Hi Lester I was speaking to the HP HV supply. Regards Paul On Tue, Nov 15, 2022 at 9:46 AM Lester Veenstra <m0ycm@veenstras.com> wrote: > Not in my ovans. They run directly oiff od 50/60 Hz line. There is no > RF freq flyback involved. > > B>T>W> These would be useful with such a variac & transformer test > supply. > > > > [image: US Stock 4pcs CL01-12 Microwave Oven High Voltage Diode Rectifier] > <https://www.ebay.com/vod/FetchOrderDetails?itemId=402568223370&transactionId=1108957800027&mkevt=1&mkpid=0&emsid=e11401.m1842.l5920&mkcid=7&ch=osgood&euid=78ef2d648c414a41a24157fcd09254de&bu=43198945816&exe=102809&ext=241959&osub=-1%7E1&crd=20221115061028&segname=11401> > > > > US Stock 4pcs CL01-12 Microwave Oven High Voltage Diode Rectifier > <https://www.ebay.com/vod/FetchOrderDetails?itemId=402568223370&transactionId=1108957800027&mkevt=1&mkpid=0&emsid=e11401.m1842.l5919&mkcid=7&ch=osgood&euid=78ef2d648c414a41a24157fcd09254de&bu=43198945816&exe=102809&ext=241959&osub=-1%7E1&crd=20221115061028&segname=11401> > > Total: $7.47 > > Item ID: 402568223370 > > > > > > > > Lester B Veenstra K1YCM MØYCM W8YCM 6Y6Y W8YCM/6Y 6Y8LV (Reformed > USNSG CTM1) > > lester@veenstras.com > > > > 452 Stable Ln > > Keyser WV 26726 USA > > > > GPS: 39.336826 N 78.982287 W (Google) > > GPS: 39.33682 N 78.9823741 W (GPSDO) > > > > > > Telephones: > > Home: +1-304-289-6057 > > US cell +1-304-790-9192 > > Jamaica cell: +1-876-456-8898 > > > > *From:* paul swed [mailto:paulswedb@gmail.com] > *Sent:* Tuesday, November 15, 2022 8:37 AM > *To:* Discussion of precise time and frequency measurement > *Cc:* Andy Talbot; Lester Veenstra > *Subject:* Re: [time-nuts] Re: 5061A HV Supply, et al. {External} > > > > In general purpose transformers 60 Hz is fine but the HV transformer is > KHz as a heads up. > > Paul > > WB8TSL > > > > On Mon, Nov 14, 2022 at 9:43 PM Lester Veenstra via time-nuts < > time-nuts@lists.febo.com> wrote: > > Of course a small “Variac” on the primary will get the voltage to what > you want > > > > Lester B Veenstra K1YCM MØYCM W8YCM 6Y6Y W8YCM/6Y 6Y8LV (Reformed > USNSG CTM1) > > <mailto:lester@veenstras.com> lester@veenstras.com > > > > 452 Stable Ln > > Keyser WV 26726 USA > > > > GPS: 39.336826 N 78.982287 W (Google) > > GPS: 39.33682 N 78.9823741 W (GPSDO) > > > > > > Telephones: > > Home: +1-304-289-6057 > > US cell +1-304-790-9192 > > Jamaica cell: +1-876-456-8898 > > > > From: Andy Talbot [mailto:andy.g4jnt@gmail.com] > Sent: Monday, November 14, 2022 3:44 PM > To: Lester Veenstra > Cc: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Re: 5061A HV Supply, et al. {External} > > > > I've got three transformers going spare ... :-) > > > > Andy G4JNT > > IO90IV58AK12 (and others) > > > > > > > > > > On Mon, 14 Nov 2022 at 20:40, Lester Veenstra <m0ycm@veenstras.com> wrote: > > Sacrifice an old microwave oven to the Time Gods for its transformer > > GPS: 39.336826 N 78.982287 W (Google) = FM09MI20DU01 > GPS: 39.33682 N 78.9823741 W (GPSDO) = FM09MI20CU70 > > > > > > > Telephones: > Home: +1-304-289-6057 > US cell +1-304-790-9192 > Jamaica cell: +1-876-456-8898 > > -----Original Message----- > From: Andy Talbot via time-nuts [mailto:time-nuts@lists.febo.com] > Sent: Monday, November 14, 2022 3:06 PM > To: Discussion of precise time and frequency measurement > Cc: Jim Muehlberg; Andy Talbot > Subject: [time-nuts] Re: 5061A HV Supply, et al. {External} > > A simple flyback SMPSU with a Cockcroft-Walton tied on the end will give > you a simple high voltage supply. A chain of high value resistors and you > can even stabilise it. > > Andy > www.g4jnt.com > > > > On Mon, 14 Nov 2022 at 20:00, Jim Muehlberg via time-nuts < > time-nuts@lists.febo.com> wrote: > > > Rodger, > > > > Thanks for the encouragement! I'm trying not to spend too much effort > > on this - sort of a distraction from real work. One would think that > > NRAO would have a HV power supply lying around somewhere, but astronomy > > has gone solid state now for decades! We have a grad student trying to > > nurse along another 5061 and we'd like to have a pair. I guess I'll > > slice open the A18 module and see what makes it tick. > > > > Thanks again, > > > > Jim > > > > On 11/10/2022 9:11 AM, Rodger via time-nuts wrote: > > > Hey Jim, > > > > > > I got a 5061a a couple years ago with high ION pump current. In my > case > > the 3500 volts was there but the tube was not pumping down, even after > > being