[time-nuts] Re: pulling some crystals

[Bob kb8tq]

Hi

Aging can easily be “direction changing” over time. What you do with early testing is try to bound the range of what will happen rather than come up with an exact number. 

Bob

> On Dec 7, 2023, at 4:44 PM, glen english LIST <glenlist at cortexrf.com.au> wrote:
> 
> Hi Bob
> 
> Your comments are appreciated
> 
> mmmm. I had some, back in 2000, some 6 MHz, 98 deg C turning point crystals used in a hot oven. after a few months, the aging went the other direction.  I never got to the bottom of it - IE was  it was oscillator components, or the crystal that was the instrumenbt in aging the other direction.
> 
> On 8/12/2023 8:38 am, Bob kb8tq wrote:
>> Hi
>> 
>> Their idea that 3 days at 105 is the same as 1 year is …. errrr …. ummm ….. questionable. Even more so in an oven application that will have the crystal running at something well above room temperature (our starting point for the thread was heating it to 60C ….).
>> 
>> Simple example:
>> 
>> A typical OCXO crystal can easily be 20C above the max temp spec on the device. If the OCXO is rated to go to 70C, that would be 90. In the case of 85C, you are up at 105C. If indeed 3 days is a year, those 85C OCXO’s would have an insane daily aging rate. In practice, that’s not what folks observe.
>>