Re: [time-nuts] homebrew H maser
jimlux wrote: Hal Murray wrote: jim...@earthlink.net said: The gas diffusing out through the drilled bolt.. sure it's drilled, but the conductance is so patheticaly low, you're literally waiting until the gas molecules happen to randomly bounce their wey up the hole. I've never worked with vacuum gear. I assume drilled bolt refers to a bolt through a drilled hole so there is some slop between the bolt and the hole. No... the bolt has a hole through it, to provide a gas path when you install it into a blind tapped hole. Otherwise, the trapped gas in the bottom of the hole slowly leaks out past the threads. Can I use vacuum grease as a seal around the bolt? Or does it outgas too much if you are going for seriously low pressures? For the most part, grease is more trouble than it's worth. Knife edge seals are where it's at. Can I use a soft(er) metal washer and mash it to a gas tight fit by tightening the bolt enough? Not exactly.. what you see is a knife edge cutting into a softer metal... mashing implies gas trapped between layers.. That kind of thing crops up in TWT manufacturing, where they stack all the parts of the gun or the collector... How low a pressure does a H maser need? Where is it relative to say fingerprints outgassing? That's a good question.. I don't know. http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2doc=GetTRDoc.pdfAD=ADA503712 http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2doc=GetTRDoc.pdfAD=ADA503712 Indicates that the operating pressure at the hydrogen dissociator is likely to be a few Torr or so. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
In message 4c7f5918.7030...@xtra.co.nz, Bruce Griffiths writes: Indicates that the operating pressure at the hydrogen dissociator is likely to be a few Torr or so. The pressure is basically: As low as possible in order to minimize hydrogen collisions (other hydrogen, walls) as much as possible. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
Poul-Henning Kamp wrote: In message4c7f5918.7030...@xtra.co.nz, Bruce Griffiths writes: Indicates that the operating pressure at the hydrogen dissociator is likely to be a few Torr or so. The pressure is basically: As low as possible in order to minimize hydrogen collisions (other hydrogen, walls) as much as possible. i.e. the mean free path of the atomic hydrogen needs to be somewhat larger than the dimensions of the (fused silica) gas containment bulb. The mean free path will be comparable to the bulb dimensions at a pressure of around 1 ubar (100 uPa) or so. Since the Hydrogen atom bounces of the fluoropolymer coated walls thousands of times before phase coherence is lost the mean free path needs to be several thousand times the containment bulb dimensions to avoid degrading the maser performance. This requires a pressure of around 1 nanobar (100nPa) or below within the storage bulb.. The (gas) conductance of the exit aperture of the dissociator is selected to achieve the required atomic hydrogen flux of at most around 3E-5 liter-Torr/sec or so for a typical hydrogen dissociator pressure of 50Torr or so. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
Bruce Griffiths wrote: Poul-Henning Kamp wrote: In message4c7f5918.7030...@xtra.co.nz, Bruce Griffiths writes: Indicates that the operating pressure at the hydrogen dissociator is likely to be a few Torr or so. The pressure is basically: As low as possible in order to minimize hydrogen collisions (other hydrogen, walls) as much as possible. i.e. the mean free path of the atomic hydrogen needs to be somewhat larger than the dimensions of the (fused silica) gas containment bulb. The mean free path will be comparable to the bulb dimensions at a pressure of around 1 ubar (100 uPa) or so. Since the Hydrogen atom bounces of the fluoropolymer coated walls thousands of times before phase coherence is lost the mean free path needs to be several thousand times the containment bulb dimensions to avoid degrading the maser performance. This requires a pressure of around 1 nanobar (100nPa) or below within the storage bulb.. The (gas) conductance of the exit aperture of the dissociator is selected to achieve the required atomic hydrogen flux of at most around 3E-5 liter-Torr/sec or so for a typical hydrogen dissociator pressure of 50Torr or so. Bruce Oops!, the pressures given in Pa above are out a few orders of magnitude. Correct values are: The mean free path will be comparable to the bulb dimensions at a pressure of around 1 ubar (0.1Pa) or so. Since the Hydrogen atom bounces of the fluoropolymer coated walls thousands of times before phase coherence is lost the mean free path needs to be several thousand times the containment bulb dimensions to avoid degrading the maser performance. This requires a pressure of around 1 nanobar (100uPa) or below within the storage bulb.. The (gas) conductance of the exit aperture of the dissociator is selected to achieve the required atomic hydrogen flux of at most around 3E-5 liter-Torr/sec or so for a typical hydrogen dissociator pressure of 50Torr or so. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
Poul-Henning Kamp wrote: In message 4c7f5918.7030...@xtra.co.nz, Bruce Griffiths writes: Indicates that the operating pressure at the hydrogen dissociator is likely to be a few Torr or so. The pressure is basically: As low as possible in order to minimize hydrogen collisions (other hydrogen, walls) as much as possible. A few torr is actually not a particularly high vacuum (e.g. your run of the mill neon sign is pumped down a lot lower before being filled to a few torr). PHKs comment implies you're looking for mean free path somewhat greater than physical dimensions... That would imply pressures less than a micron (0.001 Torr).. MFP = 5E-3/P with P in Torr.. 1 micron pressure == 5cm MFP The other thing is when you're looking at MFP comparable to dimensions, you're looking at molecular pumping in some form (no more pistons or rotary vanes or ...) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
Hi Also to pump the beast clean after you have opened it up Bob On Sep 2, 2010, at 4:04 AM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message 4c7f5918.7030...@xtra.co.nz, Bruce Griffiths writes: Indicates that the operating pressure at the hydrogen dissociator is likely to be a few Torr or so. The pressure is basically: As low as possible in order to minimize hydrogen collisions (other hydrogen, walls) as much as possible. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
