Re: [time-nuts] The 5MHz Sweet Spot
Hi One of the often seen statements about jumps is that the time between them increases as the oscillator ages. Obviously that’s only going to apply to certain mechanisms. If you OCXO jumps because there is no solder on the varicap, it may not apply. To the extent it’s true, it’s a much bigger issue for those who buy their OCXO’s straight from the factory than for those who buy them surplus. Bob On Nov 9, 2013, at 7:11 PM, Angus wrote: > Yes, but as with quartz it varies a lot. > > I have tested a few LPROs, but have never seen a frequency jump in them. > Those with more to test might have seen some jumps, but mine have been well > behaved whenever they were being logged anyway. > > I don't remember seeing actual jumps in the FE5680A's either, although the 2 > older style 1pps-only ones did often have retrace jumps (like 5-10ppt) even > after a short power down. > > The most obvious jumps I have seem were on a Temex LPRO/LPFRS which also had > a borderline low peak Rb voltage, whether that had anything to do with it or > not. At first it sometimes jumped in steps of 5-20ppt, and tapping it or even > touching the connector on the RF cable from it would also often cause a jump. > It was at its worst when I first powered it up, but even after many weeks on, > they were still there occasionally. > > I've also tried a couple of the 9.8304MHz Sa.22c things recently, and other > than being very basic spec, one had some fast frequency jumps and the other > none that I saw - although near the middle of a 7 week test run it decided to > change by 3E-11 over 15 hours or so. That is actually very like what I've > seen sometimes in quartz where many days of aging happen in a few hours - I > have MTI260's particularly keen on this trick. > > I had originally been interested in investigating jumps, but since they were > most obvious in the poorer oscillators my interest waned a bit. > > Doing a search on rubidium frequency jumps turns up a fair bit, although much > is on the GPS Rb's which unfortunately will not be cheap surplus any time > soon - unless someone really messes up! > > Angus. > > > > From: "Hal Murray" > To: "Discussion of precise time and frequency measurement" > Sent: November 3, 2013 9:28 PM > Subject: Re: [time-nuts] The 5MHz Sweet Spot > > Do low cost recycled Rubidiums have any quirks equivalent to frequency jumps > in crystals? > > > > -- > These are my opinions. I hate spam. > > > > ___ > 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] The 5MHz Sweet Spot
Yes, but as with quartz it varies a lot. I have tested a few LPROs, but have never seen a frequency jump in them. Those with more to test might have seen some jumps, but mine have been well behaved whenever they were being logged anyway. I don't remember seeing actual jumps in the FE5680A's either, although the 2 older style 1pps-only ones did often have retrace jumps (like 5-10ppt) even after a short power down. The most obvious jumps I have seem were on a Temex LPRO/LPFRS which also had a borderline low peak Rb voltage, whether that had anything to do with it or not. At first it sometimes jumped in steps of 5-20ppt, and tapping it or even touching the connector on the RF cable from it would also often cause a jump. It was at its worst when I first powered it up, but even after many weeks on, they were still there occasionally. I've also tried a couple of the 9.8304MHz Sa.22c things recently, and other than being very basic spec, one had some fast frequency jumps and the other none that I saw - although near the middle of a 7 week test run it decided to change by 3E-11 over 15 hours or so. That is actually very like what I've seen sometimes in quartz where many days of aging happen in a few hours - I have MTI260's particularly keen on this trick. I had originally been interested in investigating jumps, but since they were most obvious in the poorer oscillators my interest waned a bit. Doing a search on rubidium frequency jumps turns up a fair bit, although much is on the GPS Rb's which unfortunately will not be cheap surplus any time soon - unless someone really messes up! Angus. From: "Hal Murray" To: "Discussion of precise time and frequency measurement" Sent: November 3, 2013 9:28 PM Subject: Re: [time-nuts] The 5MHz Sweet Spot Do low cost recycled Rubidiums have any quirks equivalent to frequency jumps in crystals? -- These are my opinions. I hate spam. ___ 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] The 5MHz Sweet Spot
Re: crystal "jumps": I'm wondering if there is any correlation between the probability and/or severity of jumps and crystal drive level (recognizing that different cuts, blank sizes, etc., etc. all interact with drive level, so any correlation would likely not be to absolute drive level but rather to relative drive level for each particular physical realization). Is anyone aware of published research on this? 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] The 5MHz Sweet Spot
Bert, Let me know if you can do stable >1s loops in the analog domain with reasonable cap sizes say <220uF. I would be impressed. I tried. Bye, Said Sent From iPhone On Nov 3, 2013, at 14:51, ewkeh...@aol.com wrote: > We are looking at room temperature 5 and 10 MHz XO's for cleaning up Rb and > DDS. Filter time 1 to 20 seconds and thermal mass to keep temperature > influence low. Hard to find XO's, so what we are testing is older TCXO's > where > we remove the TC and use the tuning circuit for loop control. Any > suggestions? Maybe slightly off subject but the experts are here. > Thanks Bert Kehren > > > In a message dated 11/3/2013 4:41:43 P.M. Eastern Standard Time, > saidj...@aol.com writes: > > The partial answer is: yes as they typically use 10MHz crystals too. But > the loop BW is so wide (10Hz or more) that the crystal jumps get compensated > very quickly. > > We have not seen any real frequency jumps in 100's of CSACs we tested that > use vapor cells just like RB's do, so from my experience I have never seen > a discrete frequency jump in an Atomic oscillator.. > > Notice that CSACs do jump significantly in frequency right after power on > when they achieve atomic lock, typically about 60s after power on. > > Vapor cell atomic clocks typically have other issues such as excessive > retrace, loss of vacuum and a subsequent slow drift in frequency, and almost > instantaneous loss of atomic lock causing frequency jumps when operated > above max temperature.. > > Sent From iPhone > > On Nov 3, 2013, at 13:28, Hal Murray wrote: > >> >> Do low cost recycled Rubidiums have any quirks equivalent to frequency > jumps >> in crystals? >> >> >> >> -- >> These are my opinions. I hate spam. >> >> >> >> ___ >> 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] The 5MHz Sweet Spot
Magnus you are spot on, Quartz is one of those areas that is still as much art as science. Thomas Knox > Date: Sun, 3 Nov 2013 23:13:20 +0100 > From: mag...@rubidium.dyndns.org > To: time-nuts@febo.com > Subject: Re: [time-nuts] The 5MHz Sweet Spot > > Hi, > > Let me point out one little thing. While you can pick up stuff from the > many comments here, remember that this is a field of a whole myriad of > effects and challenges. Different insight at different periods have > provided for different "truths" and design approaches. Some of the > issues can be handled at manufacturing, some in the design etc. Just > don't expect it to be a few simple rules. > > Cheers, > Magnus > > On 11/03/2013 10:52 PM, Tom Knox wrote: > > They have crystals so it would seem so. I wonder are the jumps are model, > > brand, or design dependent and to what degree? Also thanks to everyone > > contributing their knowledge and experience to the thread. I for one am > > learning a great deal. I am still interested if anyone has insights to > > Magnus's questions on what is the current state of the art, if anyone has > > attempted these overkill design ideas, and best performance achieved to > > date. > > > > Thomas Knox > > > > > > > >> To: time-nuts@febo.com > >> From: hmur...@megapathdsl.net > >> Date: Sun, 3 Nov 2013 13:28:16 -0800 > >> Subject: Re: [time-nuts] The 5MHz Sweet Spot > >> > >> > >> Do low cost recycled Rubidiums have any quirks equivalent to frequency > >> jumps > >> in crystals? > >> > >> > >> > >> -- > >> These are my opinions. I hate spam. > >> > >> > >> > >> ___ > >> 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] The 5MHz Sweet Spot
Bert, On 11/03/2013 11:51 PM, ewkeh...@aol.com wrote: > We are looking at room temperature 5 and 10 MHz XO's for cleaning up Rb and > DDS. Filter time 1 to 20 seconds and thermal mass to keep temperature > influence low. Hard to find XO's, so what we are testing is older TCXO's > where > we remove the TC and use the tuning circuit for loop control. Any > suggestions? Maybe slightly off subject but the experts are here. > Thanks Bert Kehren Assuming we don't go very upscale in OCXO/DOCXO land in size, power and cost, the oscillators that best handles thermal stress in room temperature is either those with thermal mass surrounding the crystal (MicroCrystal and Oscilloquartz) or those where an additional shielding (Vectron has a bunch of them now). Although AT-cut, they cut the throat with competing SC-cut as far as I have seen in that package and cost. I picked up a few of the MicroCrystal ones from ebay. They have that extra weight (from the FR4 case surrounding the crystal) that none of the other DIL14 I've seen has. You can feel the difference as you hold it in your hand. It also consume less power than any of the competition OCXOs. I'm sure there might be others in the same range. You can always put a simple plastic cover over the oscillator if you need to. Careful about adding thermal mass to OCXOs thought, it may not always be beneficial to the loop. Measure and verify! Cheers, Magnus ___ 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] The 5MHz Sweet Spot
We are looking at room temperature 5 and 10 MHz XO's for cleaning up Rb and DDS. Filter time 1 to 20 seconds and thermal mass to keep temperature influence low. Hard to find XO's, so what we are testing is older TCXO's where we remove the TC and use the tuning circuit for loop control. Any suggestions? Maybe slightly off subject but the experts are here. Thanks Bert Kehren In a message dated 11/3/2013 4:41:43 P.M. Eastern Standard Time, saidj...@aol.com writes: The partial answer is: yes as they typically use 10MHz crystals too. But the loop BW is so wide (10Hz or more) that the crystal jumps get compensated very quickly. We have not seen any real frequency jumps in 100's of CSACs we tested that use vapor cells just like RB's do, so from my experience I have never seen a discrete frequency jump in an Atomic oscillator.. Notice that CSACs do jump significantly in frequency right after power on when they achieve atomic lock, typically about 60s after power on. Vapor cell atomic clocks typically have other issues such as excessive retrace, loss of vacuum and a subsequent slow drift in frequency, and almost instantaneous loss of atomic lock causing frequency jumps when operated above max temperature.. Sent From iPhone On Nov 3, 2013, at 13:28, Hal Murray wrote: > > Do low cost recycled Rubidiums have any quirks equivalent to frequency jumps > in crystals? > > > > -- > These are my opinions. I hate spam. > > > > ___ > 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] The 5MHz Sweet Spot
Hi, Let me point out one little thing. While you can pick up stuff from the many comments here, remember that this is a field of a whole myriad of effects and challenges. Different insight at different periods have provided for different "truths" and design approaches. Some of the issues can be handled at manufacturing, some in the design etc. Just don't expect it to be a few simple rules. Cheers, Magnus On 11/03/2013 10:52 PM, Tom Knox wrote: > They have crystals so it would seem so. I wonder are the jumps are model, > brand, or design dependent and to what degree? Also thanks to everyone > contributing their knowledge and experience to the thread. I for one am > learning a great deal. I am still interested if anyone has insights to > Magnus's questions on what is the current state of the art, if anyone has > attempted these overkill design ideas, and best performance achieved to date. > > Thomas Knox > > > >> To: time-nuts@febo.com >> From: hmur...@megapathdsl.net >> Date: Sun, 3 Nov 2013 13:28:16 -0800 >> Subject: Re: [time-nuts] The 5MHz Sweet Spot >> >> >> Do low cost recycled Rubidiums have any quirks equivalent to frequency jumps >> in crystals? >> >> >> >> -- >> These are my opinions. I hate spam. >> >> >> >> ___ >> 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] The 5MHz Sweet Spot
