Re: [time-nuts] HP5061 Cesium ion pump question
Hi Having watched a number of Cs tubes die ….. Measuring ADEV on your Cs is a good idea. As the tube goes downhill the signal to noise often gets worse. This shows up even at relatively short tau ADEV ( like 100 to 1000 seconds). On a 5061 era device, this means doing ADEV at the 1x10^-11 to 1x10^-12 level in the 100 to 1000 second range. A good (as in eBay for < $100) OCXO *might* cover this range adequately. A Telecom Rb probably is a better bet if you want to do a bit less “shopping” for your reference. If you have a counter that does 2x10^-11 at 1 second, it *should* get you into the right range at 100 to 1,000 seconds. No need for ultra fancy setups. We’re not trying to show how *good* a working one is with this test. We’re only trying to catch the “end of life” of the tube. Why bother? The compelling reason for playing with a Cs is accuracy. If the SNR has the stability degraded by 10X (or more ….) it will take you a *very* long time ( = very long observation times) to get to that accuracy. Indeed, the same things that degrade the SNR *may* degrade the accuracy as well. Does this mean that all old tubes are junk? No it most certainly does not mean that. There isn’t a lot of correlation between this and that and the SNR (as the term is arbitrarily used above). After pumping down for a while, it may be doing fine. It also may not be. If, even after extended this or that, it’s still very noisy, you might want to factor that into what you decide to do next. Bob > On Dec 4, 2020, at 9:16 AM, paul swed wrote: > > Exactly filaments cold. KE5FX has great details on doing this for a Cs > tube. Google his details. > Regards > Paul. > > On Fri, Dec 4, 2020 at 3:24 AM Dana Whitlow wrote: > >> I wonder if it might be good to power up the ion pump with the heaters >> cold, then >> after the ion current trails off to nil, begin operating the filaments at >> very low voltage >> (and all other voltages off except for the ion pump) and gradually ramp the >> the filament >> voltages up towards normal operating voltage, doing so slowly enough that >> the ion >> pump never trips off. Then, once things have settled down at normal >> filament voltage, >> set up and fire up the whole instrument. I think this might be easier on >> both the filaments >> and the ion pump. >> >> Comments? >> >> Dana >> >> >> On Thu, Dec 3, 2020 at 8:34 PM wrote: >> >>> Thanks very much for this info Corby. It explains the behaviour of my >> spare >>> 5061A perfectly. >>> >>> It also raises the question of what I could do with the spare tube I >> have. >>> I >>> can connect a +3500V supply to the ion pump but that won't do anything >>> about >>> any gas molecules adsorbed onto the filaments as you described. Is it >> worth >>> powering up the filaments to get rid of them or can that be left for some >>> indefinite time in the future when the tube could be reinstalled in a >>> 5061A? >>> >>> Morris >>> >>> --- >>> Date: Wed, 2 Dec 2020 11:06:22 -0800 >>> From: >>> To: time-nuts@lists.febo.com >>> Subject: [time-nuts] HP5061 Cesium ion pump question >>> >>> The gettering in the tube is only for capturing any stray Cesium atoms >>> that don't get caught in the main gettering patch. If the gettering fails >>> or gets too loaded up then the Cesium background level will get too high >>> causing poor SN. >>> >>> The ion pump is for any gases. >>> >>> When a tube is off for extended times any gas atoms lingering or leaking >>> slowly into the tube than happen to impinge on either the mass >>> Spectrometer filament or the Cs oven filaments get capture by the >>> filaments. They function as excellent getters! (this even if the ion >>> pump is on) >>> >>> Now this is not by design but results in the filaments being "loaded" >>> with the gas atoms. >>> >>> Then when you turn the tube on the filaments light up and expell a burst >>> of gas. >>> >>> This of coarse causes the ion pump current to rise and trips off the >>> filaments, >>> >>> Once the ion pump removes the burst the cycle repeats until the filaments >>> have expelled the trapped gases. >>> >>> Then the ion pump can handle the load and pump the tube down completely. >>> >>> Cheers, >>> >>> Corby >>> >>> >>> * >&g
Re: [time-nuts] HP5061 Cesium ion pump question
