Re: [time-nuts] GPSDO - internal connections question
On Wed, 21 Sep 2011 18:36:43 -0500 Chris Howard ch...@elfpen.com wrote: Thanks! Would it do any good to have the control board, GPS, or anything else within its own shielded box? I'd put everything into one big metal box, but seperate the different submodules, probably shield them from each other. Please remember, that you are doing analog design on the EFC/OCXO side. This means that you have to have low noise levels where you handle these signals. This in turn means that you want to keep all digital electronics as far away from it as possible. Also think about a proper grounding scheme, as you connect the various submodules together, otherwise ground loops will introduce additional, hard to contain (and quite potent) noise. Attila Kinali -- WYSIWYG is not a solution, it is the problem, and until we get around to realizing that very few of us are competent to design fonts, styles, or layout (14-year-old girls who dot their i's with hearts excepted, of course, the exception that nails down the lid on the coffin), we're going to have to live with that crap. -- Stephen J. Turnbull in a discussion about word processors ___ 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] Allan Deviation Calulations
Hello, I'm trying to measure the Allan Deviation of an amplifier and need help with the maths. My measurement process uses the SR620 in time interval mode and I make one measurement per second for about a day. I then use Ulrichs excellent plotter to calculate the Allan Deviation. The Allan Dev floor noise of the SR620 (without my amplifier) is as follows. 9.91E-13 (1 second) 1.59 E-13 (10 sec) 3.00 E-14 (100 sec) I then add my amplifier into the measurement process. I get the following Allan Dev results 1.09E-12 (1 sec) 2.48E-13 (10 sec) 4.32E-14 (100 sec). So the 1 sec Allan dev with my amp included, has gone up by 9.9E-14 for the 1 sec measurement. How to I calculate the actual Allan Dev of my amp for the 1 sec period? Best Regards Martyn ___ 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] Allan Deviation Calulations
Le 22/09/2011 12:35, Martyn Smith a écrit : Hello, I'm trying to measure the Allan Deviation of an amplifier and need help with the maths. My measurement process uses the SR620 in time interval mode and I make one measurement per second for about a day. I then use Ulrichs excellent plotter to calculate the Allan Deviation. The Allan Dev floor noise of the SR620 (without my amplifier) is as follows. 9.91E-13 (1 second) 1.59 E-13 (10 sec) 3.00 E-14 (100 sec) I then add my amplifier into the measurement process. I get the following Allan Dev results 1.09E-12 (1 sec) 2.48E-13 (10 sec) 4.32E-14 (100 sec). So the 1 sec Allan dev with my amp included, has gone up by 9.9E-14 for the 1 sec measurement. How to I calculate the actual Allan Dev of my amp for the 1 sec period? Best Regards I have always thought of a noise floor as the lower limit to which you can trust your measurement. Measurements below the floor can be statistically derived IIRC, but calculating the Allan deviation of it makes no sense to me. As your measurements are all above it , you can trust them. Martyn ___ 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] Allan Deviation Calulations
mike cook wrote: Le 22/09/2011 12:35, Martyn Smith a écrit : Hello, I'm trying to measure the Allan Deviation of an amplifier and need help with the maths. My measurement process uses the SR620 in time interval mode and I make one measurement per second for about a day. I then use Ulrichs excellent plotter to calculate the Allan Deviation. The Allan Dev floor noise of the SR620 (without my amplifier) is as follows. 9.91E-13 (1 second) 1.59 E-13 (10 sec) 3.00 E-14 (100 sec) I then add my amplifier into the measurement process. I get the following Allan Dev results 1.09E-12 (1 sec) 2.48E-13 (10 sec) 4.32E-14 (100 sec). So the 1 sec Allan dev with my amp included, has gone up by 9.9E-14 for the 1 sec measurement. How to I calculate the actual Allan Dev of my amp for the 1 sec period? Best Regards I have always thought of a noise floor as the lower limit to which you can trust your measurement. Measurements below the floor can be statistically derived IIRC, but calculating the Allan deviation of it makes no sense to me. As your measurements are all above it , you can trust them. Since the noise floor isnt provided your conclusion itself isnt sustainable. Martyn ___ 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] Allan Deviation Calulations