They have crystals so it would seem so. I wonder are the jumps are model, brand, or design dependent and to what degree? Also thanks to everyone contributing their knowledge and experience to the thread. I for one am learning a great deal. I am still interested if anyone has insights to Magnus's questions on what is the current state of the art, if anyone has attempted these overkill design ideas, and best performance achieved to date. Thomas Knox > To: time-nuts@febo.com > From: hmur...@megapathdsl.net > Date: Sun, 3 Nov 2013 13:28:16 -0800 > Subject: Re: [time-nuts] The 5MHz Sweet Spot > > > Do low cost recycled Rubidiums have any quirks equivalent to frequency jumps > in crystals? > > > > -- > These are my opinions. I hate spam. > > > > ___ > 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] The 5MHz Sweet Spot
On 11/03/2013 10:28 PM, Hal Murray wrote: > Do low cost recycled Rubidiums have any quirks equivalent to frequency jumps > in crystals? Consider that they have a crystal as a fly-wheel oscillator, so if that does a frequency jump, it will show, but be tracked in. If the oscillator does a phase-jump, it will show too. If there is other issues in the tracking-loop, it will show. So, yes. This is true for any passive atomic clock. I'm sure active hydrogen masers can have similar effects. Cheers, Magnus ___ 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] The 5MHz Sweet Spot
The partial answer is: yes as they typically use 10MHz crystals too. But the loop BW is so wide (10Hz or more) that the crystal jumps get compensated very quickly. We have not seen any real frequency jumps in 100's of CSACs we tested that use vapor cells just like RB's do, so from my experience I have never seen a discrete frequency jump in an Atomic oscillator.. Notice that CSACs do jump significantly in frequency right after power on when they achieve atomic lock, typically about 60s after power on. Vapor cell atomic clocks typically have other issues such as excessive retrace, loss of vacuum and a subsequent slow drift in frequency, and almost instantaneous loss of atomic lock causing frequency jumps when operated above max temperature.. Sent From iPhone On Nov 3, 2013, at 13:28, Hal Murray wrote: > > Do low cost recycled Rubidiums have any quirks equivalent to frequency jumps > in crystals? > > > > -- > These are my opinions. I hate spam. > > > > ___ > 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] The 5MHz Sweet Spot
Do low cost recycled Rubidiums have any quirks equivalent to frequency jumps in crystals? -- These are my opinions. I hate spam. ___ 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] The 5MHz Sweet Spot
Hi Warren, On 11/03/2013 08:55 PM, WarrenS wrote: > > Said Jackson posted: >> Crystal jumps are the biggest menace facing users of >> crystals/oscillators today. > > Are you including both phase jumps and frequency jumps together? > Is one more or likely to happen than the other? > Is it mostly a jump that effects just the phase or freq, or is there > everything in-between, jumps that effects both phase and freq at the > same instant in time also just as likely? A jump in frequency will cause the phase to go parabolic as it integrates the frequency difference from the previous rate. Eventually the PLL will react and hunt it it. Sluggish PLL will let the jump cause a larger phase deviation than a quick PLL, but that is expected. > We all know each effects the other, but that is only over time, > instantaneously and over short time spans phase and freq jumps are > separate things and maybe from different causes. > A true phase jump causes only a one cycle freq error and a true freq > offset jump does not cause an instantaneous phase jump. That type of phase-jump sounds like a support-oscillator having issues, possibly with not sufficient suppression of other oscillating modes of the crystal. With oven crystals, there is the effect of the oven as it gets a heat-bump och chill-bump that it takes time for the oven control to react to it. During that time, the thermal sensitivity of the crystal (complex issue as it is) will cause the crystal to run higher or lower than intended, and when the oven balance up again the frequency will be about where it was before, but as you integrate the frequency deviation, you have a phase-step in either direction. This phase-step is then being tracked in by the PLL if you have one. I know of only two oscillator products (from the same vendor) that have been trying to address this issue. It's an important aspect, as today we work with stable phase rather than stable frequency, yet many of our stabilization techniques is aimed at stable frequency, which is a step in the right direction. To make things worse, we want stable phase in challenging environments where particularly size is an issue. > > If the main causes of random freq jumps and random phase jumps are > from different things, then with a high speed, high resolution detector, > I wonder if knowing which event has really occurred, that then some > correction compensation could be applied that does not effect the other. Good idea. Keep monitoring the events and their characteristics and you might find out. I would say they have different origin. Also notice how a PLL or other control-loop can change the characteristic of a behavior, so you need to understand what processes does to the shape in order to draw conclusion of phase, frequency, drift step, ramp or whatever. > An Oversimplified example; > A Phase lock loop does not care what the instantaneous freq is, and a > true Freq Lock loop does not care what the phase difference is. > With a DDS, one can change the freq without causing a phase step or it > can cause a phase step, without causing a freq offset. > With two variables (instantaneous phase and freq offset control) and > two unknowns (instantaneous jumps in either), couldn't one apply a > correction to the right place for any random step error that occurred? > It would depend if the errors are caused by true independent random > fast jumps or just slowly drifting interacting changes. For a control-loop, you could naturally monitor the shape of the phase detector deviation and draw conclusion about what just happen to your oscillator (or input). You need to compensate or consider what the loop does to the shape. Recording of both phase and frequency to record the state of the loop will aid significantly. Cheers, Magnus ___ 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] The 5MHz Sweet Spot
Forgot one comment: the good parts' plot also shows a very nice crystal retrace stabilization in the red EFC trace over about the first 6 days or so. After that the crystal goes into it's long term crystal aging mode. Retrace is one big reason why its best to let crystals run continuously.. In a message dated 11/3/2013 12:27:18 Pacific Standard Time, saidj...@aol.com writes: Hi guys, here are two plots of the same DOCXO product, one being jump-free over the 31 days test interval, another that had about 20 jumps in just ~4 days. Needless to say the later OCXO went back to the vendor to be opened up, and the crystal replaced. I have plots of units that were perfect for two+ days, then jumped like crazy, and units that jumped for days, then stabilized and worked perfectly. It's all random when failures do happen. Warren, frequency jumps are indicated by constant changes in EFC voltage (red trace) after the jump happened. Most of these in the attached plot are frequency jumps, that cause an offset in phase (sometimes just some 10's of nanoseconds over minutes). Sometimes the frequency will "recover" and that can be seen by the EFC voltage going back to the initial voltage before the jump happened. Phase jumps would just cause a small hop in EFC voltage, sometimes so small that it cannot be perceived. Also, note that most of these jumps have 1mV to 2mV changes in EFC, which for these oscillators would equal a frequency change of about 0.1 to 0.2 parts per billion frequency change. Very small, but on a GPSDO it leaves a huge footprint in the EFC voltage plot and the phase plot. I wish every crystal we get would work as well as the one in this 31 day test plot.. Bye, Said In a message dated 11/3/2013 11:57:50 Pacific Standard Time, warrensjmail-...@yahoo.com writes: Said Jackson posted: >Crystal jumps are the biggest menace facing users of crystals/oscillators >today. Are you including both phase jumps and frequency jumps together? Is one more or likely to happen than the other? Is it mostly a jump that effects just the phase or freq, or is there everything in-between, jumps that effects both phase and freq at the same instant in time also just as likely? We all know each effects the other, but that is only over time, instantaneously and over short time spans phase and freq jumps are separate things and maybe from different causes. A true phase jump causes only a one cycle freq error and a true freq offset jump does not cause an instantaneous phase jump. If the main causes of random freq jumps and random phase jumps are from different things, then with a high speed, high resolution detector, I wonder if knowing which event has really occurred, that then some correction compensation could be applied that does not effect the other. An Oversimplified example; A Phase lock loop does not care what the instantaneous freq is, and a true Freq Lock loop does not care what the phase difference is. With a DDS, one can change the freq without causing a phase step or it can cause a phase step, without causing a freq offset. With two variables (instantaneous phase and freq offset control) and two unknowns (instantaneous jumps in either), couldn't one apply a correction to the right place for any random step error that occurred? It would depend if the errors are caused by true independent random fast jumps or just slowly drifting interacting changes. ws *** Bob, et. al., Lots of opinions in this discussion, but none of it discusses the elephant in the room affecting todays' vendors: Random crystal instability versus manufacturing techniques. I can buy oscillators from multiple vendors that have -115dBc at 1Hz or better and noise floors of -182dBc. That technology is well understood and has been mature for a very long time and to me its boring. Recently Ulrich Rhode even had a great article in the Microwave Journal detailing how exactly to build one of those units. But what does it help me to have -115dBc if the darn thing jumps 50ppt every two to three days?? Crystal jumps are the biggest menace facing users of crystals/oscillators today and so far I have never been given a reasonable explanation from any of the vendors out there what causes it and how to avoid it or how they plan to address it. In fact no vendor we know tests for it to levels of sub-ppt over days which is what is necessary for any disciplined application as disciplining will clearly show even the smallest crystal jumps. Almost every vendor will do a frequency test only, where a phase test would be needed. Users of crystals/oscillators are left with doing an exhaustive yield test during burn-in to find bad crystals. We test our boards for 3 days and more to weed out jumpy crystals, and its a pain and very expensi
Re: [time-nuts] The 5MHz Sweet Spot
