[TenTec] Omni-D, version B, drifting..........................

[dslosty]

My recently acquired Omni-D, version B, seems to drift a bit too
much - at least for my tastes.

Fronm a cold start, the rig drifts upwards for the next two hours
with a total drift of around 550HZ. Around 520HZ of the drift comes
from the PTO as would be expected. The PTO is stable (non-jumpy)
in operation and I doubt that it needs a mechanical rebuild
(in terms of the variable inductance).

The culprit seems to be the digital readout circuitry mounted above
the PTO enclosure. It generates a fair amount of heat. When the cabinet
top is removed, drift is cut in half. After around two hours, the drift
finally stops and the rig stabilizes to the extent stated in Ten-Tec
specs (around 15Hz/Degree temp change).

Is the drift of my PTO abnormal? Ten-Tec specs seem to imply
stabilization
after 1/2 hour. Two hours to settle down seems a bit long - especially
for 
running modes like Pactor. There are 4 NPO caps in the oscillator
circuit.
Anyone have experience with the aging of these caps?

This is the first non-synthesized digital readout rig that I've had.
Perhaps I'm expecting too much....

Any thought?

73,
Doug/WA1TUT

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