Technics ST-S4
¥ 44,800 (released in 1980)
Commentary
Quartz synthesizer tuner developed based on the results cultivated in ST-S5 and ST-S7.
The IF stage is equipped with a super narrow IF with an effective selectivity of 20 dB when detuned to 200 kHz in addition to a normal position of 60 dB when detuned to 400 kHz, thereby enhancing the excellent adjacent station interference rejection capability.
The quartz PLL synthesizer requires a reference frequency in order to synchronize the tuning frequency and the local frequency with the stable oscillation of the crystal. In the ST-S4, this reference frequency is set to 25 kHz outside the audio band by realizing the speedup of the microcomputer, and it prevents the reference frequency from adversely affecting the music signal.
In addition, a swirl-in counter system is adopted in the synthesizer section, and by a special frequency division method in which the 1/16 and 1/17 frequency dividers are controlled and 1/17 frequency dividers are controlled by a prescaler controller.
It is equipped with a newly developed original microcomputer with ROM and RAM of 4bitROM2k (16bit1k equivalent).
As a result, one push tuning, preset memories, display of electric field strength, etc., which are unique to digital tuners, have been improved in operability.
A total of 16 FM/AM random access memories are installed.
When the desired station is received and the memory button is pressed, the memory indicator lights for approximately 5 seconds, and the registration is completed by pressing any channel of the preset tuning button.
It is equipped with manual / auto-scan tuning. When you press and hold the tuning button and release your finger after shifting to high-speed operation, auto-scan operation is automatically started, and the nearest station is found, stopped, and quartz locked to that station.
Equipped with an auto memory function, it is possible to do everything automatically from searching for a station to memory.
If you press the memory button until the frequency display begins to scan, this function automatically searches for a station from the tuning frequency at that point in time in the up direction, and stores up to eight stations from the lowest frequency.
The front-end section uses a single-double electronic tuning circuit with a high-Q varicap tune, which is equivalent to a four FM series varicon.
The detector stage employs クワドラチュア detection, which has excellent stability over a wide band.
The MPX stage employs a double-switching PLL MPX circuit.
The AM tuner section is controlled by a 9 kHz quartz synthesizer to achieve a characteristic tuning without frequency deviation.
A large-capacity gold capacitor is installed for memory backup, and the voltage necessary for memory retention is continuously supplied even if power failure lasts for about one week.
In addition, it can be charged in approximately 30 minutes after discharge.
Equipped with an antenna terminal that can automatically tune the FM wing antenna without a switch.
A control input connection terminal is used to connect the program timer and remote controller adapter.
Equipped with FM mode selector switch.
Equipped with a quartz lock indicator.
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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:0.06% stereo:0.08% |
| Signal-to-noise ratio | mono:80dB |
| Frequency characteristic | 20 Hz ~ 15 kHz + 0.5 -1.5 dB |
| Effective selectivity | normal:60dB(400kHz) super narrow:20dB(200kHz) |
| Capture ratio | 1.0dB |
| Image interference ratio | 75dB(83MHz) |
| IF interference ratio | 95dB(83MHz) |
| Spurious interference ratio | 95dB(83MHz) |
| AM suppression ratio | 55dB |
| Stereo separation | 55dB(1kHz) 40dB(10kHz) |
| Leak Carrier (19 khz) | -35dB |
| 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 | 45dB |
| IF interference ratio | 40dB |
| <General> | |
| Output voltage | 0.6V |
| Power failure compensation | Approximately 1 week, charging system |
| Pwer | 100 VAC, 50Hz/60Hz |
| Power consumption | 7W |
| External dimensions | Width 430x Height 53x Depth 300 mm |
| Weight | 3.2kg |