Said Jackson posted: Crystal jumps are the biggest menace facing users of crystals/oscillators today. Are you including both phase jumps and frequency jumps together? Is one more or likely to happen than the other? Is it mostly a jump that effects just the phase or freq, or is there everything in-between, jumps that effects both phase and freq at the same instant in time also just as likely? We all know each effects the other, but that is only over time, instantaneously and over short time spans phase and freq jumps are separate things and maybe from different causes. A true phase jump causes only a one cycle freq error and a true freq offset jump does not cause an instantaneous phase jump. If the main causes of random freq jumps and random phase jumps are from different things, then with a high speed, high resolution detector, I wonder if knowing which event has really occurred, that then some correction compensation could be applied that does not effect the other. An Oversimplified example; A Phase lock loop does not care what the instantaneous freq is, and a true Freq Lock loop does not care what the phase difference is. With a DDS, one can change the freq without causing a phase step or it can cause a phase step, without causing a freq offset. With two variables (instantaneous phase and freq offset control) and two unknowns (instantaneous jumps in either), couldn't one apply a correction to the right place for any random step error that occurred? It would depend if the errors are caused by true independent random fast jumps or just slowly drifting interacting changes. ws *** Bob, et. al., Lots of opinions in this discussion, but none of it discusses the elephant in the room affecting todays' vendors: Random crystal instability versus manufacturing techniques. I can buy oscillators from multiple vendors that have -115dBc at 1Hz or better and noise floors of -182dBc. That technology is well understood and has been mature for a very long time and to me its boring. Recently Ulrich Rhode even had a great article in the Microwave Journal detailing how exactly to build one of those units. But what does it help me to have -115dBc if the darn thing jumps 50ppt every two to three days?? Crystal jumps are the biggest menace facing users of crystals/oscillators today and so far I have never been given a reasonable explanation from any of the vendors out there what causes it and how to avoid it or how they plan to address it. In fact no vendor we know tests for it to levels of sub-ppt over days which is what is necessary for any disciplined application as disciplining will clearly show even the smallest crystal jumps. Almost every vendor will do a frequency test only, where a phase test would be needed. Users of crystals/oscillators are left with doing an exhaustive yield test during burn-in to find bad crystals. We test our boards for 3 days and more to weed out jumpy crystals, and its a pain and very expensive to have to do this on finished goods as rework is in order for units that fail. The results are staggering, some vendors consistently have jumpy product, others consistently have excellent product, all have at least occasional batches that are worse to far worse than standard deviation. Some are so bad that one batch may yield 95% and the next batch of the same exact product will only yield 50% or less! I think this is the area of Quartz processing that has the least amount of research invested into it, and as anyone that has seen their Z38xx unit jump up and down in phase can attest to its a menace and can ruin one's day. I wish there were something besides yield testing that can be done to avoid manufacturing and shipping bad crystals to integrators. BVA seems to be one of those solutions, but how many BVA's have we seen in products that cost $400 retail?? Bye, Said ___ 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] The 5MHz Sweet Spot
ase Noise and Frequency Stability in >>> Oscillators". >>> "The process described relies on the ability to estimate the resonator's >>> quality factor. Experience indicates that the product voQ is a technical >>> constant for piezoelectric quartz resonators, in the range from 1 x 10^11 >>> to 2 >>> x 10^13. As a matter of fact, the highest values are found in 5MHz >>> resonators. ." >>> >>> I have no axe to grind on this, aside from willingly admitting to being >>> one of the confused:-), but if this is a misconception is it possible to >>> address why such a situation might have arisen? >>> >>> Regards >>> >>> Nigel >>> GM8PZR >>> >>> >>> >>> In a message dated 03/11/2013 01:46:01 GMT Standard Time, li...@rtty.us >>> writes: >>> >>> Hi >>> >>> I believe that you are talking to two very different groups, one who >>> actually design the crystals and the other who use the products that are >>> designed. One is talking about what they can buy, the other is talking >>> about what >>> could / could not be done and why. >>> >>> Bob >>> >>> On Nov 2, 2013, at 8:22 PM, Tom Knox wrote: >>> >>>> From reading your past posts I must respect your opinion. Your are >>> obviously extremely educated on the subject. So why is there some >>> disagreement >>> in two very knowledgeable groups? >>>> >>>> Thomas Knox >>>> >>>> >>>> >>>>> From: li...@rtty.us >>>>> Date: Sat, 2 Nov 2013 18:44:18 -0400 >>>>> To: time-nuts@febo.com >>>>> Subject: Re: [time-nuts] The 5MHz Sweet Spot >>>>> >>>>> Hi >>>>> >>>>> The only thing that the 5 MHz 3rd crystal is “optimum” for is a holder >>> that will accept a 0.55” max diameter blank. >>>>> >>>>> Bpb >>>>> >>>>> On Nov 2, 2013, at 6:06 PM, Tom Knox wrote: >>>>> >>>>>> Mike I think we must be talking to the same smart people. I think 5MHz >>> was adopted over 3MHz simply because 5MHz multiplies to other commonly >>> used frequencies with greater ease. I think the top frequency standards >>> have >>> evolved to 5MHz Third Overtone SC cut crystals for a reason. The evolution >>> has gone on from the days of Tesla and improved greatly during the glory >>> days of Quartz in the years leading up to atomic standards with countless >>> hours of experimentation and research. Those lessons learned are >>> constantly >>> examined through the lens of the latest science. I may be wrong, but I >>> have >>> not heard of any extreme design prototype quartz oscillator with superior >>> Phase Noise and Stability. Our house standard F1 a cesium fountain is used >>> roughly one month every few months to characterize roughly 12 5071A cesium >>> standards steering about 5 MHM 2010 cleaned up with a number of 8607 >>> option >>> 08 oscillator. (The equipment choices are not a recommendation or >>> endorsement, and there are po >>>>>> ssibly m >>>>>> any product that could meet or exceed the performance of these fine >>> products.) But the oscillators selected are 5MHz third Overtone SC cut. >>>>>> >>>>>> Thomas Knox >>>>>> >>>>>> >>>>>> >>>>>>> From: mfe...@eozinc.com >>>>>>> To: n1...@alum.dartmouth.org; time-nuts@febo.com >>>>>>> Date: Sat, 2 Nov 2013 09:50:50 -0400 >>>>>>> Subject: Re: [time-nuts] The 5MHz Sweet Spot >>>>>>> >>>>>>> Exactly - I mentioned this on here about 3 years ago and all of the >>>>>>> self-proclaimed geniuses poo-pooded it. I was told early in my >>> engineering >>>>>>> career in the early 70's, by a very smart man, when I thought I had >>> all of >>>>>>> the answers, that considering all of the trade-offs regarding >>> performance, >>>>>>> around 3 MHz for a crystal is best, operating in the 3rd overtone >>> mode, >>>>>>> hence the slow progression from the 1 and 5 MHz s
Re: [time-nuts] The 5MHz Sweet Spot
On Sun, 3 Nov 2013 09:33:57 -0800 Said Jackson wrote: > Crystal jumps are the biggest menace facing users of crystals/oscillators > today and so far I have never been given a reasonable explanation from any > of the vendors out there what causes it and how to avoid it or how they plan > to address it. Could these be related to frequency dips? Or radiation dependent jumps of unswept crystals? > I think this is the area of Quartz processing that has the least amount of > research invested into it, and as anyone that has seen their Z38xx unit > jump up and down in phase can attest to its a menace and can ruin one's day. Well one of our problems with quartz oscillators these days is, that most of the knowhow is at the manufacturers behind locked doors. It's quite hard to come by some good knowlege how to build crystall oscillators these days. The good books have been written 20-30 years ago and have been out of print for nearly as long. I talked with some of the people who are kind of famous in the field at the EFTF in Prague this summer, and half of them agreed, the other half was more like "that's a solved problem" and "look for more intersting problems to solve than crystal oscillators". Doing research in this kind of enviornment is difficult at best. Getting results out of one manufacturer is even harder. > I wish there were something besides yield testing that can be done to avoid > manufacturing and shipping bad crystals to integrators. BVA seems to be one > of those solutions, but how many BVA's have we seen in products that cost > $400 retail?? Well, considering that a BVA costs at least 10 times as much... Attila Kinali -- 1.) Write everything down. 2.) Reduce to the essential. 3.) Stop and question. -- The Habits of Highly Boring People, Chris Sauve ___ 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] The 5MHz Sweet Spot
Thanks Jackson, I think I have seen that lately, I thought that was a GPS problem related to the transition between holdover and locked but I was unable to reproduce it with a GPS simulator. It is really pronounced on the C-Mac in the unit. Thomas Knox > CC: time-nuts@febo.com > From: saidj...@aol.com > Date: Sun, 3 Nov 2013 09:33:57 -0800 > To: time-nuts@febo.com > Subject: Re: [time-nuts] The 5MHz Sweet Spot > > Bob, et. al., > > Lots of opinions in this discussion, but none of it discusses the elephant in > the room affecting todays' vendors: > > Random crystal instability versus manufacturing techniques. > > I can buy oscillators from multiple vendors that have -115dBc at 1Hz or > better and noise floors of -182dBc. That technology is well understood and > has been mature for a very long time and to me its boring. Recently Ulrich > Rhode even had a great article in the Microwave Journal detailing how exactly > to build one of those units. > > But what does it help me to have -115dBc if the darn thing jumps 50ppt every > two to three days?? > > Crystal jumps are the biggest menace facing users of crystals/oscillators > today and so far I have never been given a reasonable explanation from any of > the vendors out there what causes it and how to avoid it or how they plan to > address it. > > In fact no vendor we know tests for it to levels of sub-ppt over days which > is what is necessary for any disciplined application as disciplining will > clearly show even the smallest crystal jumps. Almost every vendor will do a > frequency test only, where a phase test would be needed. > > Users of crystals/oscillators are left with doing an exhaustive yield test > during burn-in to find bad crystals. We test our boards for 3 days and more > to weed out jumpy crystals, and its a pain and very expensive to have to do > this on finished goods as rework is in order for units that fail. > > The results are staggering, some vendors consistently have jumpy product, > others consistently have excellent product, all have at least occasional > batches that are worse to far worse than standard deviation. Some are so bad > that one batch may yield 95% and the next batch of the same exact product > will only yield 50% or less! > > I think this is the area of Quartz processing that has the least amount of > research invested into it, and as anyone that has seen their Z38xx unit jump > up and down in phase can attest to its a menace and can ruin one's day. I > wish there were something besides yield testing that can be done to avoid > manufacturing and shipping bad crystals to integrators. BVA seems to be one > of those solutions, but how many BVA's have we seen in products that cost > $400 retail?? > > Bye, > Said > > On Nov 3, 2013, at 5:09, Bob Camp wrote: > > > Hi > > > > Rubiola is looking at resonators he can buy off the shelf. They are > > constrained by the commonly available packages. The Q x F product does not > > suddenly stop going up at 5 MHz. There is good documentation that it keeps > > on going as the frequency goes down. Is Q everything - of course not. > > However *if* you wanted a much higher Q crystal than the 5 MHz, it could be > > built if you had the time and the money. > > > > Bob > > > > On Nov 3, 2013, at 7:58 AM, gandal...@aol.com wrote: > > > >> Hi Bob > >> > >> I've seen this topic discussed here before and it does seem to raise some > >> quite strong emotions and there does seem to be some confusion. > >> > >> I can remember quite clearly, historically at least, 5MHz being commonly > >> promoted as the optimum frequency for crystal oscillators on the basis > >> that > >> 5MHz crystals had this "sweet spot", presumably when it came to > >> temperature > >> stability. > >> An online search today hasn't been very forthcoming and unfortunately > >> most > >> of my reference library remains in storage, so I can't provide instant > >> references, but I know I've also seen this in print and can still > >> envisage the > >> graphs used to demonstrate it. > >> > >> The nearest to a current reference I've found is this comment from Enrico > >> Rubiola on page 156 of "Phase Noise and Frequency Stability in > >> Oscillators". > >> "The process described relies on the ability to estimate the resonator's > >> quality factor. Experience indicates that the product voQ is a technical > >> constant fo
Re: [time-nuts] The 5MHz Sweet Spot
