[time-nuts] Old Crystal.

[Bob kb8tq]

Hi

Best guess is that it’s a 1 MHz fundamental. Your magic circuit is
running it on the third overtone. 

Past that: 
	AT cut? Probably. 
	32 pf load? maybe. 
	Heated application? maybe.
	Russian manufacture? yup

Bob



> On Feb 28, 2021, at 6:35 PM, Dan Kemppainen <dan at irtelemetrics.com> wrote:
> 
> 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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