Re: [time-nuts] What interrupts aging?
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 > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/m > ailman/listinfo/time-nuts > and follow the instructions there. > -- If you gaze long into an abyss, your coffee will get cold. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] What interrupts aging?
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 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] What interrupts aging?
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 >>> ___ >>> time-nuts mailing list -- time-nuts@febo.com >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >> ___ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] What interrupts aging?
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 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] What interrupts aging?
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 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] What interrupts aging?
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 > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] What interrupts aging?
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 To: Discussion of precise time and frequency measurement 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 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[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 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