lking >> about what >> could / could not be done and why. >> >> Bob >> >> On Nov 2, 2013, at 8:22 PM, Tom Knox wrote: >> >>> From reading your past posts I must respect your opinion. Your are >> obviously extremely educated on the subject. So why is there some >> disagreement >> in two very knowledgeable groups? >>> >>> Thomas Knox >>> >>> >>> >>>> From: li...@rtty.us >>>> Date: Sat, 2 Nov 2013 18:44:18 -0400 >>>> To: time-nuts@febo.com >>>> Subject: Re: [time-nuts] The 5MHz Sweet Spot >>>> >>>> Hi >>>> >>>> The only thing that the 5 MHz 3rd crystal is “optimum” for is a holder >> that will accept a 0.55” max diameter blank. >>>> >>>> Bpb >>>> >>>> On Nov 2, 2013, at 6:06 PM, Tom Knox wrote: >>>> >>>>> Mike I think we must be talking to the same smart people. I think 5MHz >> was adopted over 3MHz simply because 5MHz multiplies to other commonly >> used frequencies with greater ease. I think the top frequency standards >> have >> evolved to 5MHz Third Overtone SC cut crystals for a reason. The evolution >> has gone on from the days of Tesla and improved greatly during the glory >> days of Quartz in the years leading up to atomic standards with countless >> hours of experimentation and research. Those lessons learned are constantly >> examined through the lens of the latest science. I may be wrong, but I >> have >> not heard of any extreme design prototype quartz oscillator with superior >> Phase Noise and Stability. Our house standard F1 a cesium fountain is used >> roughly one month every few months to characterize roughly 12 5071A cesium >> standards steering about 5 MHM 2010 cleaned up with a number of 8607 option >> 08 oscillator. (The equipment choices are not a recommendation or >> endorsement, and there are po >>>>> ssibly m >>>>> any product that could meet or exceed the performance of these fine >> products.) But the oscillators selected are 5MHz third Overtone SC cut. >>>>> >>>>> Thomas Knox >>>>> >>>>> >>>>> >>>>>> From: mfe...@eozinc.com >>>>>> To: n1...@alum.dartmouth.org; time-nuts@febo.com >>>>>> Date: Sat, 2 Nov 2013 09:50:50 -0400 >>>>>> Subject: Re: [time-nuts] The 5MHz Sweet Spot >>>>>> >>>>>> Exactly - I mentioned this on here about 3 years ago and all of the >>>>>> self-proclaimed geniuses poo-pooded it. I was told early in my >> engineering >>>>>> career in the early 70's, by a very smart man, when I thought I had >> all of >>>>>> the answers, that considering all of the trade-offs regarding >> performance, >>>>>> around 3 MHz for a crystal is best, operating in the 3rd overtone >> mode, >>>>>> hence the slow progression from the 1 and 5 MHz standards to 10 MHz. >> Now, >>>>>> getting close to 70, I just see what I can learn from all the "smart" >> people >>>>>> on here, and keep quiet most of the time. Regards - Mike >>>>>> >>>>>> Mike B. Feher, EOZ Inc. >>>>>> 89 Arnold Blvd. >>>>>> Howell, NJ, 07731 >>>>>> 732-886-5960 office >>>>>> 908-902-3831 cell >>>>>> >>>>>> -Original Message- >>>>>> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] >> On >>>>>> Behalf Of David McGaw >>>>>> Sent: Saturday, November 02, 2013 1:30 AM >>>>>> To: Discussion of precise time and frequency measurement >>>>>> Subject: Re: [time-nuts] The 5MHz Sweet Spot >>>>>> >>>>>> This all seems to be forgetting that the crystals are usually >> operated at >>>>>> 3rd or 5th harmonic. The crystal in a 10811A is 10 MHz/3rd overtone. >> A >>>>>> high quality 5 MHz/5th overtone crystal is really a 1 MHz >> fundamental, a >>>>>> large piece of quartz. Running at a harmonic greatly reduces the >> influence >>>>>> of the package. >>>>>> >>>>>> David >>>>>> >>>>>> >>>>>&
Re: [time-nuts] The 5MHz Sweet Spot
Hi, On 11/03/2013 05:22 PM, Tom Knox wrote: > I am not the right person to explain, So anyone with more knowledge please > feel free to jump in. I think basically the reasoning is as a single clock > the system at some point it would need mantainance or repair. So time is > maintained with an algorithm that monitors all the clocks and oscillators > that make up the system in which each part contributes and if any part > deviates or fails it can be removed. This system is then characterized > periodically by F1 as required to keep the system at F! accuracy. Basically, the caesiums and hydrogen masers operate as fly-wheel oscillators and they are sufficiently stable, such that the F1 only needs to operate every once in a while since the clocks have sufficient stability and what F1 provides is accurateness beyond what the individual clocks in the ensemble provides. It also helps to make the ensemble estimate accurate rather than the average of the continuous clocks of the ensemble. NIST then produce a couple of time-scales as phase and frequency adjusted from one of the clocks, which is steered to be what the ensemble estimate is judging it to be. It is the output of these which is then compared to other clocks, and these differences along with the individual differences of the clocks which is reported to BIPM. This is to show the overall principles rather than accurate detail. So, F1 could be run more often, but having the flywheel oscillators that it has, it doesn't have to. Besides, it's a lab standard, so it's physical buildup is altered in the breaks, such that it's performance have been improved through a long set of stepwise refinements. That's why F1 has had increased performance during it's operational period. Cheers, Magnus ___ 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] The 5MHz Sweet Spot
I am not the right person to explain, So anyone with more knowledge please feel free to jump in. I think basically the reasoning is as a single clock the system at some point it would need mantainance or repair. So time is maintained with an algorithm that monitors all the clocks and oscillators that make up the system in which each part contributes and if any part deviates or fails it can be removed. This system is then characterized periodically by F1 as required to keep the system at F! accuracy. Thomas Knox > Date: Sun, 3 Nov 2013 13:33:29 +0100 > From: att...@kinali.ch > To: time-nuts@febo.com > Subject: Re: [time-nuts] The 5MHz Sweet Spot > > Hi Tom, > > On Sat, 2 Nov 2013 16:06:06 -0600 > Tom Knox wrote: > > > Our house standard F1 a cesium fountain is used roughly one month every > > few months to characterize roughly 12 5071A cesium standards steering > > about 5 MHM 2010 cleaned up with a number of 8607 option 08 oscillator. > > What is the reason that the F1 isn't running continously? > I can understand the use of 12 Cs-beams for averaging, but i would > have thought that you would run your most accurate clock in parallel > as well. > > Is there a publication that explains your setup and why you've done > it this way and not another? > > Attila Kinali > > > -- > 1.) Write everything down. > 2.) Reduce to the essential. > 3.) Stop and question. > -- The Habits of Highly Boring People, Chris Sauve > ___ > 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] The 5MHz Sweet Spot
My questions exactly. For the moment I think question 4 may be covered in Archita Hati's paper State-of-the-Art RF Signal Generation From Optical Frequency Division. The other questions are what drives many Time-Nuts I know. Thomas Knox > Date: Sun, 3 Nov 2013 03:40:40 +0100 > From: mag...@rubidium.dyndns.org > To: time-nuts@febo.com > Subject: Re: [time-nuts] The 5MHz Sweet Spot > > On 11/03/2013 02:45 AM, Bob Camp wrote: > > Hi > > > > I believe that you are talking to two very different groups, one who > > actually design the crystals and the other who use the products that are > > designed. One is talking about what they can buy, the other is talking > > about what could / could not be done and why. > This is an important point. There is in fact a few different twists to this: > > 1) What is the best you could buy off the shelf > 2) What is the best you can buy off the shelf > 3) What is the best that could be built with the available tools > 4) What is the best that could be built with sky-is-the-limit budget > 5) What is the best that could be built, as physical size becomes smaller > > The last one is kind of relevant. Today packages shrink fast, and it's > very handy and all... but what about the performance we get. We can hug > our 5th overtone ovens all we want, but motivating their power and size > doesn't always cut it. It's like comparing with 5 inch blanks in Bob's > earlier post, it's more like 0,55 inch... > > Cheers, > Magnus > ___ > 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] The 5MHz Sweet Spot
On 11/3/13 4:27 AM, Magnus Danielson wrote: Hi Jim, Ground-based GPS-like transmitters could be a nice option to consider. Well, that's basically what we do today. We transmit a very stable carrier with some tones or a PN sequence modulated onto it. The spacecraft recovers it, generates a return signal locked to it, which we get on earth and analyze to determine the range and range rate (or if we've got two stations, we can do some cross range with Delta DOR or VLBI). This is known as "two way" ranging. Having a onboard high quality source means we can do "one way" ranging, so we can range without an uplink, or conceivably, the spacecraft can figure where it is by looking only at the uplink. A high quality onboard source also can be used to provide navigation signals from an orbiter to a lander that's not visible from earth 12 hours a day, there's no direct to earth link to something on the surface of Mars. An even bigger deal to something like the far side of the moon, although various and sundry schemes have been proposed (a relay satellite at L2, for instance) Would also provide a frequency reference for steering/compensation of that oscillator. Either that avoids deep space ranging, or it is only needed for verification. Onboard, so far not many people need precise time and frequency. It's almost exclusively for navigation, and low rate communications (if you're receiving 8 bps at -160dBm, the phase noise of your LO has to be pretty good). One of the hopes of the DSAC (Deep Space Atomic Clock) is that with "easy" high performance, people will come up with science measurements that depend on it. Interferometry among a constellation of satellites is one. We do a lot of gravity science by measuring the orbits of spacecraft (it is, after all, how we know the earth is pear shaped). More recently, GRACE and GRAIL used two spacecraft in the same orbit with very accurate ranging between them to accurately map the gravitational field of the Earth and Moon, respectively. Once you know the gravity, you can infer the internal structure: is it layered, or uniform, or lumpy, etc. A small very quiet clock would make putting a constellation of little spacecraft around something like Europa possible. When the entire spacecraft is a liter or two, you can't burn another liter on a USO, and even 100cc is a big chunk of volume. I thought the important part of the mission was to keep stable phase and frequency? :D We in the space telecom business KNOW that the whole reason we launch satellites with science instruments is to provide data other than random PRBS for our telecom system, so that we have something interesting to look at. Solar panels exist to provide power for our telecom system. The attitude control is to properly orient our antennas. Cheers, Magnus ___ 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] The 5MHz Sweet Spot
Hi Rubiola is looking at resonators he can buy off the shelf. They are constrained by the commonly available packages. The Q x F product does not suddenly stop going up at 5 MHz. There is good documentation that it keeps on going as the frequency goes down. Is Q everything - of course not. However *if* you wanted a much higher Q crystal than the 5 MHz, it could be built if you had the time and the money. Bob On Nov 3, 2013, at 7:58 AM, gandal...@aol.com wrote: > Hi Bob > > I've seen this topic discussed here before and it does seem to raise some > quite strong emotions and there does seem to be some confusion. > > I can remember quite clearly, historically at least, 5MHz being commonly > promoted as the optimum frequency for crystal oscillators on the basis that > 5MHz crystals had this "sweet spot", presumably when it came to temperature > stability. > An online search today hasn't been very forthcoming and unfortunately most > of my reference library remains in storage, so I can't provide instant > references, but I know I've also seen this in print and can still envisage > the > graphs used to demonstrate it. > > The nearest to a current reference I've found is this comment from Enrico > Rubiola on page 156 of "Phase Noise and Frequency Stability in > Oscillators". > "The process described relies on the ability to estimate the resonator's > quality factor. Experience indicates that the product voQ is a technical > constant for piezoelectric quartz resonators, in the range from 1 x 10^11 to > 2 > x 10^13. As a matter of fact, the highest values are found in 5MHz > resonators. ." > > I have no axe to grind on this, aside from willingly admitting to being > one of the confused:-), but if this is a misconception is it possible to > address why such a situation might have arisen? > > Regards > > Nigel > GM8PZR > > > > In a message dated 03/11/2013 01:46:01 GMT Standard Time, li...