Re: [time-nuts] What interrupts aging?

[William H. Fite]

No, it is not possible to grow absolutely perfect quartz crystals, nor do
they occur naturally. I had a connection with some Corning researchers
years ago who were trying to do exactly that. They found it impossible to
control the hundreds of variables necessary to accomplish that goal.
Happily, they also found it to be unnecessary, even for applications
considerably more demanding than the time-and-frequency issues that concern
this list.

On Monday, February 6, 2017, Richard (Rick) Karlquist 
wrote:

>
>
> On 2/5/2017 4:19 PM, Peter Reilley wrote:
>
>> I am curious: is the quartz in a high quality quartz crystal perfect?
>> That is; is the
>>
>> crystalline lattice perfect, without flaws or impurities?   I assume
>> that the quartz is
>>
>> grown in a furnace, can we grow perfect quartz crystals?
>>
>> Pete.
>>
>>
> Even a perfect crystal has thermal stress as the temperature changes.
>
> Rick
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-- 
If you gaze long into an abyss, your coffee will get cold.
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Re: [time-nuts] What interrupts aging?

[Richard (Rick) Karlquist]

On 2/5/2017 4:19 PM, Peter Reilley wrote:

I am curious: is the quartz in a high quality quartz crystal perfect?
That is; is the

crystalline lattice perfect, without flaws or impurities?   I assume
that the quartz is

grown in a furnace, can we grow perfect quartz crystals?

Pete.



Even a perfect crystal has thermal stress as the temperature changes.

Rick
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Re: [time-nuts] What interrupts aging?

[Bob Camp]

Hi

Nothing in life is perfect :)

Diffusion of ions in the lattice is one of the more obscure sources of aging. 
It is maybe 
number 10 or 15 on the list. The exception to that would be high radiation 
environments 
where you have energetic particles trying to knock things around. A similar 
(but different)
effect is the diffusion of the electrode material into the blank. For normal 
electrodes, that is 
well past number 20 or so….(and no I don’t have an exact list …)

Bob

> On Feb 5, 2017, at 7:19 PM, Peter Reilley  wrote:
> 
> I am curious: is the quartz in a high quality quartz crystal perfect?That 
> is; is the
> 
> crystalline lattice perfect, without flaws or impurities?   I assume that the 
> quartz is
> 
> grown in a furnace, can we grow perfect quartz crystals?
> 
> Pete.
> 
> 
> On 2/5/2017 6:31 PM, Bob Camp wrote:
>> Hi
>> 
>> Aging can be caused by many things. Stress on the blank (and can and leads 
>> and plating and …) is one
>> source. There are good reasons to believe that quartz vs metal stress can 
>> take > 1 month to settle out
>> to the 90% level. Particle (think borders down to atoms) equilibrium inside 
>> the can is another source.
>> Adsorption / desorption rates on many of the likely candidates also run out 
>> into the > 1 month range.
>> More or less — you can adsorb stuff in a few seconds that takes many weeks 
>> to desorb. Yes this is
>> only the start of a very long list ….
>> 
>> How long an interruption to stir things up? Does the oven go to full power 
>> after your interruption? If it
>> does, things are likely to get tossed around and aging (or retrace or warmup 
>> or whatever you want to
>> call it) is going to get going.
>> 
>> Pile on top of this the fact that crystals are not the only thing that does 
>> aging like things. Capacitors
>> have a fun characteristic known as dielectric absorption. Some (tantalums) 
>> have leakage that drops
>> a LOT with time spent at temperature and voltage. Either way,  bump the 
>> voltage and things move around
>> for a while. Use the wrong caps and it can be quite a while.
>> 
>> Next layer is keeping the OCXO at the same temperature. When a “normal” OCXO 
>> is sitting there on
>> the bench, it’s in it’s own very specific temperate zone. Convection (and 
>> maybe other things) have acted
>> over quite a while to set up that zone. Touch it / bump it / move it / blow 
>> on it …. you will change the
>> temperature. Most likely you will change the gradient across the package. 
>> Rick wrote some papers
>> back in the 90’s about why this really messes things up…. ( Again this is 
>> the start of a very long list …).
>> It’s even longer if you have DAC’s and voltage references external to the 
>> OCXO.
>> 
>> So yes, you can get aging a lot of ways. Knowing what is and what is not 
>> aging can get a bit complicated.
>> 
>> Bob
>> 
>> 
>>> On Feb 5, 2017, at 3:11 PM, John Ackermann N8UR  wrote:
>>> 
>>> We know of OCXO that have been continuously running for years and have 
>>> exceptional aging, supposedly as a result.
>>> 
>>> What does it take to interrupt that? A momentary loss of power?  The oven 
>>> cooling down?  Some long period of off-time?  Or, once the oscillator has 
>>> baked in will it return to that low aging once it has been powered up and 
>>> thermally stabilized?
>>> 
>>> John
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>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
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>> and follow the instructions there.
>> 
> 
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Re: [time-nuts] What interrupts aging?