Exactly filaments cold. KE5FX has great details on doing this for a Cs tube. Google his details. Regards Paul. On Fri, Dec 4, 2020 at 3:24 AM Dana Whitlow wrote: > I wonder if it might be good to power up the ion pump with the heaters > cold, then > after the ion current trails off to nil, begin operating the filaments at > very low voltage > (and all other voltages off except for the ion pump) and gradually ramp the > the filament > voltages up towards normal operating voltage, doing so slowly enough that > the ion > pump never trips off. Then, once things have settled down at normal > filament voltage, > set up and fire up the whole instrument. I think this might be easier on > both the filaments > and the ion pump. > > Comments? > > Dana > > > On Thu, Dec 3, 2020 at 8:34 PM wrote: > > > Thanks very much for this info Corby. It explains the behaviour of my > spare > > 5061A perfectly. > > > > It also raises the question of what I could do with the spare tube I > have. > > I > > can connect a +3500V supply to the ion pump but that won't do anything > > about > > any gas molecules adsorbed onto the filaments as you described. Is it > worth > > powering up the filaments to get rid of them or can that be left for some > > indefinite time in the future when the tube could be reinstalled in a > > 5061A? > > > > Morris > > > > ------- > > Date: Wed, 2 Dec 2020 11:06:22 -0800 > > From: > > To: time-nuts@lists.febo.com > > Subject: [time-nuts] HP5061 Cesium ion pump question > > > > The gettering in the tube is only for capturing any stray Cesium atoms > > that don't get caught in the main gettering patch. If the gettering fails > > or gets too loaded up then the Cesium background level will get too high > > causing poor SN. > > > > The ion pump is for any gases. > > > > When a tube is off for extended times any gas atoms lingering or leaking > > slowly into the tube than happen to impinge on either the mass > > Spectrometer filament or the Cs oven filaments get capture by the > > filaments. They function as excellent getters! (this even if the ion > > pump is on) > > > > Now this is not by design but results in the filaments being "loaded" > > with the gas atoms. > > > > Then when you turn the tube on the filaments light up and expell a burst > > of gas. > > > > This of coarse causes the ion pump current to rise and trips off the > > filaments, > > > > Once the ion pump removes the burst the cycle repeats until the filaments > > have expelled the trapped gases. > > > > Then the ion pump can handle the load and pump the tube down completely. > > > > Cheers, > > > > Corby > > > > > > * > > > > > > ___ > > 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] HP5061 Cesium ion pump question
I wonder if it might be good to power up the ion pump with the heaters cold, then after the ion current trails off to nil, begin operating the filaments at very low voltage (and all other voltages off except for the ion pump) and gradually ramp the the filament voltages up towards normal operating voltage, doing so slowly enough that the ion pump never trips off. Then, once things have settled down at normal filament voltage, set up and fire up the whole instrument. I think this might be easier on both the filaments and the ion pump. Comments? Dana On Thu, Dec 3, 2020 at 8:34 PM wrote: > Thanks very much for this info Corby. It explains the behaviour of my spare > 5061A perfectly. > > It also raises the question of what I could do with the spare tube I have. > I > can connect a +3500V supply to the ion pump but that won't do anything > about > any gas molecules adsorbed onto the filaments as you described. Is it worth > powering up the filaments to get rid of them or can that be left for some > indefinite time in the future when the tube could be reinstalled in a > 5061A? > > Morris > > --- > Date: Wed, 2 Dec 2020 11:06:22 -0800 > From: > To: time-nuts@lists.febo.com > Subject: [time-nuts] HP5061 Cesium ion pump question > > The gettering in the tube is only for capturing any stray Cesium atoms > that don't get caught in the main gettering patch. If the gettering fails > or gets too loaded up then the Cesium background level will get too high > causing poor SN. > > The ion pump is for any gases. > > When a tube is off for extended times any gas atoms lingering or leaking > slowly into the tube than happen to impinge on either the mass > Spectrometer filament or the Cs oven filaments get capture by the > filaments. They function as excellent getters! (this even if the ion > pump is on) > > Now this is not by design but results in the filaments being "loaded" > with the gas atoms. > > Then when you turn the tube on the filaments light up and expell a burst > of gas. > > This of coarse causes the ion pump current to rise and trips off the > filaments, > > Once the ion pump removes the burst the cycle repeats until the filaments > have expelled the trapped gases. > > Then the ion pump can handle the load and pump the tube down completely. > > Cheers, > > Corby > > > * > > > ___ > 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] HP5061 Cesium ion pump question
