Quote:
Originally Posted by G6Tanuki
Aren't they just the top ends of the 4 pins?
I'm betting that it's either a crystal or some sort of plug-in capacitor: I recall that WWII-era transmitters sometimes used plug-in "antenna-shortening" capacitors (in series with the antenna) to help a radio designed for short whip-antennas (well less than 1/4-wave) to match a longwire that may be more than 1/4-wave long.
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No, the brass fittings on the top appear to hold the ebonite(?) terminal board to the brass bottom, I think they are rivets as they are slightly proud of the board, suggesting a flat head?
The pins in the base definitely fit snugly into a B4 base, if by B4 you mean a PM2 valve base. It's not the American 4-pin base which has large and small pins. The base pins do not align with the (?) rivets on top, which are at 90 degree points around the board.
If I get chance tomorrow, I will hook it up to my sig gen which has a crystal tester built-in and I will also try it on my capacitance bridge. If it does have a antenna shortening function then I would expect the capacitor to be of a low value, 100pf at most.
73
Roger