[time-nuts] Old Crystal.

[Ken Winterling]

I am restoring my first Hallicrafters SX-100 Mark 2 and found this 100kc
XTAL in the calibrator.
It works perfectly.

[image: Hallicrafters SX-100 100kc XTAL Calibrator.jpg]
[image: Hallicrafters SX-100 100kc XTAL For Calibrator.jpg]
Ken
WA2LBI



On Sun, Feb 28, 2021 at 6:53 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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