Garren wrote:
I don't doubt that my oven could be the problem but I would think a
lot of people have their tbolts sitting in a room or basement with a
lot more temperature swing than 2.5C. I also monitor the inner oven
temperature where the oscillator is located and it remains stable at
67C regardless of the 2.5C swing of the outer oven. This makes me
wonder if the tbolt temperature is used in the algorithm that steers
the osc frequency. I'll have to try some experiments to see if I can
figure this out.
What you see is the GPS discipline doing its job.
As others have said, the temperature reported by the Thunderbolt's
internal sensor is not used by the Tbolt during locked operation (you
can find lots of posts on this subject in the archives). Note that
your white oscillator trace sits stably on frequency (at time scales
comparable to the temperature changes). This is because the Tbolt
control loop is counteracting the temperature drift of the crystal.
If the crystal frequency was not varying with temperature but the
Tbolt was running the DAC up and down in response to the internal
temperature sensor (as you posit), you would expect to see the white
oscillator trace tracking the temperature and DAC traces as the
oscillator was erroneously forced off frequency by the control loop.
Best regards,
Charles
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