Hi That pressure level pretty much rules out mechanical pumps for the operating mode. A roughing pump would still be needed to get things going. It also takes the level of machining on the fittings well beyond the reach of most machine shops. Some of the stuff has to be exact, close to a tolerance won't do the trick. Bob On Sep 2, 2010, at 4:39 AM, Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: Bruce Griffiths wrote: Poul-Henning Kamp wrote: In message4c7f5918.7030...@xtra.co.nz, Bruce Griffiths writes: Indicates that the operating pressure at the hydrogen dissociator is likely to be a few Torr or so. The pressure is basically: As low as possible in order to minimize hydrogen collisions (other hydrogen, walls) as much as possible. i.e. the mean free path of the atomic hydrogen needs to be somewhat larger than the dimensions of the (fused silica) gas containment bulb. The mean free path will be comparable to the bulb dimensions at a pressure of around 1 ubar (100 uPa) or so. Since the Hydrogen atom bounces of the fluoropolymer coated walls thousands of times before phase coherence is lost the mean free path needs to be several thousand times the containment bulb dimensions to avoid degrading the maser performance. This requires a pressure of around 1 nanobar (100nPa) or below within the storage bulb.. The (gas) conductance of the exit aperture of the dissociator is selected to achieve the required atomic hydrogen flux of at most around 3E-5 liter-Torr/sec or so for a typical hydrogen dissociator pressure of 50Torr or so. Bruce Oops!, the pressures given in Pa above are out a few orders of magnitude. Correct values are: The mean free path will be comparable to the bulb dimensions at a pressure of around 1 ubar (0.1Pa) or so. Since the Hydrogen atom bounces of the fluoropolymer coated walls thousands of times before phase coherence is lost the mean free path needs to be several thousand times the containment bulb dimensions to avoid degrading the maser performance. This requires a pressure of around 1 nanobar (100uPa) or below within the storage bulb.. The (gas) conductance of the exit aperture of the dissociator is selected to achieve the required atomic hydrogen flux of at most around 3E-5 liter-Torr/sec or so for a typical hydrogen dissociator pressure of 50Torr or so. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
This discussion reminds me of a time long ago when I worked at a University. We had one rather obnoxious Grad Student, who, although brilliant, was a Royal PITA. So, while constructing his vacuum system, and getting hassled by him, I located one of the Universities residents, a large water bug. Which I let loose in the vacuum plumbing. He was beside himself for about a week, wondering why he could not get pumped down to the level he expected. 73, Dick, W1KSZ -Original Message- From: jimlux jim...@earthlink.net Sent: Sep 2, 2010 6:29 AM To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] homebrew H maser Poul-Henning Kamp wrote: In message 4c7f5918.7030...@xtra.co.nz, Bruce Griffiths writes: Indicates that the operating pressure at the hydrogen dissociator is likely to be a few Torr or so. The pressure is basically: As low as possible in order to minimize hydrogen collisions (other hydrogen, walls) as much as possible. A few torr is actually not a particularly high vacuum (e.g. your run of the mill neon sign is pumped down a lot lower before being filled to a few torr). PHKs comment implies you're looking for mean free path somewhat greater than physical dimensions... That would imply pressures less than a micron (0.001 Torr).. MFP = 5E-3/P with P in Torr.. 1 micron pressure == 5cm MFP The other thing is when you're looking at MFP comparable to dimensions, you're looking at molecular pumping in some form (no more pistons or rotary vanes or ...) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
jim...@earthlink.net said: The gas diffusing out through the drilled bolt.. sure it's drilled, but the conductance is so patheticaly low, you're literally waiting until the gas molecules happen to randomly bounce their wey up the hole. I've never worked with vacuum gear. I assume drilled bolt refers to a bolt through a drilled hole so there is some slop between the bolt and the hole. No. It's used where a bolt goes into a blind hole. It is to vent the trapped gas more quickly to reduce virtual leaks Can I use vacuum grease as a seal around the bolt? Or does it outgas too much if you are going for seriously low pressures? Basically no. SS bolts are lubed to prevent sieze up, but not in vacuum. Can I use a soft(er) metal washer and mash it to a gas tight fit by tightening the bolt enough? Conflat (and other) fittings use OHFC copper gaskets (one use only. Take it appart and you must use new ones). Also Indium and Gold are used. How low a pressure does a H maser need? Where is it relative to say fingerprints outgassing? The vacuum areas must be really clean. Think vapor degreasing with Trichlor. Is there an easy to understand scale of difficulty? (like dishes rattle for the Richter scale) On a scale of 1 to 10: 1 getting a GPS DO working. 3 getting a Rb working from scratch. 9 getting a H2 MASER working scratch. 15+ getting an Ion trap working. And, like the Richter, this is a log scale. FWIW, -John == -- These are my opinions, not necessarily my employer's. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
I am rally interested to be part of a team of people with the target to built an active H Maser. If there are in the world persons who are really interested in, it will be a good starting point. To built specific parts there are several way to do it in ham saving mode, for example for the cavity I can find a friend of main that have high precision machine to phisically prepare it and so on. First of all is important to find the team. Hope hear you, Luciano P. S. Paramithiotti -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of J. Forster Sent: giovedì 2 settembre 2010 18.59 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] homebrew H maser jim...@earthlink.net said: The gas diffusing out through the drilled bolt.. sure it's drilled, but the conductance is so patheticaly low, you're literally waiting until the gas molecules happen to randomly bounce their wey up the hole. I've never worked with vacuum gear. I assume drilled bolt refers to a bolt through a drilled hole so there is some slop between the bolt and the hole. No. It's used where a bolt goes into a blind hole. It is to vent the trapped gas more quickly to reduce virtual leaks Can I use vacuum grease as a seal around the bolt? Or does it outgas too much if you are going for seriously low pressures? Basically no. SS bolts are lubed to prevent sieze up, but not in vacuum. Can I use a soft(er) metal washer and mash it to a gas tight fit by tightening the bolt enough? Conflat (and other) fittings use OHFC copper gaskets (one use only. Take it appart and you must use new ones). Also Indium and Gold are used. How low a pressure does a H maser need? Where is it relative to say fingerprints outgassing? The vacuum areas must be really clean. Think vapor degreasing with Trichlor. Is there an easy to understand scale of difficulty? (like dishes rattle for the Richter scale) On a scale of 1 to 10: 1 getting a GPS DO working. 3 getting a Rb working from scratch. 9 getting a H2 MASER working scratch. 15+ getting an Ion trap working. And, like the Richter, this is a log scale. FWIW, -John == -- These are my opinions, not necessarily my employer's. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