Le 22/09/2011 13:45, Bruce Griffiths a écrit : I have always thought of a noise floor as the lower limit to which you can trust your measurement. Measurements below the floor can be statistically derived IIRC, but calculating the Allan deviation of it makes no sense to me. As your measurements are all above it , you can trust them. Since the noise floor isnt provided your conclusion itself isnt sustainable. Indeed Bruce, It has to be measured. I was really meaning that provided measurements of the DUT are above the floor, then it doesn't have to be factored in. Am I wrong 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] Allan Deviation Calulations
A couple of things to consider If you have two independent noise sources they add with their RMS sum But for two noise readings that are close, the difference is more likely statistical variations than RMS adding, especially at your 100 sec time periods. Assuming you have a system that is not limited by the SR620 25 ps noise floor (which is more like 1e-11 @ 1sec, or your limited data collection time, and that your data is correct, You solve for X knowing that total noise = [Square root of (X^2 + Y^2)] The noise floor does not have to be factored in if the difference is much larger and you want an approximate answer. The sum of two equal noise sources is times 1.4 Sum of two noise sources 10 to one apart give a 1% error. ws * Martyn Smith martyn at ptsyst.com Hello, I'm trying to measure the Allan Deviation of an amplifier and need help with the maths. My measurement process uses the SR620 in time interval mode and I make one measurement per second for about a day. I then use Ulrichs excellent plotter to calculate the Allan Deviation. The Allan Dev floor noise of the SR620 (without my amplifier) is as follows. 9.91E-13 (1 second) 1.59 E-13 (10 sec) 3.00 E-14 (100 sec) I then add my amplifier into the measurement process. I get the following Allan Dev results 1.09E-12 (1 sec) 2.48E-13 (10 sec) 4.32E-14 (100 sec). So the 1 sec Allan dev with my amp included, has gone up by 9.9E-14 for the 1 sec measurement. How to I calculate the actual Allan Dev of my amp for the 1 sec period? Best Regards Martyn ___ 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] SR620 Floor Noise
Hello, My measurement technique is from Stanford's own application note. The two 10 MHz are fed to Ch A and B. The measurement is a time interval gated at 1 kHz from the SR620's ref out. So we make 1000 measurements per second. So the one shot 25 ps SR620 spec is reduced by square root of 1000. So the theoretical floor noise is 0.8 ps per measurement. I also have plenty of 3048A phase noise test sets and I also use them to make ADEV measurements. The answer I've received has confirmed what I thought, so thank you for all the replies. I really want to build the high resolution counter projects that have been mentioned on time nuts and did even buy the pcb's. But just haven't got the time to build them. Martyn ___ 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] Allan Deviation Calulations
Sqrt(adev_meas^2-adev_ref^2) should do it, but you are close to the floor so confidence bounds will have to be small for meaningfull values. Cheers, Magnus Martyn Smith mar...@ptsyst.com skrev: Hello, I'm trying to measure the Allan Deviation of an amplifier and need help with the maths. My measurement process uses the SR620 in time interval mode and I make one measurement per second for about a day. I then use Ulrichs excellent plotter to calculate the Allan Deviation. The Allan Dev floor noise of the SR620 (without my amplifier) is as follows. 9.91E-13 (1 second) 1.59 E-13 (10 sec) 3.00 E-14 (100 sec) I then add my amplifier into the measurement process. I get the following Allan Dev results 1.09E-12 (1 sec) 2.48E-13 (10 sec) 4.32E-14 (100 sec). So the 1 sec Allan dev with my amp included, has gone up by 9.9E-14 for the 1 sec measurement. How to I calculate the actual Allan Dev of my amp for the 1 sec period? Best Regards Martyn ___ 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] HP5062C connector pinouts
Fellow time-nuts, I am in need of the pinning for the HP5062C connectors, in particular the AC and time code connectors. A manual would be great. 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] HP5062C connector pinouts
-Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts- boun...@febo.com] On Behalf Of Magnus Danielson Sent: Thursday, September 22, 2011 5:37 AM To: time-nuts@febo.com Subject: [time-nuts] HP5062C connector pinouts Fellow time-nuts, I am in need of the pinning for the HP5062C connectors, in particular the AC and time code connectors. A manual would be great. Cheers, Magnus I sent my paper edition of the 5062C service manual to Artek Media and they did a good job scanning it as usual (1836A prefix). They have both the operating and service .PDFs. For the AC connector, I ended up removing the old one in favor of a standard IEC jack. Life is too short to deal with those oddball military power connectors. It's not going to take the Coppa Bella Machina trophy at the next HP Owner's Club meeting, but it gets the electrons where they need to go... -- john, KE5FX ___ 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] Tek high voltage probes
