[time-nuts] OCXO with ADEV of 1E-13 on Pluto Mission

[KA2WEU at aol.com]

What you describe correctly is an art and some luck , there are some  
special things that can be done and some trade off's. Low aging vs noise  ...
 
Ulrich N1UL
 
 
In a message dated 7/17/2015 5:56:49 P.M. Eastern Daylight Time,  
attila at kinali.ch writes:

On Thu,  16 Jul 2015 15:24:08 -0400
"Brian, WA1ZMS" <wa1zms at att.net>  wrote:

> The crystal in the ref osv. came from Bliley. The part  number is BG-61.  
I 
> have no idea what the current cost is, but  like most very good 
oscillators 
> the crystals were hand sorted and  graded.

I had a short chat with Gregory Weaver (the guy behind the USO)  two years 
ago.
Basically, they start with a lot of crystal slabs, select  the best ones
after each processing step. In the end, they have maybe a  dozen (or less)
crystals that are then fit into oscillators, which again  are tuned by hand
and selected. The best oscillators are then send onto the  mission.

A fun fact here is, that the oscillators are not tuned for  maximum
Q of the resonator. Instead they are slightly damped and some Q  is
traded for lower noise of the sustaining amplifier.

Another fun  fact is, that the glass housing acts like a getter
when put in vacuum. Thus  the stability increases increases over
time, when the whole system is in  space.


Attila  Kinali

-- 
It is upon moral qualities that a society is ultimately  founded. All 
the prosperity and technological sophistication in the world  is of no 
use without that foundation.
-- Miss Matheson, The Diamond Age, Neil  Stephenson
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