[time-nuts] It is possible to "recharge" a hydrogen maser?
Luiz, Found some more info on replenishing the Hydrogen in the Kvarz CH1-76 and CH1-75. Anders had the procedure pretty close for a fully charged canister from the vendor. However recharging the original is a bit more challenging! Use care and protective gear from the high and low temperatures involved! Here are added steps somewhat paraphrased: - open up (HFO, mag-shield etc.) enough to have access to the H-canister - open the insulation around the canister and remove it from its oven. - disconnect the canister from the Maser. (Threaded connector) - connect canister to a manifold and vacuum pump and pump it down for 24 hours. - make an oven and heat the canister to 300 Degrees C for another 24 hours while still running the vacuum system - Close off valves to isolate the evacuated canister and remove vacuum pump. - Attach a hydrogen regulator set to 240PSI to the manfold and purge the lines up to the isolating valve. - Open the isolating valve and leave the hydrogen connected to the canister - the canister should get warm as it charges, you can blow cold air on it to help. - Once the cannister no longer heats and has cooled down close off the Hydrogen valve. - Also close the isolation valve to the canister. Now here I'm not sure as I would think there is a step to purge the air from the Maser lines. Not sure how that would be done? - with the canister still connected and the isolation valve closed immerse the canister in liguid Nitrogen until it stops boiling off, then wait 5 more minutes. - now while the canister is still cold remove it from the manifold and reconnect it to the Maser. (Gloves Please) At this point once the canister comes back up to room temperature you would be ready to leak test and reassemble the Maser. I'm actually working with a friend to install a new Hydrogen system into a CH1-76. NO LN2 or 300 Degree temperature involved! The new system will be outside the shield and use a commercial hydride canister. A Solid-H BL-18. Here is the rough outline for it's installation. - open up (HFO, mag-shield etc.) enough to have access to the H-canister - open the insulation around the canister and remove it from its oven. - disconnect the canister from the Maser. (Threaded connector) - mount the new fully charged canister with its attached valves on the bottom right underside of the Maser (charging the new canister is similar to that detailed above) - run the new hydrogen line to where one of the slots in the shield will be. - Screw the Maser hydrogen line onto the new lines fitting. - Attach a vacuum pump to the 1/4" hose barb on the purge valve - Run the pump and open the purge valve. Wait 20 minutes to purge the line. - close the purge valve and remove the vacuum pump - Open the canister valve to allow Hydrogen into the Maser. - leak test the lines and reassemble the Maser. Pictures and more details will be showing up in the EEVBlog Metrology forum. Keep in mind that since you have more room in the CH1-75 you could probably install a small compressed Hydrogen bottle and regulator instead of the Hydride storage outlined! 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] It is possible to "recharge" a hydrogen maser?
Thank you for the experience / instruction! Em ter, 9 de jul de 2019 12:05, escreveu: > Luiz, > Ch1-75 Hydrogen storage details. > “The compound LaNi5H, is used for storing molecular hydrogen. > The LaHi5H, is characterized by high hydrogen partial pressure (2 to 5 > atmospheres) at +(20-50) degrees C. > 250 grams of the compound contains 18 liters of hydrogen at normal > pressure. > It is sufficient for maser continuous operation for more than 40 000 > hours.” > I believe that the container holding the LaHi5H is heated and > thermostatically controlled to maintain the proper pressure into the > purifier. > First you should be able to power up the maser just far enough so that > the ion pumps can operate. Monitor their current and it should drop down > to almost zero within a few hours. If not you may need to get the ion > pumps rebuilt. > There are commercial outfits that can rebuild them but if there are not > isolation valves to close and isolate the Maser when you remove the ion > pumps you will not be able to proceed! Since the Russian Masers also use > a getter pump in concert with the ion pumps, opening up the vacuum system > will contaminate the getter pump. The process of clearing the getter is > very detailed and involves temperatures of up to 800 degrees C, and > without careful instructions on how to do it you risk damaging other > portions of the Maser! > If the pressure does drop down, then you need to determine if there is > any Hydrogen left. I know that some Russian Masers will give you an alarm > that tells you if you are out, and some have a mechanical pressure gage, > but I’m not sure about the CH1-75. You will need to check the manuals. If > it does not provide an alarm or have a gage