Re: [time-nuts] Oscillators and Ovens

Hi I would say there are *very* few companies out there that will sell you high grade precision OCXO crystals in single piece quantities. I think you would get one much quicker and cheaper by pulling it out of an eBay OCXO. You can do good far removed phase noise with a lot of crystals.

Re: [time-nuts] Oscillators and Ovens

Hi Jim, On Wed, 1 Nov 2017 11:39:32 -0700 jimlux wrote: > So, it would be nice to have a *cheap* lowish power packaged part that > has the Q of an OCXO, but without the power consumption of the oven > (typically measured in watts). > > yeah, I'd be operating it *way*

Re: [time-nuts] Oscillators and Ovens

On 11/1/17 1:38 PM, Hal Murray wrote: In general, OCXOs have crystals with high Q -> low phase noise, especially compared to a TCXO, which *can't* have high Q, or the temperature compensation circuit can't do it's work. I don't understand that. Why can't I build a high Q TCXO? I don't

Re: [time-nuts] Oscillators and Ovens

Hi As mentioned in Rick’s post, it’s not really Q, it’s the motional capacitance that is the issue. Even if you resonate out C0, you still have to deal with Cm. The only practical high Q designs for crystals are very low Cm resonators. Yes, if you could do a design that had Rm of 0.1 ohms it

Re: [time-nuts] Oscillators and Ovens

On 11/1/2017 3:44 PM, Dana Whitlow wrote: Bob, This discussion is getting really interesting. In thinking about the crystal Q versus tuning range conundrum, two (presumably-overlapping) concerns come to mind: 1. The motional parameters of a high-Q crystal are such that the external network

Re: [time-nuts] Oscillators and Ovens

Bob, This discussion is getting really interesting. In thinking about the crystal Q versus tuning range conundrum, two (presumably-overlapping) concerns come to mind: 1. The motional parameters of a high-Q crystal are such that the external network needed to pull it very far would be wholly

Re: [time-nuts] Oscillators and Ovens

Hi A high Q crystal by design is very difficult to tune. Putting it in a circuit that will swing it far enough to compensate it degrades the Q. In addition, thermal noise will come into the compensation circuit (even if it is noise free) and degrade things. Bob > On Nov 1, 2017, at 4:38 PM,

Re: [time-nuts] Oscillators and Ovens

On Wed, November 1, 2017 3:38 pm, Hal Murray wrote: > >> In general, OCXOs have crystals with high Q -> low phase noise, >> especially >> compared to a TCXO, which *can't* have high Q, or the temperature >> compensation circuit can't do it's work. > > I don't understand that. Why can't I build a

Re: [time-nuts] Oscillators and Ovens

> In general, OCXOs have crystals with high Q -> low phase noise, especially > compared to a TCXO, which *can't* have high Q, or the temperature > compensation circuit can't do it's work. I don't understand that. Why can't I build a high Q TCXO? I don't need to change the compensation very

Re: [time-nuts] Oscillators and Ovens

On 11/1/17 10:59 AM, Attila Kinali wrote: Hi Jim, On Wed, 1 Nov 2017 06:17:31 -0700 jimlux wrote: That's why I wish they'd sell OCXOs, cheap, without the oven. Or maybe look for regular XO (no TC). Those might have a more "pure" (read lower order) freq vs temp

[time-nuts] Oscillators and Ovens (was: Designing an embedded precision GPS time)

Hi Jim, On Wed, 1 Nov 2017 06:17:31 -0700 jimlux wrote: > That's why I wish they'd sell OCXOs, cheap, without the oven. Or maybe > look for regular XO (no TC). Those might have a more "pure" (read lower > order) freq vs temp characteristic. It feels like I have asked

Re: [time-nuts] oscillators

Hi Observing a curve and being able to compensate it are often two different things. Hysteresis is one very obvious example. Another is simple sensor lag. A some what less obvious one is that the temperature performance is also influenced by the rate of change in temperature. Here's another

Re: [time-nuts] oscillators

On 9/1/12 8:32 AM, Bob Camp wrote: Hi Observing a curve and being able to compensate it are often two different things. Hysteresis is one very obvious example. Another is simple sensor lag. A some what less obvious one is that the temperature performance is also influenced by the rate of

