[time-nuts] Looking for QST Jan 1990 Article on Crystal S, Q & R testing By DeMaw

Didier Juges didier at cox.net
Thu Dec 21 03:31:59 UTC 2006


I did just that to check the 50 MHz crystal in my HP 3586 and convince 
myself it was not dead. The 50 MHz VCXO did not oscillate, for some 
reason, and finding a replacement crystal would have been a long shot 
and would have probably cost more than I paid for the instrument.

Seeing the proper response (I used the spectrum analyzer instead of a 
scope, but that's the same idea, I used an HP 8656A as a source, which 
was not optimum because of the 100 Hz step size, but it worked), I 
determined the crystal was most likely OK.

I added a small cap to the VCXO circuit to increase gain a little bit 
and the oscillator came alive. It's been working for over a year now.

Didier KO4BB


Mike Feher wrote:
> Brooke -
>
> In that case why do not just use a signal generator like an 8640B with the
> crystal in series with the hot lead and then the other side of the crystal
> terminated in 1K or so. Then you can put a scope across the 1K resistor and
> watch the scope as you tune across the suspected resonant frequency. I have
> done this a lot when I was not sure of the crystal frequency, or, if it was
> working or not. Real simple to do. If all else fails, I am sure I have the
> QST you mentioned, and could scan the relevant pages for you. I also have a
> military crystal activity meter that does do a full characterization, but,
> it is big and bulky, and, I hardly ever use it. 73 & Merry Christmas - Mike 
>
>  
>  
> Mike B. Feher, N4FS
> 89 Arnold Blvd.
> Howell, NJ, 07731
> 732-886-5960
>  
>  
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Brooke Clarke
> Sent: Wednesday, December 20, 2006 5:15 PM
> To: Discussion of precise time and frequency measurement
> Subject: [time-nuts] Looking for QST Jan 1990 Article on Crystal S,Q & R
> testing By DeMaw
>
> Hi:
>
> I'm looking for  the subject article on crystal testing, or any other 
> articles on testing crystals.
> This is more related to knowing if a given crystal is alive than 
> characterizing it, i.e. a Crystal Activity Meter type thing.
>
> Have Fun,
>
> Brooke Clarke
>
>   





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