@rtty.us > writes: > > Hi > > I believe that you are talking to two very different groups, one who > actually design the crystals and the other who use the products that are > designed. One is talking about what they can buy, the other is talking about > what > could / could not be done and why. > > Bob > > On Nov 2, 2013, at 8:22 PM, Tom Knox wrote: > >> From reading your past posts I must respect your opinion. Your are > obviously extremely educated on the subject. So why is there some > disagreement > in two very knowledgeable groups? >> >> Thomas Knox >> >> >> >>> From: li...@rtty.us >>> Date: Sat, 2 Nov 2013 18:44:18 -0400 >>> To: time-nuts@febo.com >>> Subject: Re: [time-nuts] The 5MHz Sweet Spot >>> >>> Hi >>> >>> The only thing that the 5 MHz 3rd crystal is “optimum” for is a holder > that will accept a 0.55” max diameter blank. >>> >>> Bpb >>> >>> On Nov 2, 2013, at 6:06 PM, Tom Knox wrote: >>> >>>> Mike I think we must be talking to the same smart people. I think 5MHz > was adopted over 3MHz simply because 5MHz multiplies to other commonly > used frequencies with greater ease. I think the top frequency standards have > evolved to 5MHz Third Overtone SC cut crystals for a reason. The evolution > has gone on from the days of Tesla and improved greatly during the glory > days of Quartz in the years leading up to atomic standards with countless > hours of experimentation and research. Those lessons learned are constantly > examined through the lens of the latest science. I may be wrong, but I > have > not heard of any extreme design prototype quartz oscillator with superior > Phase Noise and Stability. Our house standard F1 a cesium fountain is used > roughly one month every few months to characterize roughly 12 5071A cesium > standards steering about 5 MHM 2010 cleaned up with a number of 8607 option > 08 oscillator. (The equipment choices are not a recommendation or > endorsement, and there are po >>>> ssibly m >>>> any product that could meet or exceed the performance of these fine > products.) But the oscillators selected are 5MHz third Overtone SC cut. >>>> >>>> Thomas Knox >>>> >>>> >>>> >>>>> From: mfe...@eozinc.com >>>>> To: n1...@alum.dartmouth.org; time-nuts@febo.com >>>>> Date: Sat, 2 Nov 2013 09:50:50 -0400 >>>>> Subject: Re: [time-nuts] The 5MHz Sweet Spot >>>>> >>>>
Re: [time-nuts] The 5MHz Sweet Spot
Hi Bob I've seen this topic discussed here before and it does seem to raise some quite strong emotions and there does seem to be some confusion. I can remember quite clearly, historically at least, 5MHz being commonly promoted as the optimum frequency for crystal oscillators on the basis that 5MHz crystals had this "sweet spot", presumably when it came to temperature stability. An online search today hasn't been very forthcoming and unfortunately most of my reference library remains in storage, so I can't provide instant references, but I know I've also seen this in print and can still envisage the graphs used to demonstrate it. The nearest to a current reference I've found is this comment from Enrico Rubiola on page 156 of "Phase Noise and Frequency Stability in Oscillators". "The process described relies on the ability to estimate the resonator's quality factor. Experience indicates that the product voQ is a technical constant for piezoelectric quartz resonators, in the range from 1 x 10^11 to 2 x 10^13. As a matter of fact, the highest values are found in 5MHz resonators. ." I have no axe to grind on this, aside from willingly admitting to being one of the confused:-), but if this is a misconception is it possible to address why such a situation might have arisen? Regards Nigel GM8PZR In a message dated 03/11/2013 01:46:01 GMT Standard Time, li...@rtty.us writes: Hi I believe that you are talking to two very different groups, one who actually design the crystals and the other who use the products that are designed. One is talking about what they can buy, the other is talking about what could / could not be done and why. Bob On Nov 2, 2013, at 8:22 PM, Tom Knox wrote: > From reading your past posts I must respect your opinion. Your are obviously extremely educated on the subject. So why is there some disagreement in two very knowledgeable groups? > > Thomas Knox > > > >> From: li...@rtty.us >> Date: Sat, 2 Nov 2013 18:44:18 -0400 >> To: time-nuts@febo.com >> Subject: Re: [time-nuts] The 5MHz Sweet Spot >> >> Hi >> >> The only thing that the 5 MHz 3rd crystal is “optimum” for is a holder that will accept a 0.55” max diameter blank. >> >> Bpb >> >> On Nov 2, 2013, at 6:06 PM, Tom Knox wrote: >> >>> Mike I think we must be talking to the same smart people. I think 5MHz was adopted over 3MHz simply because 5MHz multiplies to other commonly used frequencies with greater ease. I think the top frequency standards have evolved to 5MHz Third Overtone SC cut crystals for a reason. The evolution has gone on from the days of Tesla and improved greatly during the glory days of Quartz in the years leading up to atomic standards with countless hours of experimentation and research. Those lessons learned are constantly examined through the lens of the latest science. I may be wrong, but I have not heard of any extreme design prototype quartz oscillator with superior Phase Noise and Stability. Our house standard F1 a cesium fountain is used roughly one month every few months to characterize roughly 12 5071A cesium standards steering about 5 MHM 2010 cleaned up with a number of 8607 option 08 oscillator. (The equipment choices are not a recommendation or endorsement, and there are po >>> ssibly m >>> any product that could meet or exceed the performance of these fine products.) But the oscillators selected are 5MHz third Overtone SC cut. >>> >>> Thomas Knox >>> >>> >>> >>>> From: mfe...@eozinc.com >>>> To: n1...@alum.dartmouth.org; time-nuts@febo.com >>>> Date: Sat, 2 Nov 2013 09:50:50 -0400 >>>> Subject: Re: [time-nuts] The 5MHz Sweet Spot >>>> >>>> Exactly - I mentioned this on here about 3 years ago and all of the >>>> self-proclaimed geniuses poo-pooded it. I was told early in my engineering >>>> career in the early 70's, by a very smart man, when I thought I had all of >>>> the answers, that considering all of the trade-offs regarding performance, >>>> around 3 MHz for a crystal is best, operating in the 3rd overtone mode, >>>> hence the slow progression from the 1 and 5 MHz standards to 10 MHz. Now, >>>> getting close to 70, I just see what I can learn from all the "smart" people >>>> on here, and keep quiet most of the time. Regards - Mike >>>> >>>> Mike B. Feher, EOZ Inc. >>>> 89 Arnold Blvd. >>>> Howell, NJ, 07731 >>>> 732-886-5960 office >>>> 908-902-3831 cell >>>&g
Re: [time-nuts] The 5MHz Sweet Spot
Hi Tom, On Sat, 2 Nov 2013 16:06:06 -0600 Tom Knox wrote: > Our house standard F1 a cesium fountain is used roughly one month every > few months to characterize roughly 12 5071A cesium standards steering > about 5 MHM 2010 cleaned up with a number of 8607 option 08 oscillator. What is the reason that the F1 isn't running continously? I can understand the use of 12 Cs-beams for averaging, but i would have thought that you would run your most accurate clock in parallel as well. Is there a publication that explains your setup and why you've done it this way and not another? Attila Kinali -- 1.) Write everything down. 2.) Reduce to the essential. 3.) Stop and question. -- The Habits of Highly Boring People, Chris Sauve ___ 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] The 5MHz Sweet Spot
Hi Jim, On 11/03/2013 05:21 AM, Jim Lux wrote: > On 11/2/13 7:40 PM, Magnus Danielson wrote: >> On 11/03/2013 02:45 AM, Bob Camp wrote: >>> Hi >>> >>> I believe that you are talking to two very different groups, one who >>> actually design the crystals and the other who use the products that >>> are designed. One is talking about what they can buy, the other is >>> talking about what could / could not be done and why. >> This is an important point. There is in fact a few different twists >> to this: >> >> 1) What is the best you could buy off the shelf >> 2) What is the best you can buy off the shelf >> 3) What is the best that could be built with the available tools >> 4) What is the best that could be built with sky-is-the-limit budget >> 5) What is the best that could be built, as physical size becomes >> smaller >> > > > AS someone who gets involved in buying #4s, and also interested in > #5s, this is very true. Myself I try to fight people doing smallest possible, but not always thinking about performance, so #5 is important, while I would like somewhat more #2 normally. For my hobby #1 and #2 is much more like it. > > The appeal of the trapped mercury ion clock (aka DSAC) is that it > gives orders of magnitude better performance than a state of the art > USO with the rock in a dewar, with lower power and comparable 1 liter > size. > > When it comes to shrinking, I think there would be substantial > interest in a "very small" oscillator with USO kinds of phase > noise/ADEV, in say, a 50 cc/50 gram package (size of the standard 2x2" > OCXO). Not everyone will want to invest in DSAC 2x2" size is a way too large oscillator in telecom these days. DIL14 is large and 7x5 mm is on the large side, but could be crammed in. Some better oscillators is a little in between DIL14 and 7x5, but that's OK since you use one per board. Things are really crammed up, and finding a thermally quiet spot on a board is ehm... challenging, as there is really no way to go. CSAC may be nice, but there is an overbelief in it, just because it is caesium. Saw that in a presentation not to long ago. But yes, there is good use for it. > Bear in mind that "substantial interest" in the scientific space probe > biz is a few units per year, max, with enormous lead times. One > reason we keep buying USOs that aren't a heck of a lot different than > the ones of 20 years ago is that they're a known quantity. Large volume. Whoppa... (not) > I find those MEMS silicon ring resonators in the 3x3mm package really > interesting, just becase they're so darn tiny. Figure out a way to > get really good ADEV performance in the 10-100 second sorts of tau, > even if the frequency drifts and ages over days and months, and that's > an interesting part for doing deep space navigation on very small > satellites. I find that performance have been improving with each generation. Close-in phase-noise have been terrible and is often not even shown. I consider them useful for free-running clocks which just drives logic or when locked up to a reference. "MEMS" by itself is a low frequency oscillator and a CMOS oscillator which is locked to the low frequency MEMS oscillator. Last one I saw in that regard had cleaned up their act in several regards and started to have pretty respectable phase-noise plots... for being a MEMS. The one sales-rep that do listen to me now comes better prepared with phase-noise and ADEV plots as I have requested. > There's a huge problem as folks want to send cube-sats past GEO with > "how do you know where it is" (GPS doesn't work when you get to lunar > distances), so you need to do traditional deep space ranging of one > sort or another. Ground-based GPS-like transmitters could be a nice option to consider. Would also provide a frequency reference for steering/compensation of that oscillator. Either that avoids deep space ranging, or it is only needed for verification. > When the entire spacecraft is a liter or two, you can't burn another > liter on a USO, and even 100cc is a big chunk of volume. I thought the important part of the mission was to keep stable phase and frequency? :D Cheers, Magnus ___ 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] The 5MHz Sweet Spot
On 11/2/13 7:40 PM, Magnus Danielson wrote: On 11/03/2013 02:45 AM, Bob Camp wrote: Hi I believe that you are talking to two very different groups, one who actually design the crystals and the other who use the products that are designed. One is talking about what they can buy, the other is talking about what could / could not be done and why. This is an important point. There is in fact a few different twists to this: 1) What is the best you could buy off the shelf 2) What is the best you can buy off the shelf 3) What is the best that could be built with the available tools 4) What is the best that could be built with sky-is-the-limit budget 5) What is the best that could be built, as physical size becomes smaller AS someone who gets involved in buying #4s, and also interested in #5s, this is very true. The appeal of the trapped mercury ion clock (aka DSAC) is that it gives orders of magnitude better performance than a state of the art USO with the rock in a dewar, with lower power and comparable 1 liter size. When it comes to shrinking, I think there would be substantial interest in a "very small" oscillator with USO kinds of phase noise/ADEV, in say, a 50 cc/50 gram package (size of the standard 2x2" OCXO). Not everyone will want to invest in DSAC Bear in mind that "substantial interest" in the scientific space probe biz is a few units per year, max, with enormous lead times. One reason we keep buying USOs that aren't a heck of a lot different than the ones of 20 years ago is that they're a known quantity. I find those MEMS silicon ring resonators in the 3x3mm package really interesting, just becase they're so darn tiny. Figure out a way to get really good ADEV performance in the 10-100 second sorts of tau, even if the frequency drifts and ages over days and months, and that's an interesting part for doing deep space navigation on very small satellites. There's a huge problem as folks want to send cube-sats past GEO with "how do you know where it is" (GPS doesn't work when you get to lunar distances), so you need to do traditional deep space ranging of one sort or another. When the entire spacecraft is a liter or two, you can't burn another liter on a USO, and even 100cc is a big chunk of volume. The last one is kind of relevant. Today packages shrink fast, and it's very handy and all... but what about the performance we get. We can hug our 5th overtone ovens all we want, but motivating their power and size doesn't always cut it. It's like comparing with 5 inch blanks in Bob's earlier post, it's more like 0,55 inch... Cheers, Magnus ___ 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] The 5MHz Sweet Spot