On 09/21/2011 04:57 AM, David C. Partridge wrote: Howsabout HFC-236fa - very similar properties to R114 but not banned. Tektronix used a Freon in their 40 KV High Voltage probes. The Vapor pressure of some of those compounds is low at 70F, but they do have to be sealed. I use several of the Tek probes in my work (and of course am too cheap to buy the newer solid dielectric ones). When my freon ran out, I searched around for a replacement fluid and found ordinary butane straight from the Ronsonol can to be equal to or maybe even better than the original freon. About a decade ago I wrote up a procedure on how to do the fill without introducing condensate into the chamber. I posted it to Usenet. I think that it's archived at http://yarchive.net. John -- John DeArmond Tellico Plains, Occupied TN http://www.neon-john.com-- email from here http://www.johndearmond.com -- Best damned Blog on the net PGP key: wwwkeys.pgp.net: BCB68D77 ___ 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] Tek high voltage probes
John: One big difference is that when most of the butane leaked out and air leaked in, you'd get a very clear indication when arcs occur. I wouldn't want to be holding it. I think Tek degrades the P6015 to 13kV without Freon - enough for my needs. Maybe someone will find out that Home Depot Bathtub Selant #17 has a breakdown of 60kV and we can all do one last refill... Jose -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of NeonJohn Sent: Thursday, September 22, 2011 10:35 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Tek high voltage probes On 09/21/2011 04:57 AM, David C. Partridge wrote: Howsabout HFC-236fa - very similar properties to R114 but not banned. Tektronix used a Freon in their 40 KV High Voltage probes. The Vapor pressure of some of those compounds is low at 70F, but they do have to be sealed. I use several of the Tek probes in my work (and of course am too cheap to buy the newer solid dielectric ones). When my freon ran out, I searched around for a replacement fluid and found ordinary butane straight from the Ronsonol can to be equal to or maybe even better than the original freon. About a decade ago I wrote up a procedure on how to do the fill without introducing condensate into the chamber. I posted it to Usenet. I think that it's archived at http://yarchive.net. John -- John DeArmond Tellico Plains, Occupied TN http://www.neon-john.com-- email from here http://www.johndearmond.com -- Best damned Blog on the net PGP key: wwwkeys.pgp.net: BCB68D77 ___ 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] Tek high voltage probes
For those that reflexively will add that butane is explosive in air: There isn't any air in the probe if you let the butane boil for a few seconds, and as long as there is liquid butane in the probe there won't be any air leaking in. However, if there is no liquid, you will need to purge out the butane before operating the probe dry, or add more butane. When I finally do run out of my supply of R114, butane will be my substitute of choice for the R114. -Chuck Harris NeonJohn wrote: On 09/21/2011 04:57 AM, David C. Partridge wrote: Howsabout HFC-236fa - very similar properties to R114 but not banned. Tektronix used a Freon in their 40 KV High Voltage probes. The Vapor pressure of some of those compounds is low at 70F, but they do have to be sealed. I use several of the Tek probes in my work (and of course am too cheap to buy the newer solid dielectric ones). When my freon ran out, I searched around for a replacement fluid and found ordinary butane straight from the Ronsonol can to be equal to or maybe even better than the original freon. About a decade ago I wrote up a procedure on how to do the fill without introducing condensate into the chamber. I posted it to Usenet. I think that it's archived at http://yarchive.net. 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] Tek high voltage probes
On 9/22/11 10:34 AM, NeonJohn wrote: On 09/21/2011 04:57 AM, David C. Partridge wrote: Howsabout HFC-236fa - very similar properties to R114 but not banned. Tektronix used a Freon in their 40 KV High Voltage probes. The Vapor pressure of some of those compounds is low at 70F, but they do have to be sealed. I use several of the Tek probes in my work (and of course am too cheap to buy the newer solid dielectric ones). When my freon ran out, I searched around for a replacement fluid and found ordinary butane straight from the Ronsonol can to be equal to or maybe even better than the original freon. Yes.. most hydrocarbons make a fine dielectric (viz. transformer oil). To a certain extent, density is key, which is why the halogenated ones are nice (F or C are more massive than H). The other thing is that those halogens are