Sony ST-P7J (1979–1981)
A digitally tuned FM/AM stereo receiver from Sony's Precise P7 series, with quartz-locked tuning and feather-touch controls.
Overview
The Sony ST-P7J is a stereo tuner made by Sony Corporation in Tokyo between 1979 and 1981. It belongs to the Precise P7 system and shares design elements with the ST-J60 and ST-A6B. The Japanese version has both FM and AM bands. The export version is FM-only, and you can spot it by the missing extra AM button. It has an 8-preset memory IC and slot-in station cards for recalling stations.
Specifications
| Type | Mono/Stereo Tuner |
| Tuning Bands | FM |
| Tuning Scale | Digital |
| Quieting sensitivity | 10.3 dBf (1,8µV ; 30 dB , mono) 16,1 dBf (3,5µV ; 50 dB , mono) 37.3 dBf (40µV ; 50 dB , stereo) |
| S/N ratio | 77 dB (mono) 72 dB (stereo) |
| THD | 0,06% (100 Hz , mono) 0,06% (1 Khz , mono) 0,06% (10 Khz , mono) 0,08% (100 Hz , stereo) 0,08% (1 Hz , stereo) 0,015% (10 Khz , stereo) |
| IMD | 0,06% (mono) 0,08% (stereo) |
| Frequency response | 30 Hz ...15 Khz (+0,2 / -0,5 dB ) |
| Stereo separation | 48 dB (100 Hz ) 50 dB (1 Khz ) 45 dB (10 Khz ) |
| AM suppression | 60 dB |
| Image rejection | 85 dB |
| Spurious response ratio | 100 dB |
| Subcarrier response ratio | 70 dB |
| IF response ratio | 95 dB |
| RF intermodulation | 70 dB |
| Componentry | 16 ICs / 3 FETs / 16 LEDs 32 transistors / 42 diodes |
| Power consumption | PC : 13W |
| Dimensions | 21,5 x 7,5 x 33 cm |
| Weight | 3,6 kg |
| Original price | 65,800 ¥ |
Design
The ST-P7J uses varactor/Mos-Fet tuning with a dual-FET balanced mixer and Uni-Phase IF filters. Quartz crystal locking works in 0.1 MHz steps. A memory IC holds eight station presets. The controls are feather-touch, and saved stations go on slot-in cards.
Context
The ST-P7J is part of Sony's Precise P7 system. It is closely related to the ST-J60 and takes design elements from the ST-A6B. Sony positioned it as a high-precision tuner with digital tuning and memory functions.
Market
One pre-owned unit was listed for EUR 25.00. Other listings on platforms like Hifishark and Yahoo Auctions Japan have offered tested working units, and one listing in Germany was priced at €90.
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