If you can reasonably safely run the ion pump I would do that. At least you are getting rid of stuff ahead of using the tube. It will shorten the time to get the tube into operation. If the ION pump is hooked up and after a month the current is higher than 40 ua you could expect that the tube would most likely never work. They look nice as a paper weight. Regards Paul WB8TSL On Thu, Dec 3, 2020 at 9:34 PM wrote: > Thanks very much for this info Corby. It explains the behaviour of my spare > 5061A perfectly. > > It also raises the question of what I could do with the spare tube I have. > I > can connect a +3500V supply to the ion pump but that won't do anything > about > any gas molecules adsorbed onto the filaments as you described. Is it worth > powering up the filaments to get rid of them or can that be left for some > indefinite time in the future when the tube could be reinstalled in a > 5061A? > > Morris > > --- > Date: Wed, 2 Dec 2020 11:06:22 -0800 > From: > To: time-nuts@lists.febo.com > Subject: [time-nuts] HP5061 Cesium ion pump question > > The gettering in the tube is only for capturing any stray Cesium atoms > that don't get caught in the main gettering patch. If the gettering fails > or gets too loaded up then the Cesium background level will get too high > causing poor SN. > > The ion pump is for any gases. > > When a tube is off for extended times any gas atoms lingering or leaking > slowly into the tube than happen to impinge on either the mass > Spectrometer filament or the Cs oven filaments get capture by the > filaments. They function as excellent getters! (this even if the ion > pump is on) > > Now this is not by design but results in the filaments being "loaded" > with the gas atoms. > > Then when you turn the tube on the filaments light up and expell a burst > of gas. > > This of coarse causes the ion pump current to rise and trips off the > filaments, > > Once the ion pump removes the burst the cycle repeats until the filaments > have expelled the trapped gases. > > Then the ion pump can handle the load and pump the tube down completely. > > Cheers, > > Corby > > > * > > > ___ > 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] HP5061 Cesium ion pump question
Thanks very much for this info Corby. It explains the behaviour of my spare 5061A perfectly. It also raises the question of what I could do with the spare tube I have. I can connect a +3500V supply to the ion pump but that won't do anything about any gas molecules adsorbed onto the filaments as you described. Is it worth powering up the filaments to get rid of them or can that be left for some indefinite time in the future when the tube could be reinstalled in a 5061A? Morris --- Date: Wed, 2 Dec 2020 11:06:22 -0800 From: To: time-nuts@lists.febo.com Subject: [time-nuts] HP5061 Cesium ion pump question The gettering in the tube is only for capturing any stray Cesium atoms that don't get caught in the main gettering patch. If the gettering fails or gets too loaded up then the Cesium background level will get too high causing poor SN. The ion pump is for any gases. When a tube is off for extended times any gas atoms lingering or leaking slowly into the tube than happen to impinge on either the mass Spectrometer filament or the Cs oven filaments get capture by the filaments. They function as excellent getters! (this even if the ion pump is on) Now this is not by design but results in the filaments being "loaded" with the gas atoms. Then when you turn the tube on the filaments light up and expell a burst of gas. This of coarse causes the ion pump current to rise and trips off the filaments, Once the ion pump removes the burst the cycle repeats until the filaments have expelled the trapped gases. Then the ion pump can handle the load and pump the tube down completely. Cheers, Corby * ___ 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] HP5061 Cesium ion pump question
Just very curious. > > Regards > > Paul > > WB8TSL > > > > > > On Wed, Dec 2, 2020 at 6:23 AM wrote: > > > > > I think there's quite a bit of variation in leakage rates between > > > individual > > > physics packages, and there's also variation in the accuracy of the > > > metering. I recently started up my spare 5061A after over a year in > > > storage. > > > The Ion current meter showed zero with the Cs off but about 40 in the > > Open > > > Loop position. I tried connecting an external +3500V supply through a > > > microammeter as described in the manual and that showed less than 10 > uA. > > > The > > > unit kept trying to start and pulsed for about 12 hours at a peak > reading > > > of > > > 40 and then settled down nicely to a zero reading and hasn't missed a > > beat > > > since. > > > > > > I have a spare tube sitting here that hasn't been