TX-1 VFO Drift Problem-Ideas, Anyone?

[digital-conjurers at ADELPHIA.NET]

Have been having some problems with my TX-1 VFO; it seems to drift down in frequency about 1.5-2.0 Khz an hour, even after a 60 minute warm-up.  In later service bulletins, Heath suggested:

1. Replacing the VFO caps with NPO types
2. Using a 6AH6 instead of a 6AU6 (...with a cautionary note about 6AH6 filament demands...what are you supposed to do? Replace the filament transformer too?)

The original owner of this unit was appearantly so plagued by this he wired up the filament of the 6AU6 VFO tube to be constantly "on".  Now, that _does_ cut down on the problem a bit, but it's not a fix.

If anyone out there has heard of some other cures for the Apache TX-1 VFO drift problem, I'd like to hear them.

Thanks to the group in advance.

-Lin/KJ6EF

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