Re: [time-nuts] Fury OEM GPSDO board
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY In a message dated 10/15/2007 03:51:20 Pacific Daylight Time, [EMAIL PROTECTED] writes: >A week ago I made a PayPal Payment ($575.00). >I heard nothing further. >Could you confirm this payment? Hello Renso, thanks for the inquiry, most units went out today with USPS, and the remaining units will be sent tomorrow. Everyone that paid so far should have their unit soon. Thanks again everyone! Said ** See what's new at http://www.aol.com ___ 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] Improving the stability of crystal oscillators
Don Collie wrote: > Hi Hal, > I was thinking of attaching a temparature sensor [AKA Star Treck] to the > cold side of a Peltier [what`s the other type? Are they available/better?] > pile. and driving the pile from the output of some sort of servo loop to > maintain a temparature of ,say , 0 Degree C. > If you wanted a double oven, you could heatsink a small oven, > containing the crystal, the oscillator, and buffer[s] to this, and use a > second servo loop to raise the temparature of this to 25 Degrees C working > against the Peltier. In this way, you could maintain the crystal, and > circuitry at 25 Deg C., over an ambient temparature of 0 to ,say 70 Deg C. > Yes, you can cut a crystal to have an inversion temp at 25Deg C. [well > certainly with an AT cut - I`m not sure about the SC cut.] > Cheers,Don C. > > - Original Message - > Don With such a wide swing in the temperature differeence across the Peltier stack, you will need to adjust the PID loop parameters to maintain optimum control. A fixed set of parameters is only useful for a temperature range of up to 10C. The Peltier stack performance varies significantly with the temperature difference across the stack. Consequently you also need to sense the peltier device heatsink temperature. Bruce ___ 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] Improving the stability of crystal oscillators
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY This is something I have thought about but never did any experimentation. With the low cost and increased availability of thermoelectric coolers, I am interested in pursuing this concept. The unfortunate thing is that the crystals are ground for 25C or the higher turnover temperature point. If someone has a crystal that has drifted, it may be a good candidate for experimentation. Another thought would be to let the crystal operate at its natural frequency, divide it down to 1 or ten Hz and then phase lock a more convenient crystal frequency to the low pulse rate. The idea is to save an otherwise aged and well performing crystal. John WA4WDL - Original Message - From: "Tom Van Baak" <[EMAIL PROTECTED]> To: "Discussion of precise time and frequency measurement" Sent: Monday, October 15, 2007 10:12 PM Subject: Re: [time-nuts] Improving the stability of crystal oscillators > As far as I can tell, temperature curve plots for quartz typically > show both an upper and a lower turnover point (for example, > see the pages below). Since the upper is well above maximum > ambient, it makes sense that this point is used in O[ven]CXO. > > The question is -- does anyone know if the lower turnover point > (LTP) is ever used? I ask because I heard that a quartz oscillator > might have slightly better short-term stability at the LTP compared > to the UTP. If so, this might argue for the extra trouble of using > TEC for cooling in some low-noise applications. > > /tvb > > http://www.ieee-uffc.org/freqcontrol/tutorials/vig3/vig3_files/slide0164.htm > http://www.ieee-uffc.org/freqcontrol/tutorials/vig3/vig3_files/slide0306.htm > > > ___ > 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] Improving the stability of crystal oscillators
Hi Rick, Perhaps I should have said : "Temperature at which the lowest change of frequency with temperature occurs". What cut of crystal is used in these high quality crystal references, please? Cheers,Don C. - Original Message - From: "Richard (Rick) Karlquist" <[EMAIL PROTECTED]> To: "Don Collie" <[EMAIL PROTECTED]>; "Discussion of precise time and frequency measurement" Sent: Tuesday, October 16, 2007 2:54 PM Subject: Re: [time-nuts] Improving the stability of crystal oscillators > Don Collie wrote: > >> Yes, you can cut a crystal to have an inversion temp at 25Deg C. >> [well certainly with an AT cut - I`m not sure about the SC cut.] >> Cheers,Don C. > > The AT cut has an inflection point at 25 degrees C. You cannot > get a "turnover" (which is what I think you mean an "inversion") > at the inflection point. > > As SC cut inventor Jack Kusters explained to me, the "true" SC cut > has an inflection point temperature of around 85 degrees C. You can get > a turnover above or below this, depending on minor angle changes. > Some crystal fabs make a so called "fake SC" cut where they attempt > to change the inflection point. However, when this is done the stress > compensation is degraded or lost. > > Rick Karlquist N6RK > > > -- > No virus found in this incoming message. > Checked by AVG Free Edition. Version: 7.5.488 / Virus Database: > 269.14.12/1072 - Release Date: 10/15/2007 5:55 PM > ___ 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] Improving the stability of crystal oscillators
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY As far as I can tell, temperature curve plots for quartz typically show both an upper and a lower turnover point (for example, see the pages below). Since the upper is well above maximum ambient, it makes sense that this point is used in O[ven]CXO. The question is -- does anyone know if the lower turnover point (LTP) is ever used? I ask because I heard that a quartz oscillator might have slightly better short-term stability at the LTP compared to the UTP. If so, this might argue for the extra trouble of using TEC for cooling in some low-noise applications. /tvb http://www.ieee-uffc.org/freqcontrol/tutorials/vig3/vig3_files/slide0164.htm http://www.ieee-uffc.org/freqcontrol/tutorials/vig3/vig3_files/slide0306.htm ___ 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] Improving the stability of crystal oscillators