powered up for > several > > > years. It was removed from a junked 5061A that wouldn't start at all > but > > > after the unit was parted out some failed caps were found in one of the > > > modules that could have explained the fault. I plan to try it on the > > bench > > > with the +3500 V supply and microammeter but I don't know whether I can > > > trust the reading. If the tube in one of my functioning units fails one > > day > > > then I'll give it a try. > > > > > > Morris > > > > > > -- > > > From: paul swed > > > To: Time-nuts > > > Subject: [time-nuts] HP5061 Cesium ion pump question > > > > > > > > > During my HP 5061Cesium testing last week I was watching the ion pump > > > current and am curious. > > > What is the typical behavior people see on the tube after say 3 months > of > > > being turned off. > > > With 3 units I see one that pumps doen from 8 to 2 in 40 minutes. > Another > > > maybe at 25 and takes 28 hours to get to 18. Just seems to be all over > > the > > > place. > > > Regards > > > Paul > > > WB8TSL > > > > > > > > > -- > > > > > > Message: 10 > > > Date: Tue, 01 Dec 2020 06:19:25 + > > > From: "Poul-Henning Kamp" > > > To: Discussion of precise time and frequency measurement > > > , paul swed > > > Subject: Re: [time-nuts] HP5065a cfield issue > > > Message-ID: <86443.1606803...@critter.freebsd.dk> > > > Content-Type: text/plain; charset="us-ascii" > > > > > > > > > paul swed writes: > > > > > > > Guessing far less than 3 ma. by adding up resistors. > > > > > > More like typical 4 mA: there is a factory select resistor in > > > parallel with the current-setting resistor. > > > > > > > > > -- > > > 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. > > > > > > > > > > > > -- > > > > > > Message: 11 > > > Date: Tue, 1 Dec 2020 10:40:54 + (UTC) > > > From: ew > > > To: time-nuts@lists.febo.com > > > Subject: Re: [time-nuts] EOL Motorola Oncore Remote Antenna > > > Message-ID: <1292998389.3097482.1606819254...@mail.yahoo.com> > > > Content-Type: text/plain; charset="utf-8" > > > > > > Jim, I agree. As part of my OSA 8607A GPSDO project I planned to place > > the > > > OCXO in an aluminium box to eliminate pressure change. Step one > included > > > buying a separate unit to make sure the rubber gasket did do the job. > > > Attached first results. Temperature does change pressure more than > > ambient. > > > The vertical steps are the result of gentle tightening the lid, did not > > > know > > > how much lid had to be tightened. Now I know and have a 10 day test > > > running. > > > With AC running, the AC control at the other end of the house lab > > > temperature stays within ! C. Today a cold front hit, no AC and > > temperature > > > will drop more than 1 C. Taking advantage of the forecast I am > extending > > > the > > > test for a couple more days.? ? ? ? ? ?
Re: [time-nuts] HP5061 Cesium ion pump question
Corby that explains what I have been seeing and wondering about over the years I have had Cesiums. Get it all pumped down and then the next time I get those bursts. I am letting a recent 5061 pump down. It seems to get really dirty each time I start it but gets down to 16 on the meter after some 48 hours. I run the Cesiums at least per quarter. Really appreciate this insight you shared. Thank you. Paul WB8TSL On Wed, Dec 2, 2020 at 2:27 PM wrote: > The gettering in the tube is only for capturing any stray Cesium atoms > that don't get caught in the main gettering patch. If the gettering fails > or gets too loaded up then the Cesium background level will get too high > causing poor SN. > > The ion pump is for any gases. > > When a tube is off for extended times any gas atoms lingering or leaking > slowly into the tube than happen to impinge on either the mass > Spectrometer filament or the Cs oven filaments get capture by the > filaments. They function as excellent getters! (this even if the ion > pump is on) > > Now this is not by design but results in the filaments being "loaded" > with the gas atoms. > > Then when you turn the tube on the filaments light up and expell a burst > of gas. > > This of coarse causes the ion pump current to rise and trips off the > filaments, > > Once the ion pump removes the burst the cycle repeats until the filaments > have expelled the trapped gases. > > Then the ion pump can handle the load and pump the tube down completely. > > Cheers, > > Corby > > > ___ > 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] HP5061 Cesium ion pump question
