Hi > On Feb 17, 2021, at 11:08 AM, Magnus Danielson <magnus@rubidium.se> wrote: > > Hi Tom, > > On 2021-02-17 16:24, Tom Van Baak wrote: >> See pages 20-29 in the Mar-1981 HPJ for the "new SC-cut" 10811 >> article(s): >> >> https://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1981-03.pdf >> >> It talks about 10544A/C/B and 10811A/B in detail. It compares AT/BT/SC >> cuts. >> >> Read especially "The SC Cut, a Brief Summary" on page 22. > > Thanks for reminding us of this HPJ. > > In here it is also noted that the 10544 is a BT cut, and this comes to > contrast that HP never come clean with which cut was used, as some have > said. Here we have some clear evidence. Indeed, once they no longer were *using* the BT cut, they would talk about it. > > Also note that it traces the SC-cut back to 1974, and that the same cut > also been called TTC and TS in early papers. It's interesting to note > that HP had double-angle cut machines since 1965, so the new cut did not > caused them a big challenge. Depends on what you call a big challenge. Gear that actually could cut an SC with > 1% yields was indeed very much “in the future” back the early 1970’s. It continued to be somewhat rare through the early 1980’s. Bob > Exactly which double-angle cut's they did > before SC remains to be found. > > It is however interesting. They also refer to early papers in page 22 > and 23. > > Cheers, > Magnus > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there.

Hi Paul, On 2021-02-17 15:38, paul swed wrote: > Bob > I thought SC's were around a long time. (Not that I doubt you on that) This > thing should be the 1970s vintage from the one bit I have found on it. Research-wise, you come back to about 1974 it seems. Production seems to start at about 1981. > Magnus always appreciate your comments. Uhm, I did not know that my appreciation for someones comments was used as a hallmark for quality. I sit here in amazement of what just happen. Bob has delivered insight from so many decades in the industry, and that insight shows of in quality of posts, that is always appreciated. > As I heat it up from room temperature what exactly would I look for? Sort of the > temperature/frequency behaviors I see in various charts? > When cold the units sit 4Hz high. and when warm its currently .119 Hz high. > It used to go below by .6 Hz. Not sure what has changed. So, as you heat up from 20 C to 85 C the frequency shift. Depending on cut, the start offset (cold frequency - nominal frequency) have different sign and size, depending on cut. It's fairly easy to spot different cuts that way we concluded. You can dig up frequency error vs. temperature graphs for various cuts. The AT-cut one is well spread third degree shape going up to a saddle-point, going down to a saddle-point and then going up again. Minimum sensitivity to temperature happens on those saddle-points. I remembered a setup where someone used SC-cut oscillators in cryogenic temperature setup to detect axions. He noted that they where fighting temperature variations to the oscillators. I simply asked if the SC-cut crystals had been cut for that temperature, and apparently not. Well, there is a basic magic to the stability, and if you do not respect that magic, do not expect the result to be so spectacular either. That said from someone who have yet to design a single crystal oscillator beyond following standard datasheet setup. The Gerber & Ballato "Precision Frequency Control" books is a good read. Chapter 12 by Sam Stein I know exists as separate PDF, maybe other parts too. It has tabulated coefficients for AT, BT, IT and SC cuts cubic temperature dependence. Cheers, Magnus

