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 <[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.
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