[time-nuts] How to get unknown frequency quartz crystals oscillating

Brooke Clarke brooke at pacific.net
Sat Jun 4 15:39:23 EDT 2016

Hi George:

A Crystal Activity Meter is the most straight forward way:

Have Fun,

Brooke Clarke
The lesser of evils is still evil.

-------- Original Message --------
> Hi,
> I have a number of crystals either in glass, bakelite, ceramic or metal housings that I would like to get resonating . They are of three basic types.
>   Square, or rectangular flat
>   Round flat
>   Bar  square section
> Sizes range from 2-10cm or more in the longest face.
> Some have frequency markings. ranging from IKHz 5MHz.
> Others have none.
> Some are of  Military origin, probably radios and as they have markings I can probably find a schematic from the radios to see how to proceed.  There may be dedicated testers still around. I am not so interested in this bunch at the moment.
> Others have no known origin so I have no idea what oscillator circuits were used with them.
> In terms of vintage, I would guess pre 1940  to late 50s
> I have built a little Pierce circuit an tried a few. Some of the later 1-5MHz crystals will oscillate but there are a lot of parasitic signals as well as the supposed fundamental. I cannot make any of the low frequency / big crystals to react.
> So my question:
> If you had a crystal with unknown frequency and drive requirements that you wanted to investigate. How would you go about it?
> If I can get them going I will share the Adevs. I don’t have a spectrum analyser so I can’t do phase noise.
> Regards
> "The power of accurate observation is commonly called cynicism by those who have not got it. »
> George Bernard Shaw
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