electronegative which tends to suppress breakdown (why SF6 is great.. not only is it really dense, but it's also non flammable AND it's got fluorine in it) The halogenated ones are preferred in some cases because you can get other vapor pressures and/or they don't burn. There is, of course, a whole class of nice dielectric fluids based on halogenating double ring structures: PCBs. They're really inert, great dielectric strength, immiscible with contaminants (no dissolved water, which ruins dielectric properties). The problem is that there's an unavoidable carcinogenic contaminant (dioxin-like PCBs and PCDFs). And, because they ARE so resistant to breakdown, they persist forever, and, unfortunately, are fat soluble and taken up by wildlife. ___ 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] Tek high voltage probes
Note that if you change the dielectric in the probe, especially to a liquid, you may no longer be able to compensate it properly. The higher dielectric constant will increase the stray capacitances. Best, -John On 9/22/11 10:34 AM, NeonJohn wrote: On 09/21/2011 04:57 AM, David C. Partridge wrote: Howsabout HFC-236fa - very similar properties to R114 but not banned. Tektronix used a Freon in their 40 KV High Voltage probes. The Vapor pressure of some of those compounds is low at 70F, but they do have to be sealed. I use several of the Tek probes in my work (and of course am too cheap to buy the newer solid dielectric ones). When my freon ran out, I searched around for a replacement fluid and found ordinary butane straight from the Ronsonol can to be equal to or maybe even better than the original freon. Yes.. most hydrocarbons make a fine dielectric (viz. transformer oil). To a certain extent, density is key, which is why the halogenated ones are nice (F or C are more massive than H). The other thing is that those halogens are electronegative which tends to suppress breakdown (why SF6 is great.. not only is it really dense, but it's also non flammable AND it's got fluorine in it) The halogenated ones are preferred in some cases because you can get other vapor pressures and/or they don't burn. There is, of course, a whole class of nice dielectric fluids based on halogenating double ring structures: PCBs. They're really inert, great dielectric strength, immiscible with contaminants (no dissolved water, which ruins dielectric properties). The problem is that there's an unavoidable carcinogenic contaminant (dioxin-like PCBs and PCDFs). And, because they ARE so resistant to breakdown, they persist forever, and, unfortunately, are fat soluble and taken up by wildlife. ___ 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] Tek high voltage probes
It's going on 10 years now since I last filled a probe. That's the major advantage of butane. It doesn't diffuse out like the freon did. On 09/22/2011 01:53 PM, Jose Camara wrote: John: One big difference is that when most of the butane leaked out and air leaked in, you'd get a very clear indication when arcs occur. I wouldn't want to be holding it. -- John DeArmond Tellico Plains, Occupied TN http://www.neon-john.com-- email from here http://www.johndearmond.com -- Best damned Blog on the net PGP key: wwwkeys.pgp.net: BCB68D77 ___ 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] Tek high voltage probes
Neither diffuses out. They leak. They could certainly leak at different rates because of differing MWs, but how tight you made the sealing screw is likely far more important. -John == It's going on 10 years now since I last filled a probe. That's the major advantage of butane. It doesn't diffuse out like the freon did. On 09/22/2011 01:53 PM, Jose Camara wrote: John: One big difference is that when most of the butane leaked out and air leaked in, you'd get a very clear indication when arcs occur. I wouldn't want to be holding it. -- John DeArmond Tellico Plains, Occupied TN http://www.neon-john.com-- email from here http://www.johndearmond.com -- Best damned Blog on the net PGP key: wwwkeys.pgp.net: BCB68D77 ___ 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] Tek high voltage probes
Just a FYI, some claim Ronsonol butane isn't very pure as compared to other brands. Some lighter manufacturers suggest not to use it in their devices. I have no idea what trace substances they object to. Reality? Who knows. Seems most butane comes out of Korea and could simply be repackaged/branded. Hopefully there are few smokers on the list, and if you do, don't smoke near your instruments. I only use a lighter for camping. You guys in the UK have the best: Turboflame. I've repaired (soldered) antennas in the field with a turboflame. http://www.turboflame.co.uk/ Try lighting an Esbit square with a regular lighter versus a turbo. On 9/22/2011 10:34 AM, NeonJohn wrote: On 09/21/2011 04:57 AM, David C. Partridge wrote: I use several of the Tek probes in my work (and of course am too cheap to buy the newer solid dielectric ones). When my freon ran out, I searched around for a replacement fluid and found ordinary butane straight from the Ronsonol can to be equal to or maybe even better than the original freon. ___ 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] HP 10811 Response I Replies
