[time-nuts] HP 10811 stabilizing time

[Charles Steinmetz]

Rick wrote:

> Basically, no counter that we ever made AFAIK had
> any provision for EFC.

The later HP5328 "oscillator helper" boards have EFC pots for fine 
tuning the timebase frequency.  This includes the US military versions 
that are so prevalent in the US.  I have schematics showing this with 
both the 10544 (support board 05328-60027) and 10811 (support board 
05328-60038) oscillators (production shifted from the 10544 to the 10811 
during the 5328's run).

These work fine, but one can easily build an EFC circuit with much 
better drift characteristics (i.e., first-order temperature 
compensation).  I published such a circuit some time ago and posted it 
to this list at least once.  My circuit also reduces the EFC adjustment 
range to make it easier to adjust precisely.

That circuit is on Didier's site (ko4bb.com).  Search for a doc named 
"HP 10544 10811 EFC fine adjustment.pdf".

Best regards,

Charles