[time-nuts] Glass Envelope Quartz Crystals

Philip Gladstone pjsg-timenuts at nospam.gladstonefamily.net
Wed Feb 3 08:21:17 EST 2016

I dug around in my junk box, and found this:


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....


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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