Re: [time-nuts] Super stable BVA Quartz resonators... BVA??
Bruce Griffiths wrote: Bernd T-Online wrote: Bi-convex contours are more difficult to manufacture, as it is required that the symmetry axis of the upper and lower contour must coincide. Also other parameters become worse. For the BVA the manufacturability would also be much worse as it already is. Regards Bernd DK1AG Bernd Whilst traditional optical edging techniques can easily remove any wedge when both surfaces are convex, maintaining alignment of the lens axis with respect to the crystal axes is another matter, at least when using traditional surfacing techniques, with computer controlled surfacing techniques even this can be done. With a planoconvex lens bias polishing or an equivalent technique can be used to adjust the inclination of the plano surface with respect to the crystal axes and this alignment is maintained during edging leaving only axial thickness adjustments to be made. The etching process used to remove cracks and defects after mechanical polishing is anisotropic which may introduce further complications in maintaining alignment and shape. Bruce So Bruce, what source did you read that led you to change your original answer from --it's easy--, to --it's difficult--? (reference your quoted text below: Bi-convex contours are more difficult to manufacture, as it is required that the symmetry axis of the upper and lower contour must coincide. That problem was solved over a century ago in optical lens manufacture. If the two surfaces are spherical, then such decentering is equivalent to adding a wedge, which is easily removed by optical centering and edging techniques. Also other parameters become worse. For the BVA the manufacturability would also be much worse as it already is. -Chuck Harris ___ 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] Super stable BVA Quartz resonators... BVA??
Chuck Harris wrote: Bruce Griffiths wrote: Bernd T-Online wrote: Bi-convex contours are more difficult to manufacture, as it is required that the symmetry axis of the upper and lower contour must coincide. Also other parameters become worse. For the BVA the manufacturability would also be much worse as it already is. Regards Bernd DK1AG Bernd Whilst traditional optical edging techniques can easily remove any wedge when both surfaces are convex, maintaining alignment of the lens axis with respect to the crystal axes is another matter, at least when using traditional surfacing techniques, with computer controlled surfacing techniques even this can be done. With a planoconvex lens bias polishing or an equivalent technique can be used to adjust the inclination of the plano surface with respect to the crystal axes and this alignment is maintained during edging leaving only axial thickness adjustments to be made. The etching process used to remove cracks and defects after mechanical polishing is anisotropic which may introduce further complications in maintaining alignment and shape. Bruce So Bruce, what source did you read that led you to change your original answer from --it's easy--, to --it's difficult--? (reference your quoted text below: No reference (unless you want references to optical manufacturing techniques), its obvious when you stop to think about it, the various crystal cuts (AT, BT, SC etc) require a specific crystallographic orientation, changing the orientation changes the characteristics. When I realised that Bernd hadn't explicitly stated the requirement to maintain crystallographic alignment when contouring the 2 surfaces the real cause of the difficulty of manufacture became obvious. Introducing wedge when generating the spherical (other contours are much more difficult to produce unless one uses computer controlled equipment together with optical shape measurement) surfaces is geometrically equivalent to changing the crystallographic orientation of the blank. This doesnt arise when imparting a spherical contour to only one surface, as the plane surface defines the crystallographic orientation before and after removing any wedge using optical centering/edging techniques. The original statement merely indicated that well known techniques provide a solution to his actual statement of the problem of centering the 2 surfaces. Bi-convex contours are more difficult to manufacture, as it is required that the symmetry axis of the upper and lower contour must coincide. That problem was solved over a century ago in optical lens manufacture. If the two surfaces are spherical, then such decentering is equivalent to adding a wedge, which is easily removed by optical centering and edging techniques. Also other parameters become worse. For the BVA the manufacturability would also be much worse as it already is. -Chuck Harris ___ 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] Super stable BVA Quartz resonators... BVA??
Jeff Mock wrote: How does crystal aging look on a graph of temp versus frequency What does this graph look like as a crystal ages? Does the optimal operating temperature change over time, that is, does the graph tend to move left and right, or does aging tend to move the graph vertically (the optimal freq stays the same, but the optimal operating temperature changes as a result of aging). I can confirm Rick's statement, that there is no noticable effect of aging on the turnover temperature (TOT). Looking at it from physics standpoint, frequncy aging is mainly caused by minor changes of vibrating mass and/or by changes in elastic properties (both due to various mechanisms). See my earlier thrad on aging mechanisms. On the other hand, the turn-over temperature is primarily governed by the cut angle (in connection with the resonator shape etc.). Mass loading, i.e. changes of electrode mass, has also an infuence, but this is much weaker. Roughly stated: a change of the TOT by one degC may be caused by a variation of the mass loading by an amount eqivalent to a frequency change of n*1000 ppm or so. This means that usual long term aging of precision crystals of a few 100 ppb or even one or two ppm may cause changes of TOT in the range of mK or less, which is - much smaller than the accuracy of the determination of TOT - neglictable compared to the impact of the aging of thermistors and of the frequency determining capacitors and inductors of the sustaining oscillator stage Regards Bernd DK1AG ___ 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] Super stable BVA Quartz resonators... BVA??