Hi My guess is that you put the adjuster entirely inside the vacuum enclosure. Pump the gizmo down, stabilize it, measure where it's at. Do some math, pop it open move the adjuster x.xx turns. Step and repeat. Possibly have a fine and a coarse mechanical adjust screw. It's a one time only sort of thing. You can afford to do it the hard way. Another option would be to allow the screws to come through the envelope and leak a little bit during the adjust process. Once you were done with adjustment, seal them up with a low out gassing epoxy. My guess is that would be a problem thermally. If you need 0.001C gradients, you can't have more than one thermal path to the cavity. That's all getting complicated, and we're only talking about the easy to understand and address stuff... My understanding is that the guys at Kvarz spent years poking at their design in the secret back room before it worked as well as it does today. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Attila Kinali Sent: Tuesday, August 31, 2010 12:13 PM To: j...@quik.com; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] homebrew H maser On Sun, 29 Aug 2010 10:03:02 -0700 (PDT) J. Forster j...@quik.com wrote: [snip] complicating aspect is the self-tuning stuff for which several strategies may be chosen. I'd start here at getting a cavity that is resonant at the frequency at all. Getting sub-milimeter precision in tooling is quite easy (given you have the tools and knowledge, or can pay someone to do it for you), but if the cavity has to be resonant within a couple of Hz of the 1.4xxxGHz, then you have to get a precission in the range of 10^-9 which basically impossible mechanically. So the cavity would need to have a mechanical tuning system too, but one that doesn't lower the cavity's Q or add any additional resonant modes. A tuning plunger driven with a Burleigh Inchworm, either through a bellows or with a vacuum Inchworm. Yes, but that's only half of the story. How do you make it vacuum tight? And how do you design the end in the cavity so that you do not create unwanted resonant modi? Attila Kinali -- If you want to walk fast, walk alone. If you want to walk far, walk together. -- African proverb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
Hi My guess is that you put the adjuster entirely inside the vacuum enclosure. Pump the gizmo down, stabilize it, measure where it's at. Do some math, pop it open move the adjuster x.xx turns. Step and repeat. Possibly have a fine and a coarse mechanical adjust screw. This kind of thing is done with Inchworms, totally in vacuum. Only a few (4 to 6)small wires come out through a vacuum feedthrough. Or you can use mechanical linkages and SS or copper bellows. The Inchworms can have several inches of travel with sub-micron sized steps. They are grab-move-release incremental piezoelectric actuarors. It's a one time only sort of thing. You can afford to do it the hard way. Another option would be to allow the screws to come through the envelope and leak a little bit during the adjust process. Once you were done with adjustment, seal them up with a low out gassing epoxy. My guess is that would be a problem thermally. If you need 0.001C gradients, you can't have more than one thermal path to the cavity. With the vacuums in the MASER manual, you cannot have any leaks. Even so, they rough pump the thing, pinch of metal seals, and then run Ion pumps. If you try to cut corners with high vacuun technology, you will be disappointed. Even with all new parts and carefull assembly, you will almost certainly have to He Leak Detect the system to get it tight. I've done this stuff. It is doable but certainly not trivial. And you cannot be sloppy. YMMV, -John == That's all getting complicated, and we're only talking about the easy to understand and address stuff... My understanding is that the guys at Kvarz spent years poking at their design in the secret back room before it worked as well as it does today. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Attila Kinali Sent: Tuesday, August 31, 2010 12:13 PM To: j...@quik.com; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] homebrew H maser On Sun, 29 Aug 2010 10:03:02 -0700 (PDT) J. Forster j...@quik.com wrote: [snip] complicating aspect is the self-tuning stuff for which several strategies may be chosen. I'd start here at getting a cavity that is resonant at the frequency at all. Getting sub-milimeter precision in tooling is quite easy (given you have the tools and knowledge, or can pay someone to do it for you), but if the cavity has to be resonant within a couple of Hz of the 1.4xxxGHz, then you have to get a precission in the range of 10^-9 which basically impossible mechanically. So the cavity would need to have a mechanical tuning system too, but one that doesn't lower the cavity's Q or add any additional resonant modes. A tuning plunger driven with a Burleigh Inchworm, either through a bellows or with a vacuum Inchworm. Yes, but that's only half of the story. How do you make it vacuum tight? And how do you design the end in the cavity so that you do not create unwanted resonant modi? Attila Kinali -- If you want to walk fast, walk alone. If you want to walk far, walk together. -- African proverb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
On 9/1/2010 12:18 PM, Bob Camp wrote: Hi My guess is that you put the adjuster entirely inside the vacuum enclosure. Pump the gizmo down, stabilize it, measure where it's at. Do some math, pop it open move the adjuster x.xx turns. Step and repeat. Possibly have a fine and a coarse mechanical adjust screw. How about getting really evil. Why not just deform the cavity for coarse adjustment and rely on elastic deformation for fine? It's a one time only sort of thing. You can afford to do it the hard way. or the dirty evil way ;-) Another option would be to allow the screws to come through the envelope and leak a little bit during the adjust process. Once you were done with adjustment, seal them up with a low out gassing epoxy. Given the quality of vacuum the manual seems to imply, I'm guessing this wont cut it. I'll bet that even low impurity Teflon has a long bakeout period. My guess is that would be a problem thermally. If you need 0.001C gradients, you can't have more than one thermal path to the cavity. That's all getting complicated, and we're only talking about the easy to understand and address stuff... My understanding is that the guys at Kvarz spent years poking at their design in the secret back room before it worked as well as it does today. I've been told that this is business is still highly empirical, so that tracks. Bob Oz (in DFW - Rich Osman) -- mailto:o...@ozindfw.net Oz POB 93167 Southlake, TX 76092 (Near DFW Airport) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser (dangerous topic drift)
On 9/1/2010 3:30 PM, Chris Howard wrote: Given the quality of vacuum the manual seems to imply, I'm guessing this wont cut it. I'll bet that even low impurity Teflon has a long bakeout period. Too bad they don't have some kind of getter to allow lower vacuum specs. I expect they thought of that. The thing does sound like a giant hydrogenated vacuum tube. Contents: Partially hydrogenated vacuum. -- mailto:o...@ozindfw.net Oz POB 93167 Southlake, TX 76092 (Near DFW Airport) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
