Re: [time-nuts] OCXO pressure sensitivity before TCXO
In message , jimlux writes: >One other thing to know about those USOs - they start about 1000 quartz >blanks that are mounted in holders, and wind up with a couple dozen >oscillators in dewars, and then run them all for a long time (many >months) and watch them. 2 or 3 out of a batch will be the ones selected >for use - based on their observed stability - Do you know where their trash bin is located, and if it is locked ? :-) I would love to get my hands on a unit from, say, the 10-25 tier of that process. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@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. ___ 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.
Re: [time-nuts] OCXO pressure sensitivity before TCXO
On 8/5/19 2:21 PM, Poul-Henning Kamp wrote: In message , jimlux writes: One other thing to know about those USOs - they start about 1000 quartz blanks that are mounted in holders, and wind up with a couple dozen oscillators in dewars, and then run them all for a long time (many months) and watch them. 2 or 3 out of a batch will be the ones selected for use - based on their observed stability - Do you know where their trash bin is located, and if it is locked ? :-) I would love to get my hands on a unit from, say, the 10-25 tier of that process. I think they do get reused - the aging process is just the oscillator without all the rest of the electronics. And there's always a need for engineering models and qual units for environmental testing. I'll bet that's why they developed the USO with a built in DDS - so that one that turned out to be 22.12345 MHz can be "reprogrammed" for 10.00 MHz ___ 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.
Re: [time-nuts] HP OCXO's 10544A and 10811A
Oops, my bad. I think it was a BT cut. But the BT cut isn't any better on warmup than an AT cut, right? I don't know much about the 10544. It was already obsolete by the time I started at HP 40 years ago. Rick N6RK On 8/5/2019 10:20 AM, Scott Newell wrote: At 10:25 AM 8/5/2019, tim...@timeok.it wrote: The 10811 is a SC cut crystal oscillator and the 10544 is an AT cut. I thought the 10544 used a BT rock. Seems like I measured the warmup curve of my 5345A to verify this, but maybe I'm confusing something else. ___ 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.
Re: [time-nuts] HP OCXO's 10544A and 10811A
At 10:25 AM 8/5/2019, tim...@timeok.it wrote: The 10811 is a SC cut crystal oscillator and the 10544 is an AT cut. I thought the 10544 used a BT rock. Seems like I measured the warmup curve of my 5345A to verify this, but maybe I'm confusing something else. -- newell N5TNL ___ 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.
Re: [time-nuts] HP OCXO's 10544A and 10811A
is there a comparison of the key characteristics of these two sub-assembles? The newer 10811 works in older 10544 instruments but not the other way around; the reason is the additional power supply requirements of the 10544. See the data sheets for the 10544 and 10811: http://leapsecond.com/museum/10544/1972-Oct-hp-10544A.pdf http://leapsecond.com/museum/10811a/10811a.pdf Also the 10544 output is spec'd for 1 Vrms into 1000R load; the 10811 is 0.5 V into 50R load. There are differences about warmup time (AT- vs SC-cut). That's important for a often turned-on/off bench instrument; but less important if the oscillator is used as a never-turned-off frequency standard. More info, including data sheets, schematics, and an excellent set of papers by fellow time-nut Charles: http://leapsecond.com/museum/10544/ /tvb ___ 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] HP OCXO's 10544A and 10811A
Walter, The 10811 uses an SC cut crystal and a more modern oven control circuit. Much better short term stability and warmup than the 10544 it replaced! Cheers, Corby http://www.leapsecond.com/museum/10544/1972-Oct-hp-10544A.pdf http://www.leapsecond.com/museum/10811a/90027-1.pdf ___ 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.
