[ARC5] Crystal Tester

[Brooke Clarke]

Hi Bill:

A crystal activity meter is a quick way to see if the crystal oscillates and roughly it's frequency.
http://www.prc68.com/I/Xam.html

To measure the design parameters of a crystal the accepted way is to make a series frequency sweep using an impedance 
transformation to 12.5 Ohms on either side of the crystal.
The plots on my crystal equivalent circuit web page http://www.prc68.com/I/Xec.shtml were done at 50 Ohms so are 
different than a crystal manufacturer would measure.  Note this requires a very narrow resolution bandwidth for high-Q 
crystals.  As the frequency of a crystal gets lower it's Q increases.  So measuring the parameters of a watch (32768 Hz) 
crystal is extremely difficult.

Also see the Z-Transformation test method at:
http://www.prc68.com/I/4395A.shtml#ZT
Which also lists modern crystal impedance test equipment.

-- 
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
The lesser of evils is still evil.

-------- Original Message --------
> Hi,
>
> It sounds like we are talking about using the crystals in something like a crystal IF filter and not just using them 
> in something like a MOPA. For those purposes my comment about using... well.. a MOPA.. will obviously not apply. I 
> have been gnawing on the "methods and materials" to get the results needed for xtal filter construction, too. 
> Meanwhile I throw some xtals that oscillate on near the same frequency and live with the results. I duplicated a 
> published design (by DeMaw) without sorting through xtals and got some very happy results. My other adventures gave 
> been single xtal filters. I have been intimidated by the voodoo *required* to get something like an SSB filter from a 
> handful of FT-243 xtals or a shoe box full of "computer" xtals. It seems to me as I circle around the unruly pile of 
> methods that it can be done in several passes to gather the information. That wouldn't be handy at a hamfest table 
> though. The MOPA could be a "go-no go" test. Would that be appropriate for a "take the whole box for a dollar" offer?
>
> 73,
>
> Bill  KU8H
>

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