[ARC5] T-17 Microphone

[Mike Everette via ARC5]

Something that will likely work quite well would be an older style Motorola amplified dynamic mic element of the kind used from the mid-late 50s through the 70s at least.  These elements have a metal (silver) back portion.  You do have to watch the polarity on them.  If I remember right, the amp board contains a couple of germanium transistors.

The Motorola elements are kind of thick and I honestly don't know if they'll fit into a T-17 with the mouthpiece in place.  However, any Motorola dynamic hand mic, or handset, up through the type used with the Motrac series radios should work great with the Command Set or any other WW2 rig, and give excellent audio.

I'll have to dig out a manual and verify what the actual voltage is that's supplied to the element from the transmitter.  Some Motorola radios had a resistor in the audio line which was shorted out if a carbon mic or handset was used, to raise the mic voltage; but once the "first" narrow-banding took place and modulation was pulled back to +/- 5 kc rather than +/- 15 kc (happened about 1960) it didn't really make much difference what kind of mic was used.  There was plenty of audio for the lower modulation level.

I think the Motorola elements are in the neighborhood of 150 ohms impedance but need to verify that figure.

General Electric and Aerotron (ERRORtron -- EEEEEUUUGGGGH!) used high impedance mics, so these obviously are not what you need.

If you can find one, there was a WW2 "desk mic" which looked like an old candlestick phone less the receiver... these were often used in airfield control towers.  This mic has a good bit of room inside, so a Motorola element might do well in it.  Good luck finding one, though....

73

Mike
WA4DLF