SONY ST-J55
¥ 49,000 (around 1979)
Commentary
Synthesizer tuner using crystal lock system.
A crystal lock digital synthesizer system is used for channel selection.
This system employs a local oscillation 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.
The PLL method compares the oscillation frequency with the reference signal in phase and controls the DC voltage so that a constant frequency is always maintained. The reference signal has a frequency fluctuation of 5x10 due to temperature.-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.
Equipped with FM/AM random 8 station preset.
Non-volatile multi-process memory is used for the memory, and it is possible to store the station frequency and command without any power backup. It is also possible to store muting on ⇔ off and stereo ⇔ mono mode together with the station frequency.
4-speed tuning (direct random / quick search / sweep / step) is possible.
Equipped with CAL-TONE and notch filter.
Model Rating
| Type | Crystal lock digital synthesizer tuner |
| Practical sensitivity | 1.8 μ V |
| Stereo distortion factor | 0.08% |
| Effective selectivity | 85dB |
| Spurious interference ratio | 100dB |
| Power consumption | 12W |
| External dimensions | Width 430x Height 80x Depth 325 mm |
| Weight | 3.7kg |