Re: [time-nuts] oscillators

Hi I suspect that a good IT cut would probably do better than an SC in either application. In the deep space situation, a copper slug in a dewar sounds like a reasonable addition to the design. Bob On Sep 1, 2012, at 11:53 AM, Jim Lux jim...@earthlink.net wrote: On 9/1/12 8:32 AM, Bob Camp

Re: [time-nuts] oscillators

On 09/01/2012 05:53 PM, Jim Lux wrote: On 9/1/12 8:32 AM, Bob Camp wrote: Hi Observing a curve and being able to compensate it are often two different things. Hysteresis is one very obvious example. Another is simple sensor lag. A some what less obvious one is that the temperature performance

Re: [time-nuts] oscillators

On 9/1/12 11:00 AM, Bob Camp wrote: Hi I suspect that a good IT cut would probably do better than an SC in either application. In the deep space situation, a copper slug in a dewar sounds like a reasonable addition to the design. If you're going to do dewars, then you're talking USOs for

Re: [time-nuts] oscillators

Hi True on the volume and weight. Not as much power as an OCXO since it's passive. At 1x 2 x 0.5 you could fix the power and weight by using an EMXO. You still would have more power than the TCXO, but no were near as much as the couple watts a USO uses. Bob Bob On Sep 1, 2012, at 10:41 PM,

Re: [time-nuts] oscillators

El 30/08/2012 20:53, saidj...@aol.com escribió: There are some drawbacks to this type of SC-cut MCXO I would think, and it could possibly be replaced by a much higher performance Symmetricom CSAC, probably at a lower cost and higher availability: * Q-tech MCXO is ITAR controlled, CSAC is not

Re: [time-nuts] oscillators

Hi An SC is going to have it's temperature curve centered up around 95C or so. If it's been cut as an OCXO crystal the turns will be up there as well. By the time it gets to room temp, the delta F / delta T is moving mighty fast. Think in terms of multiple ppm/C. A typical cell phone TCXO

Re: [time-nuts] oscillators

On 8/31/12 7:06 AM, Bob Camp wrote: Hi An SC is going to have it's temperature curve centered up around 95C or so. If it's been cut as an OCXO crystal the turns will be up there as well. By the time it gets to room temp, the delta F / delta T is moving mighty fast. Think in terms of multiple

Re: [time-nuts] oscillators

Hi Ok, that gets you back to the basics of really major delta F / delta T slopes. Bob On Aug 31, 2012, at 8:55 PM, Jim Lux jim...@earthlink.net wrote: On 8/31/12 7:06 AM, Bob Camp wrote: Hi An SC is going to have it's temperature curve centered up around 95C or so. If it's been cut as an

Re: [time-nuts] oscillators

On 8/31/12 7:16 PM, Bob Camp wrote: Hi Ok, that gets you back to the basics of really major delta F / delta T slopes. Bob yeah.. but as long as you know what the curve is.. the NCO has a huge range (after all, we already have to tune over 500 kHz...a few hundred Hz isn't a big deal. A

Re: [time-nuts] oscillators

Hi An OCXO crystal needs to be good only at one temperature. The crystal in an MCXO needs to do well over a wide range of temperatures. That complicates things quite a bit. Bob On Aug 30, 2012, at 12:22 AM, Hal Murray hmur...@megapathdsl.net wrote: rich...@karlquist.com said: No it

Re: [time-nuts] oscillators

Hi The typical watch crystal has a parabolic temperature coefficient with it's peak near 90F. The slope (and difficulty of correction) goes up as you move away from the peak. A simple drop / add one cycle (or do nothing) in a second approach would be adequate to do all the steering needed.

Re: [time-nuts] oscillators

On 8/29/12 8:45 PM, Richard (Rick) Karlquist wrote: On 8/27/2012 11:45 PM, WB6BNQ wrote: A microprocessor controlled XO is a non oven crystal oscillator system that has additional computational control providing a bit more than just mere passive temperature compensation. The additional

Re: [time-nuts] oscillators

On 8/29/12 9:22 PM, Hal Murray wrote: rich...@karlquist.com said: No it doesn't use a cheap crystal. It uses a *special* SC cut crystal. This crystal could very easily cost more than an OCXO crystal. http://www.q-tech.com/mcxo.html What's special about it? Has to support the overtones

Re: [time-nuts] oscillators

on the crystal. No matter what you do, it adds cost. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Jim Lux Sent: Thursday, August 30, 2012 8:55 AM To: time-nuts@febo.com Subject: Re: [time-nuts] oscillators On 8/29/12 8:45 PM, Richard

Re: [time-nuts] oscillators

Hal Murray wrote: rich...@karlquist.com said: No it doesn't use a cheap crystal. It uses a *special* SC cut crystal. This crystal could very easily cost more than an OCXO crystal. What's special about it? First, it has to have no activity dips over the full operating temperature range.

