Quote:
Originally Posted by RichardT10829
that's great Mike, have you used this conversion yourself ?
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A friend of mine did use the modern inserts in his old valve transmitters. From memory the original carbon type microphone inserts ( mic No. 3 ? ) require around 3 Volts , these carbon insert style of microphones lend themselves towards a easier conversion to the modern electret inserts because the supply voltage is already there.
Some experts will probably correct me , but the old original moving coil inserts ( 19, 22 set ) were voice powered ,they were always a source of poor modulation, after 50 odd years they would often fail or at best be working at only 50%.
You may have to do a little searching for the 19 set wiring .