Not sure how hard it might be to get a thermocouple into the oven. That would give you a hint. Regards Paul
On Fri, Jan 15, 2021 at 8:51 PM Bob kb8tq <[email protected]> wrote: > Hi > > One of the options is that the EFC has an issue. > > Another option is that the oven control circuit has a problem. > > Either one *could* put the center frequency someplace odd. If it’s the > heater control > (or heater set point) then indeed, the temperature sensitivity will go way > up. > > Most of the OCXO’s off these boards are a sub $20 sort of item on eBay. > How good > are they? Who knows …. > > Bob > > > On Jan 15, 2021, at 8:18 PM, Scott Newell <[email protected]> > wrote: > > > > Quick update: tried using an AD780 reference + op-amp to offset the EFC > voltage. Worked great, until I slid everything back into the enclosure and > it was tuning the OCXO too high! > > > > After several disassembly/mod/reassembly passes (all tuning too high > once boxed up), I punted and went back to the simple gain stage. It's been > locked at TFOM 2 all day, but it does seem very sensitive to air currents > and temperature changes. I'm starting to think the oven setpoint may be > wrong, too. (How could it lock 1 month ago with EFC <5V, but now it needs > 8.5V to be on frequency when it's outside the enclosure? Something's fishy > there.) > > > > Check out the white OSC trace in the LH screenshot--that can't be good! > > > > Hoping to limp by until I can find either a drop-in 5V OCXO or time to > adapt a 12V OCXO into the box. > > > > > > thanks! > > newell > N5TNL<uccm_gain_2_11h.gif>_______________________________________________ > > time-nuts mailing list -- [email protected] > > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