Hi You can get epoxies with very low outgassing numbers. Also you will be using very little of it. Bob On Sep 1, 2010, at 3:28 PM, Oz-in-DFW li...@ozindfw.net wrote: On 9/1/2010 12:18 PM, Bob Camp wrote: Hi My guess is that you put the adjuster entirely inside the vacuum enclosure. Pump the gizmo down, stabilize it, measure where it's at. Do some math, pop it open move the adjuster x.xx turns. Step and repeat. Possibly have a fine and a coarse mechanical adjust screw. How about getting really evil. Why not just deform the cavity for coarse adjustment and rely on elastic deformation for fine? It's a one time only sort of thing. You can afford to do it the hard way. or the dirty evil way ;-) Another option would be to allow the screws to come through the envelope and leak a little bit during the adjust process. Once you were done with adjustment, seal them up with a low out gassing epoxy. Given the quality of vacuum the manual seems to imply, I'm guessing this wont cut it. I'll bet that even low impurity Teflon has a long bakeout period. My guess is that would be a problem thermally. If you need 0.001C gradients, you can't have more than one thermal path to the cavity. That's all getting complicated, and we're only talking about the easy to understand and address stuff... My understanding is that the guys at Kvarz spent years poking at their design in the secret back room before it worked as well as it does today. I've been told that this is business is still highly empirical, so that tracks. Bob Oz (in DFW - Rich Osman) -- mailto:o...@ozindfw.net Oz POB 93167 Southlake, TX 76092 (Near DFW Airport) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
J. Forster wrote: If you try to cut corners with high vacuun technology, you will be disappointed. Even with all new parts and carefull assembly, you will almost certainly have to He Leak Detect the system to get it tight. I've done this stuff. It is doable but certainly not trivial. And you cannot be sloppy. not trivial is an understatement.. High vacuum seems straightforward until you sweat blood on it. Oh. that fingerprint that serves as a virtual leak for weeks. That Kapton tape that trapped a few molecules of whatever under it and outgassed. The gas diffusing out through the drilled bolt.. sure it's drilled, but the conductance is so patheticaly low, you're literally waiting until the gas molecules happen to randomly bounce their wey up the hole. It is the most horribly frustrating experience you will have. Unless you're running HUGE fast pumps.. then you just don't care.. Back when I sweated this kind of thing, I would have killed for the size pumps we run at JPL on the big vacuum chambers.. Outgas, what outgas, it just gets pumped away... But when you're running a 2 or 3 inch diff or turbo pump... ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
The combination of high vacuum and milliKelvin temperatures is far, far worse. -John J. Forster wrote: If you try to cut corners with high vacuun technology, you will be disappointed. Even with all new parts and carefull assembly, you will almost certainly have to He Leak Detect the system to get it tight. I've done this stuff. It is doable but certainly not trivial. And you cannot be sloppy. not trivial is an understatement.. High vacuum seems straightforward until you sweat blood on it. Oh. that fingerprint that serves as a virtual leak for weeks. That Kapton tape that trapped a few molecules of whatever under it and outgassed. The gas diffusing out through the drilled bolt.. sure it's drilled, but the conductance is so patheticaly low, you're literally waiting until the gas molecules happen to randomly bounce their wey up the hole. It is the most horribly frustrating experience you will have. Unless you're running HUGE fast pumps.. then you just don't care.. Back when I sweated this kind of thing, I would have killed for the size pumps we run at JPL on the big vacuum chambers.. Outgas, what outgas, it just gets pumped away... But when you're running a 2 or 3 inch diff or turbo pump... ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
jim...@earthlink.net said: The gas diffusing out through the drilled bolt.. sure it's drilled, but the conductance is so patheticaly low, you're literally waiting until the gas molecules happen to randomly bounce their wey up the hole. I've never worked with vacuum gear. I assume drilled bolt refers to a bolt through a drilled hole so there is some slop between the bolt and the hole. Can I use vacuum grease as a seal around the bolt? Or does it outgas too much if you are going for seriously low pressures? Can I use a soft(er) metal washer and mash it to a gas tight fit by tightening the bolt enough? How low a pressure does a H maser need? Where is it relative to say fingerprints outgassing? Is there an easy to understand scale of difficulty? (like dishes rattle for the Richter scale) -- These are my opinions, not necessarily my employer's. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
Hal Murray wrote: jim...@earthlink.net said: The gas diffusing out through the drilled bolt.. sure it's drilled, but the conductance is so patheticaly low, you're literally waiting until the gas molecules happen to randomly bounce their wey up the hole. I've never worked with vacuum gear. I assume drilled bolt refers to a bolt through a drilled hole so there is some slop between the bolt and the hole. No... the bolt has a hole through it, to provide a gas path when you install it into a blind tapped hole. Otherwise, the trapped gas in the bottom of the hole slowly leaks out past the threads. Can I use vacuum grease as a seal around the bolt? Or does it outgas too much if you are going for seriously low pressures? For the most part, grease is more trouble than it's worth. Knife edge seals are where it's at. Can I use a soft(er) metal washer and mash it to a gas tight fit by tightening the bolt enough? Not exactly.. what you see is a knife edge cutting into a softer metal... mashing implies gas trapped between layers.. That kind of thing crops up in TWT manufacturing, where they stack all the parts of the gun or the collector... How low a pressure does a H maser need? Where is it relative to say fingerprints outgassing? That's a good question.. I don't know. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
On Sun, 29 Aug 2010 09:51:46 -0700 (PDT) J. Forster j...@quik.com wrote: If you took a modern approach by using factory built test equipment as building blocks (microwave synthesizer, lock-in amp, power supplies, etc) and commercial vacuum components (pumps, valves, fittings, controllers, etc. in Conflat or something like it), you could likely build up most of a system pretty easily. And it would be pretty expensive too. Lab grade equipment, especially in electronics, is very expensive as it has to accomodate for a broad range of needs. Specialized electronics, even if it is a one-of-a-kind thing and thus very expensive, is often cheaper because it is optimized only for one case. Much of this stuff is available on eBay at pretty reasonable prices. In the US, yes, not in Europe. Just try to find someone selling a HP counter that is not 20a old on fleabay in Europe. While there are a dozen in the US, there is at most one on the old continent. If there is even one... Attila Kinali -- If you want to walk fast, walk alone. If you want to walk far, walk together. -- African proverb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
On Sun, 29 Aug 2010 10:11:47 -0700 (PDT) J. Forster j...@quik.com wrote: I used to read Strong's book as bedtime reading. And which book would that be, for those who have not read it? Attila Kinali -- If you want to walk fast, walk alone. If you want to walk far, walk together. -- African proverb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
