Yes 550hz is a bit much. More like 150hz is normal warm up drift. When
operating cw for long periods you will also experience some drift due to
the extra heat conducted from the finals. A lid full of vent holes would
be approiate for all their rigs.
On Mon, 24 May 1999, dslosty wrote:
> 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
> after 1/2 hour. Two hours to settle down seems a bit long - especially
> running modes like Pactor. There are 4 NPO caps in the oscillator
> 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?
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Steve Ellington N4LQ
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