Re: [time-nuts] HP OCXO's 10544A and 10811A
On 8/5/2019 7:25 AM, Walter Shawlee 2 wrote: I have hp counters with both OCXO's, they seem to be electrically and mechanically interchangeable, and generally, they both have performed well. but it seems to me that the earlier 10544A runs hotter (to the touch), and is not quite as long term stable as the 10811A. how have they worked for you? is there a comparison of the key characteristics of these two sub-assembles? all the best, walter I worked with the 10811 designers when we were at HP, and I learned as much from them as possible. They were tasked with making an completely new and different oscillator (including a new crystal cut), but with the ability to be able to plug into any legacy 10544 socket. The 10811 famously used the SC cut for fast warm up, vs the AT cut used in the 10544. I remember that the 10811 oven could never draw more current than would be drawn by a 47 ohm resistor. This requirement was derived from the 10544 characteristics. It had to produce 10 MHz at +7 dBm into 50 ohms, etc. Other than the can, the edge card connector, and the location of the tuning screw hole, they started with a blank piece of paper in terms of the oscillator design. There is no similarity between the two ovens. Both oscillators may be offshoots of the Colpitts design, but the 10811 oscillator has various innovations beyond the 10544. It has the patented phase noise reduction circuit, etc. There was no requirement for 10811 sockets to support 10544's. Rick N6RK ___ 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] HP OCXO's 10544A and 10811A
I have hp counters with both OCXO's, they seem to be electrically and mechanically interchangeable, and generally, they both have performed well. but it seems to me that the earlier 10544A runs hotter (to the touch), and is not quite as long term stable as the 10811A. how have they worked for you? is there a comparison of the key characteristics of these two sub-assembles? all the best, walter -- Walter Shawlee 2 Sphere Research Corp. 3394 Sunnyside Rd. West Kelowna, BC, V1Z 2V4 CANADA Phone: +1 (250-769-1834 -:- http://www.sphere.bc.ca +We're all in one boat, no matter how it looks to you. (WS2) +All you need is love. (John Lennon) +But, that doesn't mean other things don't come in handy. (WS2) +Nature is trying very hard to make us succeed, but nature does not depend on us. We are not the only experiment. (R. Buckminster Fuller) ___ 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.
Re: [time-nuts] OCXO pressure sensitivity before TCXO
Hi Keep in mind that all those designs date “way back” in terms of OCXO design. The whole issue of pressure sensitivity really was not well understood / accepted until the mid 1990’s. Up to that point the whole “is it pressure or something else” thing was very much a hot topic. In terms of an OCXO designed for phase noise (like the 10811), pressure is pretty much a non-issue. It’s far enough down that it will only impact long term performance and even then well below the daily aging spec on the part. Humidity is often more of an issue on a 10811 than pressure. Bob > On Aug 5, 2019, at 6:30 AM, ew via time-nuts wrote: > > Today most quality OCXO's are in a sealed can but three of the best HP10811, > Austron 1150 and OSA 8600/07 are not sealed. Austroon set screw hole has a > screw with an O ring. When you try to get the best out of them not part of a > loop you may have to consider compensation like with Rb's. Maybe it is not > the Xtal but some other part of the circuit. Any Idea or experience. Pressure > will most likely be slow. Here in Florida Hurricane is on us, maybe a time > to outline a test. > Bert Kehren > In a message dated 8/5/2019 3:34:15 AM Eastern Standard Time, > att...@kinali.ch writes: > > On Sat, 3 Aug 2019 14:22:22 + (UTC) > ew via time-nuts wrote: > >> Are wee missing something. Reading Bill Slade post and old NASA >> attachments the attached plot to me was an eye opener. Our work >> has always been focused on Rb pressure compensation. Are we >> overlooking something. Has any one done some work on this subject > > No, we are not overlooking anything. Pressure sensitivity of > OCXOs has been long known and most manufacturers account for it > in their design. In most cases, the temperature induced instability > is larger than the pressure sensitive effect, together with the > pressure sensitivity measurement and characterisation being > expensive, it does not get mentioned in the datasheets. > > But, if you really want to compensate for environmental effects, > then you need to have a quite complex model. This makes it rather > difficult to parametrize, you need measurements over months if not > years. That makes these parameters also quite difficult to use, as > they exhibit memory effects (e.g. hysterisis) and change over time. > > If you are interested in this, have a look at the fields of > "System identification." Or, if you want to have it a bit simpler > and more statistical: "Principal Component Analysis" > > Attila Kinali > -- > The bad part of Zurich is where the degenerates > throw DARK chocolate at you. > > ___ > 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. ___ 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.
