STC 2-Valve AC Table Model Receiver

 Or to give the company's full name.. Standard Telephone & Cables. I spotted this set for sale many years ago, and because of its rarity, bought it. The set is quite small and comparatively light in weight and is pretty early as mains operated receivers are concerned, possibly dating from 1931 or 1932.

 

 A completely different chassis to anything else I've seen. Same sort of internal volume but standing on its end. Complete with mains energised loudspeaker.
 

 The valves are pretty ancient balloon types. Left rear is a Mazda MHL4 minus it's metalising with B5 base, Right rear is the B4-based rectifier, a Philips 1821 and front an Osram MPT4 with B5 base plus side contact. The Dubilier 8uF 450 volt smoothing condenser looks much later than the set.
 
 
 The label on the chassis. The use of BVA valves was one of the restrictive practices operating from the 1920s to WW2. British manufactured valves were double the price of foreign valves and the rather odd way of identifying them made it tricky to fit equivalents imported from the continent or the USA. Of course British valves used uniquely British bases, B4...B5 etc whilst in the US the custom was UX bases and on the continent Ct, side contact types were the norm. By the end of the 1930s nearly all valves used the International Octal base although Mazda perservered with their own MO8 which didn't quite fit the IO holder, and anyway had different pinouts. By the late 1940s bakelite bases almost disappeared and nearly all valves were either the all-glass B7G and the all-glass B9A. Exceptions were Hi-Fi amplifier valves such as the KT66 and a few TV valves like the PY301.  

 

 Here are the rear connections. Right, the aerial options presumably offering a trade-off between audio output and selectivity with "AN" perhaps being the recommended socket for a long wire.

Next to the aerial is a socket for a gramophone. This will be designed for a high output magnetic pickup with a metal needle, not a modern stylus.

Below is the long/medium wavechange switch. I'd guess that it's missing an operating rod. Note the use of "LW" and "MW" which is a new term replacing the slightly earlier usage of "Long" and "Short" meaning the same thing.

Bottom right is the mains selection panel offering an unusually large number of options because, back in 1932, mains distribution wasn't like todays National Grid with carefully maintained voltage and supply frequency.

 

 

 

 

 

 

 
 

 

 Pictures of the valves used in the STC radio. Top right the Philips 1821, a rather rare double-diode rectifier similar to a U10, above top, and left an Osram MPT4 tetrode and above an early example of an MHL4 triode.

 A view of the tuning dial which is very basic carrying only a logging scale and representative of sets from the late 1920s, although for its age the set was quite easy to use because it had only one tuning control and behind this the reaction control, used to provide volume control up to the point where the RF stage would break into oscillation.

 

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