Magnus, were they trying to use the SC-cut crystal itself as a calorimeter, or something else? if using a crystal as a calorimeter (essentially self-temperature probe) to detect axions, they do not want the crystal cut for stability at operating temperature? You want to operate the crystal where it has the steepest possible temperature slope. I know dang little about the cuts and how they behave at cryogenic temperatures. Of course vast quantities of crystals are used in particle physics but not as oscillators :-). I remember literature from back in the 60's there was some interest in crystals used as oscillator calorimeters but that's a pretty obscure corner of calorimetry today if anyone is still trying it. We've had threads in the past on time-nuts about hysteresis in HP's crystal-based temperature probes. I guess in an axion calorimeter the hysteresis limits lower limit of detection. Tim N3QE On Wed, Feb 17, 2021 at 1:04 PM Magnus Danielson <magnus@rubidium.se> wrote: > Hi Paul, > > On 2021-02-17 15:38, paul swed wrote: > > Bob > > I thought SC's were around a long time. (Not that I doubt you on that) > This > > thing should be the 1970s vintage from the one bit I have found on it. > Research-wise, you come back to about 1974 it seems. Production seems to > start at about 1981. > > Magnus always appreciate your comments. > Uhm, I did not know that my appreciation for someones comments was used > as a hallmark for quality. I sit here in amazement of what just happen. > Bob has delivered insight from so many decades in the industry, and that > insight shows of in quality of posts, that is always appreciated. > > As I heat it up from room temperature what exactly would I look for? > Sort of the > > temperature/frequency behaviors I see in various charts? > > When cold the units sit 4Hz high. and when warm its currently .119 Hz > high. > > It used to go below by .6 Hz. Not sure what has changed. > > So, as you heat up from 20 C to 85 C the frequency shift. Depending on > cut, the start offset (cold frequency - nominal frequency) have > different sign and size, depending on cut. It's fairly easy to spot > different cuts that way we concluded. > > You can dig up frequency error vs. temperature graphs for various cuts. > The AT-cut one is well spread third degree shape going up to a > saddle-point, going down to a saddle-point and then going up again. > Minimum sensitivity to temperature happens on those saddle-points. > > I remembered a setup where someone used SC-cut oscillators in cryogenic > temperature setup to detect axions. He noted that they where fighting > temperature variations to the oscillators. I simply asked if the SC-cut > crystals had been cut for that temperature, and apparently not. Well, > there is a basic magic to the stability, and if you do not respect that > magic, do not expect the result to be so spectacular either. That said > from someone who have yet to design a single crystal oscillator beyond > following standard datasheet setup. > > The Gerber & Ballato "Precision Frequency Control" books is a good read. > Chapter 12 by Sam Stein I know exists as separate PDF, maybe other parts > too. It has tabulated coefficients for AT, BT, IT and SC cuts cubic > temperature dependence. > > Cheers, > Magnus > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. >

Hi > On Feb 17, 2021, at 2:10 PM, Tim Shoppa <tshoppa@gmail.com> wrote: > > Magnus, were they trying to use the SC-cut crystal itself as a calorimeter, > or something else? > > if using a crystal as a calorimeter (essentially self-temperature probe) to > detect axions, they do not want the crystal cut for stability at operating > temperature? > > You want to operate the crystal where it has the steepest possible > temperature slope. I know dang little about the cuts and how they behave at > cryogenic temperatures. > > Of course vast quantities of crystals are used in particle physics but not > as oscillators :-). I remember literature from back in the 60's there was > some interest in crystals used as oscillator calorimeters but that's a > pretty obscure corner of calorimetry today if anyone is still trying it. > > We've had threads in the past on time-nuts about hysteresis in HP's > crystal-based temperature probes. I guess in an axion calorimeter the > hysteresis limits lower limit of detection. …… and there are whole families of crystal cuts that have been optimized for use as thermometers. There is no need to compromise on something like an AT or SC if you are after temperature. There are lots of different cuts to pick between. You *do* run into the same issues as with OCXO crystals. The number of cuts “known” is much larger than the number that are “production ready” …. Bob > > Tim N3QE > > On Wed, Feb 17, 2021 at 1:04 PM Magnus Danielson <magnus@rubidium.se> wrote: > >> Hi Paul, >> >> On 2021-02-17 15:38, paul swed wrote: >>> Bob >>> I thought SC's were around a long time. (Not that I doubt you on that) >> This >>> thing should be the 1970s vintage from the one bit I have found on it. >> Research-wise, you come back to about 1974 it seems. Production seems to >> start at about 1981. >>> Magnus always appreciate your comments. >> Uhm, I did not know that my appreciation for someones comments was used >> as a hallmark for quality. I sit here in amazement of what just happen. >> Bob has delivered insight from so many decades in the industry, and that >> insight shows of in quality of posts, that is always appreciated. >>> As I heat it up from room temperature what exactly would I look for? >> Sort of the >>> temperature/frequency behaviors I see in various charts? >>> When cold the units sit 4Hz high. and when warm its currently .119 Hz >> high. >>> It used to go below by .6 Hz. Not sure what has changed. >> >> So, as you heat up from 20 C to 85 C the frequency shift. Depending on >> cut, the start offset (cold frequency - nominal frequency) have >> different sign and size, depending on cut. It's fairly easy to spot >> different cuts that way we concluded. >> >> You can dig up frequency error vs. temperature graphs for various cuts. >> The AT-cut one is well spread third degree shape going up to a >> saddle-point, going down to a saddle-point and then going up again. >> Minimum sensitivity to temperature happens on those saddle-points. >> >> I remembered a setup where someone used SC-cut oscillators in cryogenic >> temperature setup to detect axions. He noted that they where fighting >> temperature variations to the oscillators. I simply asked if the SC-cut >> crystals had been cut for that temperature, and apparently not. Well, >> there is a basic magic to the stability, and if you do not respect that >> magic, do not expect the result to be so spectacular either. That said >> from someone who have yet to design a single crystal oscillator beyond >> following standard datasheet setup. >> >> The Gerber & Ballato "Precision Frequency Control" books is a good read. >> Chapter 12 by Sam Stein I know exists as separate PDF, maybe other parts >> too. It has tabulated coefficients for AT, BT, IT and SC cuts cubic >> temperature dependence. >> >> Cheers, >> Magnus >> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. >> > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there.

