SONY ST-J75
¥ 67,000 (around 1980)
Commentary
The Crystal Rock Synthesizer Tuner is designed to meet the needs of multiple FM stations with a high level of perfection in terms of sound quality, operability and reception performance.
The crystal lock synthesizer tuner system employs a local oscillator circuit using a VCO (voltage controlled oscillator), which is the key of the synthesizer tuner. The oscillation frequency changes in FM100kHz/AM9kHz steps depending on the magnitude of the applied DC voltage.
In the PLL system, this oscillation frequency is compared with the phase of the reference signal, and the DC voltage is controlled so as to maintain a constant frequency at all times. The frequency fluctuation due to temperature is 5x10 in the reference signal.-5It uses a crystal oscillator with the following stability, so that there is no increase in distortion due to the tuning error that occurs in the tuning system using a varicon.
All of these controls are controlled by a built-in microprocessor, which displays the frequency using a 7-segment white fluorescent indicator for accurate channel selection.
It is equipped with a direct comparator in which the comparison frequency of the synthesizer is set to 100 kHz as in the channel plan.
The front end is equipped with 5-stage varicap, and the RF amplifier and mixer are equipped with dual-gate MOS FET.
Equipped with FM/AM random 8 station preset.
Non-volatile multi-process memory is used to store station frequencies and commands without any power backup. Along with the station frequency, muting on ⇔ off and stereo ⇔ mono modes can be stored.
The station name display system using LED is adopted so that the station name can be identified at a glance by pressing which tuning button.
The attached label covers all FM/AM stations in Japan, so you won't get lost if you attach the label of the station when you preset it.
Built-in preset memory scanning function.
Equipped with a CAL-TONE circuit, notch filter and AM noise filter.
Equipped with timer compatible program function.
Model Rating
| Type | FM/AM Tuner |
| Practical sensitivity | 1.9 μ V (IHF), 10.8 dBf (new IHF) |
| Stereo distortion factor | 0.07% |
| Effective selectivity | 60dB(300kHz) 90dB(400kHz) |
| Spurious interference ratio | 100dB |
| Signal-to-noise ratio | mono:92dB stereo:86dB |
| Separation | 60dB |
| Power consumption | 20W |
| External dimensions | Width 430x Height 80x Depth 325 mm |
| Weight | 4.8kg |
| Attachment | Station name display card |