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<a class="moz-txt-link-abbreviated" href="mailto:scott@opentrac.org">scott@opentrac.org</a> wrote:
<blockquote cite="midE1EleIM-00066A-Tv@giskard.tapr.org" type="cite">
<pre wrap="">Does any existing Mic-E type hardware work with HTs that don't have a
separate PTT line? I came up with a circuit that works OK, I'm just curious
if there's something else out there already.
Scott
N1VG
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</pre>
</blockquote>
<font face="Arial">Yes. The TinyTrak has an arrangement to simulate
the "ground-the-mic-element-to-draw-current-and-transmit " arrangement
used for 2-wire mics on hand helds. <br>
<br>
All it is is a 2K resistor between the PTT line (open collector) and
the audio output line of the TT. (This is (the "R8" that is endlessly
discussed and misunderstood on the TinyTrak mailing list and
elsewhere). <br>
<br>
<br>
You connect the audio-out line only of the TT to the HT. When the TT
keys (saturates the open collector to ground), DC current flows out of
the radio's mic jack through the resistor to ground and keys the
radio, without shorting out the audio to ground. <br>
<br>
<br>
<br>
<br>
<br>
.</font><br>
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