[Boatanchors] Microphone

[Richard Knoppow]

----- Original Message ----- 
From: "David C. Hallam" <dhallam at knology.net>
To: <Boatanchors at mailman.qth.net>
Sent: Friday, February 08, 2013 12:43 PM
Subject: [Boatanchors] Microphone


>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
>
     First of all what sort of transmitter are you 
connecting this to and why is there a wall-wort?   I was 
able to download a data sheet for the mic at:

www.electrovoice.com/downloadfile.php?i=970544

It also appears at:

<http://www.ko4bb.com/Manuals/11%29_Stuff_Not_Sorted/1_Misc_Ham/Electro_Voice/619/EV_619.PDF>




--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com