Esteemed Colleagues, I will attempt to make a coherent technical reply to the remarks made about my 10811 posting. But first a bit of qualification. My remarks refer to the 10811 and that vintage of OCXO’s. Wrote: Doing what you describe will result in a very sensitive humidity sensor, having eliminated the thermometer effect. I do not understand. I believed that since the OCXO temperature will be substationally higher than the surrounding temps, any residual moisture would migrate to a lower temperature. The fiberglass insulation inside the vacuum flask prevents air currents, reduces air volume, and provides mechanical isolation. If I err, what would be a better solution? There are similar, well lauded, designs using large blocks of styrofoam instead (Shera). Why would foam be better that a vacuum bottle? Wrote: In any event, none of this affects crystal aging or frequency jumps. So true, but I never said it would. All I proposed was to as much as possible eliminate any exterior variables so all one would see is only the crystal aging characteristics. Wrote: This is what limits the E1938A which is hermetic and has a thermal gain 1000 times better than the 10811. I know it is a splendid OCXO, a much later design and costs your new-born child IF a used one can be found. Rick, you have probably forgotten more about OCXO’s than I’ll ever know. My questions are not argumentative but are for seeking knowledge. Wrote: Just how good is the thermos bottle in this case? (as in degrees / watt). You can get some very good vacuum ones and some pretty poor Styrofoam ones. I don’t know anything about its degrees/watt. It is a true wide mouth glass vacuum thermos with a protective plastic inner lining that I bought a long, long time ago. It was sold for taking hot soup to work. Speaking of Styrofoam. If you want to use one try to get one from Omaha Steaks. Wrote: Imagine that the set point is variable, and can be set below the desired temperature. Then imagine that the set point can approach the desired temperature more closely as it gets closer to the desired temperature. ... And you will have discovered (100 years late) the PID controller. It still works on the concept of successive approximation. It may have less over-shoot on start-up and the amount of over-shoot may not have a negligible effect. But it still will be there. Perhaps if one was designing a new product that might be the best solution. However my remarks were about the HP 10811. It isn’t applicable in this situation. Wrote: 30 years ago I was designing PID controllers, with a little microprocessor magic, that could quickly arrive at the set point temperature and never, I repeat, never, exceed that temperature. Someone's internal organs would have become toast if it did. From 1976 to 2001 I repaired life support equipment including hemodialysis machines (factory trained) and blood warmers. They only used thermistor bridge or mechanical thermostats. And yes we had to make sure the blood temperature never, ever went over 102F. Probably at that time reliable µprocessor control was not generally cost effective. But I don’t think that PIC technology you did would apply to OCXO’s. Here’s why: heat is added to either large amount of cold fluids entering the body or to substitute for the body’s inability to maintain proper body heat (radiant infant warmers). You have a large ongoing thermal sink. In an extremely well insulated OCXO as I understand it, there is almost no thermal sink once the set point is reached. And then there is the cost issue. Again, not to argue with your type of controller. I’m just considering the current surplus OCXO’s that are available. Regards, Perrier ___ 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] HP 10811 Response I Replies
Perry Sandeen wrote: Wrote: Doing what you describe will result in a very sensitive humidity sensor, having eliminated the thermometer effect. I do not understand. I believed that since the OCXO temperature will be substationally higher than the surrounding temps, any residual moisture would migrate to a lower temperature. The fiberglass insulation inside Heating up a space does not change the absolute humidity AFAIK. It only changes the relative humidity. We did tests where we sealed a 10811 inside a box that was held together with so-called hermetic epoxy. We put it in an environmental chamber at a constant temperature and constant low humidity and let it stabilize. We then increased the humidity to something like 80%, while holding the temperature constant. Within minutes the frequency changed more than the spec for the entire temperature range. Therefore, you should do your experiment with the hermetic version of the 10811. The hermetic version is soldered shut, rather than using epoxy, which turns out not to be hermetic, no matter what they claim. Rick Karlquist ___ 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] HP 10811 Response I Replies
