Hi Back in the early days of multiplex transmission, frequency division multiplex was king. There were a lot of systems. They used a variety of schemes to pack the baseband signals into sub 2 MHz sort of arrangements. For quite a while the state of the art was to use various low frequency crystals to generate the multitude of careers that spread out from audio up to maybe a MHz or two.
As a result of this, there were a *LOT* of crystals made at weird low frequencies. Some of these systems lived on well after the advent of digital multiplex systems. Once you have 400 miles of system A it’s easier to extend it a “few more miles” than to re-do the whole thing. Spares for these systems were made at least into the 1990’s. While these are really cool looking parts (try a strobe on your 1 KHz bar …) they rarely are very stable. They are more interesting as art than as frequency standards. Bob > On Feb 3, 2016, at 2:36 PM, Dave Brown <tract...@ihug.co.nz> wrote: > > And many of these glass envelope crystals were made on very low frequencies- > I have several below 20 kHz and one as low as 3 kHz in a B7G based envelope > that is 4 inches long. > http://homepages.ihug.co.nz/~tractorb/3k1.JPG > > DaveB, NZ > > ----- Original Message ----- From: "Alan Melia" <alan.me...@btinternet.com> > To: "Discussion of precise time and frequency measurement" > <time-nuts@febo.com> > Sent: Thursday, February 04, 2016 6:30 AM > Subject: Re: [time-nuts] Glass Envelope Quartz Crystals > > >> I think it was unlikely that that it was made "just to see where it would >> come out" That is a flexural bar possibly an NT cut. 100KHz standards were >> commonly made in this format. >> The British GPO had a factory at Mill Hill in N. London making these in >> tube-like (valve in UK) enclosures, IO GT and B7G. I have a number of unit >> saved from the dumpster (skip in the UK).when the unit closed in the early >> 60s. Remember there was a surge in telephones in this era and many of these >> frequencies were for FDM carriers on trunk sytems. This is pre-synthersiser. >> >> Also many special quality tubes were made for VHF in B7G with two or three >> inch wires instead of pins to reduce the socket parasitics. so these were >> probably still around in Russian factories to produce components for the >> "Foxbat" etc. >> >> Alan >> G3NYK >> >> >> ----- Original Message ----- From: "Philip Gladstone" >> <pjsg-timen...@nospam.gladstonefamily.net> >> To: <time-nuts@febo.com> >> Sent: Wednesday, February 03, 2016 1:21 PM >> Subject: Re: [time-nuts] Glass Envelope Quartz Crystals >> >> >>> I dug around in my junk box, and found this: >>> >>> https://plus.google.com/+PhilipGladstone/posts/JBNLMSq2rsE?pid=6247050011623528018&oid=115465617973526125523 >>> >>> This is (according to the markings) a 71.137 kHz crystal made in 1948. I >>> suspect that they just measured the crystal after manufacture rather than >>> actually trying to make a 71137Hz crystal.... >>> >>> After this discussion, I'm feeling the need to fire it up and see whether >>> it still runs, and what the aging has done to the frequency.... >>> >>> Philip >>> >>> On 03/02/2016 07:11, Bob Camp wrote: >>>> 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 <jn6...@gmail.com> 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 <kb...@n1k.org> >>>>>>>> Data: 02/02/2016 13.15 >>>>>>>> A: "Discussion of precise time and frequency >>>>>>>> measurement"<time-nuts@febo.com> >>>>>>>> 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 <watsondani...@gmail.com> >>>>>>>>> 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 -- time-nuts@febo.com >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
