Technics ST-S7A
¥ 54,800 (released in 1983)
Commentary
A quartz synthesizer tuner with flat characteristics from the ultra-low band to the high band of 5 Hz by DC amplification and DC demodulation including RF system.
The DC peak sample-and-hold MPX circuit is integrated into a single-chip IC. This circuit eliminates phase distortion by using a fast-rising pulse wave for stereo demodulation.
DC amplification, DC detection and DC demodulation, including the RF system, realize flat frequency characteristics from the ultra-low band of 5 Hz.
By installing a pilot signal canceler with auto-level adjuster, wide-band characteristics are realized.
In addition, excellent high-frequency characteristics are obtained by the jitter distortion elimination circuit.
It is equipped with a super narrow IF circuit with a narrow band high selectivity of 25 dB at ± 200 kHz detuning, and a normal IF circuit with a selectivity of 55 dB at ± 400 kHz detuning is automatically switched according to the judgment of a microcomputer, eliminating adjacent station interference.
The RF circuit is also equipped with a normal circuit and a narrow circuit. The microcomputer automatically selects the RF circuit to eliminate spurious waves caused by adjacent station interference and urban noise.
It is equipped with a random preset memory function for a total of 16 FM/AM stations. In addition, an auto memory that can be preset by pressing a button is available.
It is equipped with an auto-scan tuning function that makes manual tuning easy.
Equipped with a 10-dB 4-stage muting for selecting the reception quality.
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) |
| Distortion factor | mono:0.009% stereo:0.015% |
| Dynamic range | 100 dB (1 kHz, 100% mod, 0 dB) |
| Frequency characteristic | 5 hz to 18 khz + 0. 2-0. 5 db |
| Effective selectivity | Normal : 55 dB (± 400 kHz) Super narrow : 25 dB (± 200 kHz) |
| Capture ratio | 1.0dB |
| Image interference ratio | 90dB(83MHz) |
| IF interference ratio | 105dB(83MHz) |
| Spurious interference ratio | 110dB(83MHz) |
| AM suppression ratio | 55dB |
| Stereo separation | 60dB(20Hz) 65dB(1kHz) 50dB(10kHz) |
| Leak Carrier (19 khz) | -70dB |
| <AM Tuner Section> | |
| Receiving frequency | 522 kHz to 1611 kHz |
| Practical sensitivity (S/N = 20 dB) | 290 μ V/m, 20 μ V |
| Selectivity | 55dB |
| Image interference ratio | 40dB |
| IF interference ratio | 60dB |
| <General> | |
| Power failure compensation | About 1 week |
| Pwer | 100 VAC, 50Hz/60Hz |
| Power consumption | 8W |
| External dimensions | Width 430x Height 54x Depth 245 mm |
| Weight | 2.4kg |