Don Collie wrote: > Yes, you can cut a crystal to have an inversion temp at 25Deg C. [well > certainly with an AT cut - I`m not sure about the SC cut.] > Cheers,Don C. The AT cut has an inflection point at 25 degrees C. You cannot get a "turnover" (which is what I think you mean an "inversion") at the inflection point. As SC cut inventor Jack Kusters explained to me, the "true" SC cut has an inflection point temperature of around 85 degrees C. You can get a turnover above or below this, depending on minor angle changes. Some crystal fabs make a so called "fake SC" cut where they attempt to change the inflection point. However, when this is done the stress compensation is degraded or lost. 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] Improving the stability of crystal oscillators
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hi Hal, I was thinking of attaching a temparature sensor [AKA Star Treck] to the cold side of a Peltier [what`s the other type? Are they available/better?] pile. and driving the pile from the output of some sort of servo loop to maintain a temparature of ,say , 0 Degree C. If you wanted a double oven, you could heatsink a small oven, containing the crystal, the oscillator, and buffer[s] to this, and use a second servo loop to raise the temparature of this to 25 Degrees C working against the Peltier. In this way, you could maintain the crystal, and circuitry at 25 Deg C., over an ambient temparature of 0 to ,say 70 Deg C. Yes, you can cut a crystal to have an inversion temp at 25Deg C. [well certainly with an AT cut - I`m not sure about the SC cut.] Cheers,Don C. - Original Message - From: "Hal Murray" <[EMAIL PROTECTED]> To: "Discussion of precise time and frequency measurement" Sent: Tuesday, October 16, 2007 5:49 AM Subject: Re: [time-nuts] Improving the stability of crystal oscillators > ); SAEximRunCond expanded to false > Errors-To: [EMAIL PROTECTED] RETRY > > >> The resonator inversion temperature occurs at 70-80 degrees Celsius, >> depending on the cut angles. > > Is there something magic about quartz that has a turnover in the region > that > just happens to be handy for OCXOs? Or is it the other way around: people > chose the cut angle to get a temperature that works well for ovens? > > Could I cut a crystal with a temperature at (say) 0C or something handy > for > Peltiers? > > > -- > These are my opinions, not necessarily my employer's. 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. > > > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.5.488 / Virus Database: 269.14.12/1072 - Release Date: > 10/15/2007 5:55 PM > ___ 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] Peltier cooled double crystal oven
Hi Enrico, I accidently deleted your message to me, would you please re-send it to me. Also, I would like to respond to the points you raise on the group, please, so could I please have your permission to do this? Thankingyou,Don C. ___ 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] Info Wanted on O-1814/GRC-206 Rubidium Frequency Standard
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hi: I've received this unit, but know nothing about it. Need power connector voltages and pinout, manual or whatever I can find out. O-1814/GRC-206 Rubidium Frequency Standard -- Have Fun, Brooke Clarke http://www.PRC68.com http://www.precisionclock.com http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam ___ 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] Improving the stability of crystal oscillators
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hal For a summary of the state of the art in Peltier devices etc see: ARTI Report No. 10120-01THERMOELECTRIC TECHNOLOGY ASSESSMENT Final Report May 2007 Dr. Bao Yang A COP up to 6 or so can be achieved at around room temperature. Nanostructured materials have been used to reduce thermal conduction (via phonon scattering) whilst retaining high electrical conduction (minimal electron scattering). There are no known theoretical limits to the figure of merit attainable. However dont expect nanostructured Peltier devices to be readily available for some time. Bruce ___ 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] Improving the stability of crystal oscillators
> Is there something magic about quartz that has a turnover in the > region that > just happens to be handy for OCXOs? Or is it the other way around: > people > chose the cut angle to get a temperature that works well for ovens? First, better heat-only than heat-cool or cool-only because of - efficiency - temperature stability (see my recent mail "against" the Peltier cell) Second, think about the inside of an instrument. Think about a heat- only control. Account for some 5 degrees minimum difference between the quartz and its environment. 70-80 degrees Celsius is the most comfortable temperature. Physicists designed the resonator for the inversion temperature to be 75 deg Celsius. That's it. > Could I cut a crystal with a temperature at (say) 0C or something > handy for > Peltiers? Probably yes, if it made sense. Very best Enrico Rubiola professor of electronics web:http://rubiola.org e-mail: [EMAIL PROTECTED] FEMTO-ST Institute 32 av. de l'Observatoire 25044 Besancon, FRANCE voice: +33(0)381.853940 (E.Rubiola) voice: +33(0)381.853999 (switchboard) fax:+33(0)381.853998 ___ 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] Time-Nuts Archive?