[Peter Reilley]

I am curious: is the quartz in a high quality quartz crystal perfect?
That is; is the


crystalline lattice perfect, without flaws or impurities?   I assume 
that the quartz is


grown in a furnace, can we grow perfect quartz crystals?

Pete.


On 2/5/2017 6:31 PM, Bob Camp wrote:

Hi

Aging can be caused by many things. Stress on the blank (and can and leads and 
plating and …) is one
source. There are good reasons to believe that quartz vs metal stress can take 
> 1 month to settle out
to the 90% level. Particle (think borders down to atoms) equilibrium inside the 
can is another source.
Adsorption / desorption rates on many of the likely candidates also run out into 
the > 1 month range.
More or less — you can adsorb stuff in a few seconds that takes many weeks to 
desorb. Yes this is
only the start of a very long list ….

How long an interruption to stir things up? Does the oven go to full power 
after your interruption? If it
does, things are likely to get tossed around and aging (or retrace or warmup or 
whatever you want to
call it) is going to get going.

Pile on top of this the fact that crystals are not the only thing that does 
aging like things. Capacitors
have a fun characteristic known as dielectric absorption. Some (tantalums) have 
leakage that drops
a LOT with time spent at temperature and voltage. Either way,  bump the voltage 
and things move around
for a while. Use the wrong caps and it can be quite a while.

Next layer is keeping the OCXO at the same temperature. When a “normal” OCXO is 
sitting there on
the bench, it’s in it’s own very specific temperate zone. Convection (and maybe 
other things) have acted
over quite a while to set up that zone. Touch it / bump it / move it / blow on 
it …. you will change the
temperature. Most likely you will change the gradient across the package. Rick 
wrote some papers
back in the 90’s about why this really messes things up…. ( Again this is the 
start of a very long list …).
It’s even longer if you have DAC’s and voltage references external to the OCXO.

So yes, you can get aging a lot of ways. Knowing what is and what is not aging 
can get a bit complicated.

Bob



On Feb 5, 2017, at 3:11 PM, John Ackermann N8UR  wrote:

We know of OCXO that have been continuously running for years and have 
exceptional aging, supposedly as a result.

What does it take to interrupt that? A momentary loss of power?  The oven 
cooling down?  Some long period of off-time?  Or, once the oscillator has baked 
in will it return to that low aging once it has been powered up and thermally 
stabilized?

John
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Re: [time-nuts] What interrupts aging?

[Charles Steinmetz]

John wrote:


We know of OCXO that have been continuously running for years and have
exceptional aging, supposedly as a result.

What does it take to interrupt that? A momentary loss of power?  The
oven cooling down?  Some long period of off-time?  Or, once the
oscillator has baked in will it return to that low aging once it has
been powered up and thermally stabilized?


Short answer -- it all depends.  But it usually takes much less than 
you'd expect.


In my experience, supported by experimentation and by research into 
published and credible anecdotal sources, the aging of quartz 
oscillators often changes with little provocation (and in some cases, 
none at all that one can tell from external observations).  Sufficient 
provocaton can include the oven cooling down, trimming the frequency, 
physical shock (not necessarily very much -- sometimes just moving the 
OCXO from one place to another and setting it down pretty gently), or 
even a short loss of power.  In short, *any* electrical or physical 
disturbance.


