[time-nuts] Follow-up on Z3801A high EFC reading

John Ackermann N8UR jra at febo.com
Sat Jul 16 23:59:47 UTC 2011


Thomas, Dan, Magnus, Graham --

Thanks for the replies!

This is an interesting example of "no two oscillators are the same."

I certainly expected that there would be aging and retrace on a cold 
oscillator, but I started both Z3801As almost simultaneously and within 
about 12 hours unit #1 had stabilized and the EFC was showing normal 
noise over a fairly small range with no real trend apparent.

But unit #2 (the one shown in the plots) continued to have the very 
pronounced aging trend of after 12 hours, with one click per minute more 
than a day after power-on, as well as having a much higher absolute EFC 
value than it did before, or than unit #1 has now.

So, based on unit #1, I was suspicious of what was going on in the 
second unit.  It may just be that #2 doesn't have as good an oscillator 
as #1.

John
----
Thomas S. Knutsen said the following on 07/16/2011 05:32 PM:
> I think it is in Matthys, Crystal oscillator circuits. Can't quote
> page number now, as my verson is somwhere I cant remember. It's an
> excellent book if you do some experimentation.
> I did write an letter to R.J. Matthys a couple of years ago, and
> reveiced an answer.
>
> 73 de Thomas LA3PNA/AE5YS.
>
> 2011/7/16 Dan Rae<danrae at verizon.net>:
>> One crystal expert, who's name escapes me, sorry, told me that if you power
>> up an oscillator that has been off for an extended period, you should expect
>> a very rapid ageing process to occur with a lot of the accumulated changes
>> that would have happened had it been powered on then to occur when it was
>> restarted.
>>
>> But I can't quote chapter and verse, obviously.
>>
>> Dan
>>
>> ac6ao
>>
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>
>




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