On 11/03/2013 02:45 AM, Bob Camp wrote: > Hi > > I believe that you are talking to two very different groups, one who actually > design the crystals and the other who use the products that are designed. One > is talking about what they can buy, the other is talking about what could / > could not be done and why. This is an important point. There is in fact a few different twists to this: 1) What is the best you could buy off the shelf 2) What is the best you can buy off the shelf 3) What is the best that could be built with the available tools 4) What is the best that could be built with sky-is-the-limit budget 5) What is the best that could be built, as physical size becomes smaller The last one is kind of relevant. Today packages shrink fast, and it's very handy and all... but what about the performance we get. We can hug our 5th overtone ovens all we want, but motivating their power and size doesn't always cut it. It's like comparing with 5 inch blanks in Bob's earlier post, it's more like 0,55 inch... Cheers, Magnus ___ 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] The 5MHz Sweet Spot
Hi I believe that you are talking to two very different groups, one who actually design the crystals and the other who use the products that are designed. One is talking about what they can buy, the other is talking about what could / could not be done and why. Bob On Nov 2, 2013, at 8:22 PM, Tom Knox wrote: > From reading your past posts I must respect your opinion. Your are obviously > extremely educated on the subject. So why is there some disagreement in two > very knowledgeable groups? > > Thomas Knox > > > >> From: li...@rtty.us >> Date: Sat, 2 Nov 2013 18:44:18 -0400 >> To: time-nuts@febo.com >> Subject: Re: [time-nuts] The 5MHz Sweet Spot >> >> Hi >> >> The only thing that the 5 MHz 3rd crystal is “optimum” for is a holder that >> will accept a 0.55” max diameter blank. >> >> Bpb >> >> On Nov 2, 2013, at 6:06 PM, Tom Knox wrote: >> >>> Mike I think we must be talking to the same smart people. I think 5MHz was >>> adopted over 3MHz simply because 5MHz multiplies to other commonly used >>> frequencies with greater ease. I think the top frequency standards have >>> evolved to 5MHz Third Overtone SC cut crystals for a reason. The evolution >>> has gone on from the days of Tesla and improved greatly during the glory >>> days of Quartz in the years leading up to atomic standards with countless >>> hours of experimentation and research. Those lessons learned are constantly >>> examined through the lens of the latest science. I may be wrong, but I >>> have not heard of any extreme design prototype quartz oscillator with >>> superior Phase Noise and Stability. Our house standard F1 a cesium fountain >>> is used roughly one month every few months to characterize roughly 12 5071A >>> cesium standards steering about 5 MHM 2010 cleaned up with a number of 8607 >>> option 08 oscillator. (The equipment choices are not a recommendation or >>> endorsement, and there are po >>> ssibly m >>> any product that could meet or exceed the performance of these fine >>> products.) But the oscillators selected are 5MHz third Overtone SC cut. >>> >>> Thomas Knox >>> >>> >>> >>>> From: mfe...@eozinc.com >>>> To: n1...@alum.dartmouth.org; time-nuts@febo.com >>>> Date: Sat, 2 Nov 2013 09:50:50 -0400 >>>> Subject: Re: [time-nuts] The 5MHz Sweet Spot >>>> >>>> Exactly - I mentioned this on here about 3 years ago and all of the >>>> self-proclaimed geniuses poo-pooded it. I was told early in my engineering >>>> career in the early 70's, by a very smart man, when I thought I had all of >>>> the answers, that considering all of the trade-offs regarding performance, >>>> around 3 MHz for a crystal is best, operating in the 3rd overtone mode, >>>> hence the slow progression from the 1 and 5 MHz standards to 10 MHz. Now, >>>> getting close to 70, I just see what I can learn from all the "smart" >>>> people >>>> on here, and keep quiet most of the time. Regards - Mike >>>> >>>> Mike B. Feher, EOZ Inc. >>>> 89 Arnold Blvd. >>>> Howell, NJ, 07731 >>>> 732-886-5960 office >>>> 908-902-3831 cell >>>> >>>> -Original Message- >>>> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On >>>> Behalf Of David McGaw >>>> Sent: Saturday, November 02, 2013 1:30 AM >>>> To: Discussion of precise time and frequency measurement >>>> Subject: Re: [time-nuts] The 5MHz Sweet Spot >>>> >>>> This all seems to be forgetting that the crystals are usually operated at >>>> 3rd or 5th harmonic. The crystal in a 10811A is 10 MHz/3rd overtone. A >>>> high quality 5 MHz/5th overtone crystal is really a 1 MHz fundamental, a >>>> large piece of quartz. Running at a harmonic greatly reduces the influence >>>> of the package. >>>> >>>> David >>>> >>>> >>>> ___ >>>> 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. ___ 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] The 5MHz Sweet Spot
>From reading your past posts I must respect your opinion. Your are obviously >extremely educated on the subject. So why is there some disagreement in two >very knowledgeable groups? Thomas Knox > From: li...@rtty.us > Date: Sat, 2 Nov 2013 18:44:18 -0400 > To: time-nuts@febo.com > Subject: Re: [time-nuts] The 5MHz Sweet Spot > > Hi > > The only thing that the 5 MHz 3rd crystal is “optimum” for is a holder that > will accept a 0.55” max diameter blank. > > Bpb > > On Nov 2, 2013, at 6:06 PM, Tom Knox wrote: > > > Mike I think we must be talking to the same smart people. I think 5MHz was > > adopted over 3MHz simply because 5MHz multiplies to other commonly used > > frequencies with greater ease. I think the top frequency standards have > > evolved to 5MHz Third Overtone SC cut crystals for a reason. The evolution > > has gone on from the days of Tesla and improved greatly during the glory > > days of Quartz in the years leading up to atomic standards with countless > > hours of experimentation and research. Those lessons learned are constantly > > examined through the lens of the latest science. I may be wrong, but I > > have not heard of any extreme design prototype quartz oscillator with > > superior Phase Noise and Stability. Our house standard F1 a cesium fountain > > is used roughly one month every few months to characterize roughly 12 5071A > > cesium standards steering about 5 MHM 2010 cleaned up with a number of 8607 > > option 08 oscillator. (The equipment choices are not a recommendation or > > endorsement, and there are po > > ssibly m > > any product that could meet or exceed the performance of these fine > > products.) But the oscillators selected are 5MHz third Overtone SC cut. > > > > Thomas Knox > > > > > > > >> From: mfe...@eozinc.com > >> To: n1...@alum.dartmouth.org; time-nuts@febo.com > >> Date: Sat, 2 Nov 2013 09:50:50 -0400 > >> Subject: Re: [time-nuts] The 5MHz Sweet Spot > >> > >> Exactly - I mentioned this on here about 3 years ago and all of the > >> self-proclaimed geniuses poo-pooded it. I was told early in my engineering > >> career in the early 70's, by a very smart man, when I thought I had all of > >> the answers, that considering all of the trade-offs regarding performance, > >> around 3 MHz for a crystal is best, operating in the 3rd overtone mode, > >> hence the slow progression from the 1 and 5 MHz standards to 10 MHz. Now, > >> getting close to 70, I just see what I can learn from all the "smart" > >> people > >> on here, and keep quiet most of the time. Regards - Mike > >> > >> Mike B. Feher, EOZ Inc. > >> 89 Arnold Blvd. > >> Howell, NJ, 07731 > >> 732-886-5960 office > >> 908-902-3831 cell > >> > >> -Original Message- > >> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On > >> Behalf Of David McGaw > >> Sent: Saturday, November 02, 2013 1:30 AM > >> To: Discussion of precise time and frequency measurement > >> Subject: Re: [time-nuts] The 5MHz Sweet Spot > >> > >> This all seems to be forgetting that the crystals are usually operated at > >> 3rd or 5th harmonic. The crystal in a 10811A is 10 MHz/3rd overtone. A > >> high quality 5 MHz/5th overtone crystal is really a 1 MHz fundamental, a > >> large piece of quartz. Running at a harmonic greatly reduces the influence > >> of the package. > >> > >> David > >> > >> > >> ___ > >> 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] The 5MHz Sweet Spot
Hi The only thing that the 5 MHz 3rd crystal is “optimum” for is a holder that will accept a 0.55” max diameter blank. Bpb On Nov 2, 2013, at 6:06 PM, Tom Knox wrote: > Mike I think we must be talking to the same smart people. I think 5MHz was > adopted over 3MHz simply because 5MHz multiplies to other commonly used > frequencies with greater ease. I think the top frequency standards have > evolved to 5MHz Third Overtone SC cut crystals for a reason. The evolution > has gone on from the days of Tesla and improved greatly during the glory days > of Quartz in the years leading up to atomic standards with countless hours of > experimentation and research. Those lessons learned are constantly examined > through the lens of the latest science. I may be wrong, but I have not > heard of any extreme design prototype quartz oscillator with superior Phase > Noise and Stability. Our house standard F1 a cesium fountain is used roughly > one month every few months to characterize roughly 12 5071A cesium standards > steering about 5 MHM 2010 cleaned up with a number of 8607 option 08 > oscillator. (The equipment choices are not a recommendation or endorsement, > and there are po > ssibly m > any product that could meet or exceed the performance of these fine > products.) But the oscillators selected are 5MHz third Overtone SC cut. > > Thomas Knox > > > >> From: mfe...@eozinc.com >> To: n1...@alum.dartmouth.org; time-nuts@febo.com >> Date: Sat, 2 Nov 2013 09:50:50 -0400 >> Subject: Re: [time-nuts] The 5MHz Sweet Spot >> >> Exactly - I mentioned this on here about 3 years ago and all of the >> self-proclaimed geniuses poo-pooded it. I was told early in my engineering >> career in the early 70's, by a very smart man, when I thought I had all of >> the answers, that considering all of the trade-offs regarding performance, >> around 3 MHz for a crystal is best, operating in the 3rd overtone mode, >> hence the slow progression from the 1 and 5 MHz standards to 10 MHz. Now, >> getting close to 70, I just see what I can learn from all the "smart" people >> on here, and keep quiet most of the time. Regards - Mike >> >> Mike B. Feher, EOZ Inc. >> 89 Arnold Blvd. >> Howell, NJ, 07731 >> 732-886-5960 office >> 908-902-3831 cell >> >> -Original Message- >> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On >> Behalf Of David McGaw >> Sent: Saturday, November 02, 2013 1:30 AM >> To: Discussion of precise time and frequency measurement >> Subject: Re: [time-nuts] The 5MHz Sweet Spot >> >> This all seems to be forgetting that the crystals are usually operated at >> 3rd or 5th harmonic. The crystal in a 10811A is 10 MHz/3rd overtone. A >> high quality 5 MHz/5th overtone crystal is really a 1 MHz fundamental, a >> large piece of quartz. Running at a harmonic greatly reduces the influence >> of the package. >> >> David >> >> >> ___ >> 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] The 5MHz Sweet Spot