on for weeks. I found a Terranova 741 Ion pump power supply on > eBay > > for under $100. It was listed as not working but worked AOK when I got > > it. It's a nice supply with variable output voltage, current limiting, > > safety interlocks, etc. I hooked it up to the tube and let it run for a > > few weeks. Tube pumped down successfully and is working AOK now. My > guess > > is that my A18 wasn't capable of supplying the current needed to pump > down > > the tube but the external power supply was. > > > > > > Note: I proceeded very carefully with the external supply, letting it > > run for days at lower voltages and gradually working up to 3500. Also, I > > kept the current limit set as low as it would go. Anyway, it worked for > > me. Good luck with yours. > > > > > > Rodger > > > > > > -----Original Message----- > > > From: Jim Muehlberg via time-nuts <time-nuts@lists.febo.com> > > > Sent: Wednesday, November 9, 2022 11:07 AM > > > To: time-nuts@lists.febo.com > > > Cc: Jim Muehlberg <jmuehlbe@nrao.edu> > > > Subject: [time-nuts] 5061A HV Supply, et al. > > > > > > I've recently come into possession of a 5061A. It is claimed that the > > tube is exhausted, but I'm unwilling to scrap it (horrors!) yet. I'm not > > well equipped for HV measurements, but it appears the +3500 V supply is > not > > working. So, I'm hoping the tube just needs to be pumped since it hasn't > > been powered for years. Also missing the A3 assembly, but I'll worry > about > > that later... > > > > > > Anyone willing to part with their A18 or loan it to me? > > > > > > Thanks! > > > > > -- > > > > Jim Muehlberg > > Senior Engineer > > > > National Radio Astronomy Observatory > > ngVLA Local Oscillator Lead > > > > 1180 Boxwood Estates Rd B-111 > > Charlottesville, VA 22903-4602 > > P 434.296.0270 > > F 434.296.0324 > > www.cv.nrao.edu/~jmuehlbe > > _______________________________________________ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe send an email to time-nuts-leave@lists.febo.com > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com > >

OK, great info!  I am very nervous around HV, but now I understand that he A18 can't even handle the 10M input on the expensive Keitlhy DMM I foolishly connected. Even with the high tension lead disconnected and well away from metal, the ion pump current is still pegged. So, despite that, I built a divider which turned out to be 64.2MOhm.  Across the 103K at the bottom I got 1.2V giving about 12 uA, so the supply is only delivering about 800 volts.  Is it really this wimpy?  if it normally delivers about 10uA, that suggests a 350MOhm Load.  So, I put in another few resistors and brought the total to ~172.3M, yielding 0.472 across the 103K giving around 785V in. I even went so far as to clean the vicinity of the A18 output.  Since my hearing is not wonderful, I could not detect any corona discharge or buzzing or whatever it's should sound like. I suppose the final nail in the A18 coffin will be removing it and bench testing.  (BTW, the input voltage is good) Thanks for all the help. On 2022-11-14 9:35 PM, paul swed via time-nuts wrote: > Here is a pix of a unit I was testing. > [image: DSC04636.JPG] > > The current meter is in the lower leg of the return. You can see the high > voltage probe on the right. I recall its 68 M and feeds a fluke DVM. The > amp meter is measuring the current that the probe is consuming. The other > connections are ground and +18.7V. > The precision voltage divider in the background was not used. > Testing the supply like this is fairly easy and just look at the schematics > to understand how to hook everything up. > Regards > Paul > WB8TSL > > > > > > > On Mon, Nov 14, 2022 at 9:27 PM paul swed<paulswedb@gmail.com> wrote: > >> Jim >> OK I thought the thread said the meter is pegged and yes at turn on the >> ion pump 3500 V is always on. The switching and protection I am speaking >> about is for the other circuits. They will not start if the pump current is >> to high. The ION pump sends a signal that inhibits their start. A 1M R is >> far too low of a resistance its loading the supply down. Try something like >> 40-60 Meg. Maybe a string of 10 M with a 100k R at the bottom. Measure the >> V across the 100K. In normal operation the 3500 V will be drawing 4-14ua if >> the tubes reasonably pumped down. >> So thinking about this. There is a twist HV connector on the chassis that >> the 3500 V goes