner has an electrolytic, which can be changed without desoldering the whole unit from the baseplate, because below the tuner module the baseplate has a cropped part, which easily can be permanently removed. The removed area has no trace or coverage with cupper - but by removing it you can change only one 10uF/50V capacitor from the tuner module.



Sanyo


Sanyo was founded when Toshio Iue the brother-in-law of Konosuke Matsushita and also a former Matsushita employee, was lent an unused Matsushita plant in 1947 and used it to make bicycle generator lamps. Sanyo was incorporated in 1949; in 1952 it made Japan's first plastic radio and in 1954 Japan's first pulsator-type washing machine. The company's name means three oceans in Japanese, referring to the founder's ambition to sell their products worldwide, across the Atlantic, Pacific, and Indian oceans.


Sanyo FMT-30L

Sanyo FMT-30L

General information:

  • Manufactured between 1978-80 by Sanyo Electric Co. Ltd. (on some portals is mentioned from 1972, but the used circuits appear later)
  • 3 band analog superheterodyne tuner, LW, MW and FM
  • Coverage: LW 150kHz - 350kHz, MW 520kHz - 1.620MHz, FM 87.5MHz - 108.0MHz
  • Antenna input impedance for FM: 300 ohms balanced and 75 ohm unbalanced, for AM ferrite rod and external antenna,
  • No preset memory for FM
  • Usable sensitivity: 700uV/m for LW, 300uV/m for MW, 1.2 uV on FM mono, and 50uV on FM stereo
  • Intermediate frequencies: 455kHz for AM, and 10.7MHz
  • AM RF/IF amp and detector IC: LA1240, FM IF amp and Quadrature detector LA1230, PLL MPX Demodulator LA3350.
  • Signal to noise ratio: mono 65dB, stereo 63dB and for AM 55dB
  • Harmonic distortion: mono 0.2%, stereo 0.5% for FM
  • Stereo separation at 1kHz: 40dB
  • AM suppression: 50dB
  • Image rejection: 50dB for FM, 40dB for AM
  • IF rejection: 80dB for FM, and 35dB for AM
  • Output frequency range: 20Hz - 15kHz
  • Power: 120/220Vac 50/60Hz, consumption 12W
  • Output power: 600mV
  • Dimensions: 420x135x265mm, 4.8 kg.
  • Original price at 1978: 448 DM

Good things:

  • Has air check capability (see the description at Fisher FM3210 tuner) with 400Hz signal at the output
  • Has 2 analog instruments for signal and tuning with a green backlight
  • Good sensitivity and selectivity on FM (the AM section is not so sensible)
  • Long scale with green backlight and the tunning knob runs extremely smoothly
  • After MPX demodulator IC has separate buffer circuits at the output. The MPX signal is filtered just with RC elements.

Problematic things:

  • Has no signal output connectors, the signal comes out on a cable with RCA sockets on the end.
  • Low sensibility on AM
  • Has just 2 position on band selector switch for MF: Stereo with Muting and Mono. That means for stereo always the muting is activated - which for DXing sometime is not good.
Has a beautiful and well-designed front plate. The scale and the meters are illuminated with a green light, but just the numbers or the marker lines on them are transparent. Unfortunately, the cursor has no light, it is a shiny metallic indicator.
The schematic is similar to the FMT 301 model: the tuner, the FM IF the MPX demodulation, and the power part are the same. Differences can be found in: the IF buffer stage between 10.7MHz ceramic filters, air check signal generator, and the whole AM circuit, including the LW, which cannot be found in the FMT 301 model.
The power is separated: 10.2Vac for bulbs (3 pcs of 12V/60mA: 2 for the scale and one for instruments), and 19Vac for the whole radio circuit. I purchase it with both scale bulbs burned. Both were replaced with 6-6 warm LEDs, each formed by 3 groups of 2-2 LEDs reversed in parallel connection including 22uF MLCC, and finally in series with one 33 ohm resistor (0.5W). The result: no vibration can be seen, is completely like a bulb's backlight.
The FMT30L has 3 gangs on the FM part with a FET front stage, and 2 gangs for AM, 1+2 (in total 3) 10.7MHz ceramic filters with one IF amplifier between them. The MPX decoder is made with the famous LA3350 with 1-1 buffer formed with one PNP transistor stage at outputs and is DC coupled with the output of MPX demodulator IC.
All electrolytic were capacitors replaced. Changed values: C26 , C61 and C63 470uF/35V Nichicon, C60 1500uF/25V Kemet ESW, C46 270uF/16V Oscon, C69 to 100uF/16V Oscon. C27, C41, and C42 now are 1uF/53V ERO foil capacitors.
The sound is full of bass - I think excessively, but is very pleasant, similar to Marantz 2100.



Sharp

/ Optonica


Sharp Corporation was founded in 1912 in Tokyo by Tokuji Hayakawa as a metal workshop. In 1923 the company was relocated to Osaka and began designing the first generation of Japanese radio sets. The company was established as "Hayakawa Metal Works" in 1924, in Tanabe-cho, Osaka. In 1942, the name was changed to "Hayakawa Electric Industry Company". The Optonica brand was created and first launched by Sharp in 1976 to compete in the high-end audio market along with established brands such as Sansui Electric, Sony, Panasonic, Sanyo, Yamaha, Nakamichi, Onkyo, Fisher Electronics, Technics (brand), Pioneer Corporation, Kenwood Corporation, JVC, Harman Kardon, and Marantz. The brand was designed and built by Sharp, not contracted out to another supplier, and all of the items offered were of high quality standards and built in Japan. Sharp Corporation was responsible for marketing the products. Marketed for a few years, the line and brand were discontinued in 1991.


Sharp Optonica ST-1122H

Sharp Optonica ST-1122H

General information:

  • Manufactured at 1978 by Sharp Corporation Japan in Osaka
  • 3 band analog superheterodyne tuner, LW, MW and FM
  • Coverage: LW 150kHz - 370kHz, MW 520kHz - 1.620MHz, FM 87.6MHz - 108.0MHz
  • Antenna input impedance for FM: just 300 ohms balanced,
  • No preset memory for FM
  • Usable sensitivity: 350uV/m for LW, 450uV/m for MW and 2.0 uV on FM mono (stereo not specified)
  • Intermediate frequencies: 455kHz for AM, and 10.7MHz
  • AM RF/IF amp and detector IC: RH-IX1032AFZZ (HA1151), FM IF amp and Quadrature detector 91TLA-1230B (LA1230B), PLL MPX Demodulator 91TLA-3350 (LA3350).
  • Signal to noise ratio: mono 60dB, stereo and for AM not specified
  • Harmonic distortion: mono 0.5%, stereo not specified, and 1.5% for AM
  • Output frequency range: 40Hz - 15kHz (-2...+2dB)
  • Power: ~110/220/240V/50Hz, consumption 7W
  • Output power: 350mV on FM and 200mV on AM
  • Dimensions: 390x142x257mm, 4 kg.

Good things:

  • Has air check capability (see the description at Fisher FM3210 tuner) with 400Hz signal at the output
  • Has very special legs, with jelly balls inside which eliminate any vibration
  • Good sensitivity and selectivity on FM
  • Long scale and the tunning knob runs extremely smoothly

Problematic things:

  • Has no signal output connector. The signal comes out on a cable with a DIN socket on the end. I changed it immediately to have RCA L+R, used in my system.
  • AM and FM antenna socket is very uncommon, difficult to find. I inserted just the end of wire into them as antenna.
  • No unbalanced (75 ohms) antenna input, but for that can be used the left signal input of 300 ohms antenna socket with the ground (from AM antenna connector)
  • No backlights for meters and scale. Was necessary to install it
This tuner was a big surprise for me, I did not expect to be so good. The reception is quite sensible, warm sound, but has less room and bass on bottom side of audio band. All electrolytic capacitors changed.


Sharp Optonica ST-1616H

Sharp Optonica ST-1616H

General information:

  • Manufactured between 1978-79 by Sharp Corporation Japan in Osaka
  • 3 band analog superheterodyne tuner, LW, MW and FM
  • Coverage: LW 150kHz - 370kHz, MW 520kHz - 1.620MHz, FM 87.6MHz - 108.0MHz
  • Antenna input impedance for FM: unbalanced 75 ohms and 300 ohms balanced,
  • No preset memory for FM
  • Usable sensitivity: 450uV/m for LW, 450uV/m for MW, and 1.6 uV on FM mono (stereo not specified)
  • Intermediate frequencies: 455kHz for AM, and 10.7MHz
  • AM RF/IF amp and detector IC: RH-IX1072AFZZ (HA1197), FM IF amp and Quadrature detector RH-IX1005AFZZ (HA1137W), PLL MPX Demodulator RH-IX1105AFZZ (HA11223)).
  • Image and IF rejection: 80dB at 98MHz on FM, 36dB at 1400kHz on MW and 35dB at 340kHz on LW
  • Signal to noise ratio: mono 62dB, stereo 55dB, for AM not specified
  • Harmonic distortion: mono and stereo 0.5% on FM, 1.5% on AM
  • Output frequency range: 35Hz - 15kHz (0...-3dB)
  • Power: ~110/220/240V, 50/60Hz, consumption 10W
  • Output power: 250mV on FM and 200mV on AM
  • Dimensions: 442x144x267mm, 4.7 kg.
  • Price at 1978: 468DM

Good things:

  • Has air check capability and Hi-blend filter
  • Good sensitivity and selectivity on FM
  • Long scale and the tunning knob runs extremely smoothly

Problematic things:

  • The cover seems to be fixed via 7-7 screws on both sides, but just 4-4 are used, the others are just for fun.
  • No backlights for scale, just the pointer area is illuminated. The sensitivity and tunning indicators have illumination from the top
The ST-1616 is a 4 gang tuner on FM, with a dual-gate MOSFET front-end. This tuner is really good, I really cannot understand why the Optonica brand is so neglected. The reception is quite sensible, with a warm sound on the whole audio band.
Modifications:
All electrolytic capacitors changed, in audio with pp, in power line below 100uF with solid electrolyte type.
R117 received in series one 10uH coil, R304 one 100uH coil, and the ZD401 is connected to the base of Q401 also via 10uH coil. R405 was removed.
Some capacitors value was changed: C212 to 470uF/35V, C314 100uF/25V solid electrolyte, C404 to 2200uF/25V, C405 to 470uF/35V, C406 to 390uF/35V, C419 to 470uF/35V.



Siemens


Siemens & Halske was founded by Werner von Siemens and Johann Georg Halske on 1 October 1847. In 1848, the company built the first long-distance telegraph line in Europe; 500 km from Berlin to Frankfurt am Main. In 1867, Werner von Siemens described a dynamo without permanent magnets. A similar system was also independently invented by Ányos Jedlik and Charles Wheatstone, but Siemens became the first company to build such devices. In 1881 the company continued to grow and diversified into electric trains and light bulbs. Siemens & Halske (S & H) was incorporated in 1897, and then merged parts of its activities with Schuckert & Co., Nuremberg in 1903 to become Siemens-Schuckert. In 1919, S & H and two other companies jointly formed the Osram lightbulb company. During the 1920s and 1930s, S & H started to manufacture radios, television sets, and electron microscopes. In the 1950s, and from their new base in Bavaria, S&H started to manufacture computers, semiconductor devices, washing machines, and pacemakers.
Siemens AG today is a German multinational conglomerate and a focused technology corporation headquartered in Munich and the largest industrial manufacturing company in Europe with branch offices abroad. The principal divisions of the corporation are Industry, Energy, Healthcare (Siemens Healthineers), and Infrastructure & Cities, which represent the main activities of the corporation.


Siemens RH777

Siemens RH777

This tuner was the top model in 1979 of Siemens, part of a 6 pcs system, called System 777 (other components: RC777 three heads microprocessor control cassette deck, RW777 pll quartz-controlled direct-drive turntable, RF777 infrared remote controller and timer, RP777 stereo preamplifier and RE777 stereo power amplifier). The whole system, without the turntable, cost 3,995 DM at 1979! Just the tuner price was 748 DM. The tuner inside has a lot of Sanyo components, and also on several webpages are highlighted as OEM Sanyo - but I did not find the same Sanyo tuner. The FM tuner input stage is the same as Sanyo T55, or Sanyo T33.

General information:

  • Manufactured: by (or for?) Siemens in Japan between 1979-1983
  • Digital 2 bands tuner with remote possibility, stereo with headphone, time and alarm function
  • 16 memory presets: 8 for FM and 8 for AM
  • Coverage: MW 516kHz - 1.605MHz, FM 87.5MHz - 108.0MHz
  • Sensibility: 0.7uV for FM mono, 31uV for FM stereo
  • THD: 0.2%
  • Stereo channel separation: 35dB
  • Frequency response: 20-15000 Hz
  • Signal to noise ratio: FM mono 70dB, FM stereo 60dB, and for AM not specified
  • Intermediate frequencies: 458kHz for AM, 10.7MHz for FM
  • AM tuner circuit: LA1130; FM IF amplifier: AN278; FM IF: HA11225; core cpu: SMC6200A; LED display drivers: BA612 and BA618 (2 pcs); signal meter: TL489, noise canceling circuit: TA7324; MPX decoder: uPC1161; CMOS RAM TC5501; prescaller HD10551; microcontroller: S871; PLL synteser: MSM5806; voltage regulators: FS7805 and FS7806M; logic circuits: TC4001, TC4081 (7 pcs), TC4069
  • Antenna input: 300 ohms balanced, 75 ohms unbalanced, for AM just external (no ferrite rod antenna)
  • Intermediate frequency suppression: better than 90dB
  • Output signal level and impedance: 700mV / 4kohm
  • Power: 220Vac/50-60Hz
  • Power consumption 15W
  • Dimensions: 440x545x300 mm
  • Weight: 5kg
  • Price at 1979: 748 DM

Good things:

  • Very logical design
  • Good selectivity and sensitivity on FM
  • Robust structure, well separated the power and controller part from the tuner part

Problems:

  • Has 2 transformers, one is permanently connector to the power line - supplying the CMOS RAM
  • No internal ferrite antenna. AM can listen just with an external one
  • Audio output socket is DIN type, nowadays rarely used
  • Internal stiffeners of chassis, especially at cable glands, has burrs and the cable packs have no extra protection.
  • The signal level indicator is very deep situated in the front panel, can be seen just if they are on your eye level or from a distance
Considering, this radio appeared on the market in 1979, had the newest technology from that era: auto scan, channel number display, channel scan, slow and fast manual tunning, 16 preset memory locations, 8 for FM and 8 for AM, dual-gate MOSFET FM input stage, 4 gang FM tuner, 4 ceramic filters (2 + 2 in series), output buffer after MPX decoder, special muting circuit, microprocessor control, PLL synthesizer circuit with CMOS RAM, powered with NiCd accumulators, which still works well! After 42 years from manufacturing, the radio has just a few components that were necessary to be changed: the relay to switch on the main transformer, and some electrolytic capacitors with still work but had high ESR value.
Differences from service manual: all 3 main PCBs (control with power supply, subboard and the tuner board) look like a product in design phase, with plenty of possibilities, unmounted but numbered parts which are missing from schematics. They are not different models with new functions. Only one additional component I found, with no position number: a 0.1uF tantalum capacitor between pin3 of IC5 (TA7324) and ground.
Modifications: instead of C86 and C87 (both 4.7uF in series connection) I mounted 2.4uF pp capacitor, and also instead of C88 and C89, both were 1uF connected in series, I mounted 0.49uF pp capacitor. In several position in the power line I increased or kept their values, but I mounted solid electrolyte capacitors.
In audio signal path I mount pp capacitors, just at output their values were increased from 2.2uF to 4.7uF.


Siemens RK 621

Siemens RK621

This is one of the most famous miniradio of Siemens from end of 80s - was also manufactured under brand name Sangean SG-789 by Chinese factory (like many other Siemens small receivers). The full model name is RK621 G4. Is a stereo radio via headphone, and has a high sensibility, also on LW!

General information:

  • Manufactured: manufacturing place not mentioned, but probably was made by Sangean to Siemens between 1985-1988
  • Analog 10 band (LW-SW-MW-FM)radio with 7 SW bands, stereo with headphone
  • No memory presets
  • Coverage: LW 150kHz - 300kHz, MW 530kHz - 1.710MHz, FM 87.5MHz - 108.0MHz (stereo with headphones)
      • Shortwave bands:
    • SW1: 5900 - 6200 kHz, 49 m
    • SW2: 7100 - 7350 kHz, 41 m
    • SW3: 9400 - 9900 kHz, 31 m
    • SW4: 11600 - 12100 kHz, 25 m
    • SW5: 15100 - 15800 kHz, 19 m
    • SW6: 17480 - 17900 kHz, 16 m
    • SW7: 21450 - 21850 kHz, 13m
  • Intermediate frequencies: 450kHz for AM, 10.7MHz for FM
  • FM tuner front end: TA7352AP; AM/FM IF: TA7757PP; stereo decoder AN7415; 2 audio amplifiers AN7117
  • Antenna syste: for LW and MW built in ferrite bar, for SW and FM teleskopic antenna
  • No any other data in user or service manual
  • Distortion: max 10%THD at max volume
  • Output power: 150mW/8 ohm (3" diam) in speaker or 2x20mW in headphones via 3.5mm stereo jack
  • Power: DC in 4.5V/200mA (negative pole inside), or 3 AA (R6 or UM-3) batteries
  • Dimensions: 162x87x28 mm, 335g without batteries

Good things:

  • Low power consumption
  • Good sensitivity on FM, LW (exceptional!) and MW
  • Tunning and stereo indicator via 1-1 LED
  • The sound is acceptable at this size

Problems:

  • No stand, and with antenna at maximum is instable
Is the best LW receiver in my small size radio collection.
After changing the high capacitance electrolytics to solid electrolytic capacitors, the sensibility increased significantly. Those were dried: ESR between 0.5-5 ohms, and loss higher than 3%. Surprisingly, have no contact problems on band selectors.


Siemens RK 747

Siemens KR747

This is an interesting world receiver - was also manufactured under brand name Sangean PT-633 (Pro Traveller) by Chinese factory (like many other Siemens small receivers) and Grundig Yacht Boy 218. The full model's name is RK747 G6. Can be set the time zones, alarm, tuning LED, adjustable sleep timer, stereo/mono switch, lock switch.

General information:

  • Manufactured: by Siemens D (S.& Halske / S. Electrogeräte) GmbH at 1996
  • Analog 9 band (SW-MW-FM) radio with 7 SW bands, stereo with headphone, time and alarm function
  • No memory presets
  • Coverage: MW 530kHz - 1.710MHz, FM 87.5MHz - 108.0MHz (stereo with headphones)
      • Shortwave bands:
    • SW1: 5900 - 6200 kHz, 49 m
    • SW2: 7100 - 7350 kHz, 41 m
    • SW3: 9400 - 9900 kHz, 31 m
    • SW4: 11600 - 12100 kHz, 25 m
    • SW5: 13570 - 13870 kHz, 21 m
    • SW6: 15100 - 15800 kHz, 19 m
    • SW7: 17480 - 17900 kHz, 16 m
  • Intermediate frequencies: 450kHz for AM, 10.7MHz for FM
  • AM/FM tuner circuit with stereo decoder: TA8122AN; amplifier: TA7376P; core cpu: SMC6200A; high precision voltage regulator: S81230
  • No any other data in user or service manual
  • Output power: 150mW in speaker or 2x10mW in headphones
  • Power: DC in 4.5V/200mA (negative pole inside), or 3 AA (R6) batteries
  • Dimensions: 145x86x31 mm, 320g without batteries (450 with)

Good things:

  • Low power consumption
  • Good selectivity and sensitivity on FM, the rest of bands is jut average
  • Has a stand, and using it can stay very stable on desk

Problems:

  • Too heavy to be a pocket radio
  • The sound regarding low speaker size (50 mm) is very sharp, but is good with stereo headphones
Is a good radio on FM, but on MW and all SW bands are not as good as Sony or XHData. Like other analog multiband receivers, the band selector switch is the heart of radio - must be maintained sometimes with contact spray. Despite its "young age", is better if all electrolytic capacitors are changed.



Sony


In 1946, Masaru Ibuka started an electronics shop in Shirokiya, a department store building in the Nihonbashi area of Tokyo. On 7 May 1946, Ibuka was joined by Akio Morita to establish a company called Tokyo Tsushin Kogyo (Tokyo Telecommunications Engineering Corporation). The company built Japan's first tape recorder, called the Type-G. In 1958, the company changed its name to "Sony". The name "Sony" was chosen for the brand as a mix of two words: one was the Latin word "sonus", which is the root of sonic and sound, and the other was "sonny", a common slang term used in the 1950s America to call a young boy. In 1950s Japan, "sonny boys" was a loan word in Japanese, which connoted smart and presentable young men, which Sony founders Akio Morita and Masaru Ibuka considered themselves to be. At the time of the change, it was extremely unusual for a Japanese company to use Roman letters to spell its name instead of writing it in kanji.
Sony played a major role in the development of Japan as a powerful exporter during the 1960s, till today. It also helped to significantly improve American perceptions of "made in Japan" products. Known for its production quality, Sony was able to charge above-market prices for its consumer electronics and resisted lowering prices.
Sony's TR-63 radio "cracked open the U.S. market and launched the new industry of consumer microelectronics. By the end of 1968 Sony, in one year, sold more than 5 million units of portable transistor radios in the USA.
As a major technology company, it operates as one of the world's largest manufacturers of consumer and professional electronic products


Sony STR-7055A

Sony STR-7055A

This is a nice Sony receiver from 1976, an improved version of STR-7055, and younger brother of STR-7065A. Was one of the biggest sales successes of Sony hifi in the seventies. Has a very beautiful front, seems to be built for eternity. The frontend and the mixer are with FETs, use 7 ICs, 48 transistors and 32 diodes. Are equipped with Loudness switch, High and Low filters (Off, High, Low or Both), Muting switch, Mode switch (Reverse, Stereo, L, R or L+R/mono), Monitor (can be selected Tape 1 & 2 as source), Speaker selector (can be selected between 3 pair of speakers: Off, A, B, C, A+B and A+C), Bass and Treble adjustment (can be adjusted together or separated both channels), Function switch (Aux, Phono, FM, AM, Tape1 to 2, Tape2 to 1 copy) and via a switch on back side the preamplifier can be disconnected/separated from amplifier (Separated/Normal). The Aux input sockets can be found on back and front side. The model 7065A has a higher power output (70W instead of 40W), and a microphone input which can be mixed into amplified signal. The difference between model 7055 and 7055A: the model A has an improved selectivity and sensibility of tuner. My version is Type I (differs from Type II from selectable AC power, AM IF is 468kHz and a bit less output power; and Type III operates just from 120Vac power line with permanently attached power cord, and the dimension of chassis is different: 471 x 157 x 375 mm, bigger than Type I or II).