Mike I think we must be talking to the same smart people. I think 5MHz was adopted over 3MHz simply because 5MHz multiplies to other commonly used frequencies with greater ease. I think the top frequency standards have evolved to 5MHz Third Overtone SC cut crystals for a reason. The evolution has gone on from the days of Tesla and improved greatly during the glory days of Quartz in the years leading up to atomic standards with countless hours of experimentation and research. Those lessons learned are constantly examined through the lens of the latest science. I may be wrong, but I have not heard of any extreme design prototype quartz oscillator with superior Phase Noise and Stability. Our house standard F1 a cesium fountain is used roughly one month every few months to characterize roughly 12 5071A cesium standards steering about 5 MHM 2010 cleaned up with a number of 8607 option 08 oscillator. (The equipment choices are not a recommendation or endorsement, and there are possibly m any product that could meet or exceed the performance of these fine products.) But the oscillators selected are 5MHz third Overtone SC cut. Thomas Knox > From: mfe...@eozinc.com > To: n1...@alum.dartmouth.org; time-nuts@febo.com > Date: Sat, 2 Nov 2013 09:50:50 -0400 > Subject: Re: [time-nuts] The 5MHz Sweet Spot > > Exactly - I mentioned this on here about 3 years ago and all of the > self-proclaimed geniuses poo-pooded it. I was told early in my engineering > career in the early 70's, by a very smart man, when I thought I had all of > the answers, that considering all of the trade-offs regarding performance, > around 3 MHz for a crystal is best, operating in the 3rd overtone mode, > hence the slow progression from the 1 and 5 MHz standards to 10 MHz. Now, > getting close to 70, I just see what I can learn from all the "smart" people > on here, and keep quiet most of the time. Regards - Mike > > Mike B. Feher, EOZ Inc. > 89 Arnold Blvd. > Howell, NJ, 07731 > 732-886-5960 office > 908-902-3831 cell > > -Original Message- > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On > Behalf Of David McGaw > Sent: Saturday, November 02, 2013 1:30 AM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] The 5MHz Sweet Spot > > This all seems to be forgetting that the crystals are usually operated at > 3rd or 5th harmonic. The crystal in a 10811A is 10 MHz/3rd overtone. A > high quality 5 MHz/5th overtone crystal is really a 1 MHz fundamental, a > large piece of quartz. Running at a harmonic greatly reduces the influence > of the package. > > David > > > ___ > 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] The 5MHz Sweet Spot
Yes - me too - several even published books and papers on the subject. Regards - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: Saturday, November 02, 2013 10:01 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] The 5MHz Sweet Spot Hi Well what I've been going from is the information I was taught by the people who actually designed all those crystals back in the 40's 50's and 60's. Bob On Nov 2, 2013, at 9:50 AM, Mike Feher wrote: > Exactly - I mentioned this on here about 3 years ago and all of the > self-proclaimed geniuses poo-pooded it. I was told early in my > engineering career in the early 70's, by a very smart man, when I > thought I had all of the answers, that considering all of the > trade-offs regarding performance, around 3 MHz for a crystal is best, > operating in the 3rd overtone mode, hence the slow progression from > the 1 and 5 MHz standards to 10 MHz. Now, getting close to 70, I just > see what I can learn from all the "smart" people on here, and keep > quiet most of the time. Regards - Mike > > Mike B. Feher, EOZ Inc. > 89 Arnold Blvd. > Howell, NJ, 07731 > 732-886-5960 office > 908-902-3831 cell > > -Original Message- > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] > On Behalf Of David McGaw > Sent: Saturday, November 02, 2013 1:30 AM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] The 5MHz Sweet Spot > > This all seems to be forgetting that the crystals are usually operated > at 3rd or 5th harmonic. The crystal in a 10811A is 10 MHz/3rd > overtone. A high quality 5 MHz/5th overtone crystal is really a 1 MHz > fundamental, a large piece of quartz. Running at a harmonic greatly > reduces the influence of the package. > > David > > > ___ > 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] The 5MHz Sweet Spot
Hi Well what I’ve been going from is the information I was taught by the people who actually designed all those crystals back in the 40’s 50’s and 60’s. Bob On Nov 2, 2013, at 9:50 AM, Mike Feher wrote: > Exactly - I mentioned this on here about 3 years ago and all of the > self-proclaimed geniuses poo-pooded it. I was told early in my engineering > career in the early 70's, by a very smart man, when I thought I had all of > the answers, that considering all of the trade-offs regarding performance, > around 3 MHz for a crystal is best, operating in the 3rd overtone mode, > hence the slow progression from the 1 and 5 MHz standards to 10 MHz. Now, > getting close to 70, I just see what I can learn from all the "smart" people > on here, and keep quiet most of the time. Regards - Mike > > Mike B. Feher, EOZ Inc. > 89 Arnold Blvd. > Howell, NJ, 07731 > 732-886-5960 office > 908-902-3831 cell > > -Original Message- > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On > Behalf Of David McGaw > Sent: Saturday, November 02, 2013 1:30 AM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] The 5MHz Sweet Spot > > This all seems to be forgetting that the crystals are usually operated at > 3rd or 5th harmonic. The crystal in a 10811A is 10 MHz/3rd overtone. A > high quality 5 MHz/5th overtone crystal is really a 1 MHz fundamental, a > large piece of quartz. Running at a harmonic greatly reduces the influence > of the package. > > David > > > ___ > 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] The 5MHz Sweet Spot
Exactly - I mentioned this on here about 3 years ago and all of the self-proclaimed geniuses poo-pooded it. I was told early in my engineering career in the early 70's, by a very smart man, when I thought I had all of the answers, that considering all of the trade-offs regarding performance, around 3 MHz for a crystal is best, operating in the 3rd overtone mode, hence the slow progression from the 1 and 5 MHz standards to 10 MHz. Now, getting close to 70, I just see what I can learn from all the "smart" people on here, and keep quiet most of the time. Regards - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of David McGaw Sent: Saturday, November 02, 2013 1:30 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] The 5MHz Sweet Spot This all seems to be forgetting that the crystals are usually operated at 3rd or 5th harmonic. The crystal in a 10811A is 10 MHz/3rd overtone. A high quality 5 MHz/5th overtone crystal is really a 1 MHz fundamental, a large piece of quartz. Running at a harmonic greatly reduces the influence of the package. David ___ 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] The 5MHz Sweet Spot
Hi All the numbers I gave assume you are starting from a 3rd / 5th at 10 MHz. Bob On Nov 2, 2013, at 1:30 AM, David McGaw wrote: > This all seems to be forgetting that the crystals are usually operated at 3rd > or 5th harmonic. The crystal in a 10811A is 10 MHz/3rd overtone. A high > quality 5 MHz/5th overtone crystal is really a 1 MHz fundamental, a large > piece of quartz. Running at a harmonic greatly reduces the influence of the > package. > > David > > > On 11/2/13 1:07 AM, Bob Camp wrote: >> Hi >> >> The real answer is that nobody knows. The economics essentially make finding >> out very expensive. Q most certainly goes up, I don’t think anybody disputes >> that. The questions about flicker / ADEV all revolve around small blank >> parts with major edge sensitivity issues. They also probably were not >> running in a very good oven. Unless somebody with very deep pockets decides >> they need to find out, it’s going to be an un-answered question. >> >> Bob >> >> >> On Nov 1, 2013, at 11:41 PM, Richard (Rick) Karlquist >> wrote: >> >>> >>> On 11/1/2013 8:28 PM, Bob Camp wrote: HI If you doubled the diameter of the blank each time you cut the frequency in half, all sorts of nice things might happen. If you start with a 1/2” blank in at 10 MHz that goes to 1” at 5 MHz and 2” at 2.5 MHz. Around 1 MHz you would get to a 5” blank. Good luck finding high grade quartz bars to cut 5” (or even 1”) blanks out of. You are going to have to go back to the autoclave fixtures at the very least. Since growth is (at best) linear you cost of quartz will scale with the size of the blank. I’d bet it scales a bit more than that if you want to keep the material at a high level of performance. >>> You've explained the excuses vendors give for not making full >>> size crystals. But the question is, given these realities, >>> does this reduce the theoretical advantage of the lower frequency >>> and by how much? >>> >>> Rick Karlquist N6RK >>> ___ >>> 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] The 5MHz Sweet Spot
Hi As I mentioned there is data. It’s from parts made in small packages. Even back in the days of glass packages they didn’t / couldn’t go for full size blanks at low frequencies. There *is* a lot of data that things like flicker noise are not improved when you have a blank edge very much involved in the resonator. Bob On Nov 2, 2013, at 7:16 AM, Magnus Danielson wrote: > Hi Bob, > > On 11/02/2013 06:07 AM, Bob Camp wrote: >> Hi >> >> The real answer is that nobody knows. The economics essentially make finding >> out very expensive. Q most certainly goes up, I don’t think anybody disputes >> that. The questions about flicker / ADEV all revolve around small blank >> parts with major edge sensitivity issues. They also probably were not >> running in a very good oven. Unless somebody with very deep pockets decides >> they need to find out, it’s going to be an un-answered question. > You can get some answers by looking back and use older crystals of > bigger size. If needed a modern amplifier could be used. > > Cheers, > Magnus > ___ > 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] The 5MHz Sweet Spot
Hi Bob, On 11/02/2013 06:07 AM, Bob Camp wrote: > Hi > > The real answer is that nobody knows. The economics essentially make finding > out very expensive. Q most certainly goes up, I don’t think anybody disputes > that. The questions about flicker / ADEV all revolve around small blank parts > with major edge sensitivity issues. They also probably were not running in a > very good oven. Unless somebody with very deep pockets decides they need to > find out, it’s going to be an un-answered question. You can get some answers by looking back and use older crystals of bigger size. If needed a modern amplifier could be used. Cheers, Magnus ___ 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] The 5MHz Sweet Spot
This all seems to be forgetting that the crystals are usually operated at 3rd or 5th harmonic. The crystal in a 10811A is 10 MHz/3rd overtone. A high quality 5 MHz/5th overtone crystal is really a 1 MHz fundamental, a large piece of quartz. Running at a harmonic greatly reduces the influence of the package. David On 11/2/13 1:07 AM, Bob Camp wrote: Hi The real answer is that nobody knows. The economics essentially make finding out very expensive. Q most certainly goes up, I don’t think anybody disputes that. The questions about flicker / ADEV all revolve around small blank parts with major edge sensitivity issues. They also probably were not running in a very good oven. Unless somebody with very deep pockets decides they need to find out, it’s going to be an un-answered question. Bob On Nov 1, 2013, at 11:41 PM, Richard (Rick) Karlquist wrote: On 11/1/2013 8:28 PM, Bob Camp wrote: HI If you doubled the diameter of the blank each time you cut the frequency in half, all sorts of nice things might happen. If you start with a 1/2” blank in at 10 MHz that goes to 1” at 5 MHz and 2” at 2.5 MHz. Around 1 MHz you would get to a 5” blank. Good luck finding high grade quartz bars to cut 5” (or even 1”) blanks out of. You are going to have to go back to the autoclave fixtures at the very least. Since growth is (at best) linear you cost of quartz will scale with the size of the blank. I’d bet it scales a bit more than that if you want to keep the material at a high level of performance. You've explained the excuses vendors give for not making full size crystals. But the question is, given these realities, does this reduce the theoretical advantage of the lower frequency and by how much? Rick Karlquist N6RK ___ 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] The 5MHz Sweet Spot
HI There’s no real reason why you would have more microphonic issues with a scaled larger blank. The bigger blank is likely to have a lower mechanical resonance (mount springs to blank mass) so it’s not going to be a star performer in vibration. Bob On Nov 1, 2013, at 11:50 PM, Bob Stewart wrote: > "If you have a 5” blank, your OCXO scales around it. Yes you can do some > neat things, but the package is getting bigger. You now need to convince > people to buy OCXO’s that are bigger than anything they have seen since the > 1960’s. In most cases that OCXO will be 2 to 10 times larger than > their entire sub-system. That’s going to be a tough sell." > > Does it become more susceptible to microphonics with larger blanks? > > Bob > ___ > 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] The 5MHz Sweet Spot
