[time-nuts] Re: pulling some crystals

[Richard (Rick) Karlquist]

On 12/7/2023 12:07 PM, glen english LIST wrote:
>
> All our crystals have undergo the process of preaging, also called 
> "accelerated aging" (i.e. 3 days storage at +105 deg.C). This aging is 
> equivalent to one year aging at normal temperature (according standard 
> IEC 60122-1). The crystals produced for you had frequency shift after 
> this preaging below 1.0 ppm, so it guaranties aging below 10 ppm after 
> 10 years. The aging curve shows deceleration (saturation) in time.
> Information to pulling parameter:

This kind of discussion about "guaranteed aging" is completely at odds
with everything I observed over many years working for HP.  The top
HP experts on crystals never talked about crystals being so predictable.
These experts were involved in inventing the SC cut, etc.
They taught the rest of the industry how to make crystals.
I personally observed many crystals aging vs time and vs temperature
trying to "sort" out the good ones.  Crystals would be good for while, 
then for no reason might drift in the opposite direction.  I am
especially skeptical of "3 days at 105 deg C is worth 10 years of
aging."  The E1938A oscillator had an oven set point of around
105 degrees C.  It did not accelerate the aging compared to an
80 degree set point and certainly didn't accelerate it following
a hockey stick curve.

Rick