The effects can range from a short period of settling with an asymptotic 
slope back to the neighborhood of the previously-established aging rate, 
all the way to beginning a completely new aging regime.  Not 
infrequently, even the sign of the aging rate changes.  Further, any 
given oscillator can react differently each time it is disturbed -- an 
oscillator that previously settled quickly back to the neighborhood of 
the previously-established aging may start a whole new aging regime the 
next time it is disturbed.


That said, OCXOs may exhibit trends, behaving at least somewhat 
consistently from one electrical disturbance to another (their reactions 
to physical disturbances are always less consistent, IME).


Best regards,

Charles


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Re: [time-nuts] What interrupts aging?

[Bob Camp]

Hi

Aging can be caused by many things. Stress on the blank (and can and leads and 
plating and …) is one
source. There are good reasons to believe that quartz vs metal stress can take 
> 1 month to settle out 
to the 90% level. Particle (think borders down to atoms) equilibrium inside the 
can is another source. 
Adsorption / desorption rates on many of the likely candidates also run out 
into the > 1 month range. 
More or less — you can adsorb stuff in a few seconds that takes many weeks to 
desorb. Yes this is 
only the start of a very long list ….

How long an interruption to stir things up? Does the oven go to full power 
after your interruption? If it
does, things are likely to get tossed around and aging (or retrace or warmup or 
whatever you want to 
call it) is going to get going. 

Pile on top of this the fact that crystals are not the only thing that does 
aging like things. Capacitors 
have a fun characteristic known as dielectric absorption. Some (tantalums) have 
leakage that drops
a LOT with time spent at temperature and voltage. Either way,  bump the voltage 
and things move around
for a while. Use the wrong caps and it can be quite a while. 

Next layer is keeping the OCXO at the same temperature. When a “normal” OCXO is 
sitting there on 
the bench, it’s in it’s own very specific temperate zone. Convection (and maybe 
other things) have acted 
over quite a while to set up that zone. Touch it / bump it / move it / blow on 
it …. you will change the 
temperature. Most likely you will change the gradient across the package. Rick 
wrote some papers 
back in the 90’s about why this really messes things up…. ( Again this is the 
start of a very long list …). 
It’s even longer if you have DAC’s and voltage references external to the OCXO. 

So yes, you can get aging a lot of ways. Knowing what is and what is not aging 
can get a bit complicated. 

Bob


> On Feb 5, 2017, at 3:11 PM, John Ackermann N8UR  wrote:
> 
> We know of OCXO that have been continuously running for years and have 
> exceptional aging, supposedly as a result.
> 
> What does it take to interrupt that? A momentary loss of power?  The oven 
> cooling down?  Some long period of off-time?  Or, once the oscillator has 
> baked in will it return to that low aging once it has been powered up and 
> thermally stabilized?
> 
> John
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Re: [time-nuts] What interrupts aging?

[Bob Stewart]

Hi John,
My experience, which is far from scientific, is that any disturbance to the 
Trimbles I use is like a slap in the face.  It can be just a momentary power 
loss or a large change in the EFC.  After either of these events, it goes into 
some period of retrace before it settles back down.  The longer the time or the 
bigger the EFC excursion, the longer it takes to settle back down.  But, as 
mentioned, I haven't done any real tests to measure the impacts.

Bob -
AE6RV.com

GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info

  From: John Ackermann N8UR <j...@febo.com>
 To: Discussion of precise time and frequency measurement <time-nuts@febo.com> 
 Sent: Sunday, February 5, 2017 2:11 PM
 Subject: [time-nuts] What interrupts aging?
   
We know of OCXO that have been continuously running for years and have 
exceptional aging, supposedly as a result.

What does it take to interrupt that? A momentary loss of power?  The 
oven cooling down?  Some long period of off-time?  Or, once the 
oscillator has baked in will it return to that low aging once it has 
been powered up and thermally stabilized?

John
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[time-nuts] What interrupts aging?

[John Ackermann N8UR]

We know of OCXO that have been continuously running for years and have 
exceptional aging, supposedly as a result.


What does it take to interrupt that? A momentary loss of power?  The 
oven cooling down?  Some long period of off-time?  Or, once the 
oscillator has baked in will it return to that low aging once it has 
been powered up and thermally stabilized?


John
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