[time-nuts] HP5065A C-field mods and optical unit mods

cdelect at juno.com cdelect at juno.com
Mon Nov 20 13:24:32 EST 2017


Most all Rubidium standards do not have active current drive.  
The HP 5065A is the exception. However the mod I installed is not active.
The C-field coils are roughly temperature compensated as they are near
the cell oven that is regulated.
If you check out Poul-Hennings "hacking the 5065a" you will see that the
C-field coil does exhibit some temperature effect even with active
current regulation, and the stock C-field circuit also introduces some 
effects. Now these amount to a small coefficient but we are Time Nuts
here so we can do better!

My circuit gives a precise current into the coil (for a fixed temperature
of the coil), and with the active temperature stabilization I am adding
to the outside of the sealed optical unit enclosure  those effects will
be eliminated.



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