In message [EMAIL PROTECTED], Bernd T-Online writes: Jeff Mock wrote: I can confirm Rick's statement, that there is no noticable effect of aging on the turnover temperature (TOT). You got me wondering: How is the TOT determined ? Is it per unit or is it per batch ? How precisely does an OCXO hold the temperature on the TOT ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 [EMAIL PROTECTED] | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Super stable BVA Quartz resonators... BVA??
Poul-Henning Kamp wrote: You got me wondering: How is the TOT determined ? Is it per unit or is it per batch ? How precisely does an OCXO hold the temperature on the TOT ? For crystals used in precision OCXO the TOT is measured and recorded per unit. There are two main methods: passive and active In the passive method the crystal is inserted in a test fixture and its frequency and other parameters are measured using a network analyzer (state of the art). The crystals with its test fixture is in a precision temperature chamber, whose temperature is varied in fine steps in the vicinity of the expected TOT. The TOT is then calculated by curve fitting of the f(T) data by using a 2nd or 3rd order curve fitting algorithm, depending on the temperature span. Accuracy and repeatability are in the range of a (few) tenth of a degC. In the active method the crystal is operating in its oven, whose temperature is varied over a certain interval. Evaluation of the TOT by similar curve fitting as above. Accuracy and reproducibility is about 1/100 degC or slightly better. The temperature accuracy and stability of an oven dpends strongly on its construction, and there are several orders of magnitude difference betewen a simple low-cost DIL14 size OCXO and a high-end OCXO with sub-ppb stability. THe electronic part of the temperature control is not the difficult task, the main issue is to have a UNIFORM temperature over all frequency determining components, which is accurate and stable - and uniformity needs physical size. Regarding stability over time, the most critical components are the temperature sensors, mostly thermistors. Regards Bernd DK1AG ___ 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] Super stable BVA Quartz resonators... BVA??
Bernd T-Online [EMAIL PROTECTED] wrote: I can confirm Rick's statement, that there is no noticable effect of aging on the turnover temperature (TOT). Looking at it from physics standpoint, frequncy aging is mainly caused by minor changes of vibrating mass and/or by changes in elastic properties (both due to various mechanisms). See my earlier thrad on aging mechanisms. On the other hand, the turn-over temperature is primarily governed by the cut angle (in connection with the resonator shape etc.). Mass loading, i.e. changes of electrode mass, has also an infuence, but this is much weaker. Roughly stated: a change of the TOT by one degC may be caused by a variation of the mass loading by an amount eqivalent to a frequency change of n*1000 ppm or so. This means that usual long term aging of precision crystals of a few 100 ppb or even one or two ppm may cause changes of TOT in the range of mK or less, which is - much smaller than the accuracy of the determination of TOT - neglictable compared to the impact of the aging of thermistors and of the frequency determining capacitors and inductors of the sustaining oscillator stage For a while, didn't HP sell temperature probes which were in fact quartz crystals? Oscillation frequency was converted by some simple electronics to a temperature, and at the time (60's?) they were exquisitely convenient for measuring way better than a tenth of a degree. Either the frequency drift was negligible or it was so slow that I don't remember any manual removal of frequency drift effects. I'm guessing the probe crystals were some special cut (don't know which!) which was fairly linear or at least monotonic over the measurement temperatures. I'm guessing that HP chose a cut which had a very large tempco such that tempco dominated over any frequency drift. Tim. ___ 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] Super stable BVA Quartz resonators... BVA??
Tim Shoppa escribió: For a while, didn't HP sell temperature probes which were in fact quartz crystals? Oscillation frequency was converted by some simple electronics to a temperature, and at the time (60's?) they were exquisitely convenient for measuring way better than a tenth of a degree. Either the frequency drift was negligible or it was so slow that I don't remember any manual removal of frequency drift effects. At least one model is the 2804A. Not much info about it in the Agilent web site, but according to the 1986 catalog 'the temperature sensor is a quartz crystal whose precise angle of cut gives an stable and repeatable relationship between the resonant frequency and temperature'. But also is mentioned there that 'The only adjustment necessary to remove effects of thermal history on the sensor is a simple ice point or triple point calibration adjustment using the front panel thumbwheel switches'. Since the ice-point calibration would only be able to remove an offset, I understand that this is the manual removal of frequency drift effects. Of course, I suppose that the dritft would be small compared with the quartz temperature coefficient. Anyway, a 10544 oscillator has a cold offset that can easily be of 1000Hz, so if at 80 deg. C the offset is zero, and at 25 deg. C the offset is 1000Hz, you easily have a rough 15Hz/deg C average tempco in that range - and the aging drift for this oscillator is quite less than that. Best regards, Javier, EA1CRB ___ 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] Super stable BVA Quartz resonators... BVA??
