Al,
Check to see if there are trimmer capacitors that set the BFO/carrier
oscillator offsets. When they get old they can take shifts. I had this
happen on my Paragon. Shoot them with contact cleaner and turn the
rotors a few times to clean them, BUT FIRST, make sure that you have a
way to bring them back on frequency with a good frequency counter or
other reference.
73,
Bob WB2VUF
wb5jnc@juno.com wrote:
>
> Greetings all,
>
> I have been hearing a random frequency shift on transmit from my dad's Delta
> 580 during our contacts on 40M CW. The pitch of the received signal will
> shift down several hundred hertz (estimated) for a few characters every so
> often and then go back up. It has to be from his transmitter because the
> background QRM doesn't change pitch and another op in our roundtable has
> noticed the same thing I'm hearing. My first thought was the PTO needing a
> "lube job" but it seems too consistent for that -- it never shifts during a
> character, apparently only between, and the amount of the shift stays
> consistent. I'm now more inclined to think something in the TX switching is
> the culprit, like it is sometimes picking up the sideband offset instead of
> the one for CW. Anyone else out there ever encountered this? (Also I don't
> think he has an external VFO for it, so I can't blame it on that.)
>
> TNX/73, Al
>
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