through. I am reluctant to say this but if that were off >> and far away from anything to arc to and the ion pump meter went to close >> to zero then you would know the supply is most likely working and you have >> a very dirty tube. I just do not like the thought of a 3500 V plug floating >> free. >> Regards >> Paul >> WB8TSL >> >> >> On Mon, Nov 14, 2022 at 7:51 PM Jim Muehlberg via time-nuts < >> time-nuts@lists.febo.com> wrote: >> >>> Paul, >>> >>> My understanding is that the 3500 V is on as soon as power is applied. >>> Disconnected, I get 750V at the HV lead. I first connected a 1M Ohm >>> resistor divider because I don't really have HV measuring stuff (10K to >>> 1) and it read 350 V. Indeed the meter is pegged, but I suspect that is >>> due to some internal fault in the A18 as well. So unless there is some >>> turn on signal to the 3500 V supply, I suspect it is bad. This whole >>> thing may be a basket case. No one knows the history. >>> >>> I'm also missing the divider assembly, so that may put the brakes on the >>> whole project, but I'll worry about that once I have attempted to pump >>> down. >>> >>> Thanks for the advice! >>> >>> Jim >>> >>> On 11/14/2022 3:25 PM, paul swed via time-nuts wrote: >>>> Jim >>>> I may be missing something here. Your suggesting the 3500 V ion pump >>> supply >>>> is bad. >>>> But I believe the ion pump meter is pegged from an earlier post. If true >>>> then the 3500 V is fine. If the tubes dirty and drawing too much current >>>> there is a lockout circuit on a15 that will not allow the CS oven and >>> 2500 >>>> V to come up until the ion pump is below about 15-20ua on the meter. It >>>> senses the current being drawn by the 3500 HV. Enters a15 on pin 1 and >>>> inhibits the rest of the system. >>>> If my thoughts are correct then you need to pump down the tube as Rodger >>>> says with a 3500 V supply and as I suggested 300 ua is way more than >>>> enough. There is a chance the tube may work in a relative quality sense. >>>> That is it could lock but there are so few Cs that the output of the >>> system >>>> is noisy. >>>> >>>> Regards >>>> Paul >>>> WB8TSL >>>> >>>> >>>> On Mon, Nov 14, 2022 at 3:00 PM Jim Muehlberg via time-nuts < >>>> time-nuts@lists.febo.com> wrote: >>>> >>>>> Rodger, >>>>> >>>>> Thanks for the encouragement! I'm trying not to spend too much effort >>>>> on this - sort of a distraction from real work. One would think that >>>>> NRAO would have a HV power supply lying around somewhere, but astronomy >>>>> has gone solid state now for decades! We have a grad student trying to >>>>> nurse along another 5061 and we'd like to have a pair. I guess I'll >>>>> slice open the A18 module and see what makes it tick. >>>>> >>>>> Thanks again, >>>>> >>>>> Jim >>>>> >>>>> On 11/10/2022 9:11 AM, Rodger via time-nuts wrote: >>>>>> Hey Jim, >>>>>> >>>>>> I got a 5061a a couple years ago with high ION pump current. In my >>> case >>>>> the 3500 volts was there but the tube was not pumping down, even after >>>>> being on for weeks. I found a Terranova 741 Ion pump power supply on >>> eBay >>>>> for under $100. It was listed as not working but worked AOK when I got >>>>> it. It's a nice supply with variable output voltage, current limiting, >>>>> safety interlocks, etc. I hooked it up to the tube and let it run for >>> a >>>>> few weeks. Tube pumped down successfully and is working AOK now. My >>> guess >>>>> is that my A18 wasn't capable of supplying the current needed to pump >>> down >>>>> the tube but the external power supply was. >>>>>> Note: I proceeded very carefully with the external supply, letting it >>>>> run for days at lower voltages and gradually working up to 3500. >>> Also, I >>>>> kept the current limit set as low as it would go. Anyway, it worked >>> for >>>>> me. Good luck with yours. >>>>>> Rodger >>>>>> >>>>>> -----Original Message----- >>>>>> From: Jim Muehlberg via time-nuts<time-nuts@lists.febo.com> >>>>>> Sent: Wednesday, November 9, 2022 11:07 AM >>>>>> To:time-nuts@lists.febo.com >>>>>> Cc: Jim Muehlberg<jmuehlbe@nrao.edu> >>>>>> Subject: [time-nuts] 5061A HV Supply, et al. >>>>>> >>>>>> I've recently come into possession of a 5061A. It is claimed that the >>>>> tube is exhausted, but I'm unwilling to scrap it (horrors!) yet. I'm >>> not >>>>> well equipped for HV measurements, but it appears the +3500 V supply >>> is not >>>>> working. So, I'm hoping the tube just needs to be pumped