[R-390] Some Crystal Info

[ANTHONY CASORSO]

It's funny how these things happen. I looked all over for info about these 
crystals several times. Now that I made that post yesterday, suddenly I can 
find it easily.

I'm not sure if links are OK in a post here. There is a good pdf with a 
table of all of the military CR types and their specs at

www dot euroquartz dot co dot uk slash pdf slash cr-crystals.pdf

Tony




>From: Bob Camp <ham at cq.nu>
>To: Tony Casorso <canthony15 at msn.com>
>CC: <R-390 at mailman.qth.net>
>Subject: Re: [R-390] Some Crystal Info
>Date: Tue, 23 Oct 2007 07:47:49 -0400
>
>Hi
>
>If you rummage around long enough, there is a military specification  on 
>all of the crystals in the R-390. It's pretty specific about the  load, 
>temperature, and tolerance of each crystal. They even go into  stuff like 
>spurs, resistance, aging, and  motional parameters. What  makes it *very* 
>confusing is that after the military standardized  everything we all 
>started using the mil designations to refer to the  crystal packages rather 
>than what's inside ....
>
>All of the military crystals were designed under contract out of Ft.  
>Monomoth. The agency involved changed names so often it's sometimes  tough 
>to figure out who is who. Some of what was done is reported in  the 
>Proceedings of the Frequency Control Symposium. A lot of what was  done was 
>published in separate reports. Most of those are *tough* to  find these 
>days. Occasionally you will find references to them in the  FCS papers.
>
>Bob
>KB8TQ
>
>
>On Oct 22, 2007, at 10:42 PM, Tony Casorso wrote:
>
>>Hi everybody. Sorry that my image thread got so long. I'm still  looking 
>>at the problem but I'll keep the details to myself and only  post here if 
>>I make some headway.
>>
>>For a while now I've been wondering what the difference between a  CR36/U 
>>and a CR27/U crystal was. I found a reference to them in an  old paper 
>>that is only available to paying members of IEEE. I  believe the paper is 
>>from the 1950s as it is full of tube  oscillator circuits. I started a new 
>>job in July and it turns out  that I have access to all of the IEEE 
>>papers. This one is called  "Design Data for Crystal Oscillators" By H.E. 
>>Gruen of the Armour  Research Foundation. It says that the CR18/U, CR27/U, 
>>and CR36/U  crystals are all designed for 32pf loads to be used in 
>>parallel  resonant mode (antiresonant mode in the paper). The difference  
>>between them is that the CR18/U is not for use in ovens while the  CR27/U 
>>is for oven applications at 75 degrees C and the CR36/U is  for oven 
>>applications at 85 degrees C.
>>
>>Hopefully someone will find this information useful.
>>
>>Cheers,
>>
>>Tony
>>
>>
>>
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>