then see if the HFO > oscillator is working and if the discharge bulb is lighting up. If it > lights up you are not out of Hydrogen! > If it does not light and you have determined that the lack of Hydrogen > is indeed the problem you will need to locate the LaHi5H container. After > you locate it make sure it is being heated, this could cause an apparent > lack of Hydrogen! Then see how it is connected to the discharge bulb. > Hopefully it will be a threaded connection. This connection is on the > high pressure side of the purifier and can be removed without > compromising the vacuum. You will need to remove the container and > recharge it. I would instead replace it with a small compressed hydrogen > cylinder and regulators. > Use ultra-high purity dry Hydrogen and make sure you purge the line > going to the purifier. The purifier will block other gases from getting > into the Maser but in the process too much “foreign” gas can contaminate > and damage the purifier! > Once you manage to locate the container some pictures on where it’s > hiding would be nice! > Good luck with your efforts! > Cheers, > Corby Dawson > ___ > 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] It is possible to "recharge" a hydrogen maser?
Luiz, Ch1-75 Hydrogen storage details. The compound LaNi5H, is used for storing molecular hydrogen. The LaHi5H, is characterized by high hydrogen partial pressure (2 to 5 atmospheres) at +(20-50) degrees C. 250 grams of the compound contains 18 liters of hydrogen at normal pressure. It is sufficient for maser continuous operation for more than 40 000 hours. I believe that the container holding the LaHi5H is heated and thermostatically controlled to maintain the proper pressure into the purifier. First you should be able to power up the maser just far enough so that the ion pumps can operate. Monitor their current and it should drop down to almost zero within a few hours. If not you may need to get the ion pumps rebuilt. There are commercial outfits that can rebuild them but if there are not isolation valves to close and isolate the Maser when you remove the ion pumps you will not be able to proceed! Since the Russian Masers also use a getter pump in concert with the ion pumps, opening up the vacuum system will contaminate the getter pump. The process of clearing the getter is very detailed and involves temperatures of up to 800 degrees C, and without careful instructions on how to do it you risk damaging other portions of the Maser! If the pressure does drop down, then you need to determine if there is any Hydrogen left. I know that some Russian Masers will give you an alarm that tells you if you are out, and some have a mechanical pressure gage, but Im not sure about the CH1-75. You will need to check the manuals. If it does not provide an alarm or have a gage then see if the HFO oscillator is working and if the discharge bulb is lighting up. If it lights up you are not out of Hydrogen! If it does not light and you have determined that the lack of Hydrogen is indeed the problem you will need to locate the LaHi5H container. After you locate it make sure it is being heated, this could cause an apparent lack of Hydrogen! Then see how it is connected to the discharge bulb. Hopefully it will be a threaded connection. This connection is on the high pressure side of the purifier and can be removed without compromising the vacuum. You will need to remove the container and recharge it. I would instead replace it with a small compressed hydrogen cylinder and regulators. Use ultra-high purity dry Hydrogen and make sure you purge the line going to the purifier. The purifier will block other gases from getting into the Maser but in the process too much foreign gas can contaminate and damage the purifier! Once you manage to locate the container some pictures on where its hiding would be nice! Good luck with your efforts! Cheers, Corby Dawson ___ 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] It is possible to "recharge" a hydrogen maser?
The model of H Maser is KVARZ: CH1-75A. Thank you for the replies friends! Soon here in the lab we will start to discuss the maintenance. Best regards Luiz Em sáb, 6 de jul de 2019 às 22:01, Jim Palfreyman escreveu: > Hi Luis, > > I have experience with the NASA NR series if that’s what you have. Blue and > about the size of a household fridge, wth lovely 80s red LEDS on the front. > > If it is this model, I’d expect it is more likely that your ion pump(s) > need replacing. > > I can send all the documentation you need. > > Jim > > > On Sat, 6 Jul 2019 at 3:01 am, Luiz Paulo Damaceno < > luizpauloeletric...@gmail.com> wrote: > > > Hi friends, > > > > We have a hydrogen maser here at the university that i work. It seems the > > hydrogen is over. This is possible? If yes, It is possible to recharge > It? > > > > Best regards, > > > > Luiz. > > ___ > > 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] It is possible to "recharge" a hydrogen maser?
