Sony ST-J55 (1979–1981)

A digitally tuned AM/FM stereo tuner with a crystal-locked synthesizer system, produced by Sony from 1979 to 1981.

Overview

The Sony ST-J55 is a synthesizer tuner made in Japan between 1979 and 1981. It covers FM, MW, and LW, and an internal microprocessor handles the digital tuning. It has precise frequency control. Sony positioned it as an accessible model in the tuner lineup, sometimes called "the baby" of the range. It has an 8-station random preset memory, and each station stores its muting and stereo/mono settings. There are also several tuning modes for picking stations.

Specifications

Design

The ST-J55 picks channels with a crystal lock digital synthesizer system. The local oscillator is a VCO circuit that changes frequency in 100kHz steps for FM and 9kHz steps for AM. A PLL method compares the oscillation frequency to a crystal oscillator reference, which keeps it stable. Frequency shows on a 7-segment white fluorescent indicator. The tuner also has CAL-TONE and a notch filter, and four tuning speeds: direct random, quick search, sweep, and step.

Context

Sony called the ST-J55 "the baby" of its tuner lineup. It had the core digital tuning features in a more compact and affordable form than the higher-end models.

Market

The ST-J55 was originally priced at ¥49,000 in Japan around 1979. A 1991 US magazine later listed one for $75, so it was showing up in secondary markets.

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