Javier [EMAIL PROTECTED] wrote: Tim Shoppa escribi?: For a while, didn't HP sell temperature probes which were in fact quartz crystals? Oscillation frequency was converted by some simple electronics to a temperature, and at the time (60's?) they were exquisitely convenient for measuring way better than a tenth of a degree. Either the frequency drift was negligible or it was so slow that I don't remember any manual removal of frequency drift effects. At least one model is the 2804A. Not much info about it in the Agilent web site, but according to the 1986 catalog 'the temperature sensor is a quartz crystal whose precise angle of cut gives an stable and repeatable relationship between the resonant frequency and temperature'. But also is mentioned there that 'The only adjustment necessary to remove effects of thermal history on the sensor is a simple ice point or triple point calibration adjustment using the front panel thumbwheel switches'. Since the ice-point calibration would only be able to remove an offset, I understand that this is the manual removal of frequency drift effects. Of course, I suppose that the dritft would be small compared with the quartz temperature coefficient. Anyway, a 10544 oscillator has a cold offset that can easily be of 1000Hz, so if at 80 deg. C the offset is zero, and at 25 deg. C the offset is 1000Hz, you easily have a rough 15Hz/deg C average tempco in that range - and the aging drift for this oscillator is quite less than that. Very interesting, Javier. I'm guessing the 2804A was a 70's implementation if it had thumbwheels. Thanks for posting the details you found! The unit I remember was not digital in the readout sense - it worked like a Fluke differential voltmeter, where you dial in some big rotary switches until you get a null on an analog meter. I may be confusing a 60's era Fluke temperature probe with the HP probes though! Who else would've been building quartz temperature probes in the 60's? Fluke, Beckman, ??? And what cut crystal matches the need for a huge and mostly linear tempco? Tim. ___ 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] Super stable BVA Quartz resonators... BVA??
Tim Shoppa wrote: For a while, didn't HP sell temperature probes which were in fact quartz crystals? Oscillation frequency was converted by some simple electronics to a temperature, and at the time (60's?) they were exquisitely convenient for measuring way better than a tenth of a degree. Either the frequency drift was negligible or it was so slow that I don't remember any manual removal of frequency drift effects. I'm guessing the probe crystals were some special cut (don't know which!) which was fairly linear or at least monotonic over the measurement temperatures. I'm guessing that HP chose a cut which had a very large tempco such that tempco dominated over any frequency drift. They did indeed. This was the HP2801A, later followed by the HP2804A. It uses a so-called LC-cut (Linear Coefficient) quartz crystal sensor, which is a doubly rotated cut with ultra-linear frequency vs. temperature characteristic with a slope of 35.4 ppm/K. For more information see http://hparchive.com/Journals/HPJ-1965-03.pdf BTW: I proudly own a HP2801A plus two crystal sensor elements. However I cannot connect them to the instrument, because the 2801A has a special connector for it. It looks like a smaller version of a BNC connector, but the bayonet has three nipples instead of two. Does anyone on the list know what kind of connector that is and where to get the counterpart (plug)? Regards Bernd DK1AG ___ 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] Super stable BVA Quartz resonators... BVA??
Javier wrote: Anyway, a 10544 oscillator has a cold offset that can easily be of 1000Hz, so if at 80 deg. C the offset is zero, and at 25 deg. C the offset is 1000Hz, you easily have a rough 15Hz/deg C average tempco in that range - and the aging drift for this oscillator is quite less than that. The 10544A incorporates an AT cut crystal. The tempco is far away from being linear. From room temp to the oven temperature it follows a 3rd order parabola, which has its minimum at the oven temperature. This trun-over tempearture varies from unit to unit, which means that the slope of f(T) also changes form unit to unit. Not the best approach for measuring temperatures ;-) At the other hand, the current consumption of the 10544A decreases fairly linear with temperature, so this is a better (but rather slow) temperature sensor, which would even work without the quartz... Regards Bernd DK1AG ___ 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] Super stable BVA Quartz resonators... BVA??
DK1AG wrote: ... the 2801A has a special connector for it. It looks like a smaller version of a BNC connector, but the bayonet has three nipples instead of two. Does anyone on the list know what kind of connector that is and where to get the counterpart (plug)? Regards Bernd DK1AG Bernd, may you send me a picture of the connector? Direct email ik1odo at spin-it.com 73 - Marco IK1ODO / AI4YF ___ 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] Super stable BVA Quartz resonators... BVA??
-Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Bernd T-Online Sent: Sunday, December 09, 2007 8:44 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Super stable BVA Quartz resonators... BVA?? Not the best approach for measuring temperatures ;-) At the other hand, the current consumption of the 10544A decreases fairly linear with temperature, so this is a better (but rather slow) temperature sensor, which would even work without the quartz... See what current versus temperature looks like: http://www.ko4bb.com/Test_Equipment/HP10811-Current.png Didier KO4BB ___ 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] Super stable BVA Quartz resonators... BVA??