You had a leak. If epoxy was really as bad as you indicate, it would not be usable for holding pressure, or mild vacuum, and yet it is. Somehow, someway you left a big hole in the bucket. -Chuck Harris Rick Karlquist wrote: Perry Sandeen wrote: Wrote: Doing what you describe will result in a very sensitive humidity sensor, having eliminated the thermometer effect. I do not understand. I believed that since the OCXO temperature will be substationally higher than the surrounding temps, any residual moisture would migrate to a lower temperature. The fiberglass insulation inside Heating up a space does not change the absolute humidity AFAIK. It only changes the relative humidity. We did tests where we sealed a 10811 inside a box that was held together with so-called hermetic epoxy. We put it in an environmental chamber at a constant temperature and constant low humidity and let it stabilize. We then increased the humidity to something like 80%, while holding the temperature constant. Within minutes the frequency changed more than the spec for the entire temperature range. Therefore, you should do your experiment with the hermetic version of the 10811. The hermetic version is soldered shut, rather than using epoxy, which turns out not to be hermetic, no matter what they claim. Rick Karlquist ___ 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] HP 10811 Response I Replies
A problem I've seen when using the hermetic sealed soldered version of the 10811 from a dual oven unit, is when the case is sealed the osc makes a good barometer because of changes in its case due to barometric changes. A 1 inch difference (such as 30 to 29) caused something on the order of 1e-11 freg change. To see the effect just need to put a little pressure on the case So now I'm trying to determine which is worse, leaving the freq adj screw tight and sealed or leaking a little, inside a box containing desiccant. ws ** Heating up a space does not change the absolute humidity AFAIK. It only changes the relative humidity. We did tests where we sealed a 10811 inside a box that was held together with so-called hermetic epoxy. We put it in an environmental chamber at a constant temperature and constant low humidity and let it stabilize. We then increased the humidity to something like 80%, while holding the temperature constant. Within minutes the frequency changed more than the spec for the entire temperature range. Therefore, you should do your experiment with the hermetic version of the 10811. The hermetic version is soldered shut, rather than using epoxy, which turns out not to be hermetic, no matter what they claim. Rick Karlquist ___ 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] HP 10811 Response I Replies
Within minutes the frequency changed more than the spec For humidity to get thru something like that it takes weeks or more it does it at all. That fast of reaction, Sure sounds like some other effect like blowing a little air on the case or loading the osc output with water in the output cable etc, etc. I think it is safe to say the effect was not due to water inside, unless there was a hole. ws * Chuck Harris cfharris at erols.com You had a leak. If epoxy was really as bad as you indicate, it would not be usable for holding pressure, or mild vacuum, and yet it is. Somehow, someway you left a big hole in the bucket. -Chuck Harris Rick Karlquist wrote: Perry Sandeen wrote: Wrote: Doing what you describe will result in a very sensitive humidity sensor, having eliminated the thermometer effect. I do not understand. I believed that since the OCXO temperature will be substationally higher than the surrounding temps, any residual moisture would migrate to a lower temperature. The fiberglass insulation inside Heating up a space does not change the absolute humidity AFAIK. It only changes the relative humidity. We did tests where we sealed a 10811 inside a box that was held together with so-called hermetic epoxy. We put it in an environmental chamber at a constant temperature and constant low humidity and let it stabilize. We then increased the humidity to something like 80%, while holding the temperature constant. Within minutes the frequency changed more than the spec for the entire temperature range. Therefore, you should do your experiment with the hermetic version of the 10811. The hermetic version is soldered shut, rather than using epoxy, which turns out not to be hermetic, no matter what they claim. Rick Karlquist ___ 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] HP 10811 Response I Replies
