Hi There is actually a range of crystals shown in the pictures. The gold plated 5 MHz crystal is probably an overtone part. It could be fairly precise. The 25 MHz part is plated with something like silver. It probably is a *much* lower precision part. There likely are long stories that explain just why this or that package got used in this or that application.
Bob > On Feb 2, 2016, at 10:04 PM, Jeremy Nichols <[email protected]> wrote: > > The OP's picture looks very much like the crystals that HP's "Frequency and > Time" division in Santa Clara (02 was their division number) used to > manufacture back in the 1970s. My picture shows a 1 MHz crystal that HP used > in the predecessor to the HP-105A (perhaps the 101A). > > Jeremy > > http://s323.photobucket.com/user/Jeremy5848/media/Miscellaneous/Crystal_1140587_zps0jxjpoal.jpg.html > > > > On 2/2/2016 12:24 PM, Don Latham wrote: >> You have it right, iovane. At the least, they should be protected from light, >> thermal radiation, and emf. Won'drous things will happen if the crystal and >> its structure are subjected to radiation through the glass. I'd suggest a >> foam >> wrap in a tin can as a minimum. Put the oscillator cat in there too. >> Don >> >> iovane--- via time-nuts >>> I think that these crystals were designed to be placed in an oven, which >>> worked >>> as a shield too. I have a similar crystal made by Racal in the 60's, and in >>> my >>> case it is fitted with the classic octal tube-type plug. It was housed >>> (still >>> is) in a heavy massive shimmering chrome-plated cylindrical brass >>> enclosure, a >>> beauty to see, It was the timebase of a tube-type synthesizer with lots of >>> tubes. Themperature control was achieved by means of a mercury thermometer >>> in >>> which mercury actuated a contact when reaching a wire crossing the capillary >>> tube. >>> >>> Antonio I8IOV >>> >>>> Da: Bob Camp <[email protected]> >>>> Data: 02/02/2016 13.15 >>>> A: "Discussion of precise time and frequency >>>> measurement"<[email protected]> >>>> Ogg: Re: [time-nuts] Glass Envelope Quartz Crystals >>>> >>>> Hi >>>> >>>> Since the 25 MHz crystal has already been soldered into a circuit, putting >>>> it >>> in a >>>> socket is probably not a real good idea. It’s also a leaded part. Even with >>> fat pins >>>> sockets can be an issue. With wire leads, you are asking for trouble. >>>> >>>> Functionally, there is little there is little difference between a glass >>> package crystal >>>> and a metal package. About the only real one is the obvious - one has a >>>> metal >>> shield >>>> you can (but sometimes don’t) ground. >>>> >>>> Bob >>>> >>>> >>>>> On Feb 1, 2016, at 9:58 PM, Daniel Watson <[email protected]> wrote: >>>>> >>>>> Hi, >>>>> >>>>> I purchased a pair of interesting glass envelope crystals for a project. >>>>> Here are some pictures: >>>>> >>>>> http://syncchannel.blogspot.com/2016/02/glass-envelope-quartz-crystals.html >>>>> >>>>> Does anyone have an idea about what mount/socket I should buy for these? I >>>>> read a previous thread on the list about Bliley crystals using a B7G >>>>> mount, >>>>> but I'm not sure if that type might work here. >>>>> >>>>> Also, when building up a circuit to make these oscillate, are there any >>>>> specific differences about crystals in this package that I should keep in >>>>> mind? >>>>> >>>>> >>>>> Thanks much, >>>>> >>>>> Dan W. >>> >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >>> >> > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