General information:

  • Manufactured between 1976-1977 by Sony, made in Japan
  • 2 band analog superheterodyne receiver, MW and FM
  • Coverage: MW 530kHz - 1.605MHz, FM 87.5MHz - 108.0MHz
  • Antenna input impedance for FM: 300 ohms balanced, 75 ohms unbalanced,
  • Antenna for AM: build in ferrite core and external terminal
  • No preset memory for FM
  • Usable sensitivity: 1.6 uV on FM mono, no data for FM stereo; 30uV on AM
  • Intermediate frequencies: 455kHz for AM, and 10.7MHz for FM
  • Used ICs: FM IF amplifiers: CX-0412 2 pcs; MPX decoder HA1156; operational amplifiers CX-0462 4 pcs (the service manual indicate in this position CX-0461, but are same)
  • Signal to noise ratio: FM mono 70dB, AM 50dB
  • Output frequency range on FM: 30Hz - 15kHz (+-1dB)
  • Stereo separation (at 400Hz): 43 dB
  • THD: 0.2% for FM mono, 0.4% FM stereo, 0.8% for AM
  • Power output: 40W/8 ohms
  • Bandwidth: 10-100kHz within +0 dB...-1dB, with 0.1% THM at 1W/8ohms; 15-35kHz +-1dB 0.2% THM at 35W/8ohms
  • Damping factor: 50 at 8 ohms
  • Phono sensitivity/impedance: 2.0mV/47kohms, RIAA +-1dB
  • Phono Overload: 100mV RMS 1kHz 0.1% THD
  • RIAA curve deviation: +-0.5dB, 30...15kHz
  • Tape Play/Rec and Aux inputs sensitivity/impedance: 250mV/50kohms
  • Preamplifier output: 1V/4.7kohms; Amplifier input: 1V/50kohms
  • Bass control: +-10dB at 100 Hz
  • Treble control: +-10dB at 10 kHz
  • High Filter: 12dB/octave at 9kHz
  • Low Filter (Subsonic): 12dB/octave at 50Hz
  • Loudness: +10dB at 50 Hz and +4 dB at 10 kHz, attenuation 30dB
  • Signal to noise ratio: Phono 72dB, Tape1&2/Aux 90dB, Power amp 100dB
  • Power: 110V/120/220/240V 50/60Hz, consumption max. 320W
  • Dimensions: 471x157x375 mm, 15.3 kg.

Good things:

  • Has a very clean sound, brave bass
  • Has a separate transistor buffer at output instead of direct signal from MPX IC or via operational amplifier
  • Very good sensitivity and selectivity on FM, high stereo sensibility, good stereo space
  • Aux input on back and front panel
  • The preamplifier-amplifier can be separated via switch and both has RCA connectors

Difficult, problematic items:

  • No signal strength meter on front panel (7065A model has)
  • Difficult to repair regarding cable-jungles and PCB panels arrangement inside
With more than 44 years, is a receiver with a very pleasant sound. Was necessary to change all electrolytic capacitors, all bulbs, and to make fine adjustments after capacitors change (at MPX). The scale pointer, the Stereo indicator and the tuning meter backlight were replaced with LEDs. Power lines were improved (output buffer of MPX LC filter). Capacitors in signal path were changed to foil/PP type.
The radio on AM are with 2 gangs, on FM are with a 4-gangs variable capacitors, two IF amp stages, 2 pcs of 10.7MHz ceramic filters, and a Sony-made low-pass filter at radio output. At that time the new unit price was 1198 DM.


Sony STR-4800

Sony STR-4800

This receiver is in the middle of series of STR-2800 to STR-6800 from 76-78s. The Sony STR-4800 combines a high-performance stereo tuner and a powerful amplifier with a host of facilities, like a combined oscillator and tuning capacitor for high stability and accuracy, uniphase IF filter for high selectivity and low distortion, phase lock loop stereo decoder for high channel separation and low distortion, long linear tuning scale for ease of tuning, Tape1 to Tape2 copying facility. On the front panel you can find: A and/or B speaker selection switch, output for headphone, low and high filters switches, bass-, treble-, and balance control, low-, presence-, and loudness control, FM muting and mono switches, monitor switch for Tape1, Tape2 and copy from Tape1 to Tape2, function switch: phono, FM, AM and Aux, audion muting switch with -20dB, and AUX input also on the front panel.

General information:

  • Manufactured between 1976-1979 by Sony, made in Japan
  • 2 band analog superheterodyne receiver, MW and FM
  • Coverage: MW 530kHz - 1.605MHz, FM 87.5MHz - 108.0MHz
  • Antenna input impedance for FM: 300 ohms balanced, 75 ohms unbalanced,
  • Antena for AM: build in ferrite core and external terminal
  • No preset memory for FM
  • Usable sensitivity: 1.7 uV on FM mono, no data for FM stereo; 250uV/m with ferrite antenna, and 100uV with an external aerial antenna on AM
  • Intermediate frequencies: 455kHz for AM, and 10.7MHz for FM
  • Used ICs: FM IF amplifiers: HA1137W 2 pcs; MPX decoder HA1156; the Dolby are made with 2 pcs of noise cancelling operation amplifier CX064 (this is not mounted in my set, all related component positions are empty on tuner PCB); power amplifier SS050A (2 pcs),
  • Signal to noise ratio: FM mono 73dB, AM 50dB
  • Output frequency range on FM: 40Hz - 12.5kHz,
  • Stereo separation: 40 dB
  • THD: 0.2% for FM mono, 0.4% FM stereo, 0.5% for AM
  • Power output: 35W/8 ohms or 45W/4 ohms
  • Bandwidth: 10-35kHz within +0 dB...-1dB, with 0.1% THM at 1W/8ohms; 15-35kHz +-1dB 0.2% THM at 35W/8ohms
  • Damping factor: 35 at 8 ohms
  • Phono sensitivity/impedance: 2.5mV/50kohms, RIAA +-0.5dB
  • Phono Overload: 100mV RMS 1kHz 0.1% THD
  • RIAA curve deviation: +-1.0dB, 30...15kHz
  • Tape Play/Rec and Aux inputs sensitivity/impedance: 250mV/100kohms
  • Preamplifier output: 1V/4.7kohms; Amplifier input: 1V/50kohms
  • Bass control: +-10dB at 100 Hz
  • Treble control: +-10dB at 10 kHz
  • High Filter: 6dB/octave at 6kHz
  • Low Filter (Subsonic): 6dB/octave at 35 Hz
  • Loudness: +10dB at 50 Hz and +3 dB at 10 kHz,
  • Signal to noise ratio: Phono 70dB, Tape1&2/Aux 90dB,
  • Power: 110V/120/220/240V 50/60Hz, consumption max. 420W
  • Dimensions: 490 (W) x170 (H) x415 (D) mm, 13.9 kg.

Good things:

  • Has a very nice, classical front panel, with green color
  • The muting switch near the volume knob can decrease the volume with -20dB

Difficult, problematic items:

  • Some components are difficult to be found, like the Dual-C power capacitor made by Nichicon with 2x4700uF/50V in one can with 3 terminal (+2 unconnected). This capacitor was dried, measured values 3500uF and 2900uF
The construction of the receiver is very stable and is easy to repair: all PCBs are fixed via 2-3 screws on one side, and on the other are inserted in positioning holes of chassis. If you open the metallic frame with the PCB of the power amplifier and RIAA, and a metallic shield that isolates the radio from the audio part, you will have access to the radio PCB from the soldering side.
The ceramic filters are Murata type, SFJ10.7MA with 4 terminals and blue dot (10.67MHz). The transformer is well shielded, without noise. The volume potentiometer was necessary to be replaced, sometime gives scratchy noise.The scale pointer was made with LED, which is a miracle at that time!
The capacitors were mostly Sam Wha type, and just a few of them were Korean Chemical Com. I bought it with one amplifier channel dead. Root cause: one capacitor from the amplifier feedback network was dead (instead of 100uF I measured 2nF, completely dried). For that and regarding past 45 years, all electrolytes were changed. The first time I used dry electrolyte capacitors in the audio stage (470uF/6.3V, Oscon), and they do not influence the overall sound impression.
At that time the new unit price was 1120 DM.


Sony ST-J60

Sony ST-J60

In 1978 Sony launched the ST-J88 model, the company's first synthesizer tuner as "Crystal Rock Digital Synth" tuner with very good performance and great success. As its younger brother, the ST-J60 was Sony's second synthesizer tuner, and its operability and functionality were excellent. Surfing on the web, I found 2 versions under the same name: one with, and one without AM section. My is without AM, and I did not find the AM version's service manual - which means I cannot describe and check the AM circuit. In the front panels both have the same number of buttons: for AM version you can see an AM/FM band selector, on only the FM version this button has a Memory scan button. Based on the 1978 catalog, this was the first "slimline" after the famous tuners generation with big front plate (represented by ST-2950, ST-3950, ST-4950, ST-5950, ST-A6B, ST-A7B, etc). This slimline was represented by ST-J55, ST-J60, and the top of the line was the ST-J75. The ST-J60 has the varactor equivalent of 4 gangs, and it tunes in 0.1MHz (USA version in 0.2MHz) increments with either manual or automatic tuning, and 4 pcs of 10.7MHz ceramic filters with 280kHz bandwidth. Appears also under the name of Wega T700.

General information:

  • Manufactured between 1978-1979 by Sony, made in Japan
  • Is just an FM tuner
  • Coverage: FM 87.5MHz - 108.0MHz
  • Antenna input impedance: 300 ohms balanced, 75 ohms unbalanced,
  • 8 preset memory
  • Usable sensitivity: 1.2 uV on mono, 35 uV for stereo
  • Capture ratio: 1 dB
  • Intermediate frequencies: 10.7MHz
  • Used ICs: FM IF amplifiers: LA1231; MPX decoder KB4437; prescaler uPB552C, progamable divider uPD2819C, nonvolatile memory CX761, controller uPD552C-024, memory clock uPD4001, inverter uPD4069, muting and cal tone uPD4001 and uPD4069, signal level and multipath indicator LB1416, audio output operational amplifier uPC4558C
  • Signal to noise ratio: FM mono 77dB, FM stereo 72dB
  • Output frequency range on FM: 30Hz - 15kHz, +0.2...-0.5dB
  • Output signal level and impedance: 750mV/4kohm
  • Stereo separation: 48 dB at 100Hz, 50 dB at 1kHz, 45 dB at 10kHz
  • Image response ratio: 85dB
  • IF response ratio: 95dB
  • Spurious response ratio: 100dB
  • THD: 0.06% for FM mono, 0.08% FM stereo
  • IM Distortion: mono 0.06%, stereo 0.08%
  • Muting and auto tuning threshold: 5uV.
  • Calibration tone: 50% modulation(37.5kHz deviation), 400Hz.
  • Power: 110V/120/220/240V 50/60Hz, consumption 12W
  • Dimensions: 430 (W) x80 (H) x325 (D) mm, 3.7 kg.
  • Price at 1980: 748DM

Good things:

  • Bi-directional auto-tuning function, that allows you to automatically select the next station with a single touch of a button. A single touch of a button moves the 100 kHz tuning point, and holding it down moves it at a speed at which the digital display can be read.
  • Last tune function means that stores the last listened station in memory station It was equipped with a channel selection function such as memory.
  • In addition, the memory was equipped with permanent memory (non-volatile memory) that did not disappear even if the power was turned off and the outlet was unplugged.
  • The FM front end is equipped with a quadruple varicap equivalent to a quadruple variable condenser, and has a high spurious interference ratio of 100dB.
  • The MPX circuit uses the highly stable PLL MPX IC KB4437, and the pilot signal cancellation circuit realizes flat frequency characteristics up to high frequencies and excellent separation.
  • The tuner comes with a station name display - manually can be written station names, which is backlighted by LED when you select the related memory button.
  • The signal meter is based on 5 step LEDs and can also be used as a multipath indicator.
  • Sony has a very good balance/tonality and has a refined sound with exceptionally low background noise.
  • Has 5 voltage regulator circuits, separating the radio, audio and control units - this contributes significantly to the tuner's low background noise.
  • Is equipped with "CAL-TONE" that generates a test signal if 400Hz for adjusting the level of the cassette deck when checking the air.
  • Has a lighting sensor, which senses the lighting in the room and adjusts the brightness of the frequency display automatically. In a dark room the display is dimmed.

Difficult, problematic items:

  • Servicing is not easy: for the radio part you should unclamp backside connectors (audio and RF) and after removing PCBA's screws, you can be moved it up from the tuner side, the power wire remaining connected. In the case of the control part, at first, the whole front unit can be detached from the body via bottom and lateral screws, after you can remove the screws from the front PCBA, and last remove the screws of the main control PCBA you can move it up with the power wire connected.
  • There is no switching between WIDE and NARROW in the IF band, which was common in tuners in the 1980s, the reference frequency is still as low as 5KHz, and no measures are taken against residual noise. Measures have been taken for the high-end model ST-J75.
Sonically, this tuner is a mixed bag. In terms of pulling in and locking on to signals, it's stable in a way that people could only dream about five years earlier. Yet the audio quality is spoiled by the nasty, thin sounding 4558 op-amp output stage; this can usefully be upgraded to reveal a highly capable - if not quite top-flight - design. I check also the recommended OPA2604, but for me, the best was the LM4562.
The tantal capacitors from the audio signal path were changed to foil capacitors (4uF, respectively 10uF type, all Remix type from the end of '60s). In tuner and digital part capacitors with 16V nominal voltage now are dry electrolyte type, in the rest of power line Yageo, CapXon, and Rubycon elecrolytics.
The metalized-paper capacitors from the main switch were necessary to change it immediately: were cracked, dried, and their capacitance instead of 22nF was a few hundred pF (between 100-310pF) -> changed to 10nF/1kV ceramic type. After the power switch received an EMI filter (.68uF+2x7mH+.68uF+2.2nF).
The best thing about this tuner is its clean, retro-futuristic styling, fine ergonomics, and the fact that this long-lost, once-high end design can be picked up for pennies now.
Now the sound is equilibrated in the whole spectrum. I recommend it as an FM tuner in your high-end, because can beet the Sony's with big front, and almost any modern tuners from today.


Sony STR-232L

Sony STR-232L

This receiver is in the bottom line of 1979 models. Models in that era: STR333L, STR434L (both with LED signal/tunning meters), and top models STR-V3, -V4, -V5 and -V6. Has just the basic functions: lourdness switch, separate tone control (bass and reble), automatic muting in stereo mode, stereo indicator light and headphone socket. It appears that this device is a newer version of the STR-222L model (different circuit, better performance, higher output power, and instead of wood cover, now is plate).

General information:

  • Manufactured between 1979-1980 by Sony, made in Japan (under the name PSS-200R by Wega in Europe)
  • 3 band analog superheterodyne receiver, LW, MW and FM
  • Coverage: LW 150kHz - 350kHz, MW 530kHz - 1.605MHz, FM 87.5MHz - 108.0MHz
  • Antenna input impedance for FM: 300 ohms balanced, 75 ohms unbalanced,
  • Antena for AM: build in ferrite core and external terminal
  • No preset memory for FM
  • Usable sensitivity: 1.7 uV on FM mono, no data for FM stereo; 250uV/m for MW with ferrite antenna, 500uV/m for LW with ferrite antenna, and 100uV with an external aerial antenna on AM
  • Intermediate frequencies: 455kHz for AM, and 10.7MHz for FM
  • Used ICs: FM IF amp, FM det, AM RF amp, AM IF amp, AM det, AM osc, AM mix, demod: CX168; MPX decoder CX178; power amplifier HA1350S (2 pcs),
  • Signal to noise ratio: FM mono 73dB, FM stereo 68dB, AM 52dB at 5mV
  • Output frequency range on FM: 30Hz - 15kHz, +0.5...-2dB
  • Stereo separation: 45 dB at 1kHz
  • THD: 0.3% for FM mono, 0.5% FM stereo, 0.3% for AM (at 400 Hz)
  • AM suppression Ratio on FM: 54dB
  • Image Response Ratio on FM: 45dB
  • Spurious Response Ratio on FM: 75dB
  • Power output of amplifier: 20W/8 ohms
  • Speaker load impedance: 8-16 ohm
  • Bandwidth: 10-50kHz, +0.5...-3dB
  • THM at 1W/8ohms: 0.3%; 0.7% THM at 18W/8ohms
  • Damping factor: 20 at 1kHz/8 ohms
  • IM Distortion (60Hz:7kHz=4:1): 0.3%; 0.7% THM at 18W/8ohms
  • Residual Noise: less than 0.08uW at 8 ohm
  • Phono sensitivity/impedance: 2.5mV/50kohms
  • RIAA curve deviation: +-1.0dB, 30...15kHz
  • Tape Play/Rec inputs sensitivity/impedance: 250mV/100kohms
  • Signal output (record): 150mV/10kohm
  • Bass control: +-8dB at 100 Hz
  • Treble control: +-8dB at 10 kHz
  • Loudness: +8dB at 100 Hz and +3 dB at 10 kHz - measured at 30dB att.
  • Signal to noise ratio: Phono 70dB, Tape 90dB - measured at 1kHz,
  • Power: 220V 50/60Hz, consumption max. 110W
  • Dimensions: 410 (W) x145 (H) x305 (D) mm, 5.9 kg.

Good things:

  • Has a very nice, classical front panel, with warm background light

Difficult, problematic items:

  • No tunning indicator, just signal strength meter
This unit was also manufactured in Europe by Wega in Germany under the name Wega PSS-200R (Sony purchased WEGA in 1975).
The construction of the receiver is very stable and excepting some stiffening plates, which cover some parts of the PCB on the soldering side, you have easy access to all components.
The ceramic filter is TAIYO type, CF-107-D with 3 dots on the top's left side: red, silver and orange. Contain 2 group of double (in total 4) ceramic filters, and has 4 pins, 2-2 on both ends.
The transformer is impregnated in a plastic house, without noise - not shielded.
All capacitors were Elna type. Is interesting, the pop-up circuit without relay, just with a delay signal to the audio power ICs.
The used radio circuits, the CX168 and CX178, are soo old, cannot be found any datasheet about them on the net - just some block diagram in the service manual.
Is a nice, small unit, with relatively low output power, which sounds much more better than any current mini Chinese amplifier. Should be used with speakers which have higher impedance then 8 ohm!


Sony ST-JX3L

Sony ST-JX3L

General information:

  • Manufactured in 1982 by Sony Tokyo
  • 3 band analog PLL tuner LW, MW, and FM
  • Coverage: LW 153 - 344 kHz, MW 522 - 1602 kHz, FM 87.5 - 108.0 MHz
  • Antenna input impedance for FM: 300 ohms balanced, 75 ohms unbalanced,
  • No preset memory for FM
  • Usable sensitivity: 60uV on AM, 1.4 uV on FM (mono) and 40 uV for stereo
  • Intermediate frequencies: 450kHz for AM, and 10.7MHz for FM
  • AM tuner IC: LA1245 amp, osc, IF and det; FM det. LA1235; AFC uPC4558C; stereo decoder (MPX) LA3390; signal indicator LB1416; and one double amplifier inside FM tuner which cannot be clearly identified
  • Output frequency range: 30Hz - 15kHz (+0.3dB...-2.0dB)
  • Signal/noise ratio: AM 54dB, FM 85dB mono, 80dB stereo
  • THD: on FM 0.08% for mono, and 0.12% for stereo
  • Stereo separation: 50dB
  • Channel balance: 0.2dB
  • Power: ~220V/50Hz, consumption 12W
  • Output power: 750mV/4.7kohm
  • Dimensions: 430x55x337mm, 3.4 kg.
Has an average sound, selectivity is good, but the output load should be higher than 1.9kohm because if is less, the audio level drops and the noise will increase.


Sony ICF-7600AW

Sony ICF-7600AW

Is a predecessor of the famous Sony ICF-7600, looking very similar, but supporting a lot of major and minor improvements under the hood. Appearing the dual conversion concept on shortwave (before was very unconventional) and received a total of seven shortwave bands with increased band coverage. Selectivity and sensitivity on mediumwave and shortwave also are very good, along with decent overload rejection. The effective tone control and nice audio section and speaker were taken over from the previous model, and the power consumption remained low.

General information:

  • Analog shortwave portable (dual conversion):1st IF: 10.700 MHz; 2nd IF: 455 kHz
  • Coverage: MW 530-1605kHz, FM 76 - 108MHz (the W mark means West version, and those have a shorter FM band: 87.5-108MHz)
  • SW is not continuous, is divided in 7 bands:
    • SW1: 5950 - 6200 kHz, 49 m
    • SW2: 7100 - 7350 kHz, 41 m
    • SW3: 9500 - 9800 kHz, 31 m
    • SW4: 11700 - 12000 kHz, 25 m
    • SW5: 15100 - 15450 kHz, 19 m
    • SW6: 17700 - 17900 kHz, 16 m
    • SW7: 21450 - 21750 kHz, 13 m
  • No memory preset possibility
  • Antenna: ferrite rod inside for AM and external telescopic
  • Signal strength indicator: Tuning LED
  • FM filters: 1x 280 kHz (super wide, but can be changed to 180/150 kHz low loss type)
  • FM/AM front end+IF discriminator and amplifier HA12413; power amplifier uPC1212C
  • Output impedance and power: 8 ohm 350 mW max @ 10% distortion, diameter 77 mm
  • Dimensions/weight: 180 x 120 x 35 mm, 448 g (incl. batteries)
  • Power: four AA batteries or external 6V (minus is the center pin!)
  • Produced: 1982 ... 1988, replaced by Sony ICF-7601

Good things:

  • The noise level on MW and SW is very low
  • Very good selectivity and sensitivity on all bands
  • The dual conversion design does result in a smaller number of unwanted ghost signals that you find on single conversion sets in this price range, but is not as good as in as started from ICF-SW7600
  • Very low power consumption (more than 40 hrs with conventional AA batteries).
  • Audio tone control with 3 positions: Normal, Low (cut treble), and High - for FM, music
  • Has audio line output, 0.775V level/1kohm.

Problems:

  • No light to illuminate the scale
  • No external antenna connection possibility
  • No provision for single-side band
  • The headphone jack is just mono, with a stereo headphone you can hear just in the left speaker.
  • The band selector switches are the headache of this model. After certain time must be cleaned, later changed.
Remark:
My set was made in Japan, inside of set and also on the package box has the same serial number (125792), but the FM coverage is 76-108MHz. That means should be a Japanese version, an ICF-7600A model instead of ICF-7600AW (probably the previous owner changed the hod). This makes a bit difficult to set the radio to a certain frequency because the scale is marked from 88 to 108MHz, and I use the range of scale from 96 to 108 MHz for the rage 88-108 MHz. The selectivity is very good, and cannot be heard any adjacent channel.