Re: [time-nuts] oscillators

There are some drawbacks to this type of SC-cut MCXO I would think, and it could possibly be replaced by a much higher performance Symmetricom CSAC, probably at a lower cost and higher availability: * Q-tech MCXO is ITAR controlled, CSAC is not * MCXO has 20ppb over temp stability, CSAC has

Re: [time-nuts] oscillators

...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of saidj...@aol.com Sent: Thursday, August 30, 2012 2:54 PM To: rich...@karlquist.com; time-nuts@febo.com Subject: Re: [time-nuts] oscillators There are some drawbacks to this type of SC-cut MCXO I would think, and it could possibly

Re: [time-nuts] oscillators

On 08/30/2012 06:33 PM, Bob Camp wrote: Hi The fundamental / third approach is one of several possible ways to go. You can also run an SC on the B and C modes to get thermometer data. Early implementations used a pair of independent blanks, one cut to be a good thermometer. Some have even gone

Re: [time-nuts] oscillators

On 30 Aug, 2012, at 13:14 , Rick Karlquist wrote: The other area where a uP is useful is in an environment with high vibration. It can correct for acceleration as well as temperature. There I've never heard of this being done. Do you have a reference? I'm not sure how that would be done

Re: [time-nuts] oscillators

Interesting this third overtone/fundamental*3 idea but what makes the third overtone not equal to the fundamental*3? Is the crystal operated in series or parallel resonance? On Thu, Aug 30, 2012 at 10:30 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 08/30/2012 06:33 PM, Bob Camp

Re: [time-nuts] oscillators

Azelio Boriani wrote: Interesting this third overtone/fundamental*3 idea but what makes the third overtone not equal to the fundamental*3? Is the crystal operated in series or parallel resonance? That is where the special SC cut crystal comes into play. It's not so much that the 3rd OT is on

Re: [time-nuts] oscillators

Hi It turns out that the fundamental is not quite 1/3 of the third overtone. You can impact the degree of offset by changing the contour of the blank. The temperature coefficient is also different on the fundamental. The net result is that you can get a pretty good thermometer reading by

Re: [time-nuts] oscillators

Hi You can do the same thing with an AT as with an SC. They both exhibit the fundamental / third offset and tempo delta. Bob On Aug 30, 2012, at 5:10 PM, Rick Karlquist rich...@karlquist.com wrote: Azelio Boriani wrote: Interesting this third overtone/fundamental*3 idea but what makes the

Re: [time-nuts] oscillators

On 08/30/2012 11:10 PM, Rick Karlquist wrote: Azelio Boriani wrote: Interesting this third overtone/fundamental*3 idea but what makes the third overtone not equal to the fundamental*3? Is the crystal operated in series or parallel resonance? That is where the special SC cut crystal comes

Re: [time-nuts] oscillators

rich...@karlquist.com said: The other area where a uP is useful is in an environment with high vibration. It can correct for acceleration as well as temperature. I've never heard of this being done. Do you have a reference? This is probably the paper I was thinking of. Looks like I made

Re: [time-nuts] oscillators

On 8/30/12 9:33 AM, Bob Camp wrote: Hi The fundamental / third approach is one of several possible ways to go. You can also run an SC on the B and C modes to get thermometer data. Early implementations used a pair of independent blanks, one cut to be a good thermometer. Some have even gone as

Re: [time-nuts] oscillators

On 8/30/12 12:37 PM, Bob Camp wrote: Hi The original patents on the MCXO are government property. One of the Ft. Monmouth guys came up with the fundamental / third overtone idea back in the 80's. Several (at least three) companies were licensed by the government to make the part. Gotta be

Re: [time-nuts] oscillators

Elecraft seems to be having some trouble with the KX3 stability for WSJT on 6m. They also have a temp sensor on the bard, apparently and are also trying this out. I don't know any more about it than that. Don Jim Lux On 8/30/12 9:33 AM, Bob Camp wrote: Hi The fundamental / third approach is