The gettering in the tube is only for capturing any stray Cesium atoms that don't get caught in the main gettering patch. If the gettering fails or gets too loaded up then the Cesium background level will get too high causing poor SN. The ion pump is for any gases. When a tube is off for extended times any gas atoms lingering or leaking slowly into the tube than happen to impinge on either the mass Spectrometer filament or the Cs oven filaments get capture by the filaments. They function as excellent getters! (this even if the ion pump is on) Now this is not by design but results in the filaments being "loaded" with the gas atoms. Then when you turn the tube on the filaments light up and expell a burst of gas. This of coarse causes the ion pump current to rise and trips off the filaments, Once the ion pump removes the burst the cycle repeats until the filaments have expelled the trapped gases. Then the ion pump can handle the load and pump the tube down completely. Cheers, Corby ___ 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] HP5061 Cesium ion pump question
gt; > modules that could have explained the fault. I plan to try it on the > bench > > with the +3500 V supply and microammeter but I don't know whether I can > > trust the reading. If the tube in one of my functioning units fails one > day > > then I'll give it a try. > > > > Morris > > > > -- > > From: paul swed > > To: Time-nuts > > Subject: [time-nuts] HP5061 Cesium ion pump question > > > > > > During my HP 5061Cesium testing last week I was watching the ion pump > > current and am curious. > > What is the typical behavior people see on the tube after say 3 months of > > being turned off. > > With 3 units I see one that pumps doen from 8 to 2 in 40 minutes. Another > > maybe at 25 and takes 28 hours to get to 18. Just seems to be all over > the > > place. > > Regards > > Paul > > WB8TSL > > > > > > -- > > > > Message: 10 > > Date: Tue, 01 Dec 2020 06:19:25 + > > From: "Poul-Henning Kamp" > > To: Discussion of precise time and frequency measurement > > , paul swed > > Subject: Re: [time-nuts] HP5065a cfield issue > > Message-ID: <86443.1606803...@critter.freebsd.dk> > > Content-Type: text/plain; charset="us-ascii" > > > > > > paul swed writes: > > > > > Guessing far less than 3 ma. by adding up resistors. > > > > More like typical 4 mA: there is a factory select resistor in > > parallel with the current-setting resistor. > > > > > > -- > > 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. > > > > > > > > -- > > > > Message: 11 > > Date: Tue, 1 Dec 2020 10:40:54 + (UTC) > > From: ew > > To: time-nuts@lists.febo.com > > Subject: Re: [time-nuts] EOL Motorola Oncore Remote Antenna > > Message-ID: <1292998389.3097482.1606819254...@mail.yahoo.com> > > Content-Type: text/plain; charset="utf-8" > > > > Jim, I agree. As part of my OSA 8607A GPSDO project I planned to place > the > > OCXO in an aluminium box to eliminate pressure change. Step one included > > buying a separate unit to make sure the rubber gasket did do the job. > > Attached first results. Temperature does change pressure more than > ambient. > > The vertical steps are the result of gentle tightening the lid, did not > > know > > how much lid had to be tightened. Now I know and have a 10 day test > > running. > > With AC running, the AC control at the other end of the house lab > > temperature stays within ! C. Today a cold front hit, no AC and > temperature > > will drop more than 1 C. Taking advantage of the forecast I am extending > > the > > test for a couple more days.? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? > ? ? > > ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?Doe to the low > power > > dissipation of the 8607 fan cooling is not an option but I will use the > box > > , seal it and characterize the 8607 for pressure and temperature and use > > external pressure and temperature sensors for compensation once combined > > with a new generation GPSDO.? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? > ? ? > > ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?? > > > > > > > > I'll bet pressure changes inside the "sealed" radome due to temperature > > changes are bigger than those due to local barometer changes. > > > > But an interesting thing - water vapor will go through cracks, porosity, > > that liquid water will not. The commercial success of GoreTex is an > > example of this, but cracks, o-rings that aren't quite right, etc. are > > also ways it can happen. > > > > Making a truly hermetic box is hard. > > > > > > > > -Original Message- > > > From: Poul-Henning Kamp > > > Sent: Sunday, November 29, 2020 11:19 PM > > > To: Discussion of precise time and frequency measurement > > ; Art Sepin > > > Subject: Re: [time-nuts] EOL Motorola Oncore Remote Antenna > > > > > > > > > > > >> It's obvious from the photo that the O-Ring seal failed its purpose > > >> over its many years of service. Has the unit totally failed or does > the > > electronic portion still function? > > > >