Sony ICF-7601L

Sony ICF-7601L

Is also a predecessor of the famous Sony ICF-SW7600, and the successor of ICF-7600A, but compared with that has more SW bands. With the ICF-7601L, Sony explicitly addressed the friends of the simple receiver. In this respect, however, the double conversion set the quality bar high, the reception quality of the Sony was only rudimentarily copied by numerous similar devices with analog dials - from the Chinese ones to the last generation Grundig devices with internals from the Far East. The version ICF-7601 has 10 SW + MW and FM bands (in total 12). The ICF-7601L has 9 SW bands + LW +MW + FM band (called European version), also in total 12 bands. Instead of mechanical buttons used in ICF-7600AW, here are electronically switched buttons, there is still an OFF button to switch off the set - but this is the most problematic part of this set.

General information:

  • Analog shortwave portable (dual conversion):1st IF: 10.700 MHz; 2nd IF: 455 kHz
  • Coverage: LW 145-285kHz (just on ICF-7601L), MW 530-1605kHz, FM 87.5 - 108MHz
  • SW are not continuous, are divided in 9 (ICF7601L)/10 (ICF-7601) bands:
    • LW/SW1: -/2200 - 4200 kHz, 120 m
    • SW1/SW2: 4600 - 5200 kHz, 60m
    • SW2/SW3: 5080 - 6400 kHz, 49 m
    • SW3/SW4: 6900 - 7500 kHz, 41 m
    • SW4/SW5: 9400 - 1000 kHz, 31 m
    • SW5/SW6: 11550 - 12150 kHz, 25 m
    • SW6/SW7: 13450 - 15450 kHz, 21 m
    • SW7/SW8: 15000 - 15650 kHz, 19 m
    • SW8/SW9: 17500 - 18150 kHz, 16 m
    • SW9/SW10: 21350 - 21950 kHz, 13 m
  • No memory preset possibility
  • FM filters: 3x 280 kHz (super wide, but can be changed to 180/150 kHz low loss type)
  • FM/AM front end+IF discriminator and IF amplifier + power amplifier CX-20091; electronic switch for band selection uPD65005C-198
  • Output impedance and power: 8 ohm 350 mW max @ 10% distortion, speaker diameter 77 mm
  • Dimensions/weight: 192.5 x 122 x 35 mm, 570 g (incl. batteries)
  • Power: four AA batteries or external 6V (minus is the center pin!)
  • Produced: 1988 ... 1993 by Sony in Japan

Good things:

  • The noise level on MW and SW is very low
  • Very good selectivity and sensitivity on all bands
  • The dual conversion design does result in a smaller number of unwanted ghost signals that you find on single conversion sets in this price range, but is not as good as in as started from ICF-SW7600
  • Very low power consumption (more than 30 hrs on FM and more than 26 hrs on SW with conventional AA batteries).
  • HOLD switch - deactivates all 5 push buttons: FM, MW, SW1/LW, SW2-10/SW1-9 and Power Off

Problems:

  • No light to illuminate the scale
  • No external antenna connection possibility
  • No provision for single-side band
  • No signal level indicator
  • The headphone jack is just mono, with a stereo headphone you can hear just in the left speaker.
  • The band selector electrical switch is also the headache of this model: the uPD650005C (programmed CMOS gate array) is very sensible for ESD, and often became damaged. No replacement can be found.
  • Highlighted in the service manual: channels 5903kHz, 6207kHz, 11503kHz, 11958kHz, and 21870kHz may be difficult to receive due to internal spurious signals generated by the built-in oscillators.
Remark: "The biggest weakness of this rig is the intermodulation behavior of the second mixer - and this in spite of the FET already being quite heavily source degenerated at 33 kOhms. The problem basically is that the rx is constructed like a gain-limited low-voltage design and has too much gain (especially) in the RF amp and (not so much) the 1st mixer in combination with a wideband 1st IF, plus I guess the 2SK209-Y in the second mixer just isn't that great in terms of linearity." by Stephan Großklaß. Solution: Experiment with the value of pull-down resistor R15 (47k) to ensure that switching diodes D6, D7 are doing their job properly or decreasing the value of R30 (presently 3k9) to allow a higher V_CE and thus output voltage swing.


Sony ICF-SW7600

Sony ICF-SW7600

General information:

  • Digital shortwave portable (dual conversion): 1st IF: 55.8425 MHz (SW: 55.845 / 55.840 MHz, LW: 55.845 / 55.842 MHz); 2nd IF: 455 kHz
  • Coverage: AM 150kHz - 30MHz, FM 76.0MHz - 108.0MHz (stereo with headphones)
  • 5 kHz steps on all SW; LW: 3 kHz, MW: 9/10 kHz (selectable), FM: 100 kHz (depending by destination countries!)
  • 10 presets
  • SSB reception capability (LSB and USB)
  • Fine tuning for AM and SSB (officially +/- 5kHz, Radio Netherlands measured +/- 7 kHz) - but is not followed by frequency meter!
  • External antenna jack
  • Rec out jack (mono, mic level), plus remote jack for tape recorder switching (I never tested or use it)
  • Alarm and sleep functions
  • Frequency synthesizer / microcontroller: µPD1715G
  • Output: 400 mW max @ 10% distortion
  • Dimensions/weight: 191 x 118 x 32 mm, 615 g (incl. batteries)
  • Produced: 1990 ... 1993

Good things:

  • Low noise, good sensitivity (comparable to SW7600G, even a bit better on the low SW bands)
  • Good selectivity
  • Good frequency stability (no LO pulling) even on the high bands

Problems:

  • 5 kHz steps on SW are a bit coarse, especially for tuning SSB stations
  • Modest FM strong-signal handling and sensitivity (in case of SW7600G or SW7600GR is much better)
  • 10 presets for both AM and FM part together is very weak

Defects:

  • Typical of this model - dead electrolytics regarding poor SMT technology at that time

How I recognized which capacitors must be changed?

  • Lamp’s on/lighting time was very short
  • Audio part: FM stations sounds like AM part, almost no quality difference,
  • Often knocks at beginning of FM receiving, but after also sometime during listening.

What kind of capacitors I used?

  • For audio output and power: 470uF/10V and 1000uF/6.3V  Sanyo through hole electrolytics. All other electrolytics, like 4.7uF, 10uF, 22uF and 47uF I use tantalum, excepting audio part,
  • All audio amplifier parts (47uF/10V and 100uF/6.3V) I used Panasonic SMD electrolytics.
  • On power lines, I used tantalum capacitors
The result is quite exciting. Now really can enjoy stereo FM (with headphone).
Tantalum has its own advantage: because mostly are used for filtering (power supply or bypass), are better than electrolytics in this position.

Difficulties, what I meet:

  • In case of some electrolytics the electrolyte comes out. Does not damage the PCB pattern, but the surface of soldering are oxidized. That means is difficult to take out those capacitors – you should have a very good soldering skill (and station) to melt this composite.
  • The electrolyte goes under PCB pattern protection film, which should be removed with a glass fiber brush from damaged areas and covered the Cu pattern with solder.


Sony ICF-SW30(L)

Sony ICF-SW30

Is a portable short wave receiver for budget end of market. Sony says the ICF-SW30 is the smaller brother of ICF-SW33...in fact though it is much better value. Was the grandfather of ICF-SW55.

General information:

  • Manufactured between 1993-1996 by Sony in Japan
  • Alarm and sleep functions
  • Digital shortwave portable (dual conversion):1st IF: 10.700 MHz; 2nd IF: 500 kHz (use a 10.2 MHz quartz oscillator for conversion).
  • Coverage: AM 153-280kHz (marked as SW30L, was made just for UK and France market, but is difficult to modify the radio for LW reception), MW 531-1710kHz, FM 87.5 - 108MHz (stereo just with headphones). FM can be set to start from 76MHz via internal jumper. One of my set use the whole FM band from 76.00 MHz to 108.00 MHz.
  • SW are not continuous, are divided in 10 bands: 3700- 4200kHz, 4650-5150kHz, 5800-6300kHz, 6950- 7450kHz, 9375-10000kHz, 11525-12150kHz, 13375 -14000kHz, 14975-15600kHz, 17475-18100kHz, 21320-21950kHz
  • Adjusting steps: 1 kHz steps on SW, MW: 9/10 kHz, FM: 50 kHz steps
  • Synchronous detection
  • 15 presets (5 MW / 5 SW/ 5 FM) + 2 timer memories
  • AM bandwidth: nominal 5 kHz,
  • FM filters: 1x 280 kHz (super wide, but can be changed to 180/150 kHz low loss type)
  • Frequency synthesizer / microcontroller: µPD1724G
  • FM/AM front end+IF discri&amp CX20111, MPX LA3335M, power amp CXA1522M, 2V reg LA5002M, 3V reg S-81230AG, uOC393G battery detect
  • Output: 260 mW max @ 10% distortion - comes from a 8ohm, 0.3W with 66mm diameter speaker
  • Dimensions/weight: 169 x 112 x 35 mm, 448 g (incl. batteries)
  • Power: via 3 pcs of AA batteries or external wall plug/AC adapter, part of the pocket
  • Consumption: 25mA on MW, 30mA on FM and 50mA on SW

Good things:

  • The noise level of SW-30 is remarkably low
  • The dual conversion design does result in a smaller number of unwanted ghost signals that you find on single conversion sets in this price range.
  • Has Local/DX, tone and lock switches

Problems:

  • No light to illuminate the liquid crystal display in dark
  • No keypad for direct frequency entry
  • automatic scanning uses 1kHz on SW; 9 or 10kHz on LW and MW; and 50kHz steps on FM, but that only runs upwards, not downwards
  • no external antenna connection possibility
  • no provision for single-side band
  • a bit less sensibility compared with ICF-SW7600 family, including on FM
  • 15 presets, just 5 for FM or SW is very weak.
  • to jump from one end of the dial to another may take a bit of getting used to.
      • Recommendation: I changed the CF1 10.7Mhz (Murata type with 280kHz BW and 6-7dB loss) ceramic filter with a TDK 10.7MS type (3-4dB loss, 150kHz BW), and the sensitivity lightly increased on FM, and no any adjacent programs can be heard.
      Regarding small size, I recommend to change the normal electrolyte capacitors with solid electrolytic capacitors.
      Original price was 199 DM.


Sony ICF-SW7600G

Sony ICF-SW7600G

General information:

  • Digital shortwave portable (dual conversion):1st IF: 55.845 MHz; 2nd IF: 455 kHz
  • Coverage: AM 150kHz - 30MHz, FM 76MHz - 108MHz (stereo with headphones)
  • 1 kHz steps on LW/MW/SW plus a frequency grid: LW: 9 kHz, MW: 9/10 kHz, SW: 5 kHz; FM: 50 kHz steps
  • Synchronous detection
  • SSB reception (LSB and USB)
  • Fine tuning for SSB only (officially +/- 1.5 kHz, rather +/- 2kHz) - but is not followed by frequency meter
  • 20 presets (10 AM / 10 FM) + 2 timer memories
  • External antenna jack
  • Rec out jack (stereo, line level - I never used them)
  • Alarm and sleep functions
  • AM bandwidth: nominal 4 kHz, real more like 7 kHz (filter data: see the section about the filters below)
  • FM filters: 2x 280 kHz (super wide, but can be changed to 150/110 kHz low loss types)
  • Frequency synthesizer / microcontroller: µPD1724G
  • Output: 400 mW max @ 10% distortion
  • Dimensions/weight: 191 x 118 x 32 mm, 615 g (incl. batteries)
  • Produced: 1994 ... 2000

Good things:

  • 4 tuning keys is good (2 for fine, 2 for coarse), and entering and recalling frequencies is pretty simple
  • Good selectivity.
  • Low LO phase noise, up to 27 dB on modified sets.
  • Best-in-class SSB reception - as opposed to most other compact portables, its product detector is sideband selective. Other-sideband AGC pulling still is annoying but one cannot expect true SSB filters in this league.

Problems:

  • Muffled AM audio - this is somewhat better with sync on, but weaker stations where that doesn't work too well. Its predecessors ICF-SW7600 sounds better. The SW7600G's tone switch only allows selecting between muffled and more muffled, which is hardly helpful -> see below how to improve it
  • The sync detector generates noise of its own and fails to lock on very weak signals. Normally sync detectors help with weak stations with fading, but in this case only the sideband separation can be used. If there is a weak station with interference, SSB should be used, which is much easier to do than with the older models.
  • On batteries, sensitivity straight off the whip isn't too exciting due to lack of an RF ground. Connecting a power supply, RF ground or using an external antenna helps.
  • The power supply jack is prone to connection problems and its polarity are inverted in comparison with SW7600 model -> you cannot use same power supply. In case of both models is soldered directly onto the circuit board, which means mechanical stress may damage the solder joints or even the PCB. If such a connection problem occurs, the jack needs to be re-soldered.
  • 20 (10+10) presets for both AM and FM part are still very weak.
  • Stereo output is only possible with headphones plugged in, even if using the rec out jack.
  • Weak bass reproduction even on headphones due to overly small coupling capacitors - this contributes to the overly mid-centric AM audio also on FM band.

In this radio I corrected/modified just 4 things:

  • The light diminishes within 15 seconds -> changed capacitor C206 47uF/6.3V with 150uF/4V TA ultra slim SMD type. Now the light dims approx 50 seconds.
  • In DC-DC converter the electrolytic capacitor (C605 22uF/16V) was changed into TA type (more suitable for several kHz frequencies)  22uF/20V TA.
  • Audio amplifiers output capacitors C512 220uF/6.3V connected to speaker/left channel phone and C514 47uF/16V connected to right phone channel both changed into 330uF/6.3V Panasonic type. Now the sound is more pleasant, also in both headphone speakers.
  • Tone mode switch circuit modification:
Sony SW7600G tone circuit
Originally the S4-1 tone switch in Music mode disconnect the C456 capacitor, the signal goes through C450 in series with C449 (the equivalent capacitor is approx 66nF). In News mode with S4-1 grounds the signal via C456, cutting the high frequency of audio. That method made the poor quality of sound also in FM mode, especially at low frequencies.
Modification: the unconnected pin of S4-1 with a wire are connected to out of C449, shortening it in Music mode, the signal goes just through C450 - coupling the amplifier via 1uF instead of previous equivalent 66nF.
With this easy modification and with changed output capacitors the sound became more pleasant. Can be heard the difference when you select on the Tone switch the News or Music on FM, and sounds like the old predecessor, the SW7600.


Sony ST-SE500

Sony ST-SE500

This tuner was part of the middle line of the SE series (the bottom was the SE300, and the top SE700). The difference between later appeared sets (SE520, SE570) are just design related, as electrical circuits all are the same. Has RDS-EON/Radio Text decoding possibility, and can display the signal level value (selectable just from the menu) or the level with bars during the reception. Was sold in black and silver color.

General information:

  • Manufactured by Sony (my set was made in France) between 1997-2000
  • Digitally tuned analog superheterodyne receiver
  • Coverage: LW 144kHz - 288 kHz, MW 522kHz - 1611 kHz, FM 76MHz - 108MHz
  • Tunning stept: LW 1kHz, MW 9kHz, FM 50kHz steps
  • Has 30 presets in 3 banks (A, B, and C)
  • Antenna: aerial or loop for AM, 75 ohms unbalanced for FM
  • Sensitivity: 0.9uV for mono, 23uV for stereo on FM, 1000uV on LW, 300uV of MW
  • Intermediate frequency: 10.7MHz for FM, 450kHz for AM
  • Signal/noise ratio: 74dB for mono, 69dB for stereo on FM, 54dB for MW, 50 dB for LW
  • Used integrated circuits: LA1851 DTS tuner, LC72130 AM/FM PLL synthesizer, LA1235 FM IF, BU1922 (SAA6579) RDS decoder, uPD78205GF system controller and display driver, voltage regulator LA5667, operational amplifier 2 pcs, detector and audio line driver JRC4558D
  • THD: 0.1% for mono, 0.2% stereo on FM, 0.3% on AM
  • Channel separation: 40dB at 1kHz
  • Selectivity: at 400kHz 80dB, at 300kHz 60dB on FM, 32dB on AM
  • Frequency response: 30Hz - 15kHz +0.5--1dB
  • Power consumption: 10W
  • Power requirement: 220-230Vac, 50/60Hz
  • Dimensions/weight: 430 x 80 x 295 mm (W/H/D)
  • Weight: 2.7kg

Good things:

  • Clear design
  • Good selectivity an FM and MW bands
  • Big display with the dimming possibility (in steps)
  • Radio Text reception via RDS-EON
  • Remote controlling possibility

Problems:

  • Cannot be set the Radio Text to be "always on". This means if you change the station, you can select the RT function again from the menu.
  • No voltage selection possibility for power line - I have the 220Vac version, but in my home the power line voltage is 238Vac, and the voltage regulator is hot after several hours of listening.
  • Repair is challenging since the tuner's ground is connected to the screw that holds the antenna connector to the chassis, and the connector is soldered to the PCB, making it impossible to remove. Another challenge is that the entire tuner, including all RF components, synthesis circuitry, and demodulator circuits, is assembled on a separate PCB made by Alps and attached to the main board together with its 29 pins and shielding pale's pins. This indicates that you were denied access to this RF part's soldering side.
When you open the chassis, you'll be shocked to see a sizable mainboard that's almost completely empty, along with the voltage regulator, system controller, RDS decoder, detector, audio output operational amplifiers, one FM IF detector, and another PCB that's packed with RF components. The RF component is made by Alps (FS215-32), and it was likely pre-adjusted, meaning that the production cost was kept to a minimum at the French assembly facility. Philips also uses the LA1851 IC in their FT920 and FT930 tuners, and their SE500 facilities are identical to their FT930 facilities.
The tuner section is pretty straightforward: on FM, there are 3 gangs, followed by 2 ceramic IF filters (both Murata 10.7S with a red dot on the top-left side), and on AM, there are 2 gangs.
Changes: I installed an EMI filter (0.47uF+2x12.4mH+1.5uF) between the power switch and the transformer because it is a must for modern tuners. The switching power source of my laptop or an LED bulb no longer interferes with MW reception. In the RF PCB tuner supply supply circuit 220uF -> 270uF/16V, ICs supply (LC72130 and LA1851) 47uF -> 100uF/16V. From the main board changed caapcitors: C205 100uF/16V, C319 470uF/35V, C809 270uF/16V, C905 330uF/50V, C909 390uF/35V. The power line of IC201 (FM IF) and IC802 (RDS) received 1-1 coil of 2.2uF for noise suppression.
Is a decent general-purpose tuner with the potential for RDS/EON RT, but nothing special. Compared to the features and electronics of other models, I believe was a little overrated.


Sony ICF-SW11

It is a complete analog receiver, with a modern look, but "feels" cheap. Apparently, you did not expect too much from this, and later you will be surprised, especially if you mode it a bit.

General information:

  • Manufactured: Sony since 1999. My version was made in Japan, but now is produced in China
  • Analog 12 band (LW-MW-SW-FM) superheterodyne, stereo via jack / not selectable
  • No memory presets
  • Coverage: LW 141kHz - 290kHz, MW 525kHz - 1.620MHz, FM 87.5MHz - 108.0MHz (stereo with headphones), and 9 SW bands:
    • SW1: 4750 - 5060 kHz, 60 m
    • SW2: 5900 - 6200 kHz, 49 m
    • SW3: 7100 - 7350 kHz, 41 m
    • SW4: 9400 - 9900 kHz, 31 m
    • SW5: 11600 - 12100 kHz, 25 m
    • SW6: 13570 - 13870 kHz, 21 m
    • SW7: 15100 - 15800 kHz, 19 m
    • SW8: 17480 - 17900 kHz, 16 m
    • SW9: 21450 - 21750 kHz, 13 m
  • Intermediate frequencies: 450kHz for AM (single convertion), 10.7MHz for FM
  • Used ICs: AM/FM tuner circuit with stereo decoder: CXA1238M and amplifier: CXA1522M
  • Signal/noise ratio: no info
  • Sensitivity: no info
  • Output power: 0,14 W in speaker (4 ohms/57 mm) or 2x5mW in headphones, THD max 10%
  • Power: DC in 3V (700 mA), or 2 AA (R6) batteries. Current consumption (max): FM 22.2 mA; MW: 79.0 mA; LW: 79.0 mA; SW: 14.6 mA
  • Dimensions: 162 x 93.8 x 34.8mm, 0.34 kg including batteries

Good things:

  • In general high sensibility, including also the LW
  • Low power consumption, especially on FM and SW
  • Has a flip-stand on the backside, and the battery door is connected to the chassis against loss
  • The mechanism for indicating the selected band, moving the scale and gears to rotate the variable capacitor is top of the class.

Problems:

  • No stereo indicator, no mono/stereo switch
  • No tone control
  • The physical dimensions are too big to be used in any pockets.
Generally, is a good radio. Internally is very similar to Panasonic RF-B11 (which sounds better regarding the higher diameter of speaker, has 2 FM IF ceramic filters in serial connection, and has stereo indicator, mono/stereo and tone switches) and Philips AE3405.
Modifications:
First time I used solid capacitors on power audio output (generally are designed for power line filtering), and the result is good: C61 100uF/6.3V and C66 470uF/6.3V both replaced with 470uF/6.3V OSCON. In this radio C60 470uF/6.3V was replaced with 470uF/6.3V OSCON, and the C52 100uF/6.3V filtering capacitor of RF IC1 was also replaced with 270uF/16V OSCON. All the rest of the electrolytics were replaced with the same value TA types. The ripple rejection capacitor C45 instead of 10uF/16V was replaced with 22uF/25V TA (in Philips AE3405 are used 47uF). R16 instead of 15k mentioned in service manual, have 150kohms value, and between pin 25 and 28 of CXA1238 (IC1) was inserted a 220kohms resistor - improving the AGC and the muting (like in Panasonic RF-B11). The used FM IF ceramic filter (230kHz type) was replaced with Murata 150kHz low loss type (SFE10.7JA Murata). The R29 10 ohms resistor was changed to 39uH/2.5ohms coil in power line of IC1.
With above mentioned modifications, via headphone, you will get a small monster, detailed audio band on FM with reach bass and smooth trebles.
If you need a stereo indicator, easily can be made: connect one resistor of 2.2kohms to pin 4 of CXA1238, and on other end connect the cathode of a red LED, and the anode to the power supply (B+ 3V).