since it >>> hasn't >>>>> been powered for years. Also missing the A3 assembly, but I'll worry >>> about >>>>> that later... >>>>>> Anyone willing to part with their A18 or loan it to me? >>>>>> >>>>>> Thanks! >>>>>> >>>>> -- >>>>> >>>>> Jim Muehlberg >>>>> Senior Engineer >>>>> >>>>> National Radio Astronomy Observatory >>>>> ngVLA Local Oscillator Lead >>>>> >>>>> 1180 Boxwood Estates Rd B-111 >>>>> Charlottesville, VA 22903-4602 >>>>> P 434.296.0270 >>>>> F 434.296.0324 >>>>> www.cv.nrao.edu/~jmuehlbe >>>>> _______________________________________________ >>>>> time-nuts mailing list --time-nuts@lists.febo.com >>>>> To unsubscribe send an email totime-nuts-leave@lists.febo.com >>>> _______________________________________________ >>>> time-nuts mailing list --time-nuts@lists.febo.com >>>> To unsubscribe send an email totime-nuts-leave@lists.febo.com >>> -- >>> >>> Jim Muehlberg >>> Senior Engineer >>> >>> National Radio Astronomy Observatory >>> ngVLA Local Oscillator Lead >>> >>> 1180 Boxwood Estates Rd B-111 >>> Charlottesville, VA 22903-4602 >>> P 434.296.0270 >>> F 434.296.0324 >>> www.cv.nrao.edu/~jmuehlbe >>> _______________________________________________ >>> time-nuts mailing list --time-nuts@lists.febo.com >>> To unsubscribe send an email totime-nuts-leave@lists.febo.com >> > > _______________________________________________ > time-nuts mailing list --time-nuts@lists.febo.com > To unsubscribe send an email totime-nuts-leave@lists.febo.com -- Jim Muehlberg Senior Engineer National Radio Astronomy Observatory ngVLA Local Oscillator Lead 1180 Boxwood Estates Rd B-111 Charlottesville, VA 22903-4602 P 434.296.0270 C 434.422.2017

For the external ion pump, what would be a safe maximum current to allow the external supply be limited to, say at short circuit on the output? Lester B Veenstra K1YCM MØYCM W8YCM 6Y6Y W8YCM/6Y 6Y8LV (Reformed USNSG CTM1) lester@veenstras.com 452 Stable Ln Keyser WV 26726 USA GPS: 39.336826 N 78.982287 W (Google) GPS: 39.33682 N 78.9823741 W (GPSDO) Telephones: Home: +1-304-289-6057 US cell +1-304-790-9192 Jamaica cell: +1-876-456-8898 >

100-300 ua. The actual ion pump is maybe 50 ua. A cruddy tube needs more to clear it. On Tue, Nov 15, 2022 at 11:24 AM Lester Veenstra <m0ycm@veenstras.com> wrote: > For the external ion pump, what would be a safe maximum current to allow > the external supply be limited to, say at short circuit on the output? > > Lester B Veenstra K1YCM MØYCM W8YCM 6Y6Y W8YCM/6Y 6Y8LV (Reformed > USNSG CTM1) > lester@veenstras.com > > 452 Stable Ln > Keyser WV 26726 USA > > GPS: 39.336826 N 78.982287 W (Google) > GPS: 39.33682 N 78.9823741 W (GPSDO) > > > Telephones: > Home: +1-304-289-6057 > US cell +1-304-790-9192 > Jamaica cell: +1-876-456-8898 > > > > >

Jim you can see what I did to bench test one. As you say be very careful. It can be wimpy because its moving atoms and molecules to the getter that holds the crud. Kind of odd the HV connector is open and the Ion pump meter is still pegged. Makes no sense to me. Is the needle just stuck?? Do some hunting on time-nuts the a18 module has been discussed. I believe the current is measured off of the output HV resistor. On the bottom end to ground. On Tue, Nov 15, 2022 at 1:28 PM Jim Muehlberg via time-nuts < time-nuts@lists.febo.com> wrote: > OK, great info! I am very nervous around HV, but now I understand that > he A18 can't even handle the 10M input on the expensive Keitlhy DMM I > foolishly connected. > > Even with the high tension lead disconnected and well away from metal, > the ion pump current is still pegged. > > So, despite that, I built a divider which turned out to be 64.2MOhm. > Across the 103K at the bottom I got 1.2V giving about 12 uA, so the > supply is only delivering about 800 volts. Is it really this wimpy? if > it normally delivers about 10uA, that suggests a 350MOhm Load. So, I > put in another few resistors and brought the total to ~172.3M, yielding > 0.472 across the 103K giving around 785V in. > > I even went so far as to clean the vicinity of the A18 output. Since my > hearing is not wonderful, I could not detect any corona discharge or > buzzing or whatever it's should sound like. > > I suppose the final nail in the A18 coffin will be removing it and bench > testing. (BTW, the input voltage is good) > > Thanks for all the help. > > On 2022-11-14 9:35 PM, paul swed via time-nuts wrote: > > Here is a pix of a unit I was