Berndt I believe you are describing a Triax connector I found them through Trompeter but I believe they are sold by Farnell and RS Components in the UK. The same connector was used I think on some of the HP system digital voltmeters. Cheers de Alan G3NYK - Original Message - From: Bernd T-Online [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, December 09, 2007 2:21 PM Subject: Re: [time-nuts] Super stable BVA Quartz resonators... BVA?? Tim Shoppa wrote: For a while, didn't HP sell temperature probes which were in fact quartz crystals? Oscillation frequency was converted by some simple electronics to a temperature, and at the time (60's?) they were exquisitely convenient for measuring way better than a tenth of a degree. Either the frequency drift was negligible or it was so slow that I don't remember any manual removal of frequency drift effects. I'm guessing the probe crystals were some special cut (don't know which!) which was fairly linear or at least monotonic over the measurement temperatures. I'm guessing that HP chose a cut which had a very large tempco such that tempco dominated over any frequency drift. They did indeed. This was the HP2801A, later followed by the HP2804A. It uses a so-called LC-cut (Linear Coefficient) quartz crystal sensor, which is a doubly rotated cut with ultra-linear frequency vs. temperature characteristic with a slope of 35.4 ppm/K. For more information see http://hparchive.com/Journals/HPJ-1965-03.pdf BTW: I proudly own a HP2801A plus two crystal sensor elements. However I cannot connect them to the instrument, because the 2801A has a special connector for it. It looks like a smaller version of a BNC connector, but the bayonet has three nipples instead of two. Does anyone on the list know what kind of connector that is and where to get the counterpart (plug)? Regards Bernd DK1AG ___ 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] Super stable BVA Quartz resonators... BVA??
Yes, but that doesn't account for this part of his request (emphasis added): It looks like a *smaller* version of a BNC connector, but the bayonet has three nipples instead of two. -Chuck Harris Alan Melia wrote: Berndt I believe you are describing a Triax connector I found them through Trompeter but I believe they are sold by Farnell and RS Components in the UK. The same connector was used I think on some of the HP system digital voltmeters. Cheers de Alan G3NYK ___ 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] Super stable BVA Quartz resonators... BVA??
Marco IK1ODO wrote: may you send me a picture of the connector? Direct email ik1odo at spin-it.com Thanks, Marco. I have the unit in my QRL lab, so I can take a photo only by tomorrow. Regards Bernd DK1AG ___ 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] Super stable BVA Quartz resonators... BVA??
Yes, I know... I was only exposing it as an example of how the temperature coefficient can be quite higher compared with the aging effect even if the quartz crystal is not intended to be used as a temperature sensor :) Regards, Javier Bernd T-Online escribió: Javier wrote: Anyway, a 10544 oscillator has a cold offset that can easily be of 1000Hz, so if at 80 deg. C the offset is zero, and at 25 deg. C the offset is 1000Hz, you easily have a rough 15Hz/deg C average tempco in that range - and the aging drift for this oscillator is quite less than that. The 10544A incorporates an AT cut crystal. The tempco is far away from being linear. From room temp to the oven temperature it follows a 3rd order parabola, which has its minimum at the oven temperature. This trun-over tempearture varies from unit to unit, which means that the slope of f(T) also changes form unit to unit. Not the best approach for measuring temperatures ;-) At the other hand, the current consumption of the 10544A decreases fairly linear with temperature, so this is a better (but rather slow) temperature sensor, which would even work without the quartz... Regards Bernd DK1AG ___ 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] Super stable BVA Quartz resonators... BVA??
At 17.58 09/12/2007, Bernd wrote: Thanks, Marco. I have the unit in my QRL lab, so I can take a photo only by tomorrow. Ok, good. There are triax connectors with three and two bayonets around - ask Keithley... they have used both types. Or it may be something else, HI. 73 - Marco IK1ODO / AI4YF ___ 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] Super stable BVA Quartz resonators... BVA??
Hal Murray wrote: Why is the top domed? I assume flat would be easier to manufacture. Why is it not symmetrical? If the top is domed, why not the bottom too? For a plano-parallel qaurtz resonator the diameter must be at least 60 times larger than the thickness, otherwise the vibration amplitude would be too high at the edges, and the suspension would damp teh vibration hence the Q would be lowered. For a 10 MHz 3rd overtone SC-cut you would need a crystal of 40 to 50 mm diameter! By making a convex contour, the vibration is trapped in the center of the plate, and therefore the Q keeps high (and other parameters improve also). Bi-convex contours are more difficult to manufacture, as it is required that the symmetry axis of the upper and lower contour must coincide. Also other parameters become worse. For the BVA the manufacturability would also be much worse as it already is. Regards Bernd DK1AG ___ 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] Super stable BVA Quartz resonators... BVA??
Bernd T-Online wrote: Hal Murray wrote: Why is the top domed? I assume flat would be easier to manufacture. Why is it not symmetrical? If the top is domed, why not the bottom too? For a plano-parallel qaurtz resonator the diameter must be at least 60 times larger than the thickness, otherwise the vibration amplitude would be too high at the edges, and the suspension would damp teh vibration hence the Q would be lowered. For a 10 MHz 3rd overtone SC-cut you would need a crystal of 40 to 50 mm diameter! By making a convex contour, the vibration is trapped in the center of the plate, and therefore the Q keeps high (and other parameters improve also). Bi-convex contours are more difficult to manufacture, as it is required that the symmetry axis of the upper and lower contour must coincide. That problem was solved over a century ago in optical lens manufacture. If the two surfaces are spherical, then such decentering is equivalent to adding a wedge, which is easily removed by optical centering and edging techniques. Also other parameters become worse. For the BVA the manufacturability would also be much worse as it already is. Regards Bernd DK1AG 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] Super stable BVA Quartz resonators... BVA??