Sony ICF-SW7600GR

Sony ICF-SW7600G

Is the last and newest radio from Sony ICF SW7600 family - the best shortwave pocket radio made by Sony. The lower cost sibling of ICF-SW7600GR is the ICF-SW35

General information:

  • Digital shortwave portable (dual conversion):1st IF: 55.845 MHz; 2nd IF: 455 kHz
  • Coverage: AM 150kHz - 30MHz, FM 76MHz - 108MHz (stereo with headphones)
  • 1 kHz steps on LW/MW/SW plus a frequency grid: LW: 9 kHz, MW: 9/10 kHz, SW: 5 kHz; FM: 50 kHz steps
  • Synchronous detection
  • SSB reception (LSB and USB)
  • Fine tuning for SSB only (officially +/- 1.5 kHz, rather +/- 2kHz - but is not followed by frequency meter
  • has 100 presets divided in 10 pages, and can be mixed AM and 10 FM station in page + 2 timer memories
  • External antenna jack
  • line out jack (stereo, line level - I never used them)
  • Alarm and sleep functions
  • AM bandwidth: nominal 4 kHz, real more like 7 kHz (filter data: see the section about the filters below)
  • FM filters: 2x 280 kHz (super wide, but can be changed to 150/110 kHz low loss types)
  • Frequency synthesizer / microcontroller: µPD170734G
  • Output: 380 mW max @ 10% distortion
  • Dimensions/weight: 190 x 119 x 35 mm, 608 g (incl. batteries)
  • Produced: 2001 ... 2016

Good things:

  • 4 tuning keys is good, and entering and recalling frequencies is pretty simple
  • Good selectivity.
  • 100 memory location divided in 10 pages.
  • Best-in-class SSB reception - as opposed to most other compact portables, its product detector is sideband selective. Other-sideband AGC pulling still is annoying but one cannot expect true SSB filters in this league.

Problems:

  • Shortwave sensitivity seems to be better above 15 MHz than on the lower bands.
  • The built in telescopic antenna is very fragile and great precaution should be taken in extending it.
  • No RDS
I also refurbished my one, changing almost all 1uF, 10uF, and 47uF capacitors. To my surprise, most of them have lower rated voltage than in service manual (ex. instead of 10uF/50V was full with 10uF/16V) and the used brands I never meet before (R in a square and followed by a P and E). Their internal resistance and loss were too high. All was changed with Ta in power filtering parts, and Panasonic/Nichicon on audio. The headphone output capacitor 47uF was changed into 100uF. Now the sound is better, and the radio sounds like a new one. Also, the display green LED was changed with a very bright orange one.



Technics


Technics is a Japanese brand name of the Panasonic Corporation for audio equipment. Since 1965 under the brand name, Panasonic has produced a variety of hi-fi products, such as turntables, amplifiers, receivers, tape decks, CD players and speakers for sale in various countries. It was conceived for a line of high-end audio equipment to compete against brands such as Nakamichi.


Technics SA-5370

Technics SA-5370

Was the top model of mid-range SA-5170, SA-5270, and SA-5370 released in 1977 (the top model series are SA-5760, SA-5770, which have a higher output power (165W/channel on 8 ohm), and better sensibility (1.8uV instead of 1.9uV) and distortion (0.1% instead of 0.15%)).

General information:

  • Manufactured at 1977 by Technics, Division of Matsushita Electric Japan
  • 2 band analog superheterodyne receiver, MW and FM
  • Coverage: MW 525kHz - 1.605MHz, FM 88.0MHz - 108.0MHz
  • Antenna input impedance for FM: 300 ohms balanced and 75 ohms unbalanced,
  • No preset memory for FM
  • Usable sensitivity: 1.9 uV on FM mono and 20 uV for stereo; 30uV, 300uV/m on AM
  • Intermediate frequencies: 450kHz for AM, and 10.7MHz for FM
  • Used ICs: FM IF amplifier and AM circuit AN217; FM IF amplifier and detector: AN377 (CA3089); PLL type FM multiplex: AN363A; RIAA amplifier SVITA7129P (2 pcs)
  • Signal to noise ratio: mono 75dB, stereo 70dB for FM
  • Harmonic distortion: mono 0.15%, stereo 0.3% for FM
  • Output frequency range on FM: 20Hz - 15kHz (+0.5...-1.5dB)
  • Amplifier THD: 0.1% at rated power
  • Power bandwidth: 7Hz - 50kHz, -3dB
  • Output power: 2x56W/4 ohm or 2x48W/8 ohm continuous
  • Damping factor: 50
  • Input sensitivity: 2.5mV/47kohm Phono; 150mV/33kohm AUX; Tape 150mV/33 and 39kohm
  • Phono max input voltage: 150mV
  • Phono frequency response: +-0.2dB from standard RIAA curve
  • Tone controls: Bass 50Hz +-10dB; Treble 10kHz +-10dB
  • Loudness control (at -30dB volume) +10dB at 50Hz
  • Low filter (rumble): 100Hz -6dB/oct
  • High filter: 7kHz -6dB/oct
  • Output voltage at Tape Rec Out: 150mV
  • Channel separation and balance: 55dB, +-2.0dB
  • Headphone level and output impedance: 450mV/330 ohm
  • Power: ~220V/50Hz, consumption 450W
  • Dimensions: 450x142x330mm, 10.5 kg.

Good things:

  • Very nice backlight of scale
  • The amplifier has very warm and balanced sound, which is kept also during radio listening
  • Good sensitivity and selectivity on FM
  • Nice instruments - for signal and tuning

Problematic things:

  • The volume knob cannot be identified easily, all knobs has same diameter (bass, treble, balance, input selector), excepting the tuning knob, and is positioned almost in middle of front panel.
  • Difficult to repair (during changing all electrolytic capacitors).
With more than 40 years, is the best sounding receiver that I have. Was necessary to change all electrolytic capacitors.
Its sensibility outperforms some tuner with better specifications.
In some forums are mentioned, its sound is better than Marantz's 2220 and Technics SA-300 & SA-400. Both Technics receivers has almost same schematic with SA-5370, and the tuner part are also same with ST-8080. It retailed for about $330 back in 1977, which in today's dollars is roughly $1100!


Technics SA-80

Technics SA-80

This receiver was the bottom model of the new series from 1978 of Technics, and is completely the same as schematic with Panasonic SA80 (which chassis and knobs are made from plastic), and very similar to one year older model, the Technics SA-5070. The Power On and the Stereo indicator are originally made with LEDs, not bulbs.

General information:

  • Manufactured in 1978 by Technics, Matsushita Electric Industrial Co. Ltd., in Japan
  • 2 band analog superheterodyne receiver, MW and FM
  • Coverage: MW 525kHz - 1.605MHz, FM 88.0MHz - 108.0MHz
  • Antenna input impedance for FM: 300 ohms balanced and 75 ohms unbalanced,
  • No preset memory for FM
  • Usable sensitivity: 2.0 uV on FM mono and 22 uV for stereo; 30uV, 300uV/m on AM
  • Intermediate frequencies: 450kHz for AM, and 10.7MHz for FM
  • Used ICs: FM IF amplifier and AM circuit AN217; FM IF amplifier and detector: AN377 (CA3089); PLL type FM multiplex: AN363A; RIAA amplifier SVITA7129P (2 pcs), power amplifier STK459
  • Signal to noise ratio: mono 70dB, stereo 65dB for FM
  • Harmonic distortion: mono 0.2%, stereo 0.35% for FM
  • Output frequency range on FM: 30Hz - 15kHz (+1...-2dB)
  • Amplifier THD: 0.3% at rated power
  • Power bandwidth: 10Hz - 25kHz, -3dB
  • Output power: 2x18W/4 ohm or 2x17W/8 ohm continuous
  • Damping factor: 32 at 8 ohms
  • Input sensitivity: 2.5mV/47kohm Phono; 150mV/33kohm AUX; Tape 150mV/33kohm
  • Phono max input voltage: 95mV
  • Phono frequency response: +-1dB from standard RIAA curve
  • Tone controls: Bass 50Hz +-10dB; Treble 10kHz +-10dB
  • Loudness control (at -30dB volume) +10dB at 50Hz
  • Output voltage at Tape Rec Out: 150mV
  • Signal to noise ratio: 78dB on MM input, 93dB on other inputs
  • Channel separation and balance: 50dB, +-2.0dB
  • Headphone level and output impedance: 450mV/330 ohm
  • Power: ~220V/50Hz, consumption 100W
  • Dimensions: 441x134x277mm, 5.4 kg.

Good things:

  • Beautiful face design, warm sound

Problematic things:

  • Low output power
  • Just one instrument on the front panel (just signal strength, no tunning indicator)
  • No speaker decoupling and protection circuit, just a fuse of 3A/channel
  • No backlight for radio-scale, just for the pointer
  • The power of radio is made via an R-Dz-L divider, which is not the best and efficient voltage regulation, filtered by capacitors.
Is a nice bookshelf speaker driver - delivering just 15W/8 ohms, which means is recommended to be used with high-efficiency speakers.
All used ceramic filter are with orange mark - means their frequency is 10.73MHz.
Modifications:
Power line: C302, C701, C702 to 470uF/35V; CC413, C704 to 1000uF/35V; C310 to 270uF/25V; C619 390uF/35V
Signal: C211 1uF/63V ERO PP; C315 and C316 0.47uF/50V Wima; C411 and C412 1uF/63V ERO PP
Missing from the schematic: the power amplifier power line is fuse protected via 2 pcs of 3.15A fuse; the power switch are with 2 circuits, and both switches have in parallel 1-1 0.01uF/500V pop-up noise canceling capacitor. The power-transformer input voltage is selectable: 110-127-220-240 Vac. The pull-up resistor from the basis of output buffer transistors (Q301 and Q302) are missing from schematics and from PCB - later was soldered on the backside of PCB 1-1 27kohm resistor. The C309 on the schematic is 3.3uF/50V, in the receiver was mounted 4.7uF/50V.


Technics ST-Z1

Technics ST-Z1

Is a fine tuner with good selectivity on FM, 1.8uV, but just with one instrument with 2 functions: tune indicator on FM, and signal level on AM.

General information:

  • Manufactured by Matsushita Electric Industrial Co., Ltd. in Japan between 1980-82
  • Analog 2 bands (MW-FM) superheterodyne radio,
  • No memory presets
  • Coverage: MW 525kHz - 1.605MHz, FM 87.5MHz - 108.0MHz
  • Usable sensitivity: 30uV on MW and 1.8uV on FM mono and 25uV for FM stereo
  • Has only 3 ICs: AN278 as FM IF amplifier, AN7001 which makes all functions (IF system, MPX decoder, indicators driver), and one AN6136 pop-noise canceller.
  • Output frequency range: 20Hz - 15kHz (+1dB...-2.0dB)
  • Signal/noise ratio: FM mono 69dB, FM stereo 65dB
  • THD: on FM 0.15% for mono, and 0.3% for stereo
  • Stereo separation: 47dB
  • Channel balance: 1.5dB
  • Alternate Channel Selectivity (FM): 60dB
  • Line output impedance and level: 1.8 kohm/300mV
  • Antenna input impedance for FM: 75 ohms or 300 ohms
  • Power: 220V/50Hz, Consumption: 18W
  • Dimensions: 410x142x223mm, 3.3kg

Good things:

  • Has a very clean sound, low noise, good channel separation
  • Nice front design with backlight and one analog instrument for signal strength and right channel adjustment

Difficult, problematic items:

  • Impressive hight, but inside has plenty of room.
The heart of this tuner is an IC (AN7001ST) which has integrated all functions, like in case of WEGA JPS352 SE T (AN7000), but they are not pin compatible. This tuner additionally has 2 more ICs: one for FM IF signal amplification (AN278) and one for pop-noise canceling (AN6136). The FM IF frequency is 10.67MHz, which makes difficult to change the ceramic filters. Improved the power line with an RF filter. The IC AN278 has two stages, and just one was in use -> based of Technics ST-S1, I modified the circuit, connecting the second stage into circuit, increasing the amplification. Now is possible to connect one additional ceramic filter to improve channel selectivity, but must be paired with existing 2, with 10.67MHz center frequency (orange dot marking). IC power pin grounded with 22uF/15V MLCC capacitor, and the C305 received in parallel a 47pF/50V C0G MLCC (recommended by user manual of AN7000). The R413 6.8kohm is better to be changed with a 22kohm semi-adjustable resistor to adjust perfectly the channel separation.
Other changes: R3 390 ohm, R4 33kohm, IC101 received 1kohm between pin4 and 6, and disconnected from R103 and CF102. R103 removed, and one 390 ohm resistor connected between pin 5 and 8 of IC101, and pin 8 to CF102. Pin 9 of IC101 connected to ground via 22nF MLCC COG. To the anode of D201 and ground was mounted 3.3uF/16V OSCON. R210 33kohm, C210 390uF/35V. R409/410 now are 560 ohms, R411/412 are 4.7kohm, C407/408 1uF/50V foil capacitors. IC103 pin 9 connected to ground via 0.1uF/100V, and pin 3 and 4 connected to ground via 10nF and 22nF. C502 560uF/35V, C503 470uF/35V, C504/505 820uF/25V. D501 and T501 B-C shorted with one-one 22nF. Audio power line received one puffer capacitor 390uF/35V.
After modification was necessary to increase R102 from 220 to 270, because local stations became distorted regarding 2nd amplification stage. Now is OK. Probably can be solved inserting one more ceramic filter after CF102, but must be identical with CF102 - but this depending from tuner to tuner, because I have another set from this, and there does not caused any problem this modification.
This tuners is same as the Technics ST-2700 FM/AM Stereo Tuner and similar to the Panasonic ST-2700L FM/MW/LW Stereo Tuner. Another similar Technics tuner is the ST-S1, which has LED signal level indicator and channel tunning indicator with related circuits. Technics ST-Z1L FM/MW/LW Stereo Tuner is the version with LW receiption capability.


Technics ST-G5

Technics ST-G5

Is an older brother of ST-G3. Has a frequency shift on FM (+25kHz) to capture adjacent channels when 2 radio programs are very close. Has selection possibility between narrow and supper narrow (150kHz) FM IF filters, signal level indication in dB, and auto search mode.

General information:

  • Manufactured by Technics in Japan between at 1984-1986
  • Digital 2 bands (MW-FM) PLL radio,
  • 16 memory presets:8 for FM and 8 for AM
  • Coverage: MW 522kHz - 1.611MHz; FM 87.5MHz - 108.0MHz
  • Adjusting steps: MW 9/10kHz; FM 50/100kHz for EU/USA version (switchable on rear panel)
  • Usable sensitivity: 20uV on MW, 0.95uV on FM mono and 22uV for FM stereo
  • FM IF/AM IF amp IC: uPC1018C; FM IF det.: uPC1167C2; MPX decoder uPC1161C3; Prescaller: uPB563C-E; PLL controller uPD1704G533; Pilot cancel and DC amp: AN6552; FL display driver: AN6873
  • Output frequency range: 5Hz - 18kHz (+0.2dB...-0.5dB)
  • Signal/noise ratio: AM 55dB, FM 78dB mono, 71dB stereo
  • THD: on FM 0.03% for mono, and 0.04% for stereo
  • Stereo separation: 55dB
  • Line output level: 1000 mV
  • Antenna input impedance for FM: 75 ohms or 300 ohms
  • Power: 220V/50Hz, Consumption: 9W
  • Dimensions: 430x53x245mm, 2.4kg

Good things:

  • High quality of electrical parts used, especially in case of solid capacitors
  • Good selectivity and sensitivity on FM (0.95uV)
  • Very low distortion on FM (0.04% on stereo), good stereo separation (55dB) and high signal/noise ratio (78dB)

Difficult, problematic items:

  • The signal level indication cannot be seen together with received frequency, just separately on the same display
  • Very low profile, just 245mm deep.
Capacitors were in the wrong shape, especially the supercapacitors for memory: 2 pcs 3.3F/2.3V connected in series.


Technics ST-G3S

Technics ST-G3S

Is a quartz synthesizer LW-MW-SW-FM stereo tuner with DC linear switching MPX. Has a DCB circuit for 12-band SW reception, and signal level indication in dB. Based on the specification, was designed mostly for FM and SW DX-ing (high sensitivity), because the LW and MW sensibility is a bit less than average.

General information:

  • Manufactured by Technics in Japan between at 1985-1987
  • Digital 4 bands (LM-MW-SW-FM) PLL radio, with 12-bands on SW
  • 16 memory presets:8 for FM and 8 for AM
  • Coverage: LW 153kHz - 281kHz; MW 522kHz - 1.611MHz; SW 2.3MHz - 26.1MHz (see below), FM 87.5MHz - 108.0MHz
      • Shortwave bands:
    • SW1: 2300 - 2500 kHz, 120 m
    • SW2: 3200 - 3400 kHz, 90 m
    • SW3: 3900 - 4000 kHz, 75 m
    • SW4: 4750 - 5060 kHz, 60 m
    • SW5: 5950 - 6200 kHz, 49 m
    • SW6: 7100 - 7300 kHz, 41 m
    • SW7: 9500 - 9775 kHz, 31 m
    • SW8: 11700 - 11975 kHz, 25 m
    • SW9: 15100 - 15450 kHz, 19 m
    • SW10: 17700 - 17900 kHz, 16 m
    • SW11: 21450 - 21750 kHz, 13 m
    • SW12: 25600 - 26100 kHz, 11 m
  • Adjusting steps: LW and MW 9kHz; SW 5kHz and FM 50kHz
  • Usable sensitivity: 1000uV on LW, 500uV/m or 20uV on MW, 8uV on SW and 0.95uV on FM mono and 22uV for FM stereo
  • FM IF/AM IF amp IC: AN7274SN; FM IF amp: AN278; MPX decoder AN7472S-A; PLL controller uPD1714G511A
  • Output frequency range: 4Hz - 18kHz (+0.5dB...-1.5dB)
  • Signal/noise ratio: AM 45dB, FM 76dB mono, 71dB stereo
  • THD: on FM 0.09% for mono, and 0.2% for stereo
  • Stereo separation: 50dB
  • Line output level: 500 mV
  • Antenna input impedance for FM: 75 ohms or 300 ohms
  • Power: 220V/50Hz, Consumption: 9W
  • Dimensions: 430x53x245mm, 2.2kg

Good things:

  • High quality of electrical parts used, especially in case of solid capacitors
  • Good selectivity and sensitivity on FM (0.95uV) and SW (8uV)

Difficult, problematic items:

  • Station memories for both FM and AM are very low, especially if you use frequently the SW.
  • Very low profile, just 245mm deep.
  • Rare, I did not find any detailed info or service manual about this tuner with SW, just about the ST-G3, which is different.
Capacitors were in the wrong shape, especially the supercapacitors for memory: 2 pcs 3.3F/2.3V connected in series.


Technics ST-G450

Technics ST-G450

Is a quartz-synthesizer 2 band stereo tuner. Has Class AA output amplifier for best fidelity. The digital tuning uses an unwavering quartz crystal reference to prevent drift while promoting astounding accuracy and convenience. Use the traditional Technics DC construction which enhances waveform fidelity while extending flat frequency response down to 4Hz. Has a 24 channels random access preset memory and a large FL display.

General information:

  • Manufactured by Matsushita Electric Industrial Co. Ltd in Japan between 1988 to 1990
  • Digital 2 bands (MW-FM) PLL radio without RDS capability,
  • 24 random access memory presets, organized in 9+10+5
  • Coverage: MW 522kHz - 1.611MHz, FM 87.5MHz - 108.0MHz
  • Channel space: 9kHz for AM and 50kHz for FM
  • Intermediate frequency: 450kHz for AM and 10.7MHz for FM
  • Usable sensitivity: 20uV, 300uV/m on AM, 1.3uV on FM mono, and 21uV for FM stereo
  • Integrated circuits: FM IF IC: AN7274NS, stereo decoder: AN7472S, PLL freq. synthesizer: LM7001, electronic tuning controller and FL display driver: M50941-421SP; IF amplifier: AN278, audio output amplifier: AN6554F
  • Output frequency response on FM: 4Hz - 15kHz (+0.5...-1dB)
  • Signal/noise ratio: AM 50dB, FM 80dB mono, 72dB stereo
  • THD: on FM 0.05% for mono, 0.1% for stereo
  • Stereo separation: 50dB
  • Alternate channel selectivity: 65dB
  • Antenna input impedance for FM: unbalanced 75 ohms, for AM: loop antena connector and an external antenna connection possibility
  • Output signal level: 0.45V
  • Power: 220V/50-60Hz, consumption: 9W
  • Dimensions: 430x64x241mm, 2.2kg

Good things:

  • Has a very clean sound, low distortion, low noise
  • Big FL display

Difficult, problematic items:

  • No wide and narrow IF filters selection possibility for FM
  • Just average sensibility
  • No muting during searching. Exist auto searching mode (pushing longer the Up/Down tuning buttons, but is not so sensible
  • No fuse on primer circuit of transformer - recommended to be additionally inserted.
The schematic (as source was used one from G460 model, because the G450 I did not find on the net) is very similar to ST-G460/470/550/560/570/650, the main difference of G450 is the tuner section has just 3 gangs, uses just 2 ceramic 10.7MHz +-180kHz filters (SFE10.7MZ), no IF wide/narrow selection possibility, and less memory. The PCB contains all pads to be implemented the Wide/Narrow IF filtering selection possibility (like in GT550 or G6T). Considering the endless list of similar tuners, Technics made just minor modifications and release them as new models.

Modification (above changing all electrolytics):
Power line: C104 from 10uF to 47uF/63V, C106 & C901 from 470uF/6.3V to 1000uF/35V, C114 & C303 from 100uF/35V to 390uF/35V, IC 302 received a 100uH coil follower by a 390uF/35V puffer capacitor. C705 from 1000uF/25V to 2200uF/25V, C706 from 2200uF/25V to 3300uF/35V, C707 from 220uF/16V to 470uF/35V, C710 from 10uF/16V to 100uF/63V, C915 from 1000uF/6.3V to 2200uF/25V. At AC power input before received an EMI filter circuit formed by 2.2nF/2kV ceramic capacitor, the original filter coil, and after in parallel with primer of transformer one 1uF/275Vac pp foil capacitor. On both secunder coils received 1-1 220nF/275Vac PP capacitors. Because during usage the Q701 temperature was high, I inserted a heatsink on it.
Modifications in other circuits: at IC901 CE (pin 3) received a 100pF to ground and on AM_IN (pin 10) input line 3.3uH at the input. R102 was changed from 1.5kohms to 560 ohms, and the R103 from 330 ohms was changed into 560 ohms (like at GT550 & GT650). The pin 18 of IC102 now is connected to the power line via 100pF ceramic (like at G570).
Audio output: in case of the audio signal can be seen mostly DC connection, no capacitors - excepting the output of class AA circuit. If we take a look at the value of the output capacitor, seems very low. The output works in the best case (not considering the input resistance of the power amplifier and the impedance of output MPX filter, for simplicity) on 5.6Kohms + 2.7kohms resistor via 3.3uF, which means cannot be achieved the advertised 4Hz, as lower end of the audio band, just with a high loss. I put in this position (C315 and C316) 10uF/100V pp foil instead of 3.3uF/50V electrolytics (3x higher value!). Now the sound is in its right place with detailed bass and treble.
The new class A or called Class AA is a small trick, the output transistors conduct all time, just like the case of real class A amplifiers, for this reason, they never switch off, switching distortion is eliminated - but in reality, they work in class B. This is achieved with a special biasing of transistors: as the audio waveform begins to swing from positive to negative or vice versa, a very high-speed diode acts to raise the bias current slightly, the transistor remains in a low-level conducting state until the signal swing back again.



