[time-nuts] OCXO Adjustment Question

Frederick Bray fwbray at mminternet.com
Tue May 7 22:24:33 EDT 2013

This might be slightly off-topic, but probably there is a time-nut who 
knows the answer.

I am trying to adjust the 10 MHz OCXO in a Cushman 5110 service 
monitor.  I am using a frequency counter driven by a GPSDO.  Perhaps 
someone can educate me about a couple problems I am encountering.

I tried making small incremental adjustments but after I am done, the 
frequency drifts several Hz and then re-stabilizes at a new value.  When 
I make further adjustments, I notice strange behavior. For example, if I 
initially turned the adjustment clockwise to increase the frequency, it 
will now decrease if I turn it clockwise and increase if I turn it 
counter-clockwise.  On the next adjustment, it will reverse again.

Is there some correct procedure to adjust an OCXO?

Many thanks for any suggestions.

Fred Bray

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