Craig Roberts <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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As you may recall, I was complaining recently of RF contamination of my
TR-7's transmitted audio. The problem was traced to my "aftermarket"
PTT footswitch with unshielded leads. Removal of the footswitch cleaned
up the audio considerably -- but not entirely. I was still getting
reports of minor distortion. Some said I still had a little RF in my
signal. Others described a quality that sounded like clipping.
Then I remembered that I had installed a one-resistor mod on the ALC
board that tightened up the decay time. Could this be the problem?
I clipped out the added resistor.
I also re-aligned the transmitter section using a newly calibrated Bird
43 wattmeter and learned -- to my surprise -- that the old military
surplus wattmeter I had used to align the transmitter a few weeks ago
was reading almost 30 watts low. Therefore, my original transmitter
power output and ALC settings were based on a real power output of over
150 watts on 20 meters, rather than the recommended 120 watts or so.
(My TR-7 had arrived at my door tweaked to put out over 200 watts and
exhibited all kinds of weirdnesses, so even my first, faulty
re-alignment had been an improvement).
Anyway, re-aligning the transmitter with the correct, lower power output
and appropriate ALC setting cleaned up the audio completely and I'm now
getting reports of excellent, "broadcast quality" transmissions with a
Heil Classic mike.
I really don't know if the now-removed ALC mod was contributing to the
problem or not -- but I think I'll just leave well enough alone.
Apparently it is my mission in life to screw up so you don't have to.
73,
Craig
W3CRR
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