k4kyv at charter.net
Sun Jun 8 13:35:16 EDT 2014
I used to keep the oscillator tube in the PTO running all the time in my
converted T-368 exciter that I use for VFO. It drifts only a few hundred cps
from a cold start, but it takes it a while to completely settle down. The
only time that's a real problem is when I use it for 40m CW, and the signal
drifts out of the passband of a narrow CW filter. But I found that when
running it all the time, it substantially shortens tube life, and I was
having to replace osc tubes after less than a year of service, and now that
ANY good tube is gradually becoming less available, I decided to shut it off
whenever the receiver is turned off.
I have a couple of spare PTOs, so I need to check if they are any more
stable. I might even consider a 'tubster' in the oscillator circuit, if I
can come up with a drop-in replacement that works as well as a real tube,
and let that run 24/7 except when a lightning storm is likely.
Yes, The VF-1 is powered from the transmitter.
However, on a DX-60 the B+ is switched on/off...on the octal connector.
The Opportunity I see is to keep VF-1 powered up always up for stability.
(It's on my to-do list)
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