testing. > > [image: DSC04636.JPG] > > > > The current meter is in the lower leg of the return. You can see the high > > voltage probe on the right. I recall its 68 M and feeds a fluke DVM. The > > amp meter is measuring the current that the probe is consuming. The other > > connections are ground and +18.7V. > > The precision voltage divider in the background was not used. > > Testing the supply like this is fairly easy and just look at the > schematics > > to understand how to hook everything up. > > Regards > > Paul > > WB8TSL > > > > > > > > > > > > > > On Mon, Nov 14, 2022 at 9:27 PM paul swed<paulswedb@gmail.com> wrote: > > > >> Jim > >> OK I thought the thread said the meter is pegged and yes at turn on the > >> ion pump 3500 V is always on. The switching and protection I am speaking > >> about is for the other circuits. They will not start if the pump > current is > >> to high. The ION pump sends a signal that inhibits their start. A 1M R > is > >> far too low of a resistance its loading the supply down. Try something > like > >> 40-60 Meg. Maybe a string of 10 M with a 100k R at the bottom. Measure > the > >> V across the 100K. In normal operation the 3500 V will be drawing > 4-14ua if > >> the tubes reasonably pumped down. > >> So thinking about this. There is a twist HV connector on the chassis > that > >> the 3500 V goes through. I am reluctant to say this but if that were off > >> and far away from anything to arc to and the ion pump meter went to > close > >> to zero then you would know the supply is most likely working and you > have > >> a very dirty tube. I just do not like the thought of a 3500 V plug > floating > >> free. > >> Regards > >> Paul > >> WB8TSL > >> > >> > >> On Mon, Nov 14, 2022 at 7:51 PM Jim Muehlberg via time-nuts < > >> time-nuts@lists.febo.com> wrote: > >> > >>> Paul, > >>> > >>> My understanding is that the 3500 V is on as soon as power is applied. > >>> Disconnected, I get 750V at the HV lead. I first connected a 1M Ohm > >>> resistor divider because I don't really have HV measuring stuff (10K to > >>> 1) and it read 350 V. Indeed the meter is pegged, but I suspect that > is > >>> due to some internal fault in the A18 as well. So unless there is some > >>> turn on signal to the 3500 V supply, I suspect it is bad. This whole > >>> thing may be a basket case. No one knows the history. > >>> > >>> I'm also missing the divider assembly, so that may put the brakes on > the > >>> whole project, but I'll worry about that once I have attempted to pump > >>> down. > >>> > >>> Thanks for the advice! > >>> > >>> Jim > >>> > >>> On 11/14/2022 3:25 PM, paul swed via time-nuts wrote: > >>>> Jim > >>>> I may be missing something here. Your suggesting the 3500 V ion pump > >>> supply > >>>> is bad. > >>>> But I believe the ion pump meter is pegged from an earlier post. If > true > >>>> then the 3500 V is fine. If the tubes dirty and drawing too much > current > >>>> there is a lockout circuit on a15 that will not allow the CS oven and > >>> 2500 > >>>> V to come up until the ion pump is below about 15-20ua on the meter. > It > >>>> senses the current being drawn by the 3500 HV. Enters a15 on pin 1 and > >>>> inhibits the rest of the system. > >>>> If my thoughts are correct then you need to pump down the tube as > Rodger > >>>> says with a 3500 V supply and as I suggested 300 ua is way more than > >>>> enough. There is a chance the tube may work in a relative quality > sense. > >>>> That is it could lock but there are so few Cs that the output of the > >>> system > >>>> is noisy. > >>>> > >>>> Regards > >>>> Paul > >>>> WB8TSL > >>>> > >>>> > >>>> On Mon, Nov 14, 2022 at 3:00 PM Jim Muehlberg via time-nuts < > >>>> time-nuts@lists.febo.com> wrote: > >>>> > >>>>> Rodger, > >>>>> > >>>>> Thanks for the encouragement! I'm trying not to spend too much > effort > >>>>> on this - sort of a distraction from real work. One would think that > >>>>> NRAO would have a HV power supply lying around somewhere, but > astronomy > >>>>> has gone solid state now for decades! We have a grad student trying > to > >>>>> nurse along another 5061 and we'd like to have a pair. I guess I'll > >>>>> slice open the A18 module and see what makes it tick. > >>>>> > >>>>> Thanks again, > >>>>> > >>>>> Jim > >>>>> > >>>>> On 11/10/2022 9:11 AM, Rodger via time-nuts wrote: > >>>>>> Hey Jim, > >>>>>> > >>>>>> I got a 5061a a couple years ago with high ION pump