Hi, On 2021-02-17 20:10, Tim Shoppa wrote: > Magnus, were they trying to use the SC-cut crystal itself as a calorimeter, > or something else? No. They where used as normal stable oscillators, but measuring their difference to detect the event. The exact theory leading up to that is however beyond me, but they ended up using a pair of oscillators that where orthogaly tied to the same cavity and then experienced the event differently. > > if using a crystal as a calorimeter (essentially self-temperature probe) to > detect axions, they do not want the crystal cut for stability at operating > temperature? > > You want to operate the crystal where it has the steepest possible > temperature slope. I know dang little about the cuts and how they behave at > cryogenic temperatures. They reported the thermal sensitivity as a problem, so it was an unwanted feature. I realized they used them outside of their operational range. > Of course vast quantities of crystals are used in particle physics but not > as oscillators :-). I remember literature from back in the 60's there was > some interest in crystals used as oscillator calorimeters but that's a > pretty obscure corner of calorimetry today if anyone is still trying it. > > We've had threads in the past on time-nuts about hysteresis in HP's > crystal-based temperature probes. I guess in an axion calorimeter the > hysteresis limits lower limit of detection. Which wasn't calorimeters to start with, or at least not in the normal sense. Cheers, Magnus > > Tim N3QE > > On Wed, Feb 17, 2021 at 1:04 PM Magnus Danielson <magnus@rubidium.se> wrote: > >> Hi Paul, >> >> On 2021-02-17 15:38, paul swed wrote: >>> Bob >>> I thought SC's were around a long time. (Not that I doubt you on that) >> This >>> thing should be the 1970s vintage from the one bit I have found on it. >> Research-wise, you come back to about 1974 it seems. Production seems to >> start at about 1981. >>> Magnus always appreciate your comments. >> Uhm, I did not know that my appreciation for someones comments was used >> as a hallmark for quality. I sit here in amazement of what just happen. >> Bob has delivered insight from so many decades in the industry, and that >> insight shows of in quality of posts, that is always appreciated. >>> As I heat it up from room temperature what exactly would I look for? >> Sort of the >>> temperature/frequency behaviors I see in various charts? >>> When cold the units sit 4Hz high. and when warm its currently .119 Hz >> high. >>> It used to go below by .6 Hz. Not sure what has changed. >> So, as you heat up from 20 C to 85 C the frequency shift. Depending on >> cut, the start offset (cold frequency - nominal frequency) have >> different sign and size, depending on cut. It's fairly easy to spot >> different cuts that way we concluded. >> >> You can dig up frequency error vs. temperature graphs for various cuts. >> The AT-cut one is well spread third degree shape going up to a >> saddle-point, going down to a saddle-point and then going up again. >> Minimum sensitivity to temperature happens on those saddle-points. >> >> I remembered a setup where someone used SC-cut oscillators in cryogenic >> temperature setup to detect axions. He noted that they where fighting >> temperature variations to the oscillators. I simply asked if the SC-cut >> crystals had been cut for that temperature, and apparently not. Well, >> there is a basic magic to the stability, and if you do not respect that >> magic, do not expect the result to be so spectacular either. That said >> from someone who have yet to design a single crystal oscillator beyond >> following standard datasheet setup. >> >> The Gerber & Ballato "Precision Frequency Control" books is a good read. >> Chapter 12 by Sam Stein I know exists as separate PDF, maybe other parts >> too. It has tabulated coefficients for AT, BT, IT and SC cuts cubic >> temperature dependence. >> >> Cheers, >> Magnus >> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. >> > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there.

-------- Magnus Danielson writes: > Exactly which double-angle cut's they did before SC remains to be found. If somebody knows a crystallographer and is willing to sacrifice a unit, that is something which could be found out... -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.