If you are brave, I'd pop the cover on that oven and see if the thermistor
may have come loose and is no longer in firm contact with the metal crystal
can. There is NOT a lot that can wrong inside of those simple ovens. The
few I have had that were bad all had thermistors that were not making good
thermal contact.
TenTec was selling a rather expensive conversion board that included a TXCO
that was intended for 5 volt TTL levels. These days most digital TXCO
devices are intended for 3.3 volts. Some are spec'ed to drive TTL loads.
TenTec did bias the TTL devices after the crystal oscillator to make it
easier to drive.
I have made up several boards using a linear oscillator based TXCO, the
TXCOs came from eBay I had boards made up for the project. I was going to
make and sell kits, but I decided not to, since I don't want to get
involved if problems crop up.
My modification involved removing the existing crystal osc. oven, and
removing the cap from base to collector in the Colpitts oscillator. I use
the existing active components as a buffer, and it worked quite well in a
few of my Omni VI rigs.
If you get in a real bind where the rig is no longer operable, I could send
you a kit for postage, you'd have to assemble and test... surface mount,
and you'd have to comfortable working on the TenTec CPU board!
Otherwise, I think Gary had a supply new factory replacements for the
ovenized crystals for a good price. Check with him to see if has any left.
Pete
Pete
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