TechniSat


TechniSat is a German company founded in 1987 by Peter Lepper in Daun, Germany. Firstly, start to produce flat dishes with an edge length of 38 cm for receiving satellite DVB transmissions. In 1998 started producing the digital receiver, since 2005 HD ready LCD TVs, in 2011 started smart TV production, in 2012 DAB+ radios, and 2016 multiroom audio systems.


Viola 2 C IR

Viola 2 C IR

The VIOLA 2 C IR is a fully digital radio with a huge variety of radio reception possibilities. You can use it to enjoy digital radio via DAB+, your favorite stations via FM, or radio stations from the Internet. Once you connect to the internet via WiFi, you can also access podcasts from the Internet - sorted according to country or genre. You can also connect headphone - the listen the programs in stereo. A visual highlight of the VIOLA 2 C IR is the large color display with a screen size of 2.4 inches. When in standby mode, the dimmable display shows the time and, when in radio mode, provides information about the current program (radio text). A rechargeable LiPo battery powers the device while on the go, which can be quickly changed in just a few simple steps.

General information:

  • Principle: DSP
  • Manufacturer: TechniSat Digital GmbH, but manufactured in China between 2018-2020
  • Bands: FM with RDS (Radio Text and PTY), DAB+ and Internet radio
  • Coverage: FM 87.5 - 108 MHz; DAB+ Band III 174 - 240 MHz, channels (5A to 13F); Internet radio via WIFI 802.11 a/b/g/n (2.4GHz) with WEP and WPA/WPA2 encryption
  • Tuning frequency steps: 100kHz on FM
  • Preset memory: 30 for FM, 30 for DAB+, and 30 for Internet Radio
  • Display: 240x320pixel 2.4 inch TFT Color display
  • OSD languages: English, German, French, Polish, Italian, Dutch, Norwegian, Danish, Swedish, Finnish, Spanish, Portuguese, Turkish
  • Sleep timer settings: off, 15, 30, 45, and 60 minutes
  • Alarm: has 2 alarms settings, each with the possibility be Off, Daily (every day), Workdays (Mon-Fri) or Weekends (Sat-Sun), with the selection of buzzer, or last listened station of Internet radio, DAB+ or FM and sound level selection
  • Antenna: DAB+ / FM via telescopic aerial, for WiFi internal antenna on WiFi module
  • Used integrated circuits: DSP and display driver: unknown; power amplifier LM4863; charger: CL4056A
  • Power supply: external 5Vdc, or via rechargeable Li-Ion 3.7V/1050mAh battery (BL-5C type) with up to 5 hrs worth of charge
  • Power consumption: in operation 10W, in standby mode 1W with an active internet connection, 0W if is completely switched off
  • Audio output: 2W RMS via only one loudspeaker, via 3.5 mm headphone jack is stereo
  • Speaker: 4 ohms, 3W with 75mm (3") diameter
  • Input/output voltage of adapter: 100-240Vac, 50-60 Hz and output 5Vdc 2A with max 82% efficiency. Power consumption of adapter in standby: 0.07W
  • Dimension: 204x90x112 mm
  • Weight: 508 g, including the rechargeable battery

Good things:

  • Dimmable display light
  • Easily usable menu (excepting the WiFi setting) and selection tuning button
  • Firmware update via WiFi

Difficult, problematic items:

  • Just 3 direct memory access buttons, the rest 27 are reached via the 4th button + the tuning knob
  • The clarity of sound is not as good as in the case of analog receivers, this is mostly regarding its speaker. Via headphone is good, but with weak bass.
  • The menu system is difficult in case of WiFi setting
  • The internet radio part is not so stable
  • If the external power is disconnected, the clock setting is lost. Will be recovered fastly if you swicth the radio to an FM station with RDS.
The headphone output for the 10uF/50V output capacitors is incredibly weak and devoid of bass. At the moment, it is just as useful as a high-impedance line output. To achieve a 50Hz cut-off frequency with this coupling capacitor value, the headphone impedance must be no less than 320 ohms. If you want to use it with a 16 ohm impedanmce headphones, you should increase the output capacitor's value to at least 220uF.
I think the battery capacity is insufficient for such a mobile radio. Since the interior of the chassis is nearly empty, there is room inside for an accumulator with a considerably higher capacity, such as 4000-5000mAh.
Its sound quality is awful. I made a complete closed speaker box by replacing the speaker with a wide-range 24 ohm type with the same dimensions and a heavier magnet, gluing it to the front panel (which was the same as the original one), and isolating the front panel from the chassis using silicone. The clarity and quality of the sound immediately improved. Later, I understood why the old speaker sounded so disoriented: when it was put into the front panel, glue was dripping between the speaker's chassis and diaphragm, preventing the latter from moving freely.
Its selectivity is fairly good, but, for instance, the sound of the Tivoli Audio Model One is far superior and cannot be compared (as well as being nearly 10 times more expensive).



Telefunken


Telefunken was a German radio and television apparatus company, founded in Berlin in 1903, as a joint venture of Siemens & Halske and the Allgemeine Elektricitäts-Gesellschaft (AEG), creating Gesellschaft für drahtlose Telegraphie System Telefunken ("The Company for Wireless Telegraphy Ltd."). In 1941, Siemens transferred its Telefunken shares to AEG as part of the agreements known as the "Telefunken settlement". During the Second World War, Telefunken was a supplier of vacuum tubes, transmitters, and radio relay systems, and developed Funkmess facilities (later referred to as radar devices by the US Navy) and directional finders, as part of the German air defense against aerial bombing. During the war, manufacturing plants were shifted to and developed in the west of Germany or relocated. Thus, Telefunken, under AEG, turned into a smaller subsidiary, with the three divisions realigning and data processing technology, elements as well as broadcast, television, and phono. Telefunken was also the originator of the FM radio broadcast system. In 1967, Telefunken was merged with AEG, which was then renamed to AEG-Telefunken. When AEG was bought by Daimler in 1985, "Telefunken" was dropped from the company name. In 1995, Telefunken was sold to Tech Sym Corporation (owners of Continental Electronics Corporation of Dallas). However, Telefunken remained a German company. In August 2006, it was acquired by the Turkish company Profilo Telra, one of the largest European manufacturers of TV devices, with brand-owner Telefunken Licenses GmbH granting a license for the Telefunken trademark rights and producing televisions under that name.


Telefunken 076WK

Telefunken 076WK

This radio also comes from family, and was used from 1941 at Erzsébetváros (Elisabethstadt/Appeschterf, Orastie, in Transylvania - now part of Romania) till the end of '70s. In 2005 was completely refurbished. Now the weak point is the band selector switch (is a common problem of all radios produced during WWII).

General information:

  • Principle: superheterodyne, with IF=468kHz
  • Manufacturer: Telefunken Deutschland mbH
  • Bands: 3 - LW, MW and SW
  • Tubes: 6 pcs - ECH11, EBF11, EF11, EL11, EM11 and AZ11
  • Power supply: alternating current 110-240V, 50Hz
  • Speaker: moving coil with field excitation coil (no magnet)
  • Input: AM antenna and turntable
  • Dimension: 600x390x300 mm
Condition: working, but the band selector switch is not so stable.


Telefunken RT300

Telefunken RT300

The RT 300 is the largest and most luxurious tuner of Telefunken's 1981 lineup, and several design ideas comes from Telefunken's first fully digital tuning concept tuner, the TT750 (1979/1980). It offers almost all features one would have expected for a good tuner at that, except the timer. Was part of Telefunken's T 300 high-end component system, and it has a remote-control input that allows the drive functions to be controlled via the RP 300 pre-amplifier. The RT300 has 4 gangs on FM, 2 gangs on AM, all tuned with varicap diodes.

General information:

  • Manufactured between 1981-1982 by Telefunken, West Germany
  • 3 band analog superheterodyne receiver, LW, MW, and FM with digital PLL synthesizer
  • Coverage: LW 153 kHz - 265 kHz, MW 522kHz - 1.611MHz, FM 87.5MHz - 108.0MHz
  • Tuning frequency steps: 10kHz on FM, 1kHz on AM
  • Antenna input impedance for FM: 300 ohms balanced, 75 ohms unbalanced,
  • Antenna for AM: just external terminal
  • 40 preset memory random used by all bands
  • Usable sensitivity: 0.6 uV on FM mono, 22 uV for FM stereo on 60 ohms input; no data for AM
  • Intermediate frequencies: 460kHz for AM, and 10.7MHz for FM
  • IF bandwidth: 150 kHz for FM, 4.7 kHz for AM
  • Used ICs: FM IF TDA1047; MPX decoder TCA4500A; AM/FM switch MC14016, AM IF TDA1046, audio output buffers HA1457 (2 pcs), voltage regulator for radio LM317, signal level display module TFK D-620P (including U244B and U254B). For digital part: FM demod CA3089, 150 MHz divider by 10/prescaller SP8660, counter 74LS93, OPA LM324, DFU102 display driver, DFC103A, DFC103B controllers, BCD to decimal decoder 74LS145, voltage regulator uA78G, ER1400 EPROM, OPA CA3080 and LF355
  • Signal to noise ratio: FM mono 76dB, FM stereo 74 dB, AM 50dB
  • Output frequency range on FM: 22Hz - 15.5kHz,
  • Audio output signal level and impedance: 800mV/1kohm
  • THD: 0.3% for FM mono, 0.5% FM stereo, not specified for AM
  • Power: 110V/220 Vac, 50/60Hz, internally selectable
  • Dimensions: 435 (W) x 56 (H) x 350 (D) mm, 5.5 kg.
  • Price at 1981: 950DM

Good things:

  • Very high sensibility on FM: 0.6 uV!
  • Adjustable muting not just on FM, also separately for AM
  • Has a 10 bar signal strength meter
  • Has both types of audio output sockets: DIN and RCA - channels are not marked on the backplate

Difficult, problematic items:

  • During searching (auto or manual) when you reach one of the ends of the band, do not jump automatically to the opposite end like new tuners
  • The power cable is very short, just 1.2m
  • External antenna socket is uncommon, difficult to find
  • RCA outputs are not marked, which is the Left or Right. Fortunately, they follow the logic: on the left side is the Left output, on the right side is the Right one
The System T300 was formed from the next components: RP 300 preamplifier, RM 300 power amplifier, RT 300 tuner, RC 300 Tape deck, and RS 30 turntable - the system cost 4240 DM plus the rack system called Rack 300 additional 258 DM.
Telefunken in this tuner used the highest technology of that era: MOS controller system with EPROM, 40(!) random preset memory (no battery or supercapacitor required to keep stored stations), remote control, auto searching up and down, 10 level signal meter, etc. The digital part was made with mixed technology: SMD components used with through-hole components (glued SMD, dried in reflow, after mounting the TH, and finaly soldered via wave soldering machine). Despite 10kHz tunning steps on FM, the station transmitted frequency is detected very precisely, with no deviation after more than 40 years!
The overloading of AM input is protected by a photoresistor, which is controlled via a bulb connected to AM demodulator signal level. Also, a bulb is used to control the input current of the the digital section before the voltage regulator. Simple and effective solutions! The power of the digital part is made using an intermediate transformer driven with 17Vac from the main transformer (no PWM switching power supply, means less noise).
Components: were used very good ones. Most of the capacitors have an acceptable loss (2.5%, and their ESR are still very low) - except in the digital part. There most of capacitors were already dried, isolations hardened or capacitor leg died by the electrolyte. All electrolyte capacitors were changed to new ones (electrolyte, solid electrolyte, tantalum, or foil type. The rectifier (B30C350KP - is a selenium bridge, nowadays with a high defect ratio regarding their limited service-life, appr. 60000 hrs, progressive increase in forward resistance, increasing forward voltage drop, and reducing the rectifier's efficiency) in radio section must be changed immediately at first repair. In several related forums are recommended, because can deteriorate both controllers. In my set instead of 2 signal level drivers (U244B and U254B) is used the TFK D-620P LED bar component with 4 pins (Vp, In, and 2 GND) which has the drivers incorporated, made by Telefunken (probably which contains the before mentioned ICs), but the assumed U254B does not work, must be replaced the whole component (for this reason can be seen on the picture just 5 lighting LEDs, not 10).
For further improvement: the places of ceramic filters on PCB were made for old type filters with 4 pins and also for new type with 3 pins, and from 3 pin-types can be used 2-2 pcs on series connection. The current one after tuner is SFE10.7MX (BW +-250kHz, insertion loss 12dB, low distortion) with 3 pins, and after IF amplifier is SFJ10.7MB (BW +-190kHz, insertion loss 8.5dB) with 4 pins, both with Murata type with blue body and orange dots (center frequency is 10.73MHz). Verdict: is a very underestimated tuner, cheap on second market (30-40?), and very sensible with a good sound.


Telefunken HT850

Telefunken HT850

The HT 850 was the flagship of that period (1983-85), and inside is very similar with the later presented models, HT 870 (in which the controller and the memory functions were improved, and the FM oscillator are buffered). Has 4 gangs on FM with a dual gate MOSFET input stage, 2-2 gangs on AM (for MW an LW, swithed via one relay), all tuned with varicap diodes. Other components of the system are called T800: HA800 amplifier, HC800 tape deck, and HS800 turntable.

General information:

  • Manufactured between 1983-1985 by Telefunken, West-Germany
  • 3 band analog superheterodyne receiver, LW, MW, and FM with digital PLL synthesizer
  • Coverage: LW 153 kHz - 360 kHz, MW 522kHz - 1.611MHz, FM 87.5MHz - 108.0MHz
  • Antenna input impedance for FM: just 75 ohms unbalanced,
  • Antenna for AM: just external connection, no ferrite rod. Can get signal also from 75 ohm FM antena socket
  • 16 preset memory: 8 for FM, and 8 for AM (LW and MW together)
  • Usable sensitivity: 0.7 uV on FM mono, 25 uV for FM stereo; 10uV on MW (at 600kHz) and 100uV on LW
  • Intermediate frequencies: 455kHz for AM, and 10.7MHz for FM
  • Used ICs: FM IF HA12412; MPX decoder HA12016; AM IF LA1245, FM IF amplifier TA7060; controller TC9147; prescaller TD6104P; signal level meter M151903L; and display driver TC6301; audio buffer NJM4558DD; voltage regulator uPC78M15,
  • Signal to noise ratio: FM mono 70dB, FM stereo 64 dB, AM 50dB
  • Output frequency range on FM: 22Hz - 15kHz,
  • THD: 0.3% for FM mono, 0.3% FM stereo, not specified for AM
  • Channel separation: 40dB (1kHz)
  • Crosstalk attenuation: 40 dB (1 kHz)
  • Selectivity: 80 dB
  • Spurious rejection: 60 dB
  • Image rejection: 60 dB
  • IF Attenuation: 60dB
  • AM Rejection: 60dB
  • Audio output signal level and impedance: 200mV/2.5kohm
  • Power: 220 Vac, 50/60Hz
  • Dimensions: 440 (W) x 75 (H) x 280 (D) mm, 6 kg.
  • Price at 1983: 499DM

Good things:

  • Has a 16 preset memory (2x8)
  • Is and easy serviceable tuner, with detachable bottom plate
  • Bright, easy to read big display

Difficult, problematic items:

  • Special antenna socket for AM
  • The transformer are continuously connected to the power

The internal part is almost the same as the next generation model, HT870: the AGC's RC part is different, has 2 IF amplifiers stage, one with TA7060, and one with one transistor, the oscillator output has a buffer made with FET, the MPX circuit output has a buffer operational amplifier (NJM4558DD).
All 3 10.7MHz ceramic filters are 10.7S type with red dot on top right side.
Modification made based on HT870, mostly for noise reduction and AM signal level improving: in tunning circuit was inserted 3 pcs of 2.2uH coils before R114, R129 and the triplet of R101-R109-R110, C104 received 0.47uF in parallel, R202 and R236 removed, R206 and R207 were interchanged, and in parallel with R207 position was mounted one 560pF, C304 now is 2.2nF, C302 became 47uF/35V. The FM antenna input now is connected with AM antenna socket via 2.2uH in L201 position, and the original coil from this is incerted between AM socket and AM tuner input (C201).
Other changes: C306 10000uF/16V as memory capacitor. Now after half year still the stored memory setting works! The power line of IC302, pin 41 and 42 received the power through one 100uH coil. C227 now is 100uF + 22nF, C221 became 100uF. C164 was decreased to 0.22uF. All audio capacitors, C166, C167, C169 and C170 now are 10uF/50V Yageo type. C159 and C171 now is 470uF. Changes in the power supply: C501 now is 3300uF/25V, C504 and C507 is 470uF/50V, C510 now is 330uF/35V, and C511 270uF/16V.
The voltage stabilizer IC (7815) was mounted in the back plate to transfer the heat outside from tuner - without this, the IC became very hot after several hours of listening. All electrolytics were changed.
Status: after purchasing it (was 20$ in the middle of 2022), the reception frequency on FM was shifted to -50kHz - so the stereo signal was weak. After changing the capacitors and finalizing the above-presented improvements, this deviation became smaller but was between the exact transmitted frequency (probably -25kHz), which means became worst, because in both positions the stereo signal comes with hum. In such cases can be adjusted the FM IF circuit coils: with IF101 you can set the center (please be careful, just a very-very light movement can be made in CCW direction), and after that should be adjusted the IF103 for clarity/minimal distortion, a bit more than in case of IF102. This process should be repeated till the sound is perfect. I recommend selecting a weak station for adjustment, with stereo almost receptable.
The sound is quite good after modification. Now has seems more clear in the whole audio spectrum.


Telefunken HT660

Telefunken HT660

The HT 660 is the low grade of HT870. Has 4 gangs on FM with a dual gate MOSFET input stage, 2 gangs on AM, all tuned with varicap diodes. Other components of the system are called T660: HA660 amplifier, HC660 tape deck, and HS660 turntable.

General information:

  • Manufactured between 1987-1988 by Telefunken, but inside look like was made in South Korea
  • 3 band analog superheterodyne receiver, LW, MW, and FM with digital PLL synthesizer
  • Coverage: LW 153 kHz - 360 kHz, MW 522kHz - 1.611MHz, FM 87.5MHz - 108.0MHz
  • Tuning frequency steps: 10kHz on FM, 1kHz on AM
  • Antenna input impedance for FM: just 75 ohms unbalanced,
  • Antenna for AM: ferrite rod, no external antenna connection possibility
  • 20 preset memory (2x10) random used by all bands
  • Usable sensitivity: 1.0 uV on FM mono, 35 uV for FM stereo; 300uV/m on MW and 600uV/m on LW
  • Intermediate frequencies: 455kHz for AM, and 10.7MHz for FM
  • IF bandwidth: 150 kHz for FM, 4.7 kHz for AM
  • Used ICs: FM IF HA12412; MPX decoder HA12016; AM IF LA1245, controller and display driver (LCD) TMP47C420AF, voltage regulator uA7815,
  • Signal to noise ratio: FM mono 76dB, FM stereo 72 dB, AM 50dB
  • Output frequency range on FM: 20Hz - 16kHz,
  • Audio output signal level and impedance: 500mV/1kohm
  • THD: 0.2% for FM mono, 0.3% FM stereo, not specified for AM
  • Power: 220 Vac, 50/60Hz
  • Dimensions: 440 (W) x 77 (H) x 203 (D) mm, 2.3 kg.
  • Price at 1987: 399DM

Good things:

  • Has a 20 preset memory (2x10)
  • Detachable bottom plate to have access to PCBs solder side, rare at cheap models

Difficult, problematic items:

  • Very cheap design, plastic front which contains the front legs
  • Difficult the manual tunning/adjustment: if you push it longer the tunning buttons, the searching speeds up very rapidly and will be over.
  • The backlight of the display has low intensity

The internal part is almost the same as the flagship model, HT870: the AGC's RC part is different, has 2 IF amplifiers (at HT660 the last 2 ceramic filters are connected in series, at HT870 is one transistor amplifier between them), the oscillator output has a buffer made with FET, the MPX circuit output has lightly different RC filters and in signal path has higher capacitors, the controller and surrounding circuit is different.
All 3 pcs of 10.7MHz ceramic filters are 10.7S type with red dot on top right side.
Between schematic and real tuner are some differences: at FM input is no transformer, but has a ceramic FM band filter, the C132 1uF/50V was not mounted, C601 instead 1uF/50V is 47uF/16V, IC301 NJM4660D not mounted (the automatic search is solved with transistors)
Modification made based on HT870: in parallel with R125 was mounted 1uF/63V PP, C132 mounted as on schematic, C147, C153L and C153R changed to 4.7uF/63V PP, C148L and C148R changed from 1000pF to 820pF, R148L and R148L changed from 47k to 51k.
I think this tuner was made in South Korea: all electrolytic capacitors were SamHwa SA type, the transformer was made by Han Young Electronics Co., the design of PCB, used ICs are Far-East style.
The voltage stabilizer IC (7815) was mounted in the back plate to transfer the heat outside from tuner, and received an EMI filter before transformer (0.47uF-2x8.2mH-0.47uF). All electrolytics were changed.
The sound is quite good after modification. Now has equilibrated bass, clear trebles. The stereo image is good. From specification comes the stereo signal detection should be at 35uV signal level - I think, compared to other tuners, is at 20uV level. The transition from mono to stereo is quite smooth. As a garage tuner is a more than perfect choice, consider attaching for it a good antenna.



Tento


Elektrit Radiotechnical Society was the largest privately owned company in Wilno, Second Republic of Poland (now Vilnius, Lithuania) (1925-39). With over 1100 workers, the society produced approximately 50 thousand radio receivers annually. Elektrit proved to be a very successful company and soon became a leading radio manufacturer in Poland. Following the Soviet invasion of Poland in 1939, Wilno was occupied by the Soviet Union and the company was nationalized. In 1940 the factory was hastily dismantled and transported to Minsk, where the "Vyacheslav Molotov" Radio Factory was set up. After the war the plant was renamed Minsk Radio and Television Association "Horizont". At the beginning produced "Minsk" radio receivers, being copies of Polish pre-war models but with Soviet tube set, later start to make their own designed sets using Russian semiconductors. The factory was renamed Tento (date unknown). Most famous radio receivers of this factory from 1980's: VEF 206 and 242, Okean 214, Sokol 304, Selena B211 (210, 212) and B216 (215, 217).


