Dave:
Did you try rewiring the mic element so that it is powered all the time?
Maybe the mic power is going through the PTT switch and the turn-on
transient is putting out an audio pulse.
73,
Bob WB2VUF
On 12/18/2010 10:50 AM, K8JDC wrote:
Friends,
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).
Thanks...
Dave
K8JDC
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