The only trouble with not allowing the 10 KHz offset is that PTO mixing
products get into the passband that were shifted out by that offset. The
crystals are also shifted for those bands for the same reason.
73, Jerry, K0CQ
On 7/31/2010 7:58 PM, Jim Marco wrote:
> 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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>
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