[time-nuts] Glass Envelope Quartz Crystals

Bob Camp kb8tq at n1k.org
Wed Feb 3 18:13:49 EST 2016


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. 


> On Feb 3, 2016, at 2:36 PM, Dave Brown <tractorb at 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.melia at btinternet.com>
> To: "Discussion of precise time and frequency measurement" <time-nuts at 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-timenuts at nospam.gladstonefamily.net>
>> To: <time-nuts at 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 <jn6wfo at 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 <kb8tq at n1k.org>
>>>>>>>> Data: 02/02/2016 13.15
>>>>>>>> A: "Discussion of precise time and frequency
>>>>>>>> measurement"<time-nuts at 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 <watsondaniel3 at 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.
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