On Sun, 29 Aug 2010 10:03:02 -0700 (PDT) J. Forster j...@quik.com wrote: [snip] complicating aspect is the self-tuning stuff for which several strategies may be chosen. I'd start here at getting a cavity that is resonant at the frequency at all. Getting sub-milimeter precision in tooling is quite easy (given you have the tools and knowledge, or can pay someone to do it for you), but if the cavity has to be resonant within a couple of Hz of the 1.4xxxGHz, then you have to get a precission in the range of 10^-9 which basically impossible mechanically. So the cavity would need to have a mechanical tuning system too, but one that doesn't lower the cavity's Q or add any additional resonant modes. A tuning plunger driven with a Burleigh Inchworm, either through a bellows or with a vacuum Inchworm. Yes, but that's only half of the story. How do you make it vacuum tight? And how do you design the end in the cavity so that you do not create unwanted resonant modi? Attila Kinali -- If you want to walk fast, walk alone. If you want to walk far, walk together. -- African proverb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
On Sun, 29 Aug 2010 16:26:05 -0400 Mark Kahrs mark.ka...@gmail.com wrote: The Hahvahd physics dept. has all number of interesting papers. For example there's Humphrey's dissertation:www.physics.harvard.edu/Thesespdfs/humphrey.pdf If you've ever wanted to make your own Rb cell, how about this one?cfa-www.harvard.edu/~dphil/work/coat.pdf http://cfa-www.harvard.edu/%7Edphil/work/coat.pdf%20 Thanks, i'll have a look at those. Attila Kinali -- If you want to walk fast, walk alone. If you want to walk far, walk together. -- African proverb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
Proceedures in Experimental Physics -John = On Sun, 29 Aug 2010 10:11:47 -0700 (PDT) J. Forster j...@quik.com wrote: I used to read Strong's book as bedtime reading. And which book would that be, for those who have not read it? Attila Kinali -- If you want to walk fast, walk alone. If you want to walk far, walk together. -- African proverb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
Questions like yours are what makes a good experimental physicist. As to vacuum tight, you use bellows or put the inchworm inside the vacuum. As to RF leakage, a waveguide below cutoff is one way. Another is to design a choke seal, a 1/4 wave stub with a high Q cavity as the open end. -Jhn === On Sun, 29 Aug 2010 10:03:02 -0700 (PDT) J. Forster j...@quik.com wrote: [snip] complicating aspect is the self-tuning stuff for which several strategies may be chosen. I'd start here at getting a cavity that is resonant at the frequency at all. Getting sub-milimeter precision in tooling is quite easy (given you have the tools and knowledge, or can pay someone to do it for you), but if the cavity has to be resonant within a couple of Hz of the 1.4xxxGHz, then you have to get a precission in the range of 10^-9 which basically impossible mechanically. So the cavity would need to have a mechanical tuning system too, but one that doesn't lower the cavity's Q or add any additional resonant modes. A tuning plunger driven with a Burleigh Inchworm, either through a bellows or with a vacuum Inchworm. Yes, but that's only half of the story. How do you make it vacuum tight? And how do you design the end in the cavity so that you do not create unwanted resonant modi? Attila Kinali -- If you want to walk fast, walk alone. If you want to walk far, walk together. -- African proverb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Homebrew H Maser
On Sun, 29 Aug 2010 13:27:13 -0700 Corby Dawson cdel...@juno.com wrote: -The triple magnetic shields are VERY important. The first time I removed the top shield to access the RF section the Maser stopped oscillating! Replacing the shield restored oscillations! Hmm.. i'd guess that the oscillation went outside the cavity's resonant range. Other than shifting the resonance frequency and spreading the hyperfine lines, it should not have any other effect. But i might be very well wrong. -The cavity does not have to be machined to super precise levels, in this Maser once the coarse setting (mechanical at factory) is made, the medium tuning is done by adjusting the cavity temperature. The fine is done with the cavity varactor. This cavity is aluminum. The thermal length constant of Al is 23e-6/K, which means that per °C you get a pulling of about 23ppm of the frequency. Guestimating that more than 20°C of heating should not be done to keep the whole thing in a easy to handle range. Then we would have a maximum pulling range of +/-230ppm, which means +/-10um precission on a 10cm diameter. This is still a very thight tollerance. Not impossible, but not that easy either. -Making a homebrew collimator (at the discharge bulb output) might be hard, google it and you will see it's tricky. I couldn't find anything telling me that it is difficult to do when i did a quick search. If i understood it correctly, the collimator for a H-maser is nothing else than a tight and straight pipe from the H beam source to the state selector magnet. Did i misunderstand something here? I have, somewhere, a scan of the two manuals. There is lots of theory and full schematics. Might be a good read if you are serious in trying to homebrew one. I'll dig them up and see if anyone could host them on a website. (Files are quite large!) I would very much like to read those. Even if i dont build a maser. As John suggested, it would be IMHO best to put them on Didier's site as others might be interested as well. Attila Kinali -- If you want to walk fast, walk alone. If you want to walk far, walk together. -- African proverb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
I think the book referred to is The Scientific American Book of Projects for the Amateur Scientist by C. L. Stong (no r' in Stong) I too used to just read it - great book. It's a collection of some of The Amateur Scientist columns by Stong from Scientific American magazine. Unfortunately it's out of print and used copies can be a bit pricey or hard to find. There is a great deal available, however - a complete collection of all of The Amateur Scientist columns ever published on a CD for $27. If anyone is interested, the link is http://www.brightscience.com/ Francis -- Original Message Date: Tue, 31 Aug 2010 18:06:38 +0200 From: Attila Kinali att...@kinali.ch Subject: Re: [time-nuts] homebrew H maser To: j...@quik.com, Discussion of precise time and frequency measurement time-nuts@febo.com Message-ID: 20100831180638.16e4c656.att...@kinali.ch Content-Type: text/plain; charset=US-ASCII On Sun, 29 Aug 2010 10:11:47 -0700 (PDT) J. Forster j...@quik.com wrote: I used to read Strong's book as bedtime reading. And which book would that be, for those who have not read it? Attila Kinali ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
Nope. Proceedures in Experimental Physics. A different Strong. -John I think the book referred to is The Scientific American Book of Projects for the Amateur Scientist by C. L. Stong (no r' in Stong) I too used to just read it - great book. It's a collection of some of The Amateur Scientist columns by Stong from Scientific American magazine. Unfortunately it's out of print and used copies can be a bit pricey or hard to find. There is a great deal available, however - a complete collection of all of The Amateur Scientist columns ever published on a CD for $27. If anyone is interested, the link is http://www.brightscience.com/ Francis -- Original Message Date: Tue, 31 Aug 2010 18:06:38 +0200 From: Attila Kinali att...@kinali.ch Subject: Re: [time-nuts] homebrew H maser To: j...@quik.com, Discussion of precise time and frequency measurement time-nuts@febo.com Message-ID: 20100831180638.16e4c656.att...@kinali.ch Content-Type: text/plain; charset=US-ASCII On Sun, 29 Aug 2010 10:11:47 -0700 (PDT) J. Forster j...@quik.com wrote: I used to read Strong's book as bedtime reading. And which book would that be, for those who have not read it? Attila Kinali ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