Re: [time-nuts] oscillators

Hi The guy(s) who did the original work were indeed full time DOD employees. Bob On Aug 30, 2012, at 8:11 PM, Jim Lux jim...@earthlink.net wrote: On 8/30/12 12:37 PM, Bob Camp wrote: Hi The original patents on the MCXO are government property. One of the Ft. Monmouth guys came up with

Re: [time-nuts] oscillators

Hi If the temperature is varying slowly *and* there are no gradients you may get your order of magnitude over some range. You might be surprised at your TCXO. A lot of them are pretty darn good in the vicinity of room temp. You may already be an order of magnitude past your ppm or two for

Re: [time-nuts] oscillators

On 08/31/2012 03:12 AM, Bob Camp wrote: Hi If the temperature is varying slowly *and* there are no gradients you may get your order of magnitude over some range. You might be surprised at your TCXO. A lot of them are pretty darn good in the vicinity of room temp. You may already be an order

Re: [time-nuts] oscillators

Hi Some TCXO's have less hysteresis than others…... Bob On Aug 30, 2012, at 9:29 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 08/31/2012 03:12 AM, Bob Camp wrote: Hi If the temperature is varying slowly *and* there are no gradients you may get your order of magnitude over

Re: [time-nuts] oscillators

...@earthlink.net Sent: Thursday, August 30, 2012 8:11 PM To: time-nuts@febo.com Subject: Re: [time-nuts] oscillators On 8/30/12 12:37 PM, Bob Camp wrote: Hi The original patents on the MCXO are government property. One of the Ft. Monmouth guys came up with the fundamental / third overtone idea

Re: [time-nuts] oscillators

Hi I think they would do better to just put in a connector to drive it with a TBolt…. Bob On Aug 30, 2012, at 8:47 PM, Don Latham d...@montana.com wrote: Elecraft seems to be having some trouble with the KX3 stability for WSJT on 6m. They also have a temp sensor on the bard, apparently and

Re: [time-nuts] oscillators

I helped license government patents to companies. John -- From: Jim Lux jim...@earthlink.net Sent: Thursday, August 30, 2012 8:11 PM To: time-nuts@febo.com Subject: Re: [time-nuts] oscillators On 8/30/12 12:37 PM, Bob Camp wrote: Hi

Re: [time-nuts] oscillators

On 8/30/12 6:12 PM, Bob Camp wrote: Hi If the temperature is varying slowly *and* there are no gradients you may get your order of magnitude over some range. You might be surprised at your TCXO. A lot of them are pretty darn good in the vicinity of room temp. You may already be an order of

Re: [time-nuts] oscillators

On 8/30/12 6:29 PM, Magnus Danielson wrote: On 08/31/2012 03:12 AM, Bob Camp wrote: Hi If the temperature is varying slowly *and* there are no gradients you may get your order of magnitude over some range. You might be surprised at your TCXO. A lot of them are pretty darn good in the vicinity

Re: [time-nuts] oscillators

Hi A standard clock crystal is pretty much junk. as far as temperature performance is concerned. Even a cheap TCXO is likely to be pretty good over 25 C +/- 10C. Bob On Aug 30, 2012, at 11:35 PM, Jim Lux jim...@earthlink.net wrote: On 8/30/12 6:12 PM, Bob Camp wrote: Hi If the

Re: [time-nuts] oscillators

On 8/30/12 9:04 PM, Bob Camp wrote: Hi A standard clock crystal is pretty much junk. as far as temperature performance is concerned. Even a cheap TCXO is likely to be pretty good over 25 C +/- 10C. yes.. but, say, one had a decent SC cut with good phase noise properties, but large (but

Re: [time-nuts] oscillators

Bob: Great minds run in the same track :-) Don Bob Camp Hi I think they would do better to just put in a connector to drive it with a TBolt…. Bob On Aug 30, 2012, at 8:47 PM, Don Latham d...@montana.com wrote: Elecraft seems to be having some trouble with the KX3 stability for WSJT on

Re: [time-nuts] oscillators

On 8/27/2012 11:45 PM, WB6BNQ wrote: A microprocessor controlled XO is a non oven crystal oscillator system that has additional computational control providing a bit more than just mere passive temperature compensation. The additional computational capability deals with having coefficients

Re: [time-nuts] oscillators

Does anyone know about what technology is used in Swiss watches to get much better performance from their xtals than you might expect? I assumed that they had look up lists to insert extra counts to compensate for ambient variations, but I have never heard any details. cheers, Neville Michie