Re: [time-nuts] OCXO pressure sensitivity before TCXO
On 8/5/2019 3:30 AM, ew via time-nuts wrote: Today most quality OCXO's are in a sealed can but three of the best HP10811, Austron 1150 and OSA 8600/07 are not sealed. Austroon set screw hole has a screw with an O ring. When you try to get the best out of them not part of a loop you may have to consider The 10811 came in both an unsealed version and a solder sealed version. The unsealed version is much more common. When I was working for HP, I tested an unsealed 10811 for humidity sensitivity. It had a considerable coefficent, such that I could get more frequency shift by varying ambient humidity than I could by varying temperature. Clearly, this sensitivity is all due to the electronics, since the crystal is definitely hermetically sealed. This discovery motivated the development of the bridge stabilized oscillator circuit, which is vastly less sensitive than the 10811 circuit. Rick N6RK ___ 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.
Re: [time-nuts] OCXO pressure sensitivity before TCXO
Today most quality OCXO's are in a sealed can but three of the best HP10811, Austron 1150 and OSA 8600/07 are not sealed. Austroon set screw hole has a screw with an O ring. When you try to get the best out of them not part of a loop you may have to consider compensation like with Rb's. Maybe it is not the Xtal but some other part of the circuit. Any Idea or experience. Pressure will most likely be slow. Here in Florida Hurricane is on us, maybe a time to outline a test. Bert Kehren In a message dated 8/5/2019 3:34:15 AM Eastern Standard Time, att...@kinali.ch writes: On Sat, 3 Aug 2019 14:22:22 + (UTC) ew via time-nuts wrote: > Are wee missing something. Reading Bill Slade post and old NASA > attachments the attached plot to me was an eye opener. Our work > has always been focused on Rb pressure compensation. Are we > overlooking something. Has any one done some work on this subject No, we are not overlooking anything. Pressure sensitivity of OCXOs has been long known and most manufacturers account for it in their design. In most cases, the temperature induced instability is larger than the pressure sensitive effect, together with the pressure sensitivity measurement and characterisation being expensive, it does not get mentioned in the datasheets. But, if you really want to compensate for environmental effects, then you need to have a quite complex model. This makes it rather difficult to parametrize, you need measurements over months if not years. That makes these parameters also quite difficult to use, as they exhibit memory effects (e.g. hysterisis) and change over time. If you are interested in this, have a look at the fields of "System identification." Or, if you want to have it a bit simpler and more statistical: "Principal Component Analysis" Attila Kinali -- The bad part of Zurich is where the degenerates throw DARK chocolate at you. ___ 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.
[time-nuts] Quartz crystals in a vacuum....
Time-Nutters-- I have an assortment of quartz crystals enclosed in sealed clear glass vacuum tube enclosures. If any list members are interested in having a couple of these for your collection of "interesting stuff" let me know and I will send them to you. Postage should only be a few dollars. H Biggest issue may finding suitable little boxes to ship them in. Mike Baker Micanopy/Gainesville, FL * ___ 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.
Re: [time-nuts] OCXO pressure sensitivity before TCXO
On Sat, 3 Aug 2019 14:22:22 + (UTC) ew via time-nuts wrote: > Are wee missing something. Reading Bill Slade post and old NASA > attachments the attached plot to me was an eye opener. Our work > has always been focused on Rb pressure compensation. Are we > overlooking something. Has any one done some work on this subject No, we are not overlooking anything. Pressure sensitivity of OCXOs has been long known and most manufacturers account for it in their design. In most cases, the temperature induced instability is larger than the pressure sensitive effect, together with the pressure sensitivity measurement and characterisation being expensive, it does not get mentioned in the datasheets. But, if you really want to compensate for environmental effects, then you need to have a quite complex model. This makes it rather difficult to parametrize, you need measurements over months if not years. That makes these parameters also quite difficult to use, as they exhibit memory effects (e.g. hysterisis) and change over time. If you are interested in this, have a look at the fields of "System identification." Or, if you want to have it a bit simpler and more statistical: "Principal Component Analysis" Attila Kinali -- The bad part of Zurich is where the degenerates throw DARK chocolate at you. ___ 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.