Published or sold by lindsay books at a very reasonable price. Its from the 40s or 50s. Great book for build it from scratch --Original Message-- From: J. Forster Sender: time-nuts-boun...@febo.com To: Attila Kinali Cc: Discussion of precise time and frequency measurement ReplyTo: j...@quik.com ReplyTo: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] homebrew H maser Sent: Aug 31, 2010 09:21 Proceedures in Experimental Physics -John = On Sun, 29 Aug 2010 10:11:47 -0700 (PDT) J. Forster j...@quik.com wrote: I used to read Strong's book as bedtime reading. And which book would that be, for those who have not read it? Attila Kinali -- If you want to walk fast, walk alone. If you want to walk far, walk together. -- African proverb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. Sent via BlackBerry by ATT ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
I didn't know of the current source. I've had mine for decades. Thanks. If you are into experimental physics, it's good to know how to do things from scratch, IMO. Even if you are going to use the latest toy out of a new box. -John == Published or sold by lindsay books at a very reasonable price. Its from the 40s or 50s. Great book for build it from scratch --Original Message-- From: J. Forster Sender: time-nuts-boun...@febo.com To: Attila Kinali Cc: Discussion of precise time and frequency measurement ReplyTo: j...@quik.com ReplyTo: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] homebrew H maser Sent: Aug 31, 2010 09:21 Proceedures in Experimental Physics -John = On Sun, 29 Aug 2010 10:11:47 -0700 (PDT) J. Forster j...@quik.com wrote: I used to read Strong's book as bedtime reading. And which book would that be, for those who have not read it? Attila Kinali -- If you want to walk fast, walk alone. If you want to walk far, walk together. -- African proverb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. Sent via BlackBerry by ATT ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
gee, i used to read that book over and over. the projects have two or more wires leading off page to power supply, which i never had. now that i have a lot of power supplies, my projects have wires leading to network analyzer... about out of reach now as all those power supplies then. whine whine. i guess you can't win :-) don Francis Grosz I think the book referred to is The Scientific American Book of Projects for the Amateur Scientist by C. L. Stong (no r' in Stong) I too used to just read it - great book. It's a collection of some of The Amateur Scientist columns by Stong from Scientific American magazine. Unfortunately it's out of print and used copies can be a bit pricey or hard to find. There is a great deal available, however - a complete collection of all of The Amateur Scientist columns ever published on a CD for $27. If anyone is interested, the link is http://www.brightscience.com/ Francis -- Original Message Date: Tue, 31 Aug 2010 18:06:38 +0200 From: Attila Kinali att...@kinali.ch Subject: Re: [time-nuts] homebrew H maser To: j...@quik.com, Discussion of precise time and frequency measurement time-nuts@febo.com Message-ID: 20100831180638.16e4c656.att...@kinali.ch Content-Type: text/plain; charset=US-ASCII On Sun, 29 Aug 2010 10:11:47 -0700 (PDT) J. Forster j...@quik.com wrote: I used to read Strong's book as bedtime reading. And which book would that be, for those who have not read it? Attila Kinali ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. R. Bacon Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
The Scientific American guy is Stong. The Procedures in Experimental Physics guy is Strong. I have original copies of each, and they are fun bedside readers. -Chuck Harris J. Forster wrote: Nope. Proceedures in Experimental Physics. A different Strong. -John I think the book referred to is The Scientific American Book of Projects for the Amateur Scientist by C. L. Stong (no r' in Stong) I too used to just read it - great book. It's a collection of some of The Amateur Scientist columns by Stong from Scientific American magazine. Unfortunately it's out of print and used copies can be a bit pricey or hard to find. There is a great deal available, however - a complete collection of all of The Amateur Scientist columns ever published on a CD for $27. If anyone is interested, the link is http://www.brightscience.com/ Francis -- Original Message Date: Tue, 31 Aug 2010 18:06:38 +0200 From: Attila Kinaliatt...@kinali.ch Subject: Re: [time-nuts] homebrew H maser To: j...@quik.com, Discussion of precise time and frequency measurementtime-nuts@febo.com Message-ID:20100831180638.16e4c656.att...@kinali.ch Content-Type: text/plain; charset=US-ASCII On Sun, 29 Aug 2010 10:11:47 -0700 (PDT) J. Forsterj...@quik.com wrote: I used to read Strong's book as bedtime reading. And which book would that be, for those who have not read it? Attila Kinali ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
Thank you Bruce This is very informative, not in my life time on ebay, but ground braking for things to come. Bert Kehren In a message dated 8/29/2010 4:32:13 P.M. Eastern Daylight Time, bruce.griffi...@xtra.co.nz writes: http://tycho.usno.navy.mil/ptti/ptti2002/paper14.pdf Bruce Griffiths wrote: http://www.spectratime.com/product_downloads/PTTI_FCS_2005.pdf ewkeh...@aol.com wrote: Any links to reading material, would be nice to learn what they did to get a small package and how small is it? Bert Kehren In a message dated 8/29/2010 2:03:34 P.M. Eastern Daylight Time, p...@phk.freebsd.dk writes: In message3e227.34d2ee82.39abf...@aol.com, ewkeh...@aol.com writes: Do we know any thing about the Neuchatel design for Galileo? Bert Kehren There are plenty of papers about it. They started out with an active design, and got it inside spec (power/weight) but found that the performance was not worth the extra effort, so they switched to a passive design to further reduce weight/power. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