Selena B-211

Seleba B-211

This was one of the most famost portable radio made in the Soviet Union in Minsk made from 1975. Works on every conceivable broadcasting channel, with slight restrictions. This radio has 2 other variants: B210 (with FM 87.5-108MHz) and B212 (lacks the 16m shortwave band, but includes the 1.6-4.0MHz (75 - 187m) band used mostly by Arabic, Chinese or maybe Ukrainian countries, and FM 87.5-108MHz. Contains in total 20 transistors and 18 diodes. Durable, very sensitive, nice sound, excellent device. Was followed by the B-216 model (with Western FM band versions B-215 and B-217), which technically outperform this model.
The scale and the signal meter are luminated via 2 bulbs of 2.5V/65mA. Has audio output for tape recorder: 6mV/10kohm, treble (6.5kHz) -15...+10dB and bass (200Hz) +-10dB adjustment, AFC for FM, and switch to disconnect the AC power (not same with the Power On).

General information:

  • Manufactured between 1975-1987 by Tento (Minsk, now capital of the Republic of Belarus), Soviet Union (URSS) at that time.
  • 4 band analog superheterodyne receiver: LW, MW, SW (5) and FM
  • Coverage: LW 150kHz - 405kHz (2000-740.7m), MW 525kHz - 1.605MHz (571-187m), FM 65.8 - 73MHz (4.56-4.11m), and 5 SW bands
    • SW1: 16 meter, 17.7 - 17.9MHz
    • SW2: 19 meter, 15.1 - 15.45MHz
    • SW3: 25 meter, 11.7 - 12.1MHz
    • SW4: 31 meter, 9.5 - 9.77MHz
    • SW5: 41-50 meter, 5.95 - 7.3MHz
  • Antenna: for LW and MW is build in ferrite rod and external socket, for SW and FM telescopic antena and a 60 ohm external antena socket
  • Usable sensitivity: better than 800uV/m on LW, 600uV/m on MW, on SW 100uV/m exception 41-50m band, where is 200uV/m, and on FM 25uV/m
  • Intermediate frequencies: 465+-2kHz for AM, and 10.7MHz for FM
  • Audio bandwidth: on AM 100 - 3000Hz, on FM 100 - 6500Hz
  • Power output: 1W/8 ohms, oval type speaker (140 x 95 mm)
  • Power: from battery, 6 pcs x 1.5V (R20) cells, or 110-127V/220-240V AC (switchable via socket from back side)
  • Consumption: on average at good signal 25mA, at maximum audio level (1W) 150mA
  • Dimensions: 254x357x124 mm, Weight: 4 kg.
The first stage on FM has 2 gangs, for AM also. The IF for 10.7MHz has 4, for AM has 3 gangs.
All electrolytics must be changed immediately. All produced before 1989 made for consumer electronics are dried. Has a very pleasant and warm sound via its own speaker, and with very clear sound on AM!


VEF-222

VEF-222

The VEF-214 is succeeded by this radio model; however, aside from the nomenclature, the schematic remains unchanged. Also manufactured for West European nations under the designation VEF-221 on the CCIR FM band (87.5-108MHz). Both the VEF-2211 and VEF-2221 have been upgraded, but the distinction is a tiny window that displays the received band (means is just a mechanical upgrade). Although the set was constructed in Cuba under the name Ritmo, it appears to be an exact replica.
Contains only six selectable bands: three shortwave bands, LW, MW, and FM. Its sensitivity is particularly remarkable with regard to MW. Tone control and volume with loudness (cannot be deactivated). The scale lacks illumination and is devoid of a signal meter. There are three controls on the top: AC, AGC, and muting. Has 6mV/10kohm audio output for the tape recorder.

General information:

  • Manufactured between 1985-1992 by Tento (Minsk, now capital of the Republic of Belarus), Soviet Union (URSS) at that time.
  • 4 band analog superheterodyne receiver: LW, MW, SW (3) and FM
  • Coverage: LW 148kHz - 285kHz (2027-1050 m), MW 525kHz - 1.607MHz (572-187 m), FM 65.8 - 74MHz (4.56-4.06 m), and 3 SW bands
    • SW1: 16-19 meter, 15.0 - 17.9 MHz
    • SW2: 25-31 meter, 9.4 - 12.1 MHz
    • SW3: 41-49 meter, 5.9 - 7.5 MHz
  • Antenna: for LW and MW has a build in ferrite rod and external socket with 60 ohm impedance, for SW and FM telescopic antena and also can be used the external socket for external antena
  • Usable sensitivity: better than 1500uV/m on LW, 700uV/m on MW, on SW 300uV/m, and on FM 50uV/m
  • Intermediate frequencies: 465+-2kHz for AM, and 10.7MHz for FM
  • Audio bandwidth: on AM 150 - 4000Hz, on FM 150 - 10000Hz
  • Power output: less than 1W/8 ohms, oval type speaker (140 x 95 mm). Headphone impedance: to be between 50 - 120 ohm
  • Power: from battery, 6 pcs x 1.5V (R20) cells, or 220V AC
  • Consumption: on average at good signal 15mA, at normal audio level (150mW) 35-50mA
  • Dimensions: 297x247x80 mm, Weight: 2.3 kg.
Similarly to AM, the first stage on FM has two gangs. The 10.7MHz IF has two filters (one made of LC and the other of ceramic), while the AM IF has two LC groups.
Immediately replace all electrolytics (I discovered some with 143pF rather than 1uF, a 100uF in the power regulator with 41.4uF/3.6 ohm ESR/9.2% loss, and a 10uF that was entirely dry, whereas the 22uF had 49.99uF/4.4 ohm ESR and 6.4% loss). Everything manufactured for consumer electronics prior to 1989 is desiccated.
Modifications: Initially, I also contemplated the VEF-317 schematic: I inserted a 1k resistor between L2C14 and +5V, and a 33nF capacitance was connected to ground between this resistor and L2C14. The collector and emitter resistors of VT4 were modified to values of 0 and 1kOhm, respectively. Driver prior to tape output: a 33nF capacitor was connected in parallel with R73, and the value of R76 was altered to 3k in order to produce a signal that could be utilized at the tape output. C4 is now composed of a 270uF/16V solid electrolyte. R17 was reduced to 2.2k, C28 is now also 270uF/16V solid electrolyte (50uF on the schematic, 22uF on the device), C44 should be 1uF (originaly was 0.1uF ceramic), and C6 received 47nF in parallel with it. The 2000uF/16V C2 was substituted with a 3300uF/25V variant.
The schematic for the FM demodulator board differs from the datasheet of IC K174XA6 (which may be the same as TDA1047): C14 should be 2uF rather than 1uF, C8 should be 50uF rather than 1uF, and C7 should be 5uF rather than 2uF. C9 is fine at 10uF. Mounted C8 was 10uF and C7 was 4.7uF, which is close to the values listed on the datasheet.
This set is not as sensible as the Selena B216, B211 or VEF206.


Terta


The history of the factory dates back to 1876 as a Railway Fittings and Electrotechnical Machinery Factory (Vasúti szerelvény és elektrotechnikai gépgyár) at Budapest, Hungary. In 1894 it became a domestic division of the company A. G. vormals J. Berliner, and since 1903 it has been called the Telephone Factory (Telefongyár). The factory was little known to the wider public but was always at the forefront of the Hungarian communications industry. In 1918, it produced the first transceiver with an electron tube. Until the end of World War II, it was owned by the German Telefunken. After the nationalization in 1949, the company was "asked" to manufacture sound amplifiers and sound film projectors, railway safety, and signaling equipment, telephone and telegraph equipment, and a telephone exchange. In the second half of the 1950s, very high-quality tape recorders were produced for public use, based on their development. Among the first to be produced were tubular and then transistorized pocket radios and portable transistorized magnetophones. In 1991, during the privatization of state-owned industry, Siemens acquired Telefongyár Rt., and Siemens Telefongyár Kft. was created. In 2003, Siemens Telefongyár Kft., Siemens Investor Kft., and Siemens Rt. were legally merged, thus the name Telefongyár itself disappeared.


Orionette 1004

Orionette 1004

This is a nice portable table-radio from 1958(!) made with 7 transistors (the 8th is used as a diode), is the oldest transistor radio that I have, and is the first portable transistor radion made in Hungary via the first transistors made by the famous Tungsram (Lamps and Semiconductor factory). Has two bands, five-circuit, super heterodyne system, with a ferrite antenna, operating on 9 volts (2 batteries of 4.5V), built into a plastic-covered handmade wooden box, with the Orion symbol. Was made in 3 or 4 versions, in 2 colors - at the beginning in yellowish white, later in green. The scale is from painted glass.

General information:

  • Manufactured between 1958-1963 by Terta (Telefongyár) Hungary.
  • 2 band analog superheterodyne receiver, LW and MW
  • Coverage: LW 150kHz - 320kHz, MW 515kHz - 1.615MHz
  • Antenna for AM: build in ferrite core and external terminal
  • Usable sensitivity: better than 1000uV on LW, and better than 500uV on MW. With external antenna better than 200uV on LW and 150uV on MW.
  • Intermediate frequencies: 455kHz
  • Transistors used: 2SA15 (Hitachi) on the first stage, 2 pcs of 2SA12 (Hitachi) on AM osc and mixer, 2 pcs of P14 on AF preamplifier, and 2 pcs OC1072 on the power amplifier. OA1160 as detector diode, and one diode made from P14 transistor on AF stage. Early versions were made with 2N219 (USA), 2 pcs 2N218 (USA), 2 pcs P14 (TUN)and 2 pcs 2P6 (TUN)
  • THD: unknown
  • Power output: 300mW/3 ohms
  • Speaker: oval type 15.5x10cm
  • Power: just from the battery, 2x4.5V (3R12) cells. Consumption: on average at good signal 45mA, at maximum audio level 70mA
  • Dimensions: 240x178x79 mm, 1.8 kg.
The name Orionette and the Orion logo on the scale base should not fool anyone, at the time, for some reason, radios were associated with Orion. The imp. inscription under the Orion logo suggests that the radios were exported under the Orion brand name.
With more than 65 years, the radio is perfectly tuned in, and its reception is still good after all these years. The tuning is fine and quite accurate for the scale. The large speaker in the wooden box produces a pleasant sound, with a good volume (at the time, a small tube super couldn't do more).
Was necessary to change all electrolytic capacitors.
The transistor used as a diode has the function of thermal stability of the output audio amplifier and was used from the defective transistors from the manufacturing process.
The P14 transistor was among the first transistor models manufactured by Tungsram, under a Russian license - for this reason, this transistor looks like Russian transistors. At that time the transistors manufactured by Tungsram does not work above 1MHz, which means the manufacturer ordered high frequency transistors from Japan (2SA15, 2SA12) or from USA (2N219, 2N218) - used in the radio part.
The small coil attached to the back cover via a socket is the external antenna connection, which inductively (with a closed cover) will be very close to the inside ferrite rod, transferring the signal to the input RF circuit of the radio.
The decoration band around the radio is detachable and turns into a radio that can be hung on the shoulder.
Versions: with one transistor preamplifier between the radio parts and the power amplifier stage, later this was modified by combining this preamplifier with the first stage of the amplifier. In the early versions, the speaker was connected between the connection of 2 serially connected batteries, to reduce consumption.


Tivoli Audio


Tivoli Audio is an American manufacturing company notable for producing a line of up-market tabletop radios and related audio products. It was founded in 2000 by Tom DeVesto in collaboration with Henry Kloss, who perceived a gap in the consumer audio market for a high-quality, well designed and affordable AM/FM radio in congested urban locations, while maintaining the ability to pick out distant or low power stations. Tivoli Audio is best known for its Model One Radio. By 2006, Tivoli Audio had become a global luxury brand, selling in over 30 countries and gaining recognition in the audio and design world.


Tivoli Audio Model One

Tivoli Audio Model One

This amazingly affordable (?) and musical table radio was designed by the famous designer, Henry Kloss. Tivoli doesn't publish any specs on the Model One, but the radio has at least decent selectivity, given the cleanness and lack of ambiguity with which it pounces on every station. I have the Cherry/Silver version with a compact, handmade natural cherry wood cabinet providing an acoustically inert housing. The design is classic, almost hearkening back to old valve radios. The front has three knobs: source, volume, and tuning. The tuning knob has a quality vernier drive, is geared down 5:1 with an amber light to let you know you've got it perfectly locked on. On the front symmetrical balance to the tuning knob is achieved with a 3-inch speaker, (heavy-magnet, long-throw). The audio section is well built with a powerful amplifier, a strong magnet for the loudspeaker, and a bass port design for the wooden cabinet. All are factors that contribute to its reputation for good audio. Has been equalized for enhanced bass and treble with the mid's some 6 dB down. These are well-known tricks for getting a warm and crisp sound with universal appeal.
Antennas are internal but a rear jack allows for an external FM aerial where required (an FM telescopic aerial is included). The antenna signal is captured by a discrete-component FM tuner with GaAs MES-FET mixer, which gives low noise, high sensitivity even with closely spaced stations.

General information:

  • Designed by Tivoli Audio, Cambridge, Massachusetts, USA, but the radio is Made in China between 2000 - 2008
  • Analog 2 bands (MW-FM) mono table radio (mono also in line out/headphone jacks)
  • No memory presets
  • Coverage: MW 522kHz - 1.611MHz, FM 87.5MHz - 108.0MHz
  • Usable sensitivity: no info
  • FM/AM tuner with IF section: TEA5711; audio input TL081; equalizer/tunning indicator and voltage ref: TL084; headphone driver NE5532; power amplifier TDA7266
  • Output frequency range: no info
  • Signal/noise ratio: no info
  • THD: no info
  • Antenna input impedance for FM: 75 ohm
  • Driver: 3" (76.2 mm) full-range, 8 ohms/5W driver
  • Power: 230V/50Hz, consumption: max 25W, or via wall plug 12Vdc/800mA (diode protected)
  • Dimensions: 213x114x133mm (WxHxD), 1.9kg

Good things:

  • Has a good readable tuning knob geared down 5:1
  • Good sensibility and selectivity on both bands, AM and FM
  • Tuning indicator a well designed, easy to adjust to the highest signal/light level
  • Very robust design, well made

Difficult, problematic items:

  • One weakness that manifested itself after few years in this particular radio is that it became hard to tune, scratchy, and unstable on FM due to intermittent contacts in the tuning capacitor. Easily can be "repaired": aggressively rotate the tuning dial CW/CCW a few times, repeating this on the whole scale.
  • No possibility to get out the MPX signal for upgrade
  • The tuning dial is not entirely accurate, you can found 0.5MHz deviation
The best place to have this basic, well-sounding table radio is beside your bed, in the kitchen, or at the office for everyday listening. Are solidly constructed, however upon opening it, numerous out-of-date (NOS) inexpensive components are visible. Because they have superior qualities than low voltage ones, low value capacitors with high voltage (100V) ratings were chosen for improved performance (ABAcon, a Chinese capacitor manufacturer that some people have never heard of). All were swapped out for foil capacitors, which improved the clarity but kept the warmth and timbre. Furthermore, the used integrated circuits were over 15 years old as of the radio's initial introduction in 2000. The truth is not covered by the schematic that Radiomuseum.org has released. There the radio chip is TEA5710, but in the radio they use TEA5711T, which has stereo decoding possibility (not used in Model One, but this module is which are used in Model Three, with few additional components used for stereo). The NE5532 are used exclusively to drive the headphone output, driving separately both headphone speakers. The coupling capacitors were 100uF/25V - I changed them to 330uF/16V, to decrease the lower frequency range, and the feedback resistor value is 150k instead of 100k from schematic (higher amplification). Inside can be found 3 PCBs: one in the input selector, volume and the 2 LEDs (power and tuning indicator). The second is the power regulator, input and output circuits (Aux In and Headphone Out), the audio filter circuit, and the power amplifier. The third PCB is the radio part, with the tunning capacitor, which is connected to the tunning gear. On the power PCB was not mounted C14 and C3, before and after capacitors of low drop regulator (U4, 78L08), and the C23, which is the buffer capacitor of U3, TL084. C8 and C24 insted of 0.1uF are 10uF (changed to foil type capacitors). C29, 2.2uF was changed to 4.7uF foil type. All MLCC capacitors from audio signal path are 0.22uF X5V type, which is not the best selection, is a very cheap capacitor type with significant distortion.


Tivoli Audio Model Three

Tivoli Audio Model Three

This radio seems to copy the famous predecessor, the Model One, adding a few new items, like a quartz analog battery-powered clock with an analog alarm dial, 5 minutes snooze, 20 minutes sleep function, a stereo receiver including the stereo amplifier (the second speaker in a radio-like design box can be purchased separately!), subwoofer output, external power supply (Model One has it built-in).

General information:

  • Designed by Tivoli Audio, Cambridge, Massachusetts, USA, but the radio is Made in China between 2003 - 2010
  • Analog 2 bands (MW-FM) table radio with one speaker (stereo in line out/headphone jacks)
  • No memory presets
  • Coverage: MW 522kHz - 1.611MHz, FM 87.5MHz - 108.0MHz
  • Usable sensitivity: no info
  • FM/AM tuner with IF section: TEA5711T; audio input TL082; equalizer/tunning indicator and voltage ref: TL084; headphone driver TL082; power amplifier TDA7266
  • Output frequency range: no info
  • Signal/noise ratio: no info
  • THD: no info
  • Antenna input impedance for FM: 75 ohm
  • Driver: 3" (76.2 mm) fullrange, 8 ohms/5W driver
  • Power: external 230V/50Hz, consumption: max 25W, or via wall plug 12Vdc/1500mA (diode protected)
  • Dimensions: 212x114x133mm (WxHxD), 1.7kg

Good things:

  • Has a good readable tuning knob geared down 5:1
  • Good sensibility and selectivity on FM (not considering the thermal stability, which is the worst), the AM is just average
  • Tuning indicator a well-designed, easy to adjust to the highest signal level
  • Natural, cherry-wood cabinet

Difficult, problematic items:

  • One weakness that manifested itself after few years in this particular radio is that it became hard to tune, scratchy, and unstable on FM due to intermittent contacts in the tuning capacitor. Easily can be "repaired": aggressively rotate the tuning dial CW/CCW a few times, repeating this on the whole scale.
  • If you forget to replace the AA battery which powers the clock on a regular basis, the day will come when the clock decides to conk out in the middle of the night -- with dire consequences.
  • Because the analog clock is a 12-hour system, it'll activate twice a day unless you cycle it fully off in the morning, then back on again just before bedtime
  • The unit is monaural unless you add an external speaker.
  • The clock can be adjusted in one direction only (forward) and the alarm in the other (reverse).
  • Very expensive/overpriced (299$ at 2008), made with cheap components, often reported defects of unconnected cables, thermal deviation of frequency during listening, and low precision of the clock
  • The tuning dial is not entirely accurate, you can find a minim 0.5MHz deviation
  • Frequency stability is very-very poor: if you listen to it for 20 minutes, you need to readjust the FM station, or if you switch on again the radio, the last listened station needs to be readjusted/searched again.
The sound is like Model One, but the speaker is on the top - make it sound spatial. Compared with Model One, if you open it, you can see plenty of outdated cheap components - but now also in the tuner section. Probably this is why its frequency stability is poor - this is the worst radio considering the thermal drift. Low-value capacitors were selected for better performance with high voltage (100V) ratings (ABAcon, some never heard Chinese capacitor maker) because they have better characteristics than the low voltage ones. All were changed into foil capacitors, or dry electrolytes (OSCON) and now the sound is more clear, but the tonality/warmness remains.
On a few portals can be seen comparisons between Sangean WR-1 and WR11 with Tivoli Audio Model One, Model Two, and Model Three - and the winners are the Sangean radios, which outperform the Tivoli Audio receivers, and are much cheaper.



Uher


UHER Werke München KG, commonly abbreviated to UHER, was an electronics company in München (Germany) that was specialized in the development and manufacture of (portable) open-reel tape recorders. The company was established in 1952 and was sold in 1974. Since digital equipment has become widespread, these older analogue recording machines are no longer produced. Two parts of the Uher company still exist; one which has focused on informatics, and ATIS Uher focused on IT security. Currently the brand are owned and licensed by Assmann Electronics of Bad Homburg.


Uher EG-750

Uher EG-750

Was the top model of the 1979 catalog of UHER. Has a signal calibration for recording, emitting 333Hz, 2 instruments - one for tuning, another one switchable between signal strength and multipath, which can make easier the perfect tunning. Has AFC, mono/stereo switch, muting and adjustable audio output. The front is dominated by a large linear scale well illuminated from the backside, and the 2 analog instruments.

General information:

  • Manufactured between 1978-81, in backside written by Uher Werke, but was made in Japan by Hitachi, OEM version FT-920 (from 1976!)
  • Analog 2 bands (MW-FM) analog superheterodyne receiver
  • No memory presets
  • Coverage: MW 525kHz - 1.605MHz, FM 87.5MHz - 108.0MHz
  • Usable sensitivity: 0.9uV on 60 ohms mono, and 30uV for FM stereo, 900uV/m on AM
  • Used ICs: FM IF section: HA1137; IF amplifier HA1211, AM IF HA1138, MPX decoder HA1156W
  • Output frequency range: 20HZ - 15kHz, +0.2..-2dB
  • Signal/noise ratio: 73dB for FM mono, 68dB for FM stereo
  • THD: 0.15% for mono and 0.25% for stereo at 1kHz
  • Channel separation: 50dB at 1kHz, or 38dB between 50Hz - 10kHz
  • Antenna input impedance for FM: balanced 240 ohms, unbalanced 60 ohms
  • Output signal level and impedance: 30 - 700mV/1kohms, 15-400mV61kohms for AM
  • Power: 230V/50Hz, consumption: max 19W
  • Dimensions: 435x135x297mm (WxHxD), 6.7kg
  • Original price: 704DM

Good things:

  • Has a nice timeless front design
  • Good sensibility and selectivity on FM regarding dual-gate MOSFET frontend
  • FM multipath for easier tunning
  • Signal generator for recording level calibration
  • Two types of output signal sockets: DIN (non-adjustable) and RCA (adjustable)
  • Two output stages after MPX decoder, between them the 6 pole LC filter.

Difficult, problematic items:

  • Nowadays uncommon external antenna sockets for AM and FM
  • Low sensibility on AM, is 900uV/m!
The Uher EG750 has 4 gangs on FM and 2 gangs on AM. The single-bandwidth FM IF string contains 3 ceramic filters: a 280kHz out of the mixer, then an HA1211 IC amp followed by 2 more 280kHzs, and then into the HA1137 detector IC. The tuner stage is completely the same as used in Hitachi FT-920, including components notation on PCB and schematic.
I found just one deviation from the schematic: the power of the 333Hz signal generator has an extra 47uF/25V in the supply part.
Parts modified: C320 22uF and C303 10uF connected in series changed with only one 10uF pp foil capacitor. C602L and C602R were replaced with 1uF/63V pp, C603L and C603R were replaced with 4.7uF/63V pp.
In power part: C803 replaced with 2200uF/35V, C804 with 470uF/35V, C807 with 1000uF/35V, C124, C169 with 270uF/16V, C318 with 470uF/35V.



