The Argosy is one of my favorite radios. I've been restoring a couple of
them recently and one of them had a persistent problem where there would be
significant frequency jumps in the PTO frequency. I know this problem has
been fully discussed and documented but I discovered another reason why this
can happen.
The Argosy introduces a 10 kHz electrical offset to the PTO. This is
generated on the OSC/Mixer assembly via switch S1D. On 80, 40 and 20 meters,
the VFO shift can jump around if the ground to the switch becomes
intermittent or connector 2 becomes intermittent. Before you subject the PTO
and yourself to a rebuild or cleaning, remove the cable to connector 2 and
see if the problem goes away. If it does, resolder the connections to S1D or
simply leave the cable off on connector 2 and adjust the dial skirt as
needed.
I also highly recommend a simple non-invasive PTO clean and lube from the
Ten Tec Wiki web page where the radio is placed on end and drops of
isopropyl alcohol and Tri Flow Teflon lubricant are drizzled down the PTO
shaft and the shaft is worked repeatedly until smooth operation is realized.
Both of these procedures are easy and simple and may be all that is
necessary to restore smooth and stable PTO service on the Argosy
transceiver.
Jim Marco, WB2LHP
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