[time-nuts] Re: Temperature accuracy / repeatability / drift of double ovens

[Bob Camp]

Hi

Simple answers (and likely not much help):

Thermal gain on a single oven is likely in the 300 to 600 range.

Double oven boosts that by 10 to 30X

Thermal gain in this case: take the ambient change divide it by the thermal gain
and you get the oven temperature change. 

Long term stability: 

low enough that it does not impact aging. ( = that’s how you test it). Since that gets back
to the specific thermistor being used, you are into the ‘likely not much help” range. 

Best guess info: The crystal + circuit is < 1x10^-9 / C in the vicinity of the turn. The operating
point is offset from turn to minimize the combination of crystal + circuit. Just what the net
is ….

Still, if you can “see” aging at the parts in the (low?) 10^-11 range, it sort of kind of gets
you to a number. Maybe 0.01C / day. 

Since you are canceling the circuit with the crystal, if things got to far off, a year later the
temperature performance would not be any good. That likely gets you to something
in the < 1C per year range. 

Bob

> On Mar 30, 2023, at 6:16 PM, Gerhard Hoffmann via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> Temperature accuracy / repeatability / drift of double ovens:
> 
> What can be reached here, with a tolerable effort?
> Is there anything known about that in the public? mK-numbers?
> 
> The application is not a crystal oven this time, but diode lasers
> that interrogate Rb atoms and must be kept in lockstep at a certain
> beat frequency. The frequency tuning is mostly by temperature;
> laser diode current plays a minor role, but probably via changing the
> local temperature in the junction and a little bit later in the cavity.
> 
> Are there any GoTo thermistors / circuits for stability?
> 
> Cheers, Gerhard
> (stumbling into new territory)
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