Hi The real answer is that nobody knows. The economics essentially make finding out very expensive. Q most certainly goes up, I don’t think anybody disputes that. The questions about flicker / ADEV all revolve around small blank parts with major edge sensitivity issues. They also probably were not running in a very good oven. Unless somebody with very deep pockets decides they need to find out, it’s going to be an un-answered question. Bob On Nov 1, 2013, at 11:41 PM, Richard (Rick) Karlquist wrote: > > > On 11/1/2013 8:28 PM, Bob Camp wrote: >> HI >> >> If you doubled the diameter of the blank each time you cut the frequency in >> half, all sorts of nice things might happen. If you start with a 1/2” blank >> in at 10 MHz that goes to 1” at 5 MHz and 2” at 2.5 MHz. Around 1 MHz you >> would get to a 5” blank. >> >> Good luck finding high grade quartz bars to cut 5” (or even 1”) blanks out >> of. You are going to have to go back to the autoclave fixtures at the very >> least. Since growth is (at best) linear you cost of quartz will scale with >> the size of the blank. I’d bet it scales a bit more than that if you want to >> keep the material at a high level of performance. > > You've explained the excuses vendors give for not making full > size crystals. But the question is, given these realities, > does this reduce the theoretical advantage of the lower frequency > and by how much? > > Rick Karlquist N6RK > ___ > 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] The 5MHz Sweet Spot
In a free running (non crystal controlled) oscillator, the oscillator with the highest Q (regardless of frequency) will have the best phase noise, if all oscillators are normallized to the same frequency by ideal multiplication. So the Q gain doesn't go away in that sense. Having said that, in crystal oscillators, Q doesn't determine noise in the first place, so the point is moot. Rick Karlquist N6RK On 11/1/2013 8:48 PM, Hal Murray wrote: 1. There is a theoretical QF product for quartz. Being at 5 MHz basically doubles your Q, all other things being equal. Doesn't that Q gain from the QF product go away if you have to PLL it up to 10 MHz or 100 MHz which is what you really want? [I was about to ask why not go to 1 MHz, but Bob Camp answered that already.] ___ 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] The 5MHz Sweet Spot
"If you have a 5” blank, your OCXO scales around it. Yes you can do some neat things, but the package is getting bigger. You now need to convince people to buy OCXO’s that are bigger than anything they have seen since the 1960’s. In most cases that OCXO will be 2 to 10 times larger than their entire sub-system. That’s going to be a tough sell." Does it become more susceptible to microphonics with larger blanks? Bob ___ 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] The 5MHz Sweet Spot
> 1. There is a theoretical QF product for quartz. Being at 5 MHz basically > doubles your Q, all other things being equal. Doesn't that Q gain from the QF product go away if you have to PLL it up to 10 MHz or 100 MHz which is what you really want? [I was about to ask why not go to 1 MHz, but Bob Camp answered that already.] -- These are my opinions. I hate spam. ___ 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] The 5MHz Sweet Spot
On 11/1/2013 8:28 PM, Bob Camp wrote: HI If you doubled the diameter of the blank each time you cut the frequency in half, all sorts of nice things might happen. If you start with a 1/2” blank in at 10 MHz that goes to 1” at 5 MHz and 2” at 2.5 MHz. Around 1 MHz you would get to a 5” blank. Good luck finding high grade quartz bars to cut 5” (or even 1”) blanks out of. You are going to have to go back to the autoclave fixtures at the very least. Since growth is (at best) linear you cost of quartz will scale with the size of the blank. I’d bet it scales a bit more than that if you want to keep the material at a high level of performance. You've explained the excuses vendors give for not making full size crystals. But the question is, given these realities, does this reduce the theoretical advantage of the lower frequency and by how much? Rick Karlquist N6RK ___ 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] The 5MHz Sweet Spot
HI If you doubled the diameter of the blank each time you cut the frequency in half, all sorts of nice things might happen. If you start with a 1/2” blank in at 10 MHz that goes to 1” at 5 MHz and 2” at 2.5 MHz. Around 1 MHz you would get to a 5” blank. Good luck finding high grade quartz bars to cut 5” (or even 1”) blanks out of. You are going to have to go back to the autoclave fixtures at the very least. Since growth is (at best) linear you cost of quartz will scale with the size of the blank. I’d bet it scales a bit more than that if you want to keep the material at a high level of performance. Then you need to cut it / lap it / polish it. All of that gear scales with blank size. That’s the easy part. Now you need to build a cold weld package that will accept your 5” blank. Then you need a proper press to seal it. The ones for the little blanks come in around $2-$3M each. First one you make (with all the back and forth) probably costs you 2X that to develop. Figure the cost will scale with the size of the package. That’s at least straightforward. Its just money. If you have a 5” blank, your OCXO scales around it. Yes you can do some neat things, but the package is getting bigger. You now need to convince people to buy OCXO’s that are bigger than anything they have seen since the 1960’s. In most cases that OCXO will be 2 to 10 times larger than their entire sub-system. That’s going to be a tough sell. No customers = no money to pay for all the fun stuff. Bob On Nov 1, 2013, at 10:56 PM, Richard (Rick) Karlquist wrote: > On 11/1/2013 7:12 PM, Tom Knox wrote: >> A while ago I mentioned 5MHz oscillators were used in most metrology >> applications compared to the more commonly available 10MHz because 5MHz was >> a sweet spot for quartz. At the time I didn't know why. I finally had a >> chance to ask the person I learned this from why. The main reason is simply >> physical size. The larger crystal lattice allows many manufacturing >> advantages that allow for a higher Q. He also explained I was wrong in an >> earlier statement, metal/quartz migration on quartz oscillator was not a >> major problem even after decades, but could become more of a factor if >> driven hard. That does not mean the deposition and lead bonding has no >> negative effect. The BVA solves this by capacitive coupling the quartz >> rather then direct metal deposition. >> >> Thomas Knox >> > > A lot of issues conflated together here. > > 1. There is a theoretical QF product for quartz. Being at 5 MHz basically > doubles your Q, all other things being equal. > > 2. Having a higher Q reduces the contribution of the sustaining > amplifier, but only within the 3 dB bandwidth. With the Q being > in the millions, this is only a few Hz. > > 3. In general, the sustaining amplifier is not a player in > a well designed quartz oscillator in the first place. > > 4. Q probably has a negative correlation with flicker noise, > meaning higher Q is associated with lower flicker noise. > However, the correlation is not strong. There is no theory > that says that Q puts a bound on flicker noise. > > 5. So that leaves us with the larger physical size. Perhaps > it allows higher Q, but again it is unclear how this is connected > with flicker noise. > > 6. You didn't mention the theory that more total atoms of quartz > provides averaging flicker noise over a large population. > > 7. You didn't mention the notion that larger physical size permits > higher drive level. Since the Q is also large, perhaps it doesn't. > Also, a higher drive level is probably only going to help with > far out noise. > > 8. Many, or maybe most, 5 MHz resonators are made with undersized > blanks which are enabled by energy trapping. So we don't have a > simple scaling of all 3 dimensions. What is the effect of this > "cheating"? > > If someone can shed additional light on this, please jump in > and educate us. > > Rick Karlquist N6RK > ___ > 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] The 5MHz Sweet Spot
On 11/1/2013 7:12 PM, Tom Knox wrote: A while ago I mentioned 5MHz oscillators were used in most metrology applications compared to the more commonly available 10MHz because 5MHz was a sweet spot for quartz. At the time I didn't know why. I finally had a chance to ask the person I learned this from why. The main reason is simply physical size. The larger crystal lattice allows many manufacturing advantages that allow for a higher Q. He also explained I was wrong in an earlier statement, metal/quartz migration on quartz oscillator was not a major problem even after decades, but could become more of a factor if driven hard. That does not mean the deposition and lead bonding has no negative effect. The BVA solves this by capacitive coupling the quartz rather then direct metal deposition. Thomas Knox A lot of issues conflated together here. 1. There is a theoretical QF product for quartz. Being at 5 MHz basically doubles your Q, all other things being equal. 2. Having a higher Q reduces the contribution of the sustaining amplifier, but only within the 3 dB bandwidth. With the Q being in the millions, this is only a few Hz. 3. In general, the sustaining amplifier is not a player in a well designed quartz oscillator in the first place. 4. Q probably has a negative correlation with flicker noise, meaning higher Q is associated with lower flicker noise. However, the correlation is not strong. There is no theory that says that Q puts a bound on flicker noise. 5. So that leaves us with the larger physical size. Perhaps it allows higher Q, but again it is unclear how this is connected with flicker noise. 6. You didn't mention the theory that more total atoms of quartz provides averaging flicker noise over a large population. 7. You didn't mention the notion that larger physical size permits higher drive level. Since the Q is also large, perhaps it doesn't. Also, a higher drive level is probably only going to help with far out noise. 8. Many, or maybe most, 5 MHz resonators are made with undersized blanks which are enabled by energy trapping. So we don't have a simple scaling of all 3 dimensions. What is the effect of this "cheating"? If someone can shed additional light on this, please jump in and educate us. Rick Karlquist N6RK ___ 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] The 5MHz Sweet Spot
Hi If you pick one holder, 5 MHz will be “best”. If you pick another holder, 2.5 MHz will be “best”. Pick another one and it will be 20 MHz …. Bob On Nov 1, 2013, at 10:12 PM, Tom Knox wrote: > A while ago I mentioned 5MHz oscillators were used in most metrology > applications compared to the more commonly available 10MHz because 5MHz was a > sweet spot for quartz. At the time I didn't know why. I finally had a chance > to ask the person I learned this from why. The main reason is simply physical > size. The larger crystal lattice allows many manufacturing advantages that > allow for a higher Q. He also explained I was wrong in an earlier statement, > metal/quartz migration on quartz oscillator was not a major problem even > after decades, but could become more of a factor if driven hard. That does > not mean the deposition and lead bonding has no negative effect. The BVA > solves this by capacitive coupling the quartz rather then direct metal > deposition. > > Thomas Knox > > > > ___ > 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] The 5MHz Sweet Spot
A while ago I mentioned 5MHz oscillators were used in most metrology applications compared to the more commonly available 10MHz because 5MHz was a sweet spot for quartz. At the time I didn't know why. I finally had a chance to ask the person I learned this from why. The main reason is simply physical size. The larger crystal lattice allows many manufacturing advantages that allow for a higher Q. He also explained I was wrong in an earlier statement, metal/quartz migration on quartz oscillator was not a major problem even after decades, but could become more of a factor if driven hard. That does not mean the deposition and lead bonding has no negative effect. The BVA solves this by capacitive coupling the quartz rather then direct metal deposition. Thomas Knox ___ 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.