From: Bernd T-Online [EMAIL PROTECTED] Subject: Re: [time-nuts] Super stable BVA Quartz resonators... BVA?? Date: Sat, 08 Dec 2007 09:27:28 +0100 Message-ID: [EMAIL PROTECTED] Hal Murray wrote: Why is the top domed? I assume flat would be easier to manufacture. Why is it not symmetrical? If the top is domed, why not the bottom too? For a plano-parallel qaurtz resonator the diameter must be at least 60 times larger than the thickness, otherwise the vibration amplitude would be too high at the edges, and the suspension would damp teh vibration hence the Q would be lowered. For a 10 MHz 3rd overtone SC-cut you would need a crystal of 40 to 50 mm diameter! By making a convex contour, the vibration is trapped in the center of the plate, and therefore the Q keeps high (and other parameters improve also). Bi-convex contours are more difficult to manufacture, as it is required that the symmetry axis of the upper and lower contour must coincide. Also other parameters become worse. For the BVA the manufacturability would also be much worse as it already is. While I higly enjoy reading this thread and learning things as I read on, I notice that several fellow time-nuts have designer skills at advanced SC-level OCXOs. For those of you, what reading material is there to get better into depths with these issues? The only sufficiently indepth book I have is Gerber, Ballato Precision Frequency Control, Volume 1; Acoustic Resonators and Filters (I also got Volume II). 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] Super stable BVA Quartz resonators... BVA??
Bernd T-Online wrote: Hal Murray wrote: Why is the top domed? I assume flat would be easier to manufacture. Why is it not symmetrical? If the top is domed, why not the bottom too? For a plano-parallel qaurtz resonator the diameter must be at least 60 times larger than the thickness, otherwise the vibration amplitude would be too high at the edges, and the suspension would damp teh vibration hence the Q would be lowered. For a 10 MHz 3rd overtone SC-cut you would need a crystal of 40 to 50 mm diameter! By making a convex contour, the vibration is trapped in the center of the plate, and therefore the Q keeps high (and other parameters improve also). Bi-convex contours are more difficult to manufacture, as it is required that the symmetry axis of the upper and lower contour must coincide. Also other parameters become worse. For the BVA the manufacturability would also be much worse as it already is. Regards Bernd DK1AG Bernd Whilst traditional optical edging techniques can easily remove any wedge when both surfaces are convex, maintaining alignment of the lens axis with respect to the crystal axes is another matter, at least when using traditional surfacing techniques, with computer controlled surfacing techniques even this can be done. With a planoconvex lens bias polishing or an equivalent technique can be used to adjust the inclination of the plano surface with respect to the crystal axes and this alignment is maintained during edging leaving only axial thickness adjustments to be made. The etching process used to remove cracks and defects after mechanical polishing is anisotropic which may introduce further complications in maintaining alignment and shape. 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] Super stable BVA Quartz resonators... BVA??
Hal Murray wrote: [EMAIL PROTECTED] said: The key points which yield the BVA's improved aging are, that - the whole resonator package is made from quartz, consisting of the resonationg quartz plate in the middle section and the two mounting sealing plaates on top and bottem - you may call it a Hamburger style ;-) - the resonating plate is held through quartz bridges rather than metal suspensions, thus reducing mounting stress. Neat. Thanks. Why is the top domed? I assume flat would be easier to manufacture. Why is it not symmetrical? If the top is domed, why not the bottom too? One surface is convex to facilitate suppression of unwanted harmonics. Its actually quicker and easier to make a planoconvex lens than a biconvex one. 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] Super stable BVA Quartz resonators... BVA??
[EMAIL PROTECTED] said: The key points which yield the BVA's improved aging are, that - the whole resonator package is made from quartz, consisting of the resonationg quartz plate in the middle section and the two mounting sealing plaates on top and bottem - you may call it a Hamburger style ;-) - the resonating plate is held through quartz bridges rather than metal suspensions, thus reducing mounting stress. Neat. Thanks. Why is the top domed? I assume flat would be easier to manufacture. Why is it not symmetrical? If the top is domed, why not the bottom too? -- 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] Super stable BVA Quartz resonators... BVA??
