[time-nuts] Re: Do crystals still jump?

[Bob kb8tq]

Hi

All frequency sources move around. ADEV is one way to 
demonstrate this. ADEV is normally driven by continuous 
processes in the device. Jumps are something that happens
very rarely. 

The term jumps is normally used to describe a change in frequency
that is not driven by the external environment. It might be used
to describe a frequency perturbation that occurs over temperature.
It would be more common to see the issue described as a 
perturbation. 

Once you get past those two areas, it is uncommon to see the term 
used that way. Thus a bit of confusion when it simply gets tossed
up with no context. 

Bob

> On Sep 4, 2022, at 12:20 PM, Bill Beam <wbeam at gci.net> wrote:
> 
> I would be surprised to find a crystal that did not jump at some level.
> Remember that a crystal in use is undergoing continuous stress and strain.
> Any small defect in the crystal structure could be changed resulting in a
> small change in physical dimension thus changing its resonant frequency.
> Thump on any rock hard enough and it will change shape.
> 
> Bill, NL7F
> 
> On Sun, 4 Sep 2022 08:17:55 -0800, Bob kb8tq via time-nuts wrote:
> 
>> Hi
> 
>> There are a number of very different types of jumps. It depends
>> a lot on just which sort you are worried about. Hysteresis typically
>> comes in looking very different than a jump. Temperature driven
>> jumps can occur for a number of reasons G€¦.
> 
>> Bob
> 
>>> On Sep 3, 2022, at 5:11 PM, glenlist via time-nuts <time-nuts at lists.febo.com> wrote:
>>> 
>>> wow. Great story Detlef.
>>> 
>>> I have had crystals 'jump' but this was at the part per billion level... mainly hysteresis effects. It causes my pulling loop to go mad. There 
> might have also been some non monotonic behaviour also.
>>> 
>>> I was told by the crystal mfr (this about about 30 yrs ago) the better crystals exhibited lower hysteresis, but it was present in all crystals 
> to some degree. .
>>> 
>>> 
>>> On 4/09/2022 6:26 am, dschuecker via time-nuts wrote:
>>>> Hi,
>>>> 
>>>> yes, they do jump.
>>>> 
>>>> Some years ago our DSL-modems fell out of sync when they were exposed to a temperature jump., ie. in the warm exhaust of a vac 
> cleaner. Sure, all xtals have a temperature dependency, but with this batch of crystals there was a frequency change of 50ppm or so for a 
> temp change of 2Kelvin. These are perceived numbers, I do not have exact data. The modems' PLL could not track the frequency change 
> fast enough and the modem fell outta sync. . We had a lot of these crystals in the field and that was a pretty severe problem.
>>>> 
>>>> Cheers
>>>> 
>>>> Detlef
>>>> 
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts at lists.febo.com
>>> To unsubscribe send an email to time-nuts-leave at lists.febo.com
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at lists.febo.com
>> To unsubscribe send an email to time-nuts-leave at lists.febo.com
> 
> 
> Bill Beam
> NL7F
> 
> 
>