Swansea 3 TRF

 I've called this old home brew TRF set the "Swansea 3" because that's from where I bought it.

I think it initially dated from the late 1920s and uses some government surplus parts, notably the khaki-coloured front panel and rear terminal strip. It's been modified and cared for over the years because it has parts dating from much later... for example the RF valve which is WW2 surplus.


 The valves, left to right: a CV1246 (with KB/Z under the code) in mint condition with military arrow and "WK". This is similar in characteristics to the Mullard PM202 B4 triode or Marconi P2. Centre is unmarked but looks like a PM1LF B4-based horizontally orientated triode with a ridge down the base adjacent to the anode pin which is marked "A", and a puzzle valve on the right which has tarnished gold metalising with partly decipherable "Ever Ready" and part of a "0" so it may be a type K30 B4 triode?

The set has a nicely marked out termination panel.


 Below is a sorry-looking vaccuum resistor which measures a steady 1.78Mohms so may be a working grid leak.


 Next are pictures of the set's two interstage transformers. These are identical Lissen types.



 Above.. you can just see a bright green Mansbridge condenser. These were expensive.
 Other than that, there's not a lot to say about this ancient-looking set. I noticed it has a pilot lamp style fuse fitted to the baseboard, but as a fuse I'm not entirely sure it was really very useful as it's marked "12 volts 2.2 watts". This equates to a current of 183mA at normal brightness. There's a pair of coils. These are mounted on a mechanical arrangement which allows the pair to be moved closer or further apart. I haven't traced the circuit, but I suspect these coils are arranged to provide feedback or "reaction". The method used saves on a second variable condenser at the expense of sightly less exact adjustment. The two plug-in coils are marked "What are the Wild Waves Saying", a very common type of coil used in the early 1930s by home constructors. One is marked "150 Metres" and the other "200 Metres". I suppose they could be unplugged and swapped over to change the received wavelengths a little?

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