Technics ST-S8
¥ 98,000 (around 1980)
Commentary
A synthesizer FM/AM tuner that improves audio characteristics by realizing DC transmission.
In the front-end section, an electronic tuning circuit of double-double-double configuration, which is equivalent to a 7-series varicon, and an RF stage of MOS-FET are adopted, to cope with multi-station and improve the image interference ratio.
In the IF stage, the filter is carefully selected to achieve both excellent audio and selectivity characteristics. All stages are composed of differential amplifiers. In addition, both the RF stage and the IF stage have excellent waveform transmission characteristics by taking into consideration the flattening of group delay characteristics.
In addition to normal position, the IF stage is equipped with a super narrow IF with an effective selectivity of 25 dB or more at 200 kHz detuning. In this position, we have achieved a high selectivity that is different from the conventional one, and we have obtained excellent adjacent station interference rejection capability.
In order to prevent the leakage of the reference frequency, which accurately locks the local oscillation frequency, into the music signal, we have developed and installed our own high-speed ICs. In this ICs, the reference frequency is set to 25 kHz outside the range of audibility range to prevent adverse effects on the music signal and improve the SN ratio.
The synthesizer employs a unique swallow in counter method and a special frequency division method in which the 1/16 and 1/17 frequency dividers are controlled by a prescaler controller to suppress spurious interference in the broadcast band and improve transmission characteristics.
The MPX circuit uses a unique DC peak sample-and-hold MPX.
This circuit uses a fast-rising pulse signal instead of the usual square wave for stereo demodulation. The peak value of the composite signal is accurately sampled and held, and this, combined with the effect of DC, realizes excellent stereo separation.
The 19 kHz pilot signal, which becomes an obstacle after being used for stereo demodulation by the MPX circuit, is canceled by an electronic circuit without using a low-pass filter. In addition, an auto-level adjustment, which prevents fluctuation of the pilot signal, realizes flat characteristics.
In addition, the sharp LC band-pass filter removes the jitter distortion caused by the fluctuation of the 38 khz signal demodulated by the MPX circuit to the high-frequency audio signal.
The AM tuner section controls a 9 kHz quartz synthesizer to achieve accurate tuning and high selectivity.
It is equipped with a newly developed original 4-bit 2K microcomputer, and features such as manual / auto-tuning, FM/AM 16 stations random access memory, and auto-memory which automatically performs from station search to memory.
It is equipped with a display by FL display tube, and it is equipped with a channel number lead-out for confirming channels and stored broadcasting stations, a signal strength lead-out, and a 5-LED multi-path signal meter.
FM has 16 LEDs and AM has 15 LEDs that light up one after another depending on the tuning frequency. You can use the quartz synthesizer tuner with the conventional dial tuning feeling.
The gold capacitor enables battery-less memory backup, which can withstand power outages lasting about one week.
Switchless FM wing antenna terminal is mounted.
Slim size of panel height 1U (44 mm) has been realized.
Model Rating
| Type | Quartz synthesizer FM/AM tuner |
| FM Tuner Section | |
| Receiving frequency | 76.1 mhz to 89.9 mhz |
| Practical Sensitivity (75 Ω) | 12.8dBf/1.2 μ V (IHF' 58) |
| SN50dB Sensitivity (75 Ω) | Mono : 18.1dBf/2.2 μ V (IHF' 58) Stereo : 38.1dBf/22 μ V (IHF' 58) |
| Total harmonic distortion factor | mono:0.04%(normal) stereo:0.06%(normal) |
| Signal-to-noise ratio | mono:84dB |
| Frequency characteristic | 5 hz to 18 khz + 0. 2-0. 5 db |
| Effective selectivity | normal:55dB(400kHz) super narrow:25dB(200kHz) |
| Capture ratio | 1.0dB |
| Image interference ratio | 120dB(83MHz) |
| IF interference ratio | 140dB(83MHz) |
| Spurious interference ratio | 120dB(83MHz) |
| AM suppression ratio | 55dB |
| Stereo separation | 60dB(20Hz) 60dB(1kHz) 40dB(10kHz) |
| Leak Carrier (19 khz) | -70dB |
| Antenna | 75 Ω |
| <AM Tuner Section> | |
| Receiving frequency | 522 kHz to 1611 kHz |
| Practical sensitivity (S/N = 20 dB) | 250 μ V/m, 30 μ V |
| Selectivity | 55dB |
| Image interference ratio | 55dB |
| IF interference ratio | 45dB |
| Power failure compensation | Approximately 1 week, charging system |
| <General> | |
| Output voltage | 0.6V |
| Pwer | 100 VAC, 50Hz/60Hz |
| Power consumption | 9.9W |
| External dimensions | Width 430x Height 53x Depth 390 mm |
| Weight | 4.1kg |