[time-nuts] Aging rate of crystals

Mike Fahmie mpfahmie at lbl.gov
Wed Feb 20 00:09:27 UTC 2008


I'm not familiar with the E1938, but the 10811, I believe is one of the 
small "hi stab" units that HP put into their higher end counters. It uses a 
single oven where the 103 and 107 used double ovens. Incidentally, the 103 
uses a 1 MHz rock and the 107 uses a 5 MHz rock.
-Mike-

At 03:27 PM 2/19/2008, you wrote:
>Mike Fahmie wrote:
> > Somewhere, I have a NASA pub that describes a technique using Gamma Rays
> > to
> > accelerate aging so that later aging is much reduced, can't seem to find
> > it
> > now. I would guess that the radiation cause the stresses to relax. NASA
> > was
> > evidently interested because satellites experience a lot more radiation
> > than we receive here on the surface and it probably caused a rapid
> > frequency shift in otherwise unradiated crystals.
>
>I remember some of the crystal gurus talking about this.
>I suspect it didn't pan out or everyone would be doing it.
>I also remember them saying that radiation causes "color centers"
>to appear.
>
> > I have two HP quartz oscillators that I've been running and logging for
> > well over a decade. They run 24/7 and are on battery backup. The HP-103
> > shows about 6 parts in 10^-12/day and the HP-107 about 2 parts in
> > 10^-13/day. I attribute this to steady temperature and solid mounting in a
> > heavy rack.
> >
> > -Mike-
>
>That's incredible Mike.  I've never seen a 10811 or E1938 within a
>factor of 10 of the first number you gave, let alone the second.
>The second rate would be very respectible for a Rb standard.
>I believe those antique oscillators you have are using non-HP
>made xtals at 1 MHz (or 5 MHz at the most) in glass packages.
>While a steady temperature and solid mounting is great, it takes
>more than that to put up these kind of numbers.  Congratulations, keep
>taking good care of those old war horses.  I wish Len Cutler were
>still around to tell about it.  He proudly keep a 107 prototype
>in his office.  Len couldn't bring himself to design anything that wasn't
>a doomsday machine.
>
>Rick Karlquist, N6RK
>
>
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