Hi Luis, I have experience with the NASA NR series if that’s what you have. Blue and about the size of a household fridge, wth lovely 80s red LEDS on the front. If it is this model, I’d expect it is more likely that your ion pump(s) need replacing. I can send all the documentation you need. Jim On Sat, 6 Jul 2019 at 3:01 am, Luiz Paulo Damaceno < luizpauloeletric...@gmail.com> wrote: > Hi friends, > > We have a hydrogen maser here at the university that i work. It seems the > hydrogen is over. This is possible? If yes, It is possible to recharge It? > > Best regards, > > Luiz. > ___ > 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] It is possible to "recharge" a hydrogen maser?
Luiz, Once I know the model number of the Maser I can give some advice. I recharged the Hydrogen bottle of the EFOS2 Maser 4 times in the past with no problem. Really depends on the method of Hydrogen storage and if they made provision for field repair, I.E. threaded fittings vice welded joints. 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] It is possible to "recharge" a hydrogen maser?
The H maser that we had at NASA-DSN in the 80´s had a small H2 bottle which supplied it to the palladium valve, so it could be refilled. We never needed a refill but once we had to open the plumbing, it was necessary to reestablish the vacuum before opening the H2 valve. it was done using a mechanical pump and then a (then unknown to me) "molecular sieves" pump that was chilled with a bucket of liquid N2. The procedure was quite convoluted. Regards, Ignacio El 05/07/2019 a las 16:11, Luiz Paulo Damaceno escribió: Hi friends, We have a hydrogen maser here at the university that i work. It seems the hydrogen is over. This is possible? If yes, It is possible to recharge It? Best regards, Luiz. ___ 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. --- El software de antivirus Avast ha analizado este correo electrónico en busca de virus. https://www.avast.com/antivirus ___ 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] It is possible to "recharge" a hydrogen maser?
Er du Norsk? Ole Petter Rønningen er et Norsk navn. -Original Message- From: Ole Petter Ronningen Sent: Friday, July 05, 2019 10:04 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] It is possible to "recharge" a hydrogen maser? Just change the bottle, or hydride cartridge, whichever it is. But it is also very possible that the ion pumps are at the end of their lives, but these can also be replaced "easily". What type if maser is it? Ole On Fri, Jul 5, 2019 at 7:01 PM Luiz Paulo Damaceno < luizpauloeletric...@gmail.com> wrote: Hi friends, We have a hydrogen maser here at the university that i work. It seems the hydrogen is over. This is possible? If yes, It is possible to recharge It? Best regards, Luiz. ___ 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] It is possible to "recharge" a hydrogen maser?
Hi Luiz, We replaced H-source one Kvarz active HM during the summer of 2016. After 6-9 months of so of 'warm up' and settling down it is back up to maximum TAI weight. We got the new H-source bottle (size of a mini coke-can) and instructions from the manufacturer. >From what I recall the steps are roughly: - turn it off and turn it upside down - open up (HFO, mag-shield etc.) enough to have access to the H-bottle - disconnect the old bottle - cool down the new bottle in liquid nitrogen - connect new (cold) bottle with new seals (ethanol was used to prevent the new seals collecting water and freezing) - paint soap-bubble liquid on the pipes and look for leaks. let it warm up a day or two. - assemble, turn on, hope for the best :) - the bottle has a heater, which isn't needed in the beginning (6-9 months) when the H-pressure from the new source is high, so the heater can be off. Turn on the heater when the H-pressure monitor shows a reasonable value. hope this story helps, it's definitely doable with support from the manufacturer and basic tools/skills found in your typical time lab. Anders On Fri, Jul 5, 2019 at 8:01 PM Luiz Paulo Damaceno < luizpauloeletric...@gmail.com> wrote: > Hi friends, > > We have a hydrogen maser here at the university that i work. It seems the > hydrogen is over. This is possible? If yes, It is possible to recharge It? > > Best regards, > > Luiz. > ___ > 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] It is possible to "recharge" a hydrogen maser?
