[Boatanchors] Microphone

[David C. Hallam]

I have a wiring problem with an EV 619 High Z dynamic PTT microphone.  I 
have it connected to a 3 wire (2+ braid shield) cable.  One side of the 
element is connected to the center wire, the other side is connected to 
the braid shield. The PTT switch contacts short the element on receive 
and remove the short on transmit.  The other wire in the cable for PTT 
is connected to an NO contact on receive and a NC contact on transmit.  
The NC contact is connected to the shield.

The problem is on transmit with no audio to the microphone, there is a 
50 mV or so PTP signal from the microphone.  That is putting a 6V DC 
walwart on the PTT wires and looking at it with a scope.  When I remove 
the DC, the output from the microphone is normal with no output unless I 
speak into the microphone.

I have looked carefully several times and the PTT switch wiring and 
don't see any shorted wires or other problems.

I am baffled.

David
KW4DH

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Alexis de Tocqueville