[time-nuts] Thunderbolt oven / non-stable operating temperature

[Bob Camp]

Hi

LH can get a bit confused about OCXO tempo. It's not really the software's fault, as you point out - the data just isn't there. 

Bob

On Dec 14, 2012, at 5:36 AM, Charles P. Steinmetz <charles_steinmetz at lavabit.com> wrote:

> tvb wrote:
> 
>> do either of you have actual tempco numbers?
> 
> I checked my notes and found that I did not record any free-running tempco values.  My observations were based on the scale factors I had to use to get the temperature and DAC graphs in Lady Heather to overlay each other.  I initially noticed it because there was a very pronounced tracking of the two graphs for one Tbolt and for the other two there was not (the temperature-compensating component of the DAC voltage is mostly lost in the noise).  I had checked the actual EFC sensitivity of each oscillator in the vicinity of the operating point, so all relevant variables were more or less controlled.
> 
> My impression is that the better ones are comparable to a single-oven 10811, maybe even a bit better.  LH typically reports tempcos of 1e-12/C to 1e-11/C.  My worse unit (and, from what I can infer from LH plots posted to the list and on-line, it appears many others as well) typically reports a tempco of 1e-10/C to 1e-9/C.  Of course, the LH numbers are all to be taken with some caution since LH does not have any a priori means to separate tempco and drift.
> 
> Best regards,
> 
> Charles
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