Re: [time-nuts] oscillators

nippedLe 30/08/2012 06:12, Neville Michie a écrit : Does anyone know about what technology is used in Swiss watches to get much better performance from their xtals than you might expect? I assumed that they had look up lists to insert extra counts to compensate for ambient variations, but I

Re: [time-nuts] oscillators

Well, basically the temperature of a wrist watch is very constant at around 90F. That and a table lookup that gives an adjustment for number of cycles per tick vs temperature. All quartz watches since about 1990 are microprocessor based, and have a table lookup. They can only be regulated

Re: [time-nuts] oscillators

rich...@karlquist.com said: No it doesn't use a cheap crystal. It uses a *special* SC cut crystal. This crystal could very easily cost more than an OCXO crystal. What's special about it? I assume the cost-more aspect would be to allow an overall goodness factor competitive with an OCXO in

Re: [time-nuts] oscillators

Well, basically the temperature of a wrist watch is very constant at around 90F. That and a table lookup that gives an adjustment for number of cycles per tick vs temperature. My introduction to this area was roughly a comment like that. The other half of the comment was that watches keep

Re: [time-nuts] oscillators

Chris, That is a big no ! What the Thunderbolt is doing is adjusting the OCXO to keep it aligned with a known reference from the GPS system. The fact that a microprocessor is involved is from a totally different perspective. A microprocessor controlled XO is a non oven crystal oscillator

Re: [time-nuts] oscillators

On 8/27/12 10:45 PM, Chris Albertson wrote: On Mon, Aug 27, 2012 at 7:33 PM, Jim Lux jim...@earthlink.net wrote: On 8/27/12 4:15 PM, Rick Karlquist wrote: Several decades ago, the concept of the smart clock arose at what was then HP. The idea was as discussed here to characterize past

Re: [time-nuts] oscillators

On Mon, Aug 27, 2012 at 11:45 PM, WB6BNQ wb6...@cox.net wrote: Chris, That is a big no ! What the Thunderbolt is doing is adjusting the OCXO to keep it aligned with a known reference from the GPS system. The fact that a microprocessor is involved is from a totally different perspective.

Re: [time-nuts] oscillators

On Tue, Aug 28, 2012 at 6:17 AM, Jim Lux jim...@earthlink.net wrote: The MCXO has a one time calibration for frequency vs temperature that's programmed into it (and some use *very* clever ways to measure the temperature). The disciplining algorithms in a GPSDO are a bit smarter; Yes,

Re: [time-nuts] oscillators

] On Behalf Of Chris Albertson Sent: Tuesday, August 28, 2012 12:19 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] oscillators On Tue, Aug 28, 2012 at 6:17 AM, Jim Lux jim...@earthlink.net wrote: The MCXO has a one time calibration for frequency vs temperature

[time-nuts] oscillators

I don't know that there is any data showing the TBolt adjusting for aging during holdover. In other words: showing the holdover DAC voltage changing at a completely constant temperature. Bob I haven't seen any data either but here is information from section 5.1.2 of the 2003 Thunderbolt

Re: [time-nuts] oscillators

28, 2012 1:02 PM To: time-nuts@febo.com Subject: [time-nuts] oscillators I don't know that there is any data showing the TBolt adjusting for aging during holdover. In other words: showing the holdover DAC voltage changing at a completely constant temperature. Bob I haven't seen any data either

[time-nuts] oscillators

On 8/27/12 4:15 PM, Rick Karlquist wrote: Several decades ago, the concept of the smart clock arose at what was then HP. The idea was as discussed here to characterize past aging, predict future aging, and then correct the aging. The goal wasn't to turn a quartz oscillator into an atomic clock

Re: [time-nuts] oscillators

On Mon, Aug 27, 2012 at 7:33 PM, Jim Lux jim...@earthlink.net wrote: On 8/27/12 4:15 PM, Rick Karlquist wrote: Several decades ago, the concept of the smart clock arose at what was then HP. The idea was as discussed here to characterize past aging, predict future aging, and then correct

Re: [time-nuts] Oscillators on eBay

Hi, I listed some frequency standard related items on eBay and will be listing some more in the next week or so. search items by seller corbymite Cheers! Corby Dawson Get credit card help today. Safe, fast, and easy. Click Now.