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Thanks for pointing that out, David. I'll see if I can get Mailman to change that robot tag (it's automagically created). John Dr. David Kirkby said the following on 10/15/2007 05:02 PM: > ); SAEximRunCond expanded to false > Errors-To: [EMAIL PROTECTED] RETRY > > Jason Rabel wrote: >> >>> Is there an archive of past digests that I can search >>> for useful tidbits of information? >>> >> Yes!!! >> >> http://www.febo.com/pipermail/time-nuts/ >> >> I've spent hours on end sifting through them. Google hasn't indexed the info >> completely for some reason (maybe too many links per page?). > > > The reason Google does not index it is probably has something to do with > the following line I see in the HTML: > > > > > > > > ___ > 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] Time-Nuts Archive?
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Jason Rabel wrote: > >> Is there an archive of past digests that I can search >> for useful tidbits of information? >> > > Yes!!! > > http://www.febo.com/pipermail/time-nuts/ > > I've spent hours on end sifting through them. Google hasn't indexed the info > completely for some reason (maybe too many links per page?). The reason Google does not index it is probably has something to do with the following line I see in the HTML: ___ 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] Improving the stability of crystal oscillators
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY > The resonator inversion temperature occurs at 70-80 degrees Celsius, > depending on the cut angles. Is there something magic about quartz that has a turnover in the region that just happens to be handy for OCXOs? Or is it the other way around: people chose the cut angle to get a temperature that works well for ovens? Could I cut a crystal with a temperature at (say) 0C or something handy for Peltiers? -- These are my opinions, not necessarily my employer's. 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] Improving the stability of crystal oscillators
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Dear all, the major problem for the use of a Peltier cell with a quartz oscillator is that the cell maximum operating temperature is of the order of 80 degrees Celsius. This is due to the low melting point of the metal pairs suitable to produce the Peltier effect (reversed thermocouple). The resonator inversion temperature occurs at 70-80 degrees Celsius, depending on the cut angles. A more general problem is that a good temperature controlled oven has high thermal resistance, limited by the dissipation inside the oven. Unfortunately, the Peltier cell has low thermal resistance, which means poor isolation from the oven. This problem is made worse by the joule effect, which always go with the Peltier effect. For this reason, the temperature fluctuations of the Peltier heat sink tend to be larger than the environment fluctuations (unless you use water cooling!). Thus, the thermal fluctuations propagating through the Peltier cell tend to be an amplified version of the environment fluctuation. This phenomenon is dramatic when the Peltier cools down, and a minor problem when the Peltier cell heats up. Very best, Enrico On 13 Oct 2007, at 22:13 , Don Collie wrote: > ); SAEximRunCond expanded to false > Errors-To: [EMAIL PROTECTED] RETRY > > Has anyone concidered using a small Peltier pile to maintain the > crystal`s > temparature. I understand that these devices will heat or cool, so > it would > be possible to maintain the crystal temparature at , say, 25 degrees > celcius, over a range of ambient temparatures > [perhaps 0 to 70 degrees]. There would be several advantages in this > approach. > Cheers!,Don Collie jnr. > > > ___ > 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. Enrico Rubiola professor of electronics web:http://rubiola.org e-mail: [EMAIL PROTECTED] FEMTO-ST Institute 32 av. de l'Observatoire 25044 Besancon, FRANCE voice: +33(0)381.853940 (E.Rubiola) voice: +33(0)381.853999 (switchboard) fax:+33(0)381.853998 ___ 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.
