[time-nuts] HP 106B quartz frequency standard...the story so far

[Chuck Harris]

If I recall correctly, the HP quartz oscillator manuals say that you must allow
at least 72 hours of burn in after shipment from the factory, and 72 hours between
frequency adjustments.

Double oven quartz oscillators are dodgy things.  The Sulzer 2.5C and HP 107's that live
in my shop have an interesting characteristic:  They age upward in frequency, and I
make the appropriate adjustments every few days.  But if I break power for even an instant,
the crystals pop down in frequency to about where they were back when they were last
started...  And it takes them months to get back to where they were before the power quit.

-Chuck Harris

Mark Sims wrote:
> The first question to ask is how long had the unit been inactive and how long has it been powered up?  I have noticed
> on several 5370 counters that the oscillators took several (4-6 weeks) to stabilize after I received the units.  I am
> pretty sure that the units had been inactive for quite a while and were not recently removed from operation.
> 
> I had them connected to a Tbolt or cesium oscillator.  I would set them each morning to a few counts above 10 MHz.
> By the next morning the reading was below 10 MHz.  It took between 4 and six weeks for the units to stop drifting.
> Interestingly,  the 10544 oscillators drift much less than the 10811's  and all the oscillators drifted in the same
> direction.
> 
> Before doing any serious study of your 106B,  I would plug it in,  leave it on,  and let it cook for a couple of
> months.
> 
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