[TenTec] Corsair II PTO
Dave Moorman
dmoorman4 at comcast.net
Tue Dec 7 18:49:51 EST 2004
On Dec 7, 2004, at 11:52 AM, Paul DeWitte K9OT wrote:
> My Corsair II will drift 4 or 500HZ until warmed up. Does a PTO
> rebuild take care of this? Or do you do rebuilds just because of the
> hard grease? I have no problem with the turning of the vfo just the
> drift.
>
This may be within spec, Paul. The manual says about VFO stability:
"Less than 15 Hz change per degree averaged over a 40 degree change
from 70 to 110 degrees F after 30 minutes warmup."
This is not the plainest statement in the world, but it seems like what
they are saying is that over a 30 minute warmup period, the temp in the
VFO will climb from 70 F up to 110 F. During that warmup period, the
frequency will change 15 Hz or less per degree F. Assuming the worst
case scenario of 15 Hz per degree, then the drift would be 15 x 40 =
600 Hz. So your 400 Hz to 500 Hz drift, being less than 600 Hz, would
probably be in spec.
"Probably", because to really know this, you'd have to know the
temperature of the VFO after 30 minutes of warmup. If inside your
Corsair II the temp only goes up to 90 F, that's only 20 degrees change
and the allowable drift would be 300 Hz. At any rate, you are pretty
close to spec.
The other aspect of this situation is that the PTO rebuild, as I
understand it, is a mechanical rebuild which corrects mechanical
problems like backlash and slippage but would have no effect on warmup
drift.
The other thing I'm curious about is - why is less than half a Hertz
warmup drift a concern? Digital modes?
Dave K9SW
Corsair 2
Argonaut 2
Scout
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