Humidity is a confusing subject to many engineers and scientists. Unlike most parameters it is a quantity with two input variables, concentration and temperature. There are many ways to combine these to give different units. As a research scientist I spent most of my career working with composite materials which exhibit great sensitivity to humidity. Most composite materials respond to the Relative Humidity with only a small temperature dependance. So 80% RH has the same effect at any temperature. Note that the Absolute Humidity varies exponentially with temperature. For a fixed Absolute Humidity (say 10gms /m3) and at 70% RH the relative humidity changes about 10% per degree celsius. So if you have a sealed container with some water vapour in it the RH will vary about 10% per C*. If you have a fixed ambient humidity, a heated enclosure will have a humidity that falls 10%/K as the temperature rises. Now there are many grandiose environmental chambers sold to scientists and engineers that perform poorly. They have internal temperature gradients, so even if the concentration of water vapour is uniform the distribution of relative humidity is not. If a chamber set to 80% RH has a 2 degree gradient it could have internal condensation. The problems are made worse by the plethora of nearly useless humidity probes made by manufacturers who are having a bidding war based on claimed specs. Since there are very few facilities to calibrate humidity sensors, and no company can make a dollar by having their humidity measured more accurately, there is no pressure to improve instrument quality and the situation remains that there is a lot of misunderstanding about humidity. The instruments I have built have an inaccuracy of less than 0.1% RH, and I have built isothermal chambers that can be programmed to 0.1% RH. They are based on calculable processes for calibration, and so have absolute calibration. In the case of quartz crystals in ovens, when the oven is 30K above ambient the relative humidity is very low, so you would expect there to be very little absorbed or adsorbed water to interfere with stability. The main effects are surface leakage on hydrophilic surfaces and dielectric absorption in composite material insulators. There is a second order effect that the dielectric constant of air changes with absolute humidity. Humidity sensitivity would seem to me to be a problem of the measurement system rather than the item being tested. Cheers, Neville Michie On 23/09/2011, at 9:07 AM, Rick Karlquist wrote: Perry Sandeen wrote: Wrote: Doing what you describe will result in a very sensitive humidity sensor, having eliminated the thermometer effect. I do not understand. I believed that since the OCXO temperature will be substationally higher than the surrounding temps, any residual moisture would migrate to a lower temperature. The fiberglass insulation inside Heating up a space does not change the absolute humidity AFAIK. It only changes the relative humidity. We did tests where we sealed a 10811 inside a box that was held together with so-called hermetic epoxy. We put it in an environmental chamber at a constant temperature and constant low humidity and let it stabilize. We then increased the humidity to something like 80%, while holding the temperature constant. Within minutes the frequency changed more than the spec for the entire temperature range. Therefore, you should do your experiment with the hermetic version of the 10811. The hermetic version is soldered shut, rather than using epoxy, which turns out not to be hermetic, no matter what they claim. Rick Karlquist ___ 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] HP 10811 Response I Replies
On 9/22/2011 5:17 PM, ws at Yahoo wrote: Within minutes the frequency changed more than the spec For humidity to get thru something like that it takes weeks or more it does it at all. That fast of reaction, Sure sounds like some other effect like blowing a little air on the case or loading the osc output with water in the output cable etc, etc. I think it is safe to say the effect was not due to water inside, unless there was a hole. ws The effect we saw was like parts in 10^8 of something. Way too big to be related to output loading or air on the case. In any event, the air blowing on the case was constant during the test. We saw that when we didn't even try to seal the 10811 and also when we tried to seal it. Rick Karlquist ___ 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] Fast than light neutrino
For those of you who may be interested, here's the paper. http://arxiv.org/ftp/arxiv/papers/1109/1109.4897.pdf ___ 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.
