[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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