Unitra


UNITRA was the Association of Polish consumer electronics manufacturers (more than 60), and was established in 1961 and lasted in its original structure until 1989. After the systemic transformation, consumer products under the Unitra brand name reappeared on the market. Electronic equipment manufactured under the common Unitra brand measured up in quality to comparable equipment produced in the entire Western Europe. The Unitra equipment earned a high reputation thanks to the quality and reliability of the manufactured products. Among other things, the Association ran its own R&D department and a common commercial bureau. Due to its long-lasting tradition and user confidence the brand is recognizable to date and is prized for the high quality and durability of its products. As a result of the political transformation in 1989, manufacturers' associations were disbanded. Individual companies became independent and continued their activity with varying degrees of success.
Some important associated manufacturers: CEMI - semiconductor devices, DIORA - HiFi sets, FONICA - Turntables, stereo amplifiers, TONSIL - loudspeakers boxes, ZRK - cassette decks, stereo receivers. In general, Unitra Diora was an East European manufacturer and produced relatively good FM tuners before 1989 mostly for communist countries.


Unitra AS630

Unitra AS-630

Was one of the famous tuners made by Unitra at end of '80s, and this appears in several versions: 630 was the CCIR version, 632 was the OIRT version, 631b was the version with a digital scale, but completely same, and this board starts from 212, 618, and ended in 641 (with digital scale), 6411, 6412, 642 (all 64x with the audio buffer on output and touch-sensors for presets), and the tuner parts was used also in receivers, like WS432, etc. Has an alumina frontplate with big tunning-knob, the scale is luminated from both sides via two 12V/1W miniature bulbs in sockets.

General information:

  • Manufactured between 1985-88 by Unitra Diora, Poland
  • 3 band analog superheterodyne tuner, LW, MW and FM
  • Coverage: LW 150kHz - 285kHz, MW 520kHz - 1.620MHz, FM 87.5MHz - 108.0MHz
  • Antenna input: for FM just 75 ohms unbalanced, for AM (LW and MW) via ferrite rod and external aerial and ground
  • 5 preset memory for FM
  • Usable sensitivity: 2.0 uV on FM mono, 50uV for stereo, 800uV/m for LW and 500uV/m for MW
  • Intermediate frequencies: 465kHz for AM, and 10.7MHz
  • Used ICs: FM IF amplifier and quadrature detector UL1200 (CA3089, HA1137W), AM IF demod A244D (TCA440, UL1203), MPX decoder TCA4500A (UL1621) and voltage stabilizer UL1550 (TAA550) for UHF tunning
  • Signal to noise ratio: mono 72dB, stereo 64dB for FM, and 53dB for AM
  • Harmonic distortion: mono 0.3%, stereo 0.5% for FM, 2% for AM
  • Output audio band: 30 - 15000 Hz, +-3dB
  • Stereo separation: 42dB at 1kHz
  • Output frequency range: 30Hz - 15kHz (-2...+2dB)
  • Audio output connectors: DIN and RCA type
  • Power: ~220V/50Hz, consumption 7W
  • Output power: 500mV/3.3kohm
  • Dimensions: 440x90x260mm, 4.2 kg.
This tuner was manufactured for West Europe, works on 88-108MHz range. Has 4 gangs on FM, 3 10.7MHz ceramic filters with 280kHz bandwidth, and 2 gangs on AM.
I purchase it after AS631 model (without tunning knob, and as you can see, I replaced it. The radio part is completely same.
The sensibility is very good in comparison with specification, the sound is very pleasant, detailed, with rich bass and beautiful treble (after modification).
This tuner frontend is just with BJT, which has a higher background noise compared with MOSFET, the AM section is made with A244D (TCA440T).
The tunning indicator was upgraded (same as in AS 641) - now is amplified with 2 transistors, and has more exact feedback.
Modifications:
Power line: after R216 the power of frontend received a 100uF/16V dry cap (in not mounted but marked C210 position), C200 is 470uF/35V, C222 received in parallel 10uF/50V, C233 270uF/16V dry cap, C252 100uF/16V dry cap, C276 received 1000uF/25V in parallel, C281 received 10uF/50V in parallel, C282 470uF/63V, and instead of R267 was mounted 3.3uH coil. Now cannot be heard any noise generated by LED lamps, laptop or mobile wall-plug or switching power supplies during listening AM stations.
Other changes: C242, C252 and C262 changed to 2.2uF/100V foil cap, C269 and C274 changed to 1uF/63V foil cap. As previously was mentioned, in tunning indicator circuit was inserted the T504 BC238 and R510 12kohm, and R512 was changed from 22kOhm to 47kohm.
As tuner, just one additional modification I recommend to be made: the audio buffer, like in AS 641 model.


Unitra AS631

Unitra AS-631

This tuner was sold in West Europe under different brand names, like TECCO (my tuner's full name is TECCO Stereo Tuner AS 631 B), MacWatts, McVoice, Visonik, Brogmton, Geton, ITC, Bruns or Crown, and of course Unitra, and all were Unitra Diora products.

General information:

  • Manufactured between 1987-89 by Unitra Diora, Poland
  • 3 band analog superheterodyne tuner, LW, MW and FM
  • Coverage: LW 150kHz - 280kHz, MW 510kHz - 1.640MHz, FM 87.5MHz - 108.0MHz
  • Antenna input: for FM just 75 ohms unbalanced, for AM (LW and MW) aerial and ground
  • 5 preset memory for FM
  • Usable sensitivity: 2.0 uV on FM mono, 50uV for stereo, 800uV/m for LW and 500uV/m for MW
  • Intermediate frequencies: 450kHz for AM, and 10.7MHz
  • Used ICs: FM IF amplifier and quadrature detector UL1200 (CA3089), AM IF demod UL1203 (A244D, TCA440T), MPX decoder TCA4500A, amplifier and divider by 32/33, SAA1059 frequency counter and display driver SAA1070 and voltage stabilizer UL1550 (TAA550)
  • Signal to noise ratio: mono 72dB, stereo 64dB for FM, and 53dB for AM
  • Harmonic distortion: mono 0.3%, stereo 0.5% for FM, 2% for AM
  • Output audio band: 30 - 15000 Hz, +-3dB
  • Audio output connectors: DIN and RCA type
  • Stereo separation: 40dB at 1kHz
  • Output frequency range: 40Hz - 15kHz (-2...+2dB)
  • Power: ~220V/50Hz, consumption 12W
  • Output power: 500mV/2.2kohm
  • Dimensions: 440x90x260mm, 4.6 kg.
This tuner was manufactured for West Europe, and the TECCO brand name was sold on the Austrian market.
I purchase it specially to test it, and at the beginning, I did not expect too much from this, because I experienced the quality in post-communist countries were far from my expectation, but all goods sold to capitalist countries were well made - but almost from same components. The technology and the circuits used in this tuner seems to come from the end of 70'/beginning of 80', including the digital scale.
The sensibility is very good in comparison with specification, the sound is very pleasant, detailed, with rich bass and beautiful treble.
This tuner has a newer version, called AS 641 - the radio circuit is almost the same excepting the first stage, which uses MOSFET with AFC, the AM section is made with UL1203 (TCA440T), and at the audio output, after 2 LC filters has an output buffer on a separate PCB attached to the RCA connector. Seems a very elegant solution, and that was reproduced by me and inserted in my set. The digital part of AS 641 is completely different: use LB3500 as prescaller and LC7266 as controller, counter and display driver, and use 8 presets made with SAS580-SAS590 ICs.



Videoton


The legal predecessor of VIDEOTON was founded in 1938 under the name of Vadásztöltény Csappantyú, Gyutacs és Fémárugyár Rt (translated could be Hunter's Cartridge, Clapper, Lighter and Metal Factory Co.). After the World War II. the company was rebuilt and owned by the state between 1955-1991. It developed, produced, and sold Videoton branded consumer-, computer- and defense (military) electronics. From 1981 the company was called VIDEOTON Electronics. It has earned a serious reputation for its portable- and desktop radios, TV sets, speakers, and later Hi-Fi systems. After the political changes in the early 90s - especially due to the canceled orders of the East-European market - the company got into a difficult situation, therefore its liquidation started in 1991. The current shareholders and Hungarian Credit Bank and Euroinvest Ltd. acquired the company's assets in a public tender, and they rename the company Videoton Holding Rt. The company now is the 25th EMS (electronic manufacturing service) company in worldwide rank.


Videoton RT 7300S

Videoton RT-7300S

Videoton Electronics produced its final tuner between 1987 and 1989, coinciding with the conclusion of the communist era in Hungary. While the front appears to be an AKAI creation, Videoton engineers designed the entire radio component. AM consists of only MW and has two FM channels (OIRT and CCIR), making it an extremely complex tuner. Among the leading tuners of the communist bloc (another one, the Orion ST240, was manufactured in Hungary), but the technology and components employed suggested that it was a tuner designed in the early of 1980s. Philips designed the controller specifically for Videoton so that it could operate on both FM bands.

General information:

  • Manufactured between 1987-89 by Videoton Electronics Rt at Székesfehérvár, Hungary
  • 3 band analog superheterodyne tuner, AM/MW and FM1 (OIRT) and FM2 (CCIR)
  • Coverage: MW 519kHz - 1.621MHz, FM1 (OIRT) 65.78MHz - 73.02MHz, FM2 (CCIR) 87.48MHz - 108.02MHz
  • Tunning steps: 1kHz on AM and 10kHz on FM (fine/fast tuning possibility with same step),
  • Antenna input: for FM just 75 ohms unbalanced, for AM (MW) ferrite rod and aerial and ground
  • 9 preset memories, which can be used for any band (AM/MW, FM1, FM2)
  • Usable sensitivity: 0.9 uV on FM mono, 25uV for stereo, 400uV/m for MW
  • Intermediate frequencies: 450kHz for AM, and 10.7MHz
  • Used ICs: FM mixer TDA1062, FM IF amplifier and quadrature detector HA12412, AM IF demodulator TDA1072A and TDA120U as AFC for AM, MPX decoder HA12016, SAA1057 prescaller/divider, MAB8441 tuner controller, PCD8571 static 1k RAM, PCF8573 clock circuit, SAA1300 tuner switching circuit, U237B signal level meter, CD4511 and CD4094 (4pcs) display drivers, uA7805 and uA7815 as voltage regulators, operational amplifier on audio output TL082 (in total has 24 ICs, 4 FETs, 26 transistors and 83 diodes)
  • Signal to noise ratio: mono 70dB, stereo 60.5dB for FM, and 53dB for AM
  • Harmonic distortion: mono 0.02%, stereo 0.04% for FM, 0.5% for AM - all measured at 1kHz
  • Output audio band: 15 - 15000 Hz, 0...-0.5dB
  • Stereo separation: better than 50dB at 1kHz
  • Output levels and impedances: on fix level output 700mV/1.2kohm, on variable output 0...1.2V/0...220ohms, on headphone output 1.75V/100ohms
  • Power: ~220V/50Hz, consumption 15W
  • Dimensions and weight: 440x75x320mm, 5 kg.
  • Price at 1988: 225$ (appr. 12300 HUF at that time)

Good things:

  • Elegant and uncomplicated front plate,
  • Excellent FM selectivity and sensibility with regard to the dual-gate MOSFET frontend (BF963),
  • Adjustable muting level (located on the reverse),
  • The headphones' output is supplied by a dedicated amplifier. Their respective levels cannot be independently adjusted as their volume settings are identical to those of the variable output level adjuster, also situated on the rear panel (is better to be separated),
  • Switchable automatic noise cancellation circuit / auto blend,
  • Station storage is implemented in RAM, which is powered by one NiCd accumulator cell,
  • Automatic search capability, up/down search capability on all three bands, and manual rapid step tunning buttons (five times higher steps) that accelerate manual searching,
  • Featured with a bright, legible, large fluorescent display for signal level, station frequency and bands marks,
  • When the Time button is selected, the current time will be displayed until another button (for presets or searching) is pressed,
  • As a result of the regulators being fastened to the chassis, their heat is dissipated across the entire body and not just inside, thereby maintaining the set's temperature and frequency stability.
  • Movement of the affixed ferrite bar antenna in any direction was unprecedented among Japanese and other West European models of the era. Is easy to direct it to the received station, increasing the tuner's sensibility on AM

Difficult, problematic items:

  • Modular system, which is good during manufacturing, making possible a fast adjusting of each module - but for servicing is a nightmare. You cannot take it out for adjustment, and in its place, you have no space to adjust them. Modules: FM tuner, FM IF, AM IF, and the Stereo decoder - in total 4. Used connectors were very cheap ones, over time all contacts became oxidated, making strange malfunctions.
  • Poor soldering quality, with very minimal solder quantity in solder joints. The components moved or aligned a bit or after taking out the modules, the connector pins' soldering on the main plate easily are cracked making false contacts -> all must be resoldered
  • Both audio output signal sockets on the rear cover are DIN type
  • Nowadays uncommon external antenna sockets for AM
  • 9 preset memories for all 3 bands is far to be enough.
  • You may change the variable audio output level in addition to the headphone volume on the rear. This indicates that it is challenging to change the level while listening, but if you do so on high, you may be shocked when you turn on the amplifier to listen to the tuner. This can be solved, if you mount two other adjusting potentiometers just for the audio output inside of tuner, setting them for your audio system.
This tuner was manufactured to be able to receive 2 FM bands: the CCIR band used in West Europe and also the OIRT band used in East Europe via a clever converter. The FM stage has 5 gangs, the AM 3 gangs, and use 3 ceramic filters on FM (SFE10.7XMA)
The technology and the circuits used to come from the beginning of 80', including the digital scale. Most of the electrolytic capacitors are axial TH type regarding modular system and low profile of tuner - which are difficult to purchase. To be noted: almost each ICs are powered via LC filters, which decreases the noise transmitted via power lines. Has an output buffer (TL082), and the best one: has a built in headphone amplifier, you do not need to use a separate one. The sensibility is very good in comparison with specification, the sound is very pleasant, and detailed, similar to the Pioneer FX90, but with just a bit less dynamic, and also with a less bass - but very close.
Modifications: all electrolytics changed, and also all throug-hole 100nF ceramic capacitors.
Changes:
  • On the MPX module: DC06 and DC10 fron 10uF to 22uF Elna Fine Gold, DC05, DC17 and DC18 to 10uF/63V foil capacitors (signal in and out), HC55 from 220uF to 1000uF/25V Yageo (power)
  • Headphone amplifier: HC117 from 470uF to 1500uF/25V KEMET (power), HR118 and HC112 from 47uF to 470uF/35V Nichicon (headphone output, now can be connected headphones with 16 ohm impedance), HC151 and HC154 from 1uF electrolyte to 2uF foil type, HC89, HC91 and HC97 from 2.2uF electrolyte to 4.7uF/63V foil (input selector, AM/FM), HC113 and HC115 changed to same capacitor value 22uF/25V Fine Gold bipolar Nichicon, HC139 and HC142 chnaged frin 47uF to to 100uF/16V.
  • Digital part: power of microcontroller VC53 changed from 470uF/10V to 1800uF/10V low ESR electrolytic + 470uF/10V solid electrolyte.
  • Display board: KC99 changd from 100uF/16V to 270uF/16V c, and KC 10uF/100V to 100uF/16V, both solide electrolytic type.
  • In the AM module: AC02, AC42 and AC53 now is a 22uF/25V Ta capacitor
  • Power supply: TC7 changed from 470uF/40V to 1000uF/35V+0.1uF/50V SMT MLCC X5Y, TC11 from 1000uF/16V to 2200uF/25V+0.1uF/50V SMT MLCC X5Y. In tuner unit supply line the 2.2uF electrolytic capacitor was changed with inductionless 2.2uF/100V foil capacitor (HC167). In the prescaller power supply the 100uF electrolytic was changed to solid electrolytic type (VC09). After power switch received an EMI filer formed with 1nF/3kV ceramic + .68uF/275Vac foil + 2x11mH coils + 1nF/3kV ceramic + .68uF/275Vac foil Pi filter
  • A tiny piece of foam was adhered above the microswitch buttons on the tuning buttons. The action is more fluid in this scenario where the buttons remain in situ.
  • The cover of the tuner is secured using a mere two screws. Due to its high degree of instability, it is susceptible to vibrations. To circumvent this, small sponges were positioned on the front, where the cover could slide in, and on the interior of the cover, where it could make contact with the rear of the tuner.
Due to the fact that Videoton was an EMS manufacturer for AKAI at the time, the tuner front plate resembles that of an AKAI from that era. This tuner was prohibitively expensive at the time due to an excessive number of manual assemblies and components (no advanced automation, which was typical of communist factories at the time).
In conclusion, while it is a decent tuner, it may experience instability at times due to subpar connectors. AM performance is exceptional, surpassing that of the older Marantz receivers, while FM2 (CCIR) is nearly comparable to the Pioneer FX90. The built-in headphone amplifier is an advantage; there is no necessity to switch on additional equipment in order to listen to it.
If the tuner is properly aligned and refurbished (recaped), it can function as the primary tuner in a music center or independently. It is typically utilized in close proximity to the preferred reading location of a study desk using headphones.



WEGA

(Sony)


WEGA, was founded as Wuerttembergische Radio-Gesellschaft mbH in Stuttgart, Germany in the year 1923. Sony purchased WEGA in 1975, which means after acquisition several models were built under Sony design. Wega products were then known throughout Europe for stylish and high-quality stereo equipment, designed by Hartmut Esslinger, amongst others. Sony used the Wega name for different products (Trinitron flat screen or LCDs TV sets). Defunct at 2005.


WEGA JPS352 SE T

WEGA JPS352 SE T

General information:

  • Manufactured at 1979 by WEGA-Radio GmbH, Fellbach, (West) Germany
  • 2 band analog superheterodyne tuner, MW and FM
  • Coverage: MW 510kHz - 1.640MHz, FM 87.5MHz - 108.0MHz
  • Antenna input impedance for FM: just 75 ohms unbalanced,
  • No preset memory for FM
  • Usable sensitivity: 2.0 uV on FM mono (no any data for stereo or for AM)
  • Intermediate frequencies: 450kHz for AM, and 10.7MHz
  • Has only one IC, which makes all functions (IF system, MPX decoder, indicators driver): AN7000.
  • Signal to noise ratio: mono 72dB, stereo 64dB for FM, and 53dB for AM
  • Harmonic distortion: mono 0.2%, stereo 0.8% for FM, and 0.5% for AM
  • Output frequency range: 40Hz - 15kHz (-2...+2dB)
  • Power: ~220V/50Hz, consumption 15W
  • Output power: 750mV/2.2kohm
  • Dimensions: 430x100x230mm, 3.7 kg.
The surprise was the high level of integration: just the FM tuner, the output MPX filter, and audio amplifiers are built with discrete components, and all the rest of the functions are made just by one IC - and that was in 1979! Despite 2.0uV sensitivity, the reception is quite good, warm sound, like Technics SA-5370. Unfortunately, both meters were out of order, I changed them with real instruments.
Additionally received an AC filter. All electrolytic capacitors changed. IC power pin grounded with 1uF/35V X7R MLCC, also the C125 received in parallel a 47pF/50V C0G MLCC (recommended by user manual of AN7000), and in the audio output stage a puffer capacitor (22uF/63V).
In series with scale light bulbs received a 20ohm NTC resistor (to protect them, because the tuner was built for 220VAC, and now in my home, I can measure 238VAC).
The signal from FM antenna input socket goes into the L101 impedance adjusting transformer, which has an output for a 300-ohm antenna connection - can be used if somebody has such an antenna.
This radio on several portals are mentioned as a Sony clone.


WEGA T120

WEGA T120

General information:

  • Manufactured between 1980-82 by WEGA Elektronik GmbH, Köln, (West) Germany
  • 3 band analog superheterodyne tuner, MW and FM
  • Coverage: LW 150kHz - 344kHz, MW 522kHz - 1.602MHz, FM 87.5MHz - 108.0MHz
  • Antenna input impedance for FM: 75 ohms unbalanced and 300 ohms balanced. Has an external antenna input for AM, selectable from the backside via a switch
  • No preset memory for FM
  • Usable sensitivity: 1.3 uV on FM mono, 250uV/m with built-in antenna and 100uV/m with external antenna for MW, 500uV/m with built-in antenna and 250uV/m with external antenna for LW
  • Intermediate frequencies: 450kHz for AM, and 10.7MHz (green body, marked with white dot, inscription 10M)
  • Used ICs: FM mixer and osc: SC-114D; FM IF LA1231; MPX decoder uPC1161C; AM: LA1240; servo lock: uPC4558C; signal level: LB1416
  • Signal to noise ratio: mono 65dB, stereo 60dB for FM, and 50dB for AM
  • Harmonic distortion: mono 0.15%, stereo 0.4% for FM, and 0.5% for AM
  • Output frequency range: 40Hz - 15kHz (-2...+2dB)
  • Power: ~220V/50Hz, consumption 7W
  • Output power: 300mV/2.2kohm
  • Dimensions: 430x80x275mm, 3.6 kg.
Is completely similar to Sony's ST-A30L tuner (Wega was part of Sony). Has a very good sensibility - is just a 3 gang tuner on FM and 2 gangs on AM. In stereo mode is automatically activated the muting circuit. Has a High-Blend switch to decrease the sizzle noise in high frequency from the audio signal.
Differences compared to service manual: not mounted C602 and C603 from the AFC circuit (both 0.47uF), and the value of C204 instead of 1uF is 4.7uF/25V.
All electrolytic capacitors were changed. ICs buffer capacitors were replaced with 470uF/35V (C212, C301, and C422).
In power supply the C803 changed to 2200uF/25V, C805 to 470uF/35V, C804 and C808 to 390uF/35V, C806 to 100uF/63V.
In the audio part, I used just PP capacitors. Just the output capacitors value was changed/increased from 0.47uF to 1uF (C313 and C363), because the bass section does not need any changes. The set has a very warm sound reach in the bass section.
After the power switch, I mounted an EMI filter before power transformers primary coil (2.2nF+2x7.6mH+0.47uF), which was necessary to be shielded.
Overall, is a good tuner with high sensibility on FM, good "acute servo lock", and is very listenable! The AM section is not so good, the sound is not distorted, but the background noise is high.



