[time-nuts] Aging rate of crystals

Tom Van Baak tvb at LeapSecond.com
Wed Feb 20 02:13:02 UTC 2008


> 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

Rick,

I have an old HP 106 with similar amazingly low drift performance
and was able to talk to Len about it a few years ago. He was very
pleased to hear it was still working, and so well. It drifted a just few
parts in 10^11th over a 40 day run, which puts the daily drift rate
in the mid to low -13's. At this point the system tempco (106 or Rb)
is clearly a greater factor than the resonator drift rate (and my lab
was in the garage ten years ago). Some old plots are here:

http://www.leapsecond.com/museum/hp106b/

The 106 used a monster-sized 2.5 Mc AT-cut xtal, similar to the
original Sulzer's of that era.

/tvb





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