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Vintage Radio

Designed as a "wartime special", the Philco 40-40 is simple 4-valve receiver that was manufactured in Sydney in 1940/41. It's a compact reflexed design with some interesting features.

By Rodney Champness, VK3UG

Radio receiver design has gone through many phases, both in regard to circuit design and cabinet styling. The very first designs were basically crystal sets but there were also sets that used other forms of solid-state detectors. Valves were only just being developed at that time and in any case, the early types were much too expensive for experimenters to buy.

The next phase saw the development of coffin-style radios based on one or more valves. These were often built by experimenters, with the parts laid out on a breadboard. This was then housed in a coffin-style cabinet to protect the wiring.

Coffin-style receivers were superseded in the late 1920s by commercial receivers built on metal chassis. The period leading up to WWII was a time of rapid development in both component and circuit design and many excellent receivers were produced.

The Great Depression hit hard during the early 1930s and manufacturers responded by producing simple receivers at low prices. As the depression receded, more elaborate designs were again produced towards the end of the 1930s. Then along came WWII and the emphasis changed again.

Because of military demands, component supplies were restricted during the war years and manufacturers had to use whatever they could obtain. As in the Great Depression, the emphasis was on austerity. However, radio design had progressed considerably over this decade and the WWII austerity models are considerably better than those of the depression years.

One local manufacturer from that era was Philco Radio and Television Corporation (Aust.) Pty Ltd. Based in Auburn, NSW, they produced radio receivers from the 1930s through to at least the mid-1950s. These covered the complete range, from simple receivers up to complex multiband sets.

The Philco set described here is an austerity WWII model, circa 1940-41. It was designated the “40-40” and is a 4-valve set with a reflexed IF/audio amplifier stage.

Click for larger image
Fig.1: the Philco 40-40 employs a 4-valve reflexed circuit, with the 6B7 doing double-duty as both an IF amplifier and a first audio stage. In addition, the 6B7 functions as the detector.

General details

The Philco 40-40 is basically a compact mantel receiver. It’s housed in a Bakelite cabinet but despite its compact size, it still weighs in at 4.5kg. This particular set has a cream cabinet although it’s fairly certain that brown cabinets would also have been available and there may have been other colours as well.

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