[time-nuts] Tbolt temperature sensor

[Tom Van Baak]

>>The reason I'm asking this is because I can't figure out from
>>your descriptions or from the plots a clear way to distinguish
>>between unintended oven current-induced changes in applied
>>EFC voltage vs. direct temperature-induced changes in OCXO
>>frequency output. It seems both would have the same effect.
>
> As long as all effects are fairly linear over a given temperature
> range, then it doesn't matter where the thermal sensitivity is
> coming from.

I was thinking it might matter to an engineer. It's in our nature
to try to understand why something works the way it does.

> You may even have canceling effects (if for example the oven
> has a negative tempco, and the DAC/Vref have a positive tempco).
> So in other words, even the unintended temp-induced EFC
> changes will be compensated, because we measure absolute
> current versus absolute EFC voltage when the unit is locked,
> and calculate the parameters from this measurement, which
> includes all unintended thermal effects.

I still don't like unintended consequences. Did anyone try the
experiment to move your OCXO off-board by a foot of cable?

That might help isolate the root cause of the effect that you're
compensating for. Also, do you know if all single/double OCXO
show the same correlation of frequency output change vs. oven
current consumption change? This might be relevant for anyone
taking a Fury board and using their own external oscillator.

Rick - are there similar effects to what Said sees in his board
on the 10811? Or is this one reason the 10811 has separate
power supplies for the oscillator and oven circuits?

/tvb