Re: [time-nuts] HP5061 Cesium ion pump question
Morris I do see that of the 3 HP5061s the results are different and do know each tube leaks or internally emits stuff. But as you say maybe the metering is off. It definitely trips out at 40ua. I have my units that pulse like that and then settle down as the tube clears. But its hard to explain that if a unit is pumped down how quickly it pollutes again. Wondering if as an example the getter just releases its captured crud when the power is removed. That way you are always pumping down mostly the same stuff. Just very curious. Regards Paul WB8TSL On Wed, Dec 2, 2020 at 6:23 AM wrote: > I think there's quite a bit of variation in leakage rates between > individual > physics packages, and there's also variation in the accuracy of the > metering. I recently started up my spare 5061A after over a year in > storage. > The Ion current meter showed zero with the Cs off but about 40 in the Open > Loop position. I tried connecting an external +3500V supply through a > microammeter as described in the manual and that showed less than 10 uA. > The > unit kept trying to start and pulsed for about 12 hours at a peak reading > of > 40 and then settled down nicely to a zero reading and hasn't missed a beat > since. > > I have a spare tube sitting here that hasn't been powered up for several > years. It was removed from a junked 5061A that wouldn't start at all but > after the unit was parted out some failed caps were found in one of the > modules that could have explained the fault. I plan to try it on the bench > with the +3500 V supply and microammeter but I don't know whether I can > trust the reading. If the tube in one of my functioning units fails one day > then I'll give it a try. > > Morris > > ---------- > From: paul swed > To: Time-nuts > Subject: [time-nuts] HP5061 Cesium ion pump question > > > During my HP 5061Cesium testing last week I was watching the ion pump > current and am curious. > What is the typical behavior people see on the tube after say 3 months of > being turned off. > With 3 units I see one that pumps doen from 8 to 2 in 40 minutes. Another > maybe at 25 and takes 28 hours to get to 18. Just seems to be all over the > place. > Regards > Paul > WB8TSL > > > -- > > Message: 10 > Date: Tue, 01 Dec 2020 06:19:25 + > From: "Poul-Henning Kamp" > To: Discussion of precise time and frequency measurement > , paul swed > Subject: Re: [time-nuts] HP5065a cfield issue > Message-ID: <86443.1606803...@critter.freebsd.dk> > Content-Type: text/plain; charset="us-ascii" > > > paul swed writes: > > > Guessing far less than 3 ma. by adding up resistors. > > More like typical 4 mA: there is a factory select resistor in > parallel with the current-setting resistor. > > > -- > 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. > > > > -- > > Message: 11 > Date: Tue, 1 Dec 2020 10:40:54 + (UTC) > From: ew > To: time-nuts@lists.febo.com > Subject: Re: [time-nuts] EOL Motorola Oncore Remote Antenna > Message-ID: <1292998389.3097482.1606819254...@mail.yahoo.com> > Content-Type: text/plain; charset="utf-8" > > Jim, I agree. As part of my OSA 8607A GPSDO project I planned to place the > OCXO in an aluminium box to eliminate pressure change. Step one included > buying a separate unit to make sure the rubber gasket did do the job. > Attached first results. Temperature does change pressure more than ambient. > The vertical steps are the result of gentle tightening the lid, did not > know > how much lid had to be tightened. Now I know and have a 10 day test > running. > With AC running, the AC control at the other end of the house lab > temperature stays within ! C. Today a cold front hit, no AC and temperature > will drop more than 1 C. Taking advantage of the forecast I am extending > the > test for a couple more days.? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? > ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?Doe to the low power > dissipation of the 8607 fan cooling is not an option but I will use the box > , seal it and characterize the 8607 for pressure and temperature and use > external pressure and temperature sensors for compensation once combined > with a new generation GPSDO.? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? > ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?? > > > > I'll bet pressure changes inside the "sealed" radome due to temperature > changes are bigger than thos
Re: [time-nuts] HP5061 Cesium ion pump question