current. In my > >>> case > >>>>> the 3500 volts was there but the tube was not pumping down, even > after > >>>>> being on for weeks. I found a Terranova 741 Ion pump power supply on > >>> eBay > >>>>> for under $100. It was listed as not working but worked AOK when I > got > >>>>> it. It's a nice supply with variable output voltage, current > limiting, > >>>>> safety interlocks, etc. I hooked it up to the tube and let it run > for > >>> a > >>>>> few weeks. Tube pumped down successfully and is working AOK now. My > >>> guess > >>>>> is that my A18 wasn't capable of supplying the current needed to pump > >>> down > >>>>> the tube but the external power supply was. > >>>>>> Note: I proceeded very carefully with the external supply, letting > it > >>>>> run for days at lower voltages and gradually working up to 3500. > >>> Also, I > >>>>> kept the current limit set as low as it would go. Anyway, it worked > >>> for > >>>>> me. Good luck with yours. > >>>>>> Rodger > >>>>>> > >>>>>> -----Original Message----- > >>>>>> From: Jim Muehlberg via time-nuts<time-nuts@lists.febo.com> > >>>>>> Sent: Wednesday, November 9, 2022 11:07 AM > >>>>>> To:time-nuts@lists.febo.com > >>>>>> Cc: Jim Muehlberg<jmuehlbe@nrao.edu> > >>>>>> Subject: [time-nuts] 5061A HV Supply, et al. > >>>>>> > >>>>>> I've recently come into possession of a 5061A. It is claimed that > the > >>>>> tube is exhausted, but I'm unwilling to scrap it (horrors!) yet. I'm > >>> not > >>>>> well equipped for HV measurements, but it appears the +3500 V supply > >>> is not > >>>>> working. So, I'm hoping the tube just needs to be pumped since it > >>> hasn't > >>>>> been powered for years. Also missing the A3 assembly, but I'll worry > >>> about > >>>>> that later... > >>>>>> Anyone willing to part with their A18 or loan it to me? > >>>>>> > >>>>>> Thanks! > >>>>>> > >>>>> -- > >>>>> > >>>>> Jim Muehlberg > >>>>> Senior Engineer > >>>>> > >>>>> National Radio Astronomy Observatory > >>>>> ngVLA Local Oscillator Lead > >>>>> > >>>>> 1180 Boxwood Estates Rd B-111 > >>>>> Charlottesville, VA 22903-4602 > >>>>> P 434.296.0270 > >>>>> F 434.296.0324 > >>>>> www.cv.nrao.edu/~jmuehlbe > >>>>> _______________________________________________ > >>>>> time-nuts mailing list --time-nuts@lists.febo.com > >>>>> To unsubscribe send an email totime-nuts-leave@lists.febo.com > >>>> _______________________________________________ > >>>> time-nuts mailing list --time-nuts@lists.febo.com > >>>> To unsubscribe send an email totime-nuts-leave@lists.febo.com > >>> -- > >>> > >>> Jim Muehlberg > >>> Senior Engineer > >>> > >>> National Radio Astronomy Observatory > >>> ngVLA Local Oscillator Lead > >>> > >>> 1180 Boxwood Estates Rd B-111 > >>> Charlottesville, VA 22903-4602 > >>> P 434.296.0270 > >>> F 434.296.0324 > >>> www.cv.nrao.edu/~jmuehlbe > >>> _______________________________________________ > >>> time-nuts mailing list --time-nuts@lists.febo.com > >>> To unsubscribe send an email totime-nuts-leave@lists.febo.com > >> > > > > _______________________________________________ > > time-nuts mailing list --time-nuts@lists.febo.com > > To unsubscribe send an email totime-nuts-leave@lists.febo.com > -- > > Jim Muehlberg > Senior Engineer > > National Radio Astronomy Observatory > ngVLA Local Oscillator Lead > > 1180 Boxwood Estates Rd B-111 > Charlottesville, VA 22903-4602 > P 434.296.0270 > C 434.422.2017 > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com

FYI, on my "dirty tube" that the internal supply couldn't pump down. When I connected it to the external ION power supply, which I had previously tested to make sure it's metering was reasonably accurate, initial current draw at 3500 v was 88 ua. (fortunately, I kept records) 3 days later it was down to 55 ua. It never got below 52 ua a few more days later. I hooked it back up to the internal pump power supply and ion current was low enough that the 2500 volt power supply came up and it worked. My guess is the issue is some combination of not enough current capability for the A18 and it's internal metering is not quite right. Rodger -----Original Message----- From: paul swed via time-nuts <time-nuts@lists.febo.com> Sent: Tuesday, November 15, 2022 11:43 AM To: Lester Veenstra <m0ycm@veenstras.com> Cc: Discussion of precise time and frequency measurement <time-nuts@lists.febo.com>; paul swed <paulswedb@gmail.com> Subject: [time-nuts] Re: Question: Re: 5061A HV Supply, et