My experience is limited to the MHM-2010 at the Arecibo observatory, but I suspect they all handle the H2 supply in pretty much the same way. Th hydrogen comes from a reservoir, in the case of the MHM-2010 from a small "lecture" bottle of H2 under pressure. I assume that this is isotopically rather pure, and also fairly pure of other gaseous contaminants. In principle this should be field replaceable; however special procedures including a good vacuum pump and probably some special fittings would likely be required. You should consult the mfr of your maser about the availability of a new bottle of H2 as well as correct procedures for making the changeover. We at Arecibo had to replace one of the vacion pumps in our maser about 6 or 7 years ago. and we decided to get help from Symmetricom in the form of a field service call, to the tune of $12k. The guy who came was a physicist at heart, and was the very guy who had put together the physics package in our very maser. This included replacement of the still-working pump as well, done the following day. So on the first day, he replaced the failed pump while I asked questions and took copious notes. Then on the 2nd day, I replaced the 2nd pump while he kibitzed and stood ready to stop me before I did anything stupid. In both cases there was some difficulty getting the pumps "started up", arising because they had been open to the atmosphere for some time beforehand. They both required a lot of teasing of the voltage in little steps, while intently watching the current to be sure not to exceed ratings. IIRC, they each required more than an hour of vigilance before we could safely stand down. The interesting thing was that this maser could (and did) run quite well with only one pump working, for over a year. The delay was on our part, shuffling stuff around in the clock room to clear generous working space around the maser. The job involved a lot of "on-the-floor" work, much like working under a car without benefit of a lift. But the maser was well thought out in that subsystems could be isolated with high-vacuum valves and switches, with the result that we kept the maser operating throughout the two procedures, with only a subtle glitch in timing accuracy visible in the records when I checked after the fact. The observatory continued to operate with no disturbance the whole time. Dana Whitlow On Fri, Jul 5, 2019 at 12:01 PM Luiz Paulo Damaceno < luizpauloeletric...@gmail.com> wrote: > Hi friends, > > We have a hydrogen maser here at the university that i work. It seems the > hydrogen is over. This is possible? If yes, It is possible to recharge It? > > Best regards, > > Luiz. > ___ > 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] It is possible to "recharge" a hydrogen maser?
Hi Anything is possible. Working out exactly what happened and what needs to be done to fix it might be a bit involved. A maser is a pretty complicated piece of gear. The best bet is to dig out the manuals and go through the troubleshooting process in them. Plan for it taking a bit of time ….. Bob > On Jul 5, 2019, at 10:11 AM, Luiz Paulo Damaceno > wrote: > > H i friends, > > We have a hydrogen maser here at the university that i work. It seems the > hydrogen is over. This is possible? If yes, It is possible to recharge It? > > Best regards, > > Luiz. > ___ > 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] It is possible to "recharge" a hydrogen maser?
Just change the bottle, or hydride cartridge, whichever it is. But it is also very possible that the ion pumps are at the end of their lives, but these can also be replaced "easily". What type if maser is it? Ole On Fri, Jul 5, 2019 at 7:01 PM Luiz Paulo Damaceno < luizpauloeletric...@gmail.com> wrote: > Hi friends, > > We have a hydrogen maser here at the university that i work. It seems the > hydrogen is over. This is possible? If yes, It is possible to recharge It? > > Best regards, > > Luiz. > ___ > 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] It is possible to "recharge" a hydrogen maser?
Hi friends, We have a hydrogen maser here at the university that i work. It seems the hydrogen is over. This is possible? If yes, It is possible to recharge It? Best regards, Luiz. ___ 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.
