Hi
> On Mar 1, 2021, at 12:52 AM, Ed Palmer <[email protected]> wrote: > > On 2021-02-28 5:53 PM, Dan Kemppainen 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! > > Those are available from at least a couple of Ukrainian ebay sellers. Search > for "1000 khz". There's also one that comes complete with the oven assembly: > https://www.ebay.ca/itm/254748662460 . I picked up a few of the bare > crystals to help me understand the oscillator circuit in my HP 104AR > frequency reference. I breadboarded a circuit that was similar to the 104AR > (i.e. similar to the HP 103AR) and with a couple of circuit changes the > crystal worked properly. I changed the transistor from Germanium to Silicon > and changed C105 from 30nf to 3nf. Note that you *MUST* build the AGC > circuit or you'll probably destroy the crystal by overdriving it. Play with > the base bias voltage to get the circuit to oscillate. > > I used a Saunders 100HF meter to measure the crystal parameters, but I don't > understand the results. Cm = 16 ff and Lm = 1.6 H which are fine. But Rs < > 1 ohm?? Other crystals measured using the same technique gave me results in > the tens or hundreds of ohms. But all four of these crystals measured < 1 > ohm. That would give you a Q > 10M. While this would be a wonderful outcome, it’s not likely to happen with a 1 MHz fundamental quartz crystal. Best guess: Your 100HF needs to be calibrated. Check the manual for details. Bob > > I haven't done any temperature testing on them. > > Ed > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
