[TenTec] Fixed: TT 700 Hand Mic

[Bwana Bob]

Good, job, Dave!  It's always a joy to fix or improve something.

                 73,

                 Bob WB2VUF

On 12/18/2010 8:35 PM, K8JDC wrote:
> For what it is worth, I got rid of the big spike by making two changes.
> First, there was a 2.2K resistor in the power line leading to the mic
> element.  This resistor is between the PTT switch and the element so I
> increased that to 22K.  I tested it with a resistor substitution box and
> the mic output was unchanged until the resistor value got to about 33K.
> At 22K, the output level is the same as before so it is not too much
> resistance.
>
> Secondly, there is a capacitor from the positive terminal of the mic
> element to ground.  I added extra capacitance at that point and those
> two changes got rid of the spike completely.  My theory was to prevent a
> voltage spike from being supplied to the mic element.  So, between the
> larger resistor and the larger cap, it allows the voltage to build up
> quickly instead of being a sudden power spike.  The audio output level
> is the same as before the changes and the audio quality also seems
> unaffected to me.
>
> Just thought I would post what I did.  It was spiking to 100W every time
> I keyed the mic before the fix.  I'm not sure why but I'm happy with it now.
>
> Dave
> K8JDC
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