Sony st-jx500 (1982)
A PLL digital frequency synthesizer FM/AM tuner with quartz lock, sold in Japan for ¥42,000.
Overview
The Sony ST-JX500 is an FM/AM tuner released in Japan and sold on August 21, 1982. It features a PLL digital frequency synthesizer with quartz lock for stable reception and precise tuning. Designed with audio fidelity in mind, it uses carefully selected audio-only components and includes a centralized display via an FL tube.
Specifications
| Circuit system | PLL digital frequency synthesizer Quartz lock system, superheterodyne |
| FM Receiving frequency | 76 MHz to 90 MHz |
| FM Antenna terminal | 75 Ω unbalanced / 300 Ω balanced |
| FM Intermediate frequency | 10.7MHz |
| FM SN ratio | 50 dB |
| FM sensitivity Mono | 3.5 μ V (IHF) / 16.1 dBf (new IHF) |
| FM sensitivity Stereo | 43 μ V (IHF) / 37.9 dBf (new IHF) |
| FM Practical sensitivity | 1.8 μ V (IHF) / 10.3 dBf (new IHF) |
| FM Signal-to-noise ratio mono | 90dB |
| FM Signal-to-noise ratio stereo | 88dB |
| FM Harmonic distortion factor (1 kHz) mono | 0.06% |
| FM Harmonic distortion factor (1 kHz) stereo | 0.09% |
| FM Cross modulation distortion factor mono | 0.06% |
| FM Cross modulation distortion factor stereo | 0.09% |
| FM Stereo separation | 55dB(1kHz) |
| FM Frequency characteristic | 30 Hz to 15 kHz + 0. 2-0. 5 dB |
| FM Effective selectivity | 80dB(400kHz) 70dB(300kHz) |
| FM Capture ratio | 1.0dB |
| FM AM suppression ratio | 65dB |
| FM Image interference ratio | 80dB |
| FM IF interference ratio | 90dB |
| FM Spurious interference ratio | 100dB |
| FM RF intermodulation interference ratio | 74dB(IHF) |
| FM Carrier leak suppression ratio | 76dB |
| FM Muting level | 30dBf |
| FM Auto-tuning level | 30dBf |
| FM Output Level / Impedance | 750mV/2.2k Ω |
| AM Receiving frequency | 522 kHz to 1,602 kHz |
| AM Antenna | Built-in, with EXT terminal |
| AM Intermediate frequency | 450kHz |
| AM Sensitivity | 46dB/m (built-in ANT) 100 μ V (EXT ANT) |
| AM Signal-to-noise ratio | 55dB(50mV/m) |
| AM Harmonic distortion factor | 0.3% |
| AM Selectivity | 38dB(10kHz) 35dB(9kHz) |
| AM Image interference ratio | 42dB |
| Power supply voltage | 100 VAC, 50Hz/60Hz |
| Power consumption | 11W |
| External dimensions | Width 430x Height 55x Depth 300 mm |
| Weight | 2.9kg |
| Attachments | FM ribbon antenna, F-type antenna plug, Station name display label, Stereo connection code |
Design
The ST-JX500 uses Sony's original direct comparator system, with a comparison frequency of 100 kHz matching the receiving step. It incorporates a high-speed PLL-IC developed by Sony and a dual-gate MOS FET in the front end. The tuner features a centralized FL display tube and uses oxygen-free copper wire with polarity indication for the power cord, along with carefully selected audio-only components.
Features
The tuner allows random presetting of up to 10 FM/AM stations using multi-process memory that stores settings like muting ON/OFF. It includes a program memory function for recording messages from multiple stations and supports memory scan to recall presets sequentially. With an optional program timer, it can call up to four preset stations in order. Tuning methods include manual, sweep (scanning with ~4-second dwell per station), and auto tune for automatic station detection.
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