On 08/29/2010 03:55 PM, Attila Kinali wrote: Moin, I had a little bit too much time at hand this weekend and read a bit about H masers. I was quite astonished to see how simple these devices actually are. The electronics are basically a simple matter these days (thanks to the abundance of GHz devices for cell phones and GPS receivers). The only problem would be to build a high Q cavity, get a Teflon coated quarz bulb of the right diameter, an apropriate atomic hydrogen beam source and putting everything under high vacuum. Piece of cake ;-) Thus i wondered whether anyone had ever build a H maser outside national labs and and specialized companies. Looking at the time-nuts archives, quite a few people asked about the feasibilty of such an endeavor. A few times i read of people who actually attempted to build one, but never was there any website or any other resource with their results meantioned. Neither did big-g return any results when searching for these homebrew H masers. Does anyone know whether any of those people collected their results somewhere? And if, where i could find them? The physical package is definitely where most of the effort goes in. A complicating aspect is the self-tuning stuff for which several strategies may be chosen. You need to balance the rate of the atoms, as both too few and too many kills the oscillation. The size of the glass-bulb is not a fixed thing, during research and development different sizes glass-bulbs is used to establish the wall-shift aspects in order to adjust for it, which is needed in order to make absolute measurements on the free atom resonance or compensate into that regard. As for reference, there is about one set of books and papers from a handful of journals and a bunch of patents which needs to the read in order to build up the knowledge-base for attempting something like it. It's a complicated field and several traps to fall into on the way. It is a fairly sizeable project to attempt. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
In message 4c7a6b01.3030...@rubidium.dyndns.org, Magnus Danielson writes: On 08/29/2010 03:55 PM, Attila Kinali wrote: It's a complicated field and several traps to fall into on the way. It is a fairly sizeable project to attempt. Well, as with so much else, it depends what the level of ambition is. If you just want to be able to point to the resonance and say I did that, it is not intrinsically hard and none of the materials are hard to get hold of or particularly poisonous. Few of the problems Ramsey fought in the early 1950'ies are relevante today, for instance, the entire detection issue is trivially solved with USRP/GnuRadio. I would tend to think that $10k in materials would get you pretty close. I think the most recent H-maser design is Neuchatels design for the Galileo GNSS. Building a _good_ (ie: metrology grade) hydrogen maser, sounds like the last significant thing you did in your life, however many years you have left... Poul-Henning PS: And if you even manage to build something which works half the time, and do not suffer from ethics, there is a finite but very profitable market for audiopholery, and I'm sure somebody is willing to eliminate the last traces of jitter in his CD-player for just under $100k... -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
On Sun, 29 Aug 2010 16:13:21 +0200 Magnus Danielson mag...@rubidium.dyndns.org wrote: On 08/29/2010 03:55 PM, Attila Kinali wrote: Does anyone know whether any of those people collected their results somewhere? And if, where i could find them? The physical package is definitely where most of the effort goes in. I know, that's why i'm asking. The papers i've read sofar all suggest that the difficult part is to compensate for cavity detuning, wall shift and second order doppler effect. Somehow all these papers seem to assume that getting an oscillation at all is so easy that everyone could do it (yes, i know that this is normal with scientific papers). I thought, that if someone build a homebrew H maser, he'd write about the difficulties getting there. Which would be a very interesting reading and teach a lot about the physics (and tool making, mechanics, etc) of these devices. A complicating aspect is the self-tuning stuff for which several strategies may be chosen. I'd start here at getting a cavity that is resonant at the frequency at all. Getting sub-milimeter precision in tooling is quite easy (given you have the tools and knowledge, or can pay someone to do it for you), but if the cavity has to be resonant within a couple of Hz of the 1.4xxxGHz, then you have to get a precission in the range of 10^-9 which basically impossible mechanically. So the cavity would need to have a mechanical tuning system too, but one that doesn't lower the cavity's Q or add any additional resonant modes. You need to balance the rate of the atoms, as both too few and too many kills the oscillation. Or get to the basic requirement of getting a pure H2 source to feed the beam source. The beam source itself, including the dissociator, would be a formidable project to do at home by itself. The size of the glass-bulb is not a fixed thing, during research and development different sizes glass-bulbs is used to establish the wall-shift aspects in order to adjust for it, which is needed in order to make absolute measurements on the free atom resonance or compensate into that regard. Interestingly, i think that the bulb would be the easiest part these days. At least around here, there are a few glas blowers for the chemical/pharmaceutical industry that also do single pieces. Getting it coated would only involve finding a company that does teflon coating (there do seem enough of them). From what i gather it's shape doesnt have to be exactly spherical down to the sub-milimeter range. As for reference, there is about one set of books and papers from a handful of journals and a bunch of patents which needs to the read in order to build up the knowledge-base for attempting something like it. Which papers/books would you recommend reading? And no, i don't think i'd attempt to build a H maser. I'm quite confident i could do the electronics part, but i know that i don't know anything when it comes to mechanics. Much less about handling high vacuum and atomic gas beams. It's a complicated field and several traps to fall into on the way. It is a fairly sizeable project to attempt. Yes, but it's fun to read about it :-) Attila Kinali -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
On Sun, 29 Aug 2010 15:05:05 + Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message 4c7a6b01.3030...@rubidium.dyndns.org, Magnus Danielson writes: On 08/29/2010 03:55 PM, Attila Kinali wrote: It's a complicated field and several traps to fall into on the way. It is a fairly sizeable project to attempt. Well, as with so much else, it depends what the level of ambition is. If you just want to be able to point to the resonance and say I did that, it is not intrinsically hard and none of the materials are hard to get hold of or particularly poisonous. True. But i don't think i'd get even that far considering my knowledge in this part of physics, especially in actually building such devices. Few of the problems Ramsey fought in the early 1950'ies are relevante today, for instance, the entire detection issue is trivially solved with USRP/GnuRadio. Yes, all the electronics problems are basically solved these days. I would tend to think that $10k in materials would get you pretty close. I think so too. Though, things like high vacuum pumps are quite expensive, even used ones. I think the most recent H-maser design is Neuchatels design for the Galileo GNSS. Yes, that one seems to be a very neat devices. And quite small too. I wonder whether i should drive to Neuchchâtel and ask them for a tour trough their labs :-) Building a _good_ (ie: metrology grade) hydrogen maser, sounds like the last significant thing you did in your life, however many years you have left... Being a time-nut might get you there ;-) PS: And if you even manage to build something which works half the time, and do not suffer from ethics, there is a finite but very profitable market for audiopholery, and I'm sure somebody is willing to eliminate the last traces of jitter in his CD-player for just under $100k... ROTFL Attila Kinali -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