I think there's quite a bit of variation in leakage rates between individual physics packages, and there's also variation in the accuracy of the metering. I recently started up my spare 5061A after over a year in storage. The Ion current meter showed zero with the Cs off but about 40 in the Open Loop position. I tried connecting an external +3500V supply through a microammeter as described in the manual and that showed less than 10 uA. The unit kept trying to start and pulsed for about 12 hours at a peak reading of 40 and then settled down nicely to a zero reading and hasn't missed a beat since. I have a spare tube sitting here that hasn't been powered up for several years. It was removed from a junked 5061A that wouldn't start at all but after the unit was parted out some failed caps were found in one of the modules that could have explained the fault. I plan to try it on the bench with the +3500 V supply and microammeter but I don't know whether I can trust the reading. If the tube in one of my functioning units fails one day then I'll give it a try. Morris -- From: paul swed To: Time-nuts Subject: [time-nuts] HP5061 Cesium ion pump question During my HP 5061Cesium testing last week I was watching the ion pump current and am curious. What is the typical behavior people see on the tube after say 3 months of being turned off. With 3 units I see one that pumps doen from 8 to 2 in 40 minutes. Another maybe at 25 and takes 28 hours to get to 18. Just seems to be all over the place. Regards Paul WB8TSL -- Message: 10 Date: Tue, 01 Dec 2020 06:19:25 + From: "Poul-Henning Kamp" To: Discussion of precise time and frequency measurement , paul swed Subject: Re: [time-nuts] HP5065a cfield issue Message-ID: <86443.1606803...@critter.freebsd.dk> Content-Type: text/plain; charset="us-ascii" paul swed writes: > Guessing far less than 3 ma. by adding up resistors. More like typical 4 mA: there is a factory select resistor in parallel with the current-setting resistor. -- 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. -- Message: 11 Date: Tue, 1 Dec 2020 10:40:54 + (UTC) From: ew To: time-nuts@lists.febo.com Subject: Re: [time-nuts] EOL Motorola Oncore Remote Antenna Message-ID: <1292998389.3097482.1606819254...@mail.yahoo.com> Content-Type: text/plain; charset="utf-8" Jim, I agree. As part of my OSA 8607A GPSDO project I planned to place the OCXO in an aluminium box to eliminate pressure change. Step one included buying a separate unit to make sure the rubber gasket did do the job. Attached first results. Temperature does change pressure more than ambient. The vertical steps are the result of gentle tightening the lid, did not know how much lid had to be tightened. Now I know and have a 10 day test running. With AC running, the AC control at the other end of the house lab temperature stays within ! C. Today a cold front hit, no AC and temperature will drop more than 1 C. Taking advantage of the forecast I am extending the test for a couple more days.? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?Doe to the low power dissipation of the 8607 fan cooling is not an option but I will use the box , seal it and characterize the 8607 for pressure and temperature and use external pressure and temperature sensors for compensation once combined with a new generation GPSDO.? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?? I'll bet pressure changes inside the "sealed" radome due to temperature changes are bigger than those due to local barometer changes. But an interesting thing - water vapor will go through cracks, porosity, that liquid water will not. The commercial success of GoreTex is an example of this, but cracks, o-rings that aren't quite right, etc. are also ways it can happen. Making a truly hermetic box is hard. > > -Original Message- > From: Poul-Henning Kamp > Sent: Sunday, November 29, 2020 11:19 PM > To: Discussion of precise time and frequency measurement ; Art Sepin > Subject: Re: [time-nuts] EOL Motorola Oncore Remote Antenna > > > >> It's obvious from the photo that the O-Ring seal failed its purpose >> over its many years of service. Has the unit totally failed or does the electronic portion still function? > > No, the electronics is stone dead. > > To me it looks more like water ingress through micro-cracks in the plastic-dome, and the O-ring did its job and kept that water in. > > The microcracks are uniform and seem to follow the molding flow, and that is probably to be expected in
[time-nuts] HP5061 Cesium ion pump question
During my HP 5061Cesium testing last week I was watching the ion pump current and am curious. What is the typical behavior people see on the tube after say 3 months of being turned off. With 3 units I see one that pumps doen from 8 to 2 in 40 minutes. Another maybe at 25 and takes 28 hours to get to 18. Just seems to be all over the place. Regards Paul WB8TSL ___ 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.