Thanks for the description, it is very interesting. I have a follow up question if you don't mind. How does crystal aging look on a graph of temp versus frequency. This graph has some temperature point where the slope of frequency variation goes to zero and the crystal is quite stable around this temperature. What does this graph look like as a crystal ages? Does the optimal operating temperature change over time, that is, does the graph tend to move left and right, or does aging tend to move the graph vertically (the optimal freq stays the same, but the optimal operating temperature changes as a result of aging). I hope this makes sense... jeff Bernd T-Online wrote: Hi all, For explanation how the BVA works, please see the attached slide which shows schematically its internal construction. (The explaning text is in German, as it is from my periodically given crystal seminar.) The key points which yield the BVA's improved aging are, that - the whole resonator package is made from quartz, consisting of the resonationg quartz plate in the middle section and the two mounting sealing plaates on top and bottem - you may call it a Hamburger style ;-) - the resonating plate is held through quartz bridges rather than metal suspensions, thus reducing mounting stress. - the BVA is electrodeless, as the electrodes are evaporated on the inner side of the upper and lower mounting plates. Therefore no stress between the quartz surface and the metal eletrode. - Therefore the energizing electrical field is applied through an airgap, which represents two small load capacitors in series to the resonator, thus making the resonator electrically stiffer and less sensitive to circuit influences. On the other side you may imagine the main problems associated with such a construction: - The difficulty to manufacture the convex and concave shaped parts with such a precision, that the curvature yields a constant and very small airgap. - To realize the fine adjustment to frequency, because the unit cannot be tuned in the conventional way, i.e. by plating some metal on the electrode. - The frequency accuracy to which the resonator has to manufactured, because the resonator frequency cannot be pulled with the external circuit elements by more than some hundred ppb. It may be interesting to note, that there was a company BVA Industries, which wanted to generate their income solely from making BVA - which failed. Maybe because of the cost could not be covered by the revenues from the rather limited market. Bernd DK1AG __ AXTAL GmbH Co. KG Facility MOS Wasemweg 5 D-74821 Mosbach / Germany fon: +49 (6261) 939834 fax: +49 (6261) 939836 www.axtal.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. ___ 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] Super stable BVA Quartz resonators... BVA??
We did a lot of characterization of crystal temp vs freq in the E1938 development and never observed any aging of these curves. Even on green crystals with zero run time. Rick Karlquist N6RK Jeff Mock wrote: Thanks for the description, it is very interesting. I have a follow up question if you don't mind. How does crystal aging look on a graph of temp versus frequency. This graph has some temperature point where the slope of frequency variation goes to zero and the crystal is quite stable around this temperature. What does this graph look like as a crystal ages? Does the optimal operating temperature change over time, that is, does the graph tend to move left and right, or does aging tend to move the graph vertically (the optimal freq stays the same, but the optimal operating temperature changes as a result of aging). I hope this makes sense... jeff ___ 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] Super stable BVA Quartz resonators... BVA??
Michael Baker wrote: I have found out how a BVA resonator is fabricated, but I have not discovered what the acronym BVA stands for. I suspect that the B in BVA may refer to Raymond Besson the discoverer of the BVA quartz resonator, but I have not been able to confirm that. Can anyone on the list shed some light on this? I don't have the exact translation handy, but I ran across something indicating that BVA was an acronym in French for something like improved aging rate. John ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Super stable BVA Quartz resonators... BVA??
A googlized translation is: Improved Housing for Aging -Chuck Harris John Franke wrote: Try: Boîtier à Vieillissement Amélioré John WA4WDL - Original Message - From: John Ackermann N8UR [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Friday, December 07, 2007 11:20 AM Subject: Re: [time-nuts] Super stable BVA Quartz resonators... BVA?? Michael Baker wrote: I have found out how a BVA resonator is fabricated, but I have not discovered what the acronym BVA stands for. ___ 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] Super stable BVA Quartz resonators... BVA??
Same for me with both browsers. Daun -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Didier Juges Sent: Friday, December 07, 2007 9:02 PM To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] Super stable BVA Quartz resonators... BVA?? Same thing here, I checked with Firefox and IE, and the problem clearly is at their end... Maybe Monday? Didier -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Magnus Danielson Sent: Friday, December 07, 2007 7:56 PM To: time-nuts@febo.com; [EMAIL PROTECTED] Subject: Re: [time-nuts] Super stable BVA Quartz resonators... BVA?? From: Richard (Rick) Karlquist [EMAIL PROTECTED] Subject: Re: [time-nuts] Super stable BVA Quartz resonators... BVA?? Date: Fri, 07 Dec 2007 17:28:15 -0800 Message-ID: [EMAIL PROTECTED] Rick, Coincidentally, I just learned today that the E1983A is still being made by an OEM called Scotts Valley Magnetics. Oh, if there would manifest itself a chance to get hold of a few, I hope I can get a notice. Their products page blew up in my browser, but here they are: http://www.svmagnetics.com/ 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. ___ 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] Super stable BVA Quartz resonators... BVA??
Coincidentally, I just learned today that the E1983A is still being made by an OEM called Scotts Valley Magnetics. Rick Karlquist N6RK Magnus Danielson wrote: Is the E1938 commercially available? If not, is there a followup? 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] Super stable BVA Quartz resonators... BVA??
The 10811's specs are not in the same class with the BVA in the first place. At the 10811 spec level, frequency jumps aren't that significant compared to other frequency fluctuations, so they don't need to be specified separately. Phase noise and short term stability are easily distinguished from frequency jumps. Didier Juges wrote: I looked at the HP 10811 specification and I do not see Frequency Jumps as a specified parameter. I know what it is, I have read the (very interesting) papers and postings on this group about it and I understand it is one of the more difficult to avoid and hardest to predict cause of error in crystal oscillators. Yet, it does not seem to be adequately covered in specifications. Is it covered in other spec requirements such as phase noise or short term stability? But since these also encompass other causes, how can I tell which is which? If phase noise or short term stability encompasses frequency jumps, how can I estimate the size of frequency jumps from those specifications? Didier -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Richard (Rick) Karlquist Sent: Friday, December 07, 2007 5:52 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Super stable BVA Quartz resonators... BVA?? Having low aging is nice, but the real problem is frequency jumps. Do we know that they are the best in that respect? If a crystal can jump 1E-10, then that represents 10 days of aging all at once. Rick Karlquist, N6RK Didier Juges wrote: I am not aware of other crystal oscillators with better performance, so either I am missing something (the more likely explanation) or there is something to it. Maybe the cut is simply a smoke screen and the outstanding performance is actually due to other process detail(s) not disclosed? Or maybe their oscillators are not that good, they just blow smoke really well. Didier KO4BB -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Richard (Rick) Karlquist Sent: Friday, December 07, 2007 10:45 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Super stable BVA Quartz resonators... BVA?? Reminds me of the SC cut crystal. It either means Stress Compensated or Santa Clara, where it was discovered :-) The BVA has been around for a long time and you would think that if there was really something to it, everybody would be making them. Of course, they are very difficult to make. 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] Super stable BVA Quartz resonators... BVA??
