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[TenTec] Tentec 700 Hand Mic Question

To: tentec@contesting.com
Subject: [TenTec] Tentec 700 Hand Mic Question
From: K8JDC <K8JDC@sbcglobal.net>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Sat, 18 Dec 2010 10:50:51 -0500
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>

     I recently got a Tentec 700 hand mic and noticed that it causes the 
radio to transmit a spike every time the PTT lever is pushed.  The mic 
was set up to use a 9V battery when I got it but I have wired it to 
operate directly off my Paragon II.  It spikes on either power source 
and the spike is basically full output power so it's a bit alarming.

     I originally thought the spike was related to the operation of the 
PTT switch...i.e. a little clicking noise causing the spike but that's 
not true.  If I key the PTT with the mic disconnected from the radio and 
then connect the mic to the radio, the spike still happens so it appears 
that it is related to applying the voltage to the mic circuit or 
cartridge.  I played around a bit trying to add a capacitor to stabilize 
the power in the circuit and eliminate any transients but the spike is 
still there.

Has anybody seen this and/or have a fix?  The existing caps in the 
circuit appear to be okay (i.e not shorted) and I think the cartridge 
itself is the cause of the spike.  There is a resistor feeding power to 
the cartridge but I have not tried raising the value (yet).


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