al. {External} 100-300 ua. The actual ion pump is maybe 50 ua. A cruddy tube needs more to clear it. On Tue, Nov 15, 2022 at 11:24 AM Lester Veenstra <m0ycm@veenstras.com> wrote: > For the external ion pump, what would be a safe maximum current to > allow the external supply be limited to, say at short circuit on the output? > > Lester B Veenstra K1YCM MØYCM W8YCM 6Y6Y W8YCM/6Y 6Y8LV (Reformed > USNSG CTM1) > lester@veenstras.com > > 452 Stable Ln > Keyser WV 26726 USA > > GPS: 39.336826 N 78.982287 W (Google) > GPS: 39.33682 N 78.9823741 W (GPSDO) > > > Telephones: > Home: +1-304-289-6057 > US cell +1-304-790-9192 > Jamaica cell: +1-876-456-8898 > > > > > _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe send an email to time-nuts-leave@lists.febo.com

Update:  After tearing into the A18 and finding nothing obvious, poking prodding and testing, it decided to start working.  I hate it / love it when that happens.  I suspect a clearance issue as when I reassembled it I could hear it snap.  So I left the cover off. Voltage at pin 4 is 4.4 unloaded and about 4 connected to the tube.  In "CS Off", pump current is 1 on the scale.  Switching to "loop open" or "operate" causes the meter to peg and pin 4 goes to 0 or less.  Return to CS off, and the power supply recovers in about 20 seconds to about 4 volts. I'll leave it on over the weekend and sort through the embers on Monday. Jim On 2022-11-09 11:07 AM, Jim Muehlberg via time-nuts wrote: > I've recently come into possession of a 5061A.  It is claimed that the > tube is exhausted, but I'm unwilling to scrap it (horrors!) yet. I'm > not well equipped for HV measurements, but it appears the +3500 V > supply is not working.  So, I'm hoping the tube just needs to be > pumped since it hasn't been powered for years.  Also missing the A3 > assembly, but I'll worry about that later... > > Anyone willing to part with their A18 or loan it to me? > > Thanks! > -- Jim Muehlberg Senior Engineer National Radio Astronomy Observatory ngVLA Local Oscillator Lead 1180 Boxwood Estates Rd B-111 Charlottesville, VA 22903-4602 P 434.296.0270 C 434.422.2017

Yup good progress. Corby discussed this in the thread. Thats the crud burst I mentioned as the ionizer comes on and releases accumulated dead Cs. The system will keep toggling on and off. The key is that over time it will stay on longer and longer as the crud clears. Finally (Fingers crossed) staying on. You can also cheat given you are the NRAO. With the loop open adjust the internal 5 MHz osc as close as possible to one of your very good references after the 5 MHz osc has warmed up for a few hours. When everything is staying on. Close the loop/Operate and with a drop of luck you may see some beam current and then second harmonic. At that point Look at EFC you may be locked. Press the logic reset button. Green light? Your operating. Watch out for the lights over time the pin flattens on the lamp and may not make connection. A drop of solder/heat will reform the base. Or the bulb can simply be burned out. Regards Paul WB8TSL On Fri, Nov 18, 2022 at 5:56 PM Jim Muehlberg via time-nuts < time-nuts@lists.febo.com> wrote: > Update: After tearing into the A18 and finding nothing obvious, poking > prodding and testing, it decided to start working. I hate it / love it > when that happens. I suspect a clearance issue as when I reassembled it > I could hear it snap. So I left the cover off. > > Voltage at pin 4 is 4.4 unloaded and about 4 connected to the tube. In > "CS Off", pump current is 1 on the scale. Switching to "loop open" or > "operate" causes the meter to peg and pin 4 goes to 0 or less. Return > to CS off, and the power supply recovers in about 20 seconds to about 4 > volts. > > I'll leave it on over the weekend and sort through the embers on Monday. > > Jim > > On 2022-11-09 11:07 AM, Jim Muehlberg via time-nuts wrote: > > I've recently come into possession of a 5061A. It is claimed that the > > tube is exhausted, but I'm unwilling to scrap it (horrors!) yet. I'm > > not well equipped for HV measurements, but it appears the +3500 V > > supply is not working. So, I'm hoping the tube just needs to be > > pumped since it hasn't been powered for years. Also missing the A3 > > assembly, but I'll worry about that later... > > > > Anyone willing to part with their A18 or loan it to me? > > > > Thanks! > > > -- > > Jim Muehlberg > Senior Engineer > > National Radio Astronomy Observatory > ngVLA Local Oscillator Lead > > 1180 Boxwood Estates Rd B-111 > Charlottesville, VA 22903-4602 > P 434.296.0270 > C 434.422.2017 > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com