Didier Juges wrote: Maybe the cut is simply a smoke screen and the outstanding performance is actually due to other process detail(s) not disclosed? There's quite a bit of guff on the Oscilloquartz website - especially if you find your way to the OXCO 8607-B datasheet (pdf). I'm not qualified to weigh this all up, but they point out a double oven and an electrodeless, SC-cut, 3rd overtone crystal, decoupled from its mounting structure by four rigid bridges. And they go on to list the consquent benefits. They've made over 10,000 of them. Anyone know what they're charging...? Yours, -Brian Styles ___ 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] Super stable BVA Quartz resonators... BVA??
From: Didier Juges [EMAIL PROTECTED] Subject: Re: [time-nuts] Super stable BVA Quartz resonators... BVA?? Date: Fri, 7 Dec 2007 17:17:59 -0600 Message-ID: [EMAIL PROTECTED] I am not aware of other crystal oscillators with better performance, so either I am missing something (the more likely explanation) or there is something to it. Maybe the cut is simply a smoke screen and the outstanding performance is actually due to other process detail(s) not disclosed? Let's recall that the BVA isn't the same as a cut, but rather an approach to handle and mount the cut crystal. The BVA exists in both AT and SC cuts. The analysis of Rick et.al. for the E1938 was pointing in another improvement. Also, there are many ways to cut a crystal. :) Smokescreen or not, Oscilloquartz clearly beleive in the BVA methodology and they seems to have customers for them too. Is the E1938 commercially available? If not, is there a followup? Do we really need BVAs or similars for most new designs, considering the price, size and availability of modern telecom rubidiums? Or maybe their oscillators are not that good, they just blow smoke really well. Well, that would be stupid, since it is easy enought to 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] Super stable BVA Quartz resonators... BVA??
Try: Boîtier à Vieillissement Amélioré John WA4WDL - Original Message - From: John Ackermann N8UR [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Friday, December 07, 2007 11:20 AM Subject: Re: [time-nuts] Super stable BVA Quartz resonators... BVA?? Michael Baker wrote: I have found out how a BVA resonator is fabricated, but I have not discovered what the acronym BVA stands for. I suspect that the B in BVA may refer to Raymond Besson the discoverer of the BVA quartz resonator, but I have not been able to confirm that. Can anyone on the list shed some light on this? I don't have the exact translation handy, but I ran across something indicating that BVA was an acronym in French for something like improved aging rate. John ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Super stable BVA Quartz resonators... BVA??
Boîtier à Vieillissement Amélioré This is another version, Enrico 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] Super stable BVA Quartz resonators... BVA??
I am not aware of other crystal oscillators with better performance, so either I am missing something (the more likely explanation) or there is something to it. Maybe the cut is simply a smoke screen and the outstanding performance is actually due to other process detail(s) not disclosed? Or maybe their oscillators are not that good, they just blow smoke really well. Didier KO4BB -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Richard (Rick) Karlquist Sent: Friday, December 07, 2007 10:45 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Super stable BVA Quartz resonators... BVA?? Reminds me of the SC cut crystal. It either means Stress Compensated or Santa Clara, where it was discovered :-) The BVA has been around for a long time and you would think that if there was really something to it, everybody would be making them. Of course, they are very difficult to make. 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] Super stable BVA Quartz resonators... BVA??
From: Richard (Rick) Karlquist [EMAIL PROTECTED] Subject: Re: [time-nuts] Super stable BVA Quartz resonators... BVA?? Date: Fri, 07 Dec 2007 17:28:15 -0800 Message-ID: [EMAIL PROTECTED] Rick, Coincidentally, I just learned today that the E1983A is still being made by an OEM called Scotts Valley Magnetics. Oh, if there would manifest itself a chance to get hold of a few, I hope I can get a notice. Their products page blew up in my browser, but here they are: http://www.svmagnetics.com/ 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] Super stable BVA Quartz resonators... BVA??
