[time-nuts] Tbolt temperature sensor
SAIDJACK at aol.com
SAIDJACK at aol.com
Thu Feb 5 18:22:13 UTC 2009
Hi Tom,
I re-connected the antenna to that unit just now, so it is now GPS locked
again.
Forgot to mention: another reason why ground loop currents for these single
oven units are not an issue is that the current changes very little with
temperature. In the plots you can see that the OCXO current is typ. less than
50mA, and the variation is typically less than 4mA peak to peak.
A 4mA change is a very small change to affect ground-loop induced voltage
offset errors across the ground plane, OCXO pin, etc. Nevertheless we do Kelvin
sensing to avoid any issues for ovens with higher current variations.
bye,
Said
In a message dated 2/5/2009 09:32:31 Pacific Standard Time, SAIDJACK at aol.com
writes:
>In your plots the EFC correction seems to match so well with
>oven current (without clear evidence of the usual thermal lag)
>could it be that what you're seeing, and what you're correcting,
>is not resonator temperature at all but simply the voltage offset
>due to ground currents?
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