OK, after an 11 day hiatus, there is no change in ion pump current.  Still very low (1 uA?) in "CS OFF". Switching to another mode (any) causes the pump current to increase and the A18 output to fold over, then it recovers and keeps doing this at about a 5 second period.  The monitor point reaches about 1.2 V before folding back. So, I found a little laser HV supply that puts out 1250V at 4mA.  So, I thought I'd attach that.  On my homemade 172 MOhm Divider, the voltage turned out to be much higher, around 7kV!  Which I only found out after connecting to the tube.  Hopefully, that didn't kill it.  It drew about 50 uA at this voltage.  I ended up leaving for a few minutes before I realized what was going on, since I couldn't believe the reading from my divider. In any event, after reconnecting the A18, ion pump current is very low again, but this time the monitor point stays up at around 4V with the clock in "LOOP OPEN".  It no longer folds back at all. Recall it has no divider module so I'm not sure monitor points are useful, but most are dead, except Supply, Ion Pump I, Osc Oven, CS oven.  There is a tiny bit of Beam current. Next steps?  Did I kill it?  I may have access to a divider module... Jim On 2022-11-09 11:07 AM, Jim Muehlberg via time-nuts wrote: > I've recently come into possession of a 5061A.  It is claimed that the > tube is exhausted, but I'm unwilling to scrap it (horrors!) yet. I'm > not well equipped for HV measurements, but it appears the +3500 V > supply is not working.  So, I'm hoping the tube just needs to be > pumped since it hasn't been powered for years.  Also missing the A3 > assembly, but I'll worry about that later... > > Anyone willing to part with their A18 or loan it to me? > > Thanks! > -- Jim

Jim I don't think you did. The oven turning on and off would be expected. What happens with some luck is you will notice that the on period slowly increases. Use a watch and check every couple of hours. Each time it turns on the ion pump current should increase and then the system shuts off if over about 20 on the meter. Its a good sign if the system actually stays on. With the missing modules the system may or may not lock. Just depends on what ones. Great to see your progress. Regards Paul On Wed, Nov 30, 2022 at 3:42 PM Jim Muehlberg via time-nuts < time-nuts@lists.febo.com> wrote: > OK, after an 11 day hiatus, there is no change in ion pump current. > Still very low (1 uA?) in "CS OFF". Switching to another mode (any) > causes the pump current to increase and the A18 output to fold over, > then it recovers and keeps doing this at about a 5 second period. The > monitor point reaches about 1.2 V before folding back. > > So, I found a little laser HV supply that puts out 1250V at 4mA. So, I > thought I'd attach that. On my homemade 172 MOhm Divider, the voltage > turned out to be much higher, around 7kV! Which I only found out after > connecting to the tube. Hopefully, that didn't kill it. It drew about > 50 uA at this voltage. I ended up leaving for a few minutes before I > realized what was going on, since I couldn't believe the reading from my > divider. > > In any event, after reconnecting the A18, ion pump current is very low > again, but this time the monitor point stays up at around 4V with the > clock in "LOOP OPEN". It no longer folds back at all. > > Recall it has no divider module so I'm not sure monitor points are > useful, but most are dead, except Supply, Ion Pump I, Osc Oven, CS > oven. There is a tiny bit of Beam current. > > Next steps? Did I kill it? I may have access to a divider module... > > Jim > > On 2022-11-09 11:07 AM, Jim Muehlberg via time-nuts wrote: > > I've recently come into possession of a 5061A. It is claimed that the > > tube is exhausted, but I'm unwilling to scrap it (horrors!) yet. I'm > > not well equipped for HV measurements, but it appears the +3500 V > > supply is not working. So, I'm hoping the tube just needs to be > > pumped since it hasn't been powered for years. Also missing the A3 > > assembly, but I'll worry about that later... > > > > Anyone willing to part with their A18 or loan it to me? > > > > Thanks! > > > -- > Jim > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com