[time-nuts] Glass Envelope Quartz Crystals

Bob Camp kb8tq at n1k.org
Sat Mar 26 21:22:01 EDT 2016


Hi


> On Mar 26, 2016, at 2:49 PM, Alex Pummer <alex at pcscons.com> wrote:
> 
> I am perhaps to late now,I found the e-mail recently:
> "
>> 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
> 
> 
> "
> 
> 
> the glass packed ones will have much better vacuum, therefore higher Q
> I still have some KVG glass envelope crystals [116MHz overtone] from the 60 -ties

That may have been true in the 1950’s but once modern cold weld packages came along it quickly
became a non-issue.  The Q dependance of crystals to atmosphere is a function of frequency. A
118 MHz crystal shows much less impact from a given level of “air” than something like a 2.5 MHz
5th overtone.

Bob


> 73
> KJ6UHN
> Alex
> 
> On 2/2/2016 2:37 PM, Bob Camp wrote:
>> Hi
>> 
>> I think you will find that the Russian versions were used without ovens for a long time. In the US, the only
>> use for the glass packages past the mid 1960’s was in ovens.
>> 
>> Bob
>> 
>> 
>>> On Feb 2, 2016, at 1:43 PM, iovane--- via time-nuts <time-nuts at febo.com> wrote:
>>> 
>>> 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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