I looked at the HP 10811 specification and I do not see Frequency Jumps as a specified parameter. I know what it is, I have read the (very interesting) papers and postings on this group about it and I understand it is one of the more difficult to avoid and hardest to predict cause of error in crystal oscillators. Yet, it does not seem to be adequately covered in specifications. Is it covered in other spec requirements such as phase noise or short term stability? But since these also encompass other causes, how can I tell which is which? If phase noise or short term stability encompasses frequency jumps, how can I estimate the size of frequency jumps from those specifications? Didier -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Richard (Rick) Karlquist Sent: Friday, December 07, 2007 5:52 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Super stable BVA Quartz resonators... BVA?? Having low aging is nice, but the real problem is frequency jumps. Do we know that they are the best in that respect? If a crystal can jump 1E-10, then that represents 10 days of aging all at once. Rick Karlquist, N6RK Didier Juges wrote: I am not aware of other crystal oscillators with better performance, so either I am missing something (the more likely explanation) or there is something to it. Maybe the cut is simply a smoke screen and the outstanding performance is actually due to other process detail(s) not disclosed? Or maybe their oscillators are not that good, they just blow smoke really well. Didier KO4BB -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Richard (Rick) Karlquist Sent: Friday, December 07, 2007 10:45 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Super stable BVA Quartz resonators... BVA?? Reminds me of the SC cut crystal. It either means Stress Compensated or Santa Clara, where it was discovered :-) The BVA has been around for a long time and you would think that if there was really something to it, everybody would be making them. Of course, they are very difficult to make. 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] Super stable BVA Quartz resonators... BVA??
Brian Styles said the following on 12/07/2007 07:15 PM: There's quite a bit of guff on the Oscilloquartz website - especially if you find your way to the OXCO 8607-B datasheet (pdf). [ . . . ] They've made over 10,000 of them. Anyone know what they're charging...? Very rough numbers, but the standard 8607 is about US$4K. The option -008, which has 8x10e-14 ADEV from 2 to 30 seconds (and phase noise about -130dBc/Hz at 1 Hz offset) is about $14K. I'm told the yield of those is about a dozen per year, and the lead time to get one is around six months. John ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Super stable BVA Quartz resonators... BVA??
Having low aging is nice, but the real problem is frequency jumps. Do we know that they are the best in that respect? If a crystal can jump 1E-10, then that represents 10 days of aging all at once. Rick Karlquist, N6RK Didier Juges wrote: I am not aware of other crystal oscillators with better performance, so either I am missing something (the more likely explanation) or there is something to it. Maybe the cut is simply a smoke screen and the outstanding performance is actually due to other process detail(s) not disclosed? Or maybe their oscillators are not that good, they just blow smoke really well. Didier KO4BB -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Richard (Rick) Karlquist Sent: Friday, December 07, 2007 10:45 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Super stable BVA Quartz resonators... BVA?? Reminds me of the SC cut crystal. It either means Stress Compensated or Santa Clara, where it was discovered :-) The BVA has been around for a long time and you would think that if there was really something to it, everybody would be making them. Of course, they are very difficult to make. 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] Super stable BVA Quartz resonators... BVA??
Reminds me of the SC cut crystal. It either means Stress Compensated or Santa Clara, where it was discovered :-) The BVA has been around for a long time and you would think that if there was really something to it, everybody would be making them. Of course, they are very difficult to make. Rick Karlquist N6RK John Ackermann N8UR wrote: Michael Baker wrote: I have found out how a BVA resonator is fabricated, but I have not discovered what the acronym BVA stands for. I suspect that the B in BVA may refer to Raymond Besson the discoverer of the BVA quartz resonator, but I have not been able to confirm that. Can anyone on the list shed some light on this? I don't have the exact translation handy, but I ran across something indicating that BVA was an acronym in French for something like improved aging rate. John ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Super stable BVA Quartz resonators... BVA??
John Ackermann N8UR wrote: The option -008, ... is about $14K. I'm told the yield of those is about a dozen per year, and the lead time to get one is around six months. Hmm, not quite long enough to save up, then! Changing the subject slightly, does anyone know the Thomson-CSF PMT P5-1E ? It seems to offer a total stability of 5x10e-11 over a day and 1x10e-8 over 12 months. The latter figure isn't very far behind the best 8607. I ask because I've had one of these Thomson trinkets kicking around for a while (washed up from an abandoned project) and thought of building a clock round it. My own obsession is with long-term accuracy rather than the immediate spectrum. It has to beat the Synchronomes... If anyone's played with a PMT P5-1E, I'd be most interested to hear. Regards, -Brian Styles ___ 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] Super stable BVA Quartz resonators... BVA??
Same thing here, I checked with Firefox and IE, and the problem clearly is at their end... Maybe Monday? Didier -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Magnus Danielson Sent: Friday, December 07, 2007 7:56 PM To: time-nuts@febo.com; [EMAIL PROTECTED] Subject: Re: [time-nuts] Super stable BVA Quartz resonators... BVA?? From: Richard (Rick) Karlquist [EMAIL PROTECTED] Subject: Re: [time-nuts] Super stable BVA Quartz resonators... BVA?? Date: Fri, 07 Dec 2007 17:28:15 -0800 Message-ID: [EMAIL PROTECTED] Rick, Coincidentally, I just learned today that the E1983A is still being made by an OEM called Scotts Valley Magnetics. Oh, if there would manifest itself a chance to get hold of a few, I hope I can get a notice. Their products page blew up in my browser, but here they are: http://www.svmagnetics.com/ 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.