XHData


Is very difficult to determine the name of original manufacturer, because can be seen as made by Radiwow, or by Sihuadon. All 3 brands appear under xhdata.com.cn webpage. Sihuandon D808 is exactly same as XHdata D808, just in black color with orange backlight. Raiwow R108 is completely same with Sihuadon R108. Is quite difficult to have a clear picture who is the real manufacturer of those sets.


XHDATA D808

XHDATA D808

Is my newest pocket radio with DSP. Appears on the market in 2018, made by Radiwow, a Chinese company. Has Squelch Control (works On all bands which is unusual), Fast/Slow/Stop (Lock) Tuning Speeds. The second display is switchable: Time (Default), Signal Strength/Signal To Noise ratio, Temp (Fahrenheit or Centigrade), and Alarm Time. Tune via Knob or Up/Down Buttons with ATS (Automatic Tuning System), and Direct Frequency Entry keys.

General information:

  • Digital 5 bands (LW-MW-SW-FM-Air) DSP radio with RDS and Radio Text capability,
  • 500 memory presets, 100 for each band, all with 10-10 memory pages
  • Coverage: LW 150kHz - 450kHz, MW 522kHz - 1.620MHz/520kHz - 1710kHz, SW 1.711MHz - 29.999MHz, FM 64MHz - 108.0MHz (selectable bandwidth), AIR 118MHz - 137MHz
  • Channel space: (10k)9kHz/1kHz for LW/MW; 5kHz/1kHz for SW, 100kHz/10kHz for FM and 25kHz/1kHz for AIR
  • Fine adjusting possibility for all AM bands
  • LSB/USB selection possibility on SW
  • Selectable digital audio bandwidth filters MW/SW: 1, 1.8, 2, 2.5, 3, 4, 6kHz, and for SSB: 0.5, 1, 1.2, 2.2, 3, 4kHz
  • Usable sensitivity: 10mV/m on LW, 0.5mV/m on MW, 10uV on SW, 3uV on FM, 0.5uV on AIR. Not specified the signal level for FM stereo reception
  • Integrated circuits: Silicon Labs Si4735 DSP Chip, Air band converter FS8308, FM front end CD7358GS (same as Toshiba's TC7358), CS4863 (LM4863 equivalent) audio power amplifier IC, Li-ion battery charger TP4056
  • Stereo just via headphone
  • Has external antenna input for SW-FM-AIR
  • Built in speaker: 8 ohm/1W
  • Power: from a 3.7V Li-ion accumulator 18650/2000mAh, chargeable via a micro USB jack (new versions, since 2022 has USB-C jack), 5V (<10hrs charging time). Consumption: 130uA in Power Off status, 10mA with Power Off but LCD backlight on, 36mA with Power On and low volume, and 120mA with power on maximum volume.
  • Dimensions: 157x92x32mm
  • Weight: 265g without battery
  • The box contains: the radio + user manual + specific bag + external antenna wire + USB charge cable + 18650 Li accumulator (2000mAh)
Good things:
  • The display light can be switched permanently on and has also a temporization when is off but you press any buttons, for 30 sec
  • The 500 memory locations, distributed into 100-100 locations for each bands, and those divided into 10-10 subpages is easy and logical to be used
  • Has signal level indicator, temperature meter, time, alarm, snooze functions, etc
  • Selectable digital audio filters for AM, which is good especially on SW to cancel channel noise
  • Selectivity and sensitivity is quite good on FM and is remarkable on MW (better than Sony ICF SW7600GR or Sangean ATS-909X)
  • With one charge of Li-ion 18650/2000mAh accumulator, the radio can be used 30-34 hrs. In Standby mode the consumption is less than 90uA, which is very good.
  • USB charging possibility
  • Very easy station storage: depressing a number button on the keypad for more than 3s stores a frequency
  • The Signal Metering helps with comparative numerical readouts of both signal strength and signal to noise ratio.
  • ATS (Auto Tuning System) can be activated on any bands, just holding for more than 2 sec the band button.
  • External Antenna Jack also works on FM but does not disconnect the whip antenna.
  • Adjacent stations' rejection is very good. Example on FM at +-100kHz is -5-7dB, at +-150kHz is -30dB, at +-200kHz drops below -45dB!
Difficult, problematic items:
  • Tuning the radio, in every tuning step mutes the receiver for some percentage of a second. Pressing a button gives a "brrp" sound in the speaker. Not very nice.
  • On MW with the built in ferrite rod the reception is average in best case, but on LW the reception is worth than that. For this reason you can find some upgrade diy ideas, adding external ferrite rod to improve it.
  • Special function marks above button can be seen just in a bright environment (dark orange marks on a grey background)
  • Cannot be switched off the auto muting function during searching
  • ATS has a disadvantage: will store just the stations with good signal, and that threshold limit cannot be adjusted
  • Keyboard buttons are too flat, difficult to identify them in dark, and no button-lights (some owners put on certain key some glue-dot to solve this)
  • Does not remember the second numeric display setting, starts with temperature, and always after switch on you must set again for example to signal meter
  • The sound via speaker is sharp, via headphone is enjoyable
  • RDS/RT sensitivity is low and slow, takes time till the info will be displayed
  • At first time switch on was like an auto-configuration: poor reception quality, insensible, but after 30 minutes operation all goes to normal level (and this is not just my opinion, also are mentioned on a few blogs/forums).
Seems "inspired" (to use a generous term) by the introduction of C. Crane's breakthrough Skywave SSB model in 2017 at the same Shenzhen city, China location a few months earlier. The Chinese startup company essentially had the chance to benefit from C. Crane's substantial R&D costs, copy all of the Skywave SSB's strong points and improve upon its weak points-including the $169.99 price. The end result is a very competitive DXing radio with a current reputation for high quality. In many parts of the world this radio has become the premier portable radio for DXing purposes.
From a DSP do not expect a miracle in sound quality, but this is a quite good, cheap, and sensible pocket radio for daily listening. In conclusion this radio is very similar to C. Crane Skywave SSB (as presented before) and Digitech AR-1780 and Eton G3 Satellit, and their schematic can be used for servicing each other..

Recommendation: The radio has a quite big speaker (in diameter is approx 7cm), almost the maximum which can be mounted into its plastic chassis but sounds like a cheap pocket receiver. The reason is the low capacitance value of the output capacitors. If we consider the speaker as an 8ohm resistor, with 100uF capacitor the cutoff frequency is approx 200Hz. The used capacitor was a very cheap model with poor parameters (high dissipation factor and high ESR). I changed both of them (C145, C153) with a 470uF/6.3V Nichicon Fine Arts type (they are a bit bigger, but still can be mounted in the same position), and now the cutoff frequency became 42Hz. Now the music on FM via speaker is much better, and via headphones became alive! The second modification was to decrease the output noise which can be heard at minimum volume via headphone. For that I inserted one 6.8nF C0G MLCC capacitor connecting both outputs of audio amplifier (between + pins of obove mentioned output capacitors), 2 pcs of 150pF connected in parallel with the output amplifier's feedbak resistors (R122, R123). Is better if the capacitors are SMD (can be soldered on top of resistors), C0G or NP0 type. This method are used in old FM receivers, called "high-blend" filter, and eliminate the noise with oposite phase from the signal, and the second one is a low-pass filter. Try both modifications, and you will be surprised by this improvement in sound quality.
The original Li-ion accumulator can be replaced with a higher capacity one. Now I use a 3000mAh type, and the listening time is 50% longer. The charging time also increased acordingly, but does not cause any problem.
Remark: when you purchase as a new one, the radio can be powered on just if you put it on a charger.
Squelch capability: is not mentioned in the User manual, but can be activated by long pressing the Tuning knob, and waiting for the "Squelch" readout to show up at the bottom of the display. While still pressing in the Tuning knob you can adjust the Squelch level by turning the Tuning knob clockwise to raise the squelch level from 1 to 9. Although this Squelch function is available on all bands on the D-808, but it is apparently useful only on the AIR band.
Related links:
       Georges' review of the XHDATA D-808, is a good revies on The SWing Post about his experience with this radio.
       Reviews For: XHDATA D-808 Portable, is a revies on EHAM radio.
       XHDATA D-808 AM/FM/SW/SSB/Airband Portable Radio, is a revies on RadioJayallen, the most detailed what I found.
       A detailed review of the XHDATA D-808 and comparison with the Tecsun PL-660, is a revies made by 13dka with several replies.
       PL-330 or D-808?, is Kevin's blog, in which he objectively compare the Tecsun PL-330 with XHData D-808 from several aspects, pros and cons.



Yamaha


Nippon Gakki Co. Ltd. (currently Yamaha Corporation) was established in 1887 as a reed organ manufacturer by Torakusu Yamaha in Hamamatsu, Shizuoka Prefecture and was incorporated on October 12, 1897. In 1900 the company started the production of pianos. The first piano to be made in Japan was an upright built in 1900 by Torakusu Yamaha, founder of Nippon Gakki Co., Ltd. - later renamed Yamaha Corporation. The company's origins as a musical instrument manufacturer are still reflected today in the group's logo-a trio of interlocking tuning forks.
Yamaha has grown to become a leading manufacturer of semiconductors, audio/visual, computer related products, sporting goods, home appliances, specialty metals and industrial robots.


Yamaha T-700

Yamaha T700

Shortly about Yamaha tuners history: the slim tuner series started with T-1, T-2 in 1978 (after CT series). After comes the T-7 at 1980, T-70 at 1982. In 1981 appears the T-760/960/1060 and this was replaced by the digital series T-700/1000 in 1983, then comes the T720/1020 in 1986. In 1987 appears the TX series TX-500/900 and later TX-930/950/1000 at 1988. The top Yamaha tuners are TX-1000/2000, and those were the last great tuners before the DSP era (The TX-2000 is just a facelift of TX-1000, inside are identical).
Returning to T-700, is a middle-class FM/AM tuner from T-300/500/700/1000 series. Facilities: has a Record Calibration (333 Hz 50% modulated signal), digital frequency readout, FM noise filter, 10 station memory, and CSL (Computer Servo Locked Synthesizer Tunning System).

General information:

  • Manufactured by Nippon Gakki Co., Ltd in Japan between 1983-1984
  • Digital 2 bands (MW-FM) PLL radio without RDS capability,
  • 10 memory random presets, can be used mixed for AM or FM
  • Coverage: MW 513kHz - 1.620MHz, FM 87.5MHz - 108.0MHz
  • Channel space: 9kHz for AM and 50kHz for FM
  • Intermediate frequency: 450kHz for AM and 10.7MHz for FM
  • Usable sensitivity: 250uV on AM, 0.8uV on FM mono, and 25uV for FM stereo
  • Integrated circuits: FM IF amp: uPC577H - 2pcs, stereo decoder: LA3380, prescaller M54459L, tunning circuit LC7210, microcontroller LC6502C; display driver M54516; operational amplifier NJM4560
  • Output frequency response on FM: 30Hz - 15kHz (+0.2...-1dB)
  • Signal/noise ratio: AM 55dB, FM mono 89dB, FM stereo 84dB
  • THD: on FM 0.05% for mono, 0.07% for stereo, 0.3% on AM
  • Stereo separation: 58dB
  • Antenna input impedance for FM: 75 (unbalanced) and 300 (balanced) ohm
  • Image rejection Ratio: 50dB on FM, 40dB on AM
  • IF response ratio: 90dB
  • Spurious response ratio: on FM 70dB, on AM 50dB
  • AM Suppression Ratio: 60dB
  • Alternate Channel Selectivity: 60dB
  • Output level and impedance: 400mV/4kohm on FM, 150mV/4kohm on AM, and 250mV/4kohm on Rec Cal
  • Power: 220V/50-60Hz, consumption: 12W
  • Dimensions: 435x72x316mm,
  • Weight: 3.8kg
  • Praise: in 1983 499DM

Good things:

  • Has a very clean sound not just on FM, also on AM
  • Record calibration circuit
  • Easy to connect AM loop, arial or FM T-type antenna via push-button type connectors
  • Has a station name card holder - means above the preset buttons can be attached the station name label which is illuminated by LEDs from back side

Difficult, problematic items:

  • Just 10 preset memories are not enough, especially for both (AM/FM) bands
  • The signal level indicator has just 2 LEDs, which does not show almost nothing clear
The Yamaha CSL tuners, like most other tuners, use a circuit to determine the signal quality. In most tuners, it is used to drive the stereo/mono switchover, and muting. This is also true in the CSL circuit, but in addition, if the quality of the tuned station is above a factory set, non-adjustable level, the tuning system "switches over" from the primary tuning (based on LO frequency division) to the computer servo lock system (CSL). The circuit looks at a combination of signal strength, high-frequency noise, and in some cases multi-path problems. The secondary, "CSL" tuning system's goal is higher quality tuning for medium to strong signals. It achieves this by doing a number of things, that when added together, are felt by Yamaha designers to be a sonically superior tuning mode. How? Lower background noise, and less phase noise in the local oscillator. Specifically, the Motorola pre-scaler, whose power is controlled by the LC7210, is turned off. Therefore the high-speed, frequency-controlled PLL is also turned off, in favor of a slow time constant, analog input, analog output, and control loop. This loop is quite similar in high-level operation to AFC loops used on some older analog tuners. But with one difference - the loop is closed with a very long time constant digital algorithm implemented in a 4 bit computer. The second advantage is that the CSL tuning mode finds the lowest distortion operating point (assuming proper tuner adjustment) and tracks that low distortion point over a long period of time, regardless of changes in local operating conditions (like temperature, or power supply voltage). This is accomplished by looking at the ratio detector's secondary DC voltage. The LC7210 digitizes that input voltage, and then sends it to the 4-bit computer, where a digital servo control program, using a long-time constant algorithm, closes the loop. The computer program generates a digital correction "output", that is communicated over the 4 bit digital interface back to the LC7210, where it is output through a charge pump circuit to control the varactor tuning voltage. (summary of Bob post from FM Tuner Info)
Modifications:
Power line: all capacitors changed to dry electrolytes, except the very big values or high voltage types. Values changed: C101, C106 C128, C193 47uF/16V; C180, C182, C199 270uF/16V; C197 100uF/63V; C198 100uF/16V, C200 3300uF/25V. Because this is one side PCB, some jumpers also can be used to decrease the noise transmitted by the power line: J197 replaced with 2.2uH (supply of front end), J140 also with 2.2uH (supply of IF amplifiers), and J168 with 100uH (supply of MPX decoder). Added capacitors as decoupling elements: 1nF/50V SMD C0G at power input of front end (after J197/2.2uH coil), 10nF/50V SMD C0G between pin7 and GND of IC103 (prescaller), 680uF/16V on pin1 and GND of IC105 (MPX decoder). Received an EMI filter at the output of power transformer, made with 2 pcs of 1uF/100V pp capacitors and one noise canceling double-2 windings coil, both having 6.6mH inductance.
Audio signal: changed C139 100nF/100V pp, C155 and C156 4.7uF/50V pp.
On thing impressed me: Conclusion: with a bit better sensibility, no specialized IF ICs, has very low noise and clear sound with very low distortion - and this concept was followed during several tuner-generations by Yamaha tuner designers. Unfortunately, this was not rewarded by customers, because they buy systems, the whole system (turntable, tuner, cassette player, and amplifier), not just the tuner. With the actual filtering, including the EMI, the tuner is immune to any LED lamp connected to the same distributor as the tuner.


Yamaha R-3

Yamaha R3

Is a receiver amplifier with a very natural sound from 1985-86.

General information:

  • Digital 2 bands (MW-FM) PLL radio without RDS capability,
  • 16 memory presets, 8 for FM and 8 for AM
  • Coverage: MW 520kHz - 1.610MHz, FM 87.5MHz - 108.0MHz
  • Channel space: 9kHz for AM and 50kHz for FM
  • Intermediate frequency: 450kHz for AM and 10.7MHz for FM
  • Usable sensitivity: 250uV on AM, 1.55uV on FM mono and 21uV for FM stereo
  • Integrated circuits: FM IF IC: LA1235, stereo decoder: LA3400, PLL freq. synthesizer: LC7000, electronic tuning controller: LC7030; display driver LB1214; BA618 LED signal level indicator; M5220L OPA for RIAA
  • Output frequency response on FM: 30Hz - 15kHz (-1...+1dB)
  • Signal/noise ratio: AM 50dB, FM 81dB mono, 76dB stereo
  • THD: on FM 0.1% for mono, 0.20% for stereo
  • Stereo separation: 40dB
  • Antenna input impedance for FM: 75 and 300 ohm
  • Amplifier part: continuous power on 8 ohm: 35 W / channel, THD 0.01% (10...40000 Hz)
  • Amplifier input sensitivity: PHONO (MM) 2.5mV / 47 kohm; CD, VIDEO and TAPE 150mV / 4.7 kohm;
  • Amplifier tone control: Bass 50Hz ±10dB, Treble 20kHz ±10dB, Bass extension *8dB 60Hz
  • Amplifier signal to noise ratio (A weightened) 88dB for PHONO, 103dB for other inputs
  • Power: 220V/50-60Hz, consumption: 180W
  • Dimensions: 436x126x289mm, 5.2kg

Good things:

  • Has a very clean sound, beautiful bass, low noise
  • Has signal level indicator

Difficult, problematic items:

  • 2x8 preset memories are not enough, especially for FM
Considering its age, was necessary to change almost all electrolyte capacitors.




FM stations received at my home (Budapest, 2nd district, close to Danube river), signal strengths measured with XH Data D808 radio with its telescopic antenna (without any external one, inside my home):

88.1 MHz

Info Radio - news

31 dB/u

88.8 MHz

Maria Radio - religious

40 dB/u

89.5 MHz

Radio1 - Pop music

60 dB/u

90.3 MHz

Tilos

49 dB/u

90.7 MHz

Bartok - classical music

17 dB/u

90.9 MHz

Jazzy - Jazz music

31 dB/u

91.7 MHz

Maria Radio - religious

15 dB/u

92.1 MHz

Klasszik - classical music

52 dB/u

92.9 MHz

Spirit - general

34 dB/u

94.2 MHz

Trend FM - general

45 dB/u

94.8 MHz

Petofi - general

46 dB/u

95.3 MHz

Karc FM - general

43 dB/u

95.5 MHz

Kossuth - general

21 dB/u

95.8 MHz

Slager - general

51 dB/u

96.4 MHz

Base FM - pop music

34 dB/u

96.9 MHz

Regina, Slovakian - general

5 dB/u

97.3 MHz

Maria Radio - religious

25 dB/u

98.0 MHz

Cafe Radio - pop music

43 dB/u

98.6 MHz

Manna FM - general

47 dB/u

99.5 MHz

Best FM - general

55 dB/u

99.8 MHz

Danko - popular music

8 dB/u

99.9 MHz

Best FM - general

13 dB/u

100.3 MHz

Radio Dikh - Gypsy radio

43 dB/u

100.8 MHz

Danko - popular music

52 dB/u

101.6 MHz

Sola - religious

34 dB/u

102.1 MHz

Katolikus Radio - religious + classical music

48 dB/u

102.7 MHz

Petofi - general

25 dB/u

103.3 MHz

Retro Radio - retro music ('60, '70 and '80)

57 dB/u

103.9 MHz

A Rock - rock music

49 dB/u

104.3 MHz

Slovakian radio

6 dB/u

104.7 MHz

Retro Radio - retro music ('60, '70 and '80)

21 dB/u

105.3 MHz

Bartok - classical music

53 dB/u

105.6 MHz

Bartok - classical music

16 dB/u

105.9 MHz

Sport radio - sport and music

37 dB/u

107.2 MHz

Kossuth - general

11 dB/u

107.8 MHz

Kossuth - general

49 dB/u

Stations list was updated at 05.11.2022. In total 36 individual frequencies and 26 different radio programs.


Useful links


The FM ceramic filter page - by Bruce Carter. Is a short presentation of ceramic filters theory and practical recommendations
The 10.7 MHz IF filters, is a ceramic IF filters page from the old Tuner review page. Can be downloaded Murata IF filter catalog from 1991!
Matching matters: Case study of 110 kHz narrow filters - by fmdxing. The editor of this website has modified his Denon TU-1500RD radio with 110 KHz filters in the 'narrow' tuning mode in 2006 and saw a marked improvement in reception.
How to select a FM tuner for 88-108MHz DX by Todd Emslie - a good article and tuners comparison
Receivers for FM DX recommended by New Zeeland Radio DX League
Hungarian DXers page - contains all Hungarian and its surrounding countries FM stations frequencies, propagation info etc. Just in Hungarian
FM Tuner Information Center is a good collection of vintage stereo tuners.
FM Tuner Information Center has also a DIY or mod section. I highly recommend to read general DIY and modification tips, sometime you can find ideas/recommendation directly for your tuner
List/database of best vintage tuners, made by audiophile panelist Jim and published on FM Tuner Information Center. Can be a good reference if you would like to buy a vintage tuner. The list was made between 2002-2006, and in 2016 received some updates as Shootouts 2.0
FM Pre-Emphasis and De-Emphasis is a good explanation of de-emphasis (time constants) used by FM transmitters in Amerika (75us) and Europe (50us).
HD Radio Self-Noise - a good page about HD transmission used in America, and a list of tuner which are immune to this noise generated by HD transmission.
Superheterodyne Receiver - a collection of theory of superheterodyne receivers from Science Direct.
Double & Triple Conversion Superheterodyne Radios - a good explanation of double conversion reason and effect used in AM radios from Electronics Notes.
Marantz FAQ: "Frequently Asked Questions" - a good FAQ collection well explained, including also technical functions of tuners, signals, etc.
FM Frequencies for Budapest a webpage, which can list all receivable FM stations frequesncies in a defined location.


Tips to repair tuners:
First rule: don't touch anything until you have confirmed which part is the discriminator coil as random twiddling will ruin any tuner. Note the position of anything you touch so that it can be returned to its original setting if the desired results are not obtained. Once identified, buy or make a non-metallic tool with which to adjust the coil's core.
For tuners with digital displays, tune to a strong local station whose frequency is known to you then set the tuning so the display is correct (even if the sound is then distorted or absent). If possible, with the model in hand, next select mono reception and adjust the discriminator coil gently and carefully for the best reception. Half a turn in one direction or the other is normally all that is required. Try some other stations and confirm that they appear at the correct frequency.
When it comes to mechanically tuned models the process is different. Tune to a local station again and turn on the set's AFC (automatic frequency control) function. Adjust the discriminator for the best sound quality as above, or if the tuner has a balance meter adjust to center the needle. That is normally all that is required.
If the stereo decoder still doesn't work and it's a PLL (Phase Locked Loop) type, the 19kHz oscillator may be out of adjustment. This is normally a preset resistor near the chip (PLL types are invariably IC based) and slight adjustment may be required. Never touch the 'separation' adjustment as an FM stereo signal generator is required to set that up that correctly.



Note: If you need the owner or service manuals for above presented radios (I have almost all of them), or you see some problems on webpage, broken links, please contact me.