[Boatanchors] Microphone

[David C. Hallam]

Well, a little more information.  I connected it to an SBE-33.  What 
happened was when I pushed the PTT switch, I got full output on the 
SBE-33 with no audio input to the microphone.  The purpose of the 
walwart to to simulate on the bench the voltage applied through the 
switch contacts when it was connected to the SBE-33 while I observed 
what was happening on the scope.

I have downloaded the same file.  Looking at the switch diagram in the 
file.  I have the microphone connected to contacts 1 & 2. Contact 1 is 
also connected to the braid shield.  PTT wires are connected to contacts 
4 &5.  Contact 4 is also connected to the shield.

David
KW4DH

On 2/8/2013 5:15 PM, Richard Knoppow wrote:
>
> ----- 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
>
>
>

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