Hi,
If you have access to a Network Analyzer, either Scalar or Vector, you
can measure the crystal parameters. You need a test fixture (homemade)
to convert the impedance to 12.5 Ohm and you sweep the crystal to obtain
its serial resonance and the -3dB points. From these there are formulas
to obtain the motional resistance, inductance and capacitance, and the
crystal Q. Even some low cost hobby type analyzers have a mode for
measuring crystals with these calculations integrated.
Regards,
Ignacio EB4APL
El 01/03/2021 a las 0:35, Dan Kemppainen escribió:
Hi All,
I've picked up a couple of old crystals. Mostly because they look
neat. They are 1Mhz, in a glass tube. The quartz is ~25mm dia, at
about 1 mm thick. Was able to get them to oscillate using a Colpitts
circuit. They will oscillate at 2.851Mhz (probably some strange mode)
if given the chance.
I've been scouring my reference books here, and haven't had much luck
finding any details on how one would even guess at the parameters of a
quartz like this.
There area few numbers on them, 33 stamped on the side, 1000 (KHz???)
on the top, 87 on the top, and hand written 501 (probably a SN).
Digging on line, I'd guess an AT cut based on thickness. I'm guessing
the 33 is capacitance in pF. 87, might be year.
If any of you have any suggestions on where to find information on how
to get something like this to oscillate properly, guess at correct
parameters, or even measure any of the parameters I would really
appreciate it.
I'm sure these are really nothing special, but it would be neat to
give them a fighting chance to show what they can or can't do without
breaking them!
Thanks,
Dan
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