This is a World War II vintage carbon microphone. It has a patented Push To Talk - Twist to Lock button.
The 1/4" Phone Plug Ring is connected
to the carbon microphone case.
The 1/4" Phone Plug Sleeve is connected to the carbon microphone center terminal.
The 1/4" Phone Plug Tip is connected to the Push To Talk switch terminal which gets shorted to the sleeve when pressed.
This is a poor design in that the mike is always connected to the Sleeve and Ring and so could be used for eavesdropping.
The resistance of the mike varies
between 2k and 12k, not sure if it's good or bad?
& Military Cloning - Fill - Retransmission
HP 204B Audio Oscillator from HP 3350 Carrier Test Set (AN/USM-181 Telephone Test Set
HP 241A Audio Oscillator w/Radio Buttons
Military Audio Accessories
Audio Patch Panel
TS-585 Audio Level Meter
U-229 Audio Accessories
U-229 Pin Out by Function
Brooke's PRC68, Products for Sale, Military Information, Electronics Page page created May 29, 2012.