Sony

This Sony SRF-A200 is quite rare being one of four or five AM Stereo sets sold in Australia.

In the eaely 1980s FM was establishing itself as the prefered medium for everything execpt voice. AM stations were loosing the war and were looking for a way to return their audience share to where it was prior to the introduction of  commercial FM in 1980.

Harris/Magnavox/Motorola, and the second, Kahn-Hazeltene. There are two main classes of systems: independent sideband (ISB) systems, promoted principally by American broadcast engineer Leonard R. Kahn or Kahn-Hazeltene. The second being quadrature amplitude modulation (QAM) multiplexing systems (conceptually closer to FM stereo) or Harris/Magnavox/Motorola.

Prior to 1960 stereo was broadcast on two sepert frequencies, needing two radios to here the stereo effect. Few people had two receivers of the same type and separation was limited to cater for people with only one radio.

The FCC in the United States eventually let the five systems fight it out, and official broadcasts began with the C-QUAM system in 1980. Australia's AM stations saw the potential and started broadcasting soon after, with AM Stereo officially begining in 1985. 

AM Stereo was not the saviour AM stations first thought. It has has fizzled out over the past 40 years, and only one station in Queensland is known to broadcast in the format.

The main reason for the failure was that the recievers were expensive, meaning that people didn't see the cost benefit of buying a new radio, especially car radio,

Sony were the main sellers of AM Stereo radios sold in Australia, and in the end released seven models. (See the Electronics Australia article from 1986 below.) These included the Sony I own, and the later model variation with the single C-QUAM system.  A Sanyo boombox and car radio, and a Tandy Realistic tuner were also sold. There maybe others, but I wasn't interested at the time.

The SRF-A200

My SRF-A200 is not currently working. It was working when I put it in a box  just prior to COVID lockdowns.

It was used daily for over 30 years as my bedside radio. It was on a timer and turned on in the morning and for 2 hours at night.

It was bought in late 1984 when tests of AM Stereo were happening and cost the not inconsiderable sum of $125 from the Myer city store. I took it to work each day for the first few years.

If you stuck you  head right up to the radio the stereo separation wasn't to bad, like wise on headphones. However, a metre away you could not tell the difference whether it was stereo or mono.

Sound quality was good, with little difference between AM and FM. The Wide position opened up the frequency responce on AM quite markedly. However, through the stereo system there was a marked difference.

The clipping is from Electronics Australia in 1986.