If you took a modern approach by using factory built test equipment as building blocks (microwave synthesizer, lock-in amp, power supplies, etc) and commercial vacuum components (pumps, valves, fittings, controllers, etc. in Conflat or something like it), you could likely build up most of a system pretty easily. You could probably even build much of the specialized stuff from the Meccano like vacuum parts made by Kimball Physics. Much of this stuff is available on eBay at pretty reasonable prices. In thinking about it, it would be a terrific project to run with LabView! PLEASE! Don't tempt me further!! Best, -John = In message 4c7a6b01.3030...@rubidium.dyndns.org, Magnus Danielson writes: On 08/29/2010 03:55 PM, Attila Kinali wrote: It's a complicated field and several traps to fall into on the way. It is a fairly sizeable project to attempt. Well, as with so much else, it depends what the level of ambition is. If you just want to be able to point to the resonance and say I did that, it is not intrinsically hard and none of the materials are hard to get hold of or particularly poisonous. Few of the problems Ramsey fought in the early 1950'ies are relevante today, for instance, the entire detection issue is trivially solved with USRP/GnuRadio. I would tend to think that $10k in materials would get you pretty close. I think the most recent H-maser design is Neuchatels design for the Galileo GNSS. Building a _good_ (ie: metrology grade) hydrogen maser, sounds like the last significant thing you did in your life, however many years you have left... Poul-Henning PS: And if you even manage to build something which works half the time, and do not suffer from ethics, there is a finite but very profitable market for audiopholery, and I'm sure somebody is willing to eliminate the last traces of jitter in his CD-player for just under $100k... -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
In message 57157.12.6.201.2.1283100706.squir...@popaccts.quikus.com, J. Fors ter writes: In thinking about it, it would be a terrific project to run with LabView! Rubbish, LabView would _never_ be able to do that. PLEASE! Don't tempt me further!! Ooops, sorry! :-) Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
J. Forster wrote: If you took a modern approach by using factory built test equipment as building blocks (microwave synthesizer, lock-in amp, power supplies, etc) and commercial vacuum components (pumps, valves, fittings, controllers, etc. in Conflat or something like it), you could likely build up most of a system pretty easily. You definitely need a copy of this book http://www.amazon.com/Building-Scientific-Apparatus-John-Moore/dp/0813340063/ref=tmm_pap_title_0/182-2347235-0798235 Building Scientific Apparatus by Moore, Davies, and Coplan How to build that ion gun, or cobble together the high vacuum system, etc. Lots of useful references.. You'd also do well to get a catalog from Kurt.J.Lesker Company (http://www.lesker.com/) and from several of the vacuum equipment companies. Vacuum stuff is available used quite widely. Between the book and the catalog(s), you've got plenty of reading and dreaming material for months. Be aware, though, that high vacuum is like amateur telescope mirror making.. frustrating, tedious, and gratifying when it works. There's a surprising amount of craft in it. (and entirely in keeping with time-nuttery) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
[snip] complicating aspect is the self-tuning stuff for which several strategies may be chosen. I'd start here at getting a cavity that is resonant at the frequency at all. Getting sub-milimeter precision in tooling is quite easy (given you have the tools and knowledge, or can pay someone to do it for you), but if the cavity has to be resonant within a couple of Hz of the 1.4xxxGHz, then you have to get a precission in the range of 10^-9 which basically impossible mechanically. So the cavity would need to have a mechanical tuning system too, but one that doesn't lower the cavity's Q or add any additional resonant modes. A tuning plunger driven with a Burleigh Inchworm, either through a bellows or with a vacuum Inchworm. You need to balance the rate of the atoms, as both too few and too many kills the oscillation. There are commercial adjustable leaks and Mass Flow Controllers by MKS for example. Or get to the basic requirement of getting a pure H2 source to feed the beam source. The beam source itself, including the dissociator, would be a formidable project to do at home by itself. Kimball Physics sells parts for doing this. The size of the glass-bulb is not a fixed thing, during research and development different sizes glass-bulbs is used to establish the wall-shift aspects in order to adjust for it, which is needed in order to make absolute measurements on the free atom resonance or compensate into that regard. Interestingly, i think that the bulb would be the easiest part these days. At least around here, there are a few glas blowers for the chemical/pharmaceutical industry that also do single pieces. Getting it coated would only involve finding a company that does teflon coating (there do seem enough of them). From what i gather it's shape doesnt have to be exactly spherical down to the sub-milimeter range. As for reference, there is about one set of books and papers from a handful of journals and a bunch of patents which needs to the read in order to build up the knowledge-base for attempting something like it. Which papers/books would you recommend reading? And no, i don't think i'd attempt to build a H maser. I'm quite confident i could do the electronics part, but i know that i don't know anything when it comes to mechanics. Much less about handling high vacuum and atomic gas beams. The pumping is pretty straight forward. You would likely need a source of LN2, at least for a while. The vacuum needs to be clean, which means traps. Sorbtion ion or Ti sub pumps would be a better idea. It's a complicated field and several traps to fall into on the way. It is a fairly sizeable project to attempt. Yes, but it's fun to read about it :-) Attila Kinali Best, -John === ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
I used to read Strong's book as bedtime reading. WARNING: There are few things more addictive than collecting: Conflat Vacuum Fittings Standard Taper Glassware and worst: Linos (Spindler Hoyer) MicroBench and NanoBench optical breadboarding. BE WARNED! -John == J. Forster wrote: If you took a modern approach by using factory built test equipment as building blocks (microwave synthesizer, lock-in amp, power supplies, etc) and commercial vacuum components (pumps, valves, fittings, controllers, etc. in Conflat or something like it), you could likely build up most of a system pretty easily. You definitely need a copy of this book http://www.amazon.com/Building-Scientific-Apparatus-John-Moore/dp/0813340063/ref=tmm_pap_title_0/182-2347235-0798235 Building Scientific Apparatus by Moore, Davies, and Coplan How to build that ion gun, or cobble together the high vacuum system, etc. Lots of useful references.. You'd also do well to get a catalog from Kurt.J.Lesker Company (http://www.lesker.com/) and from several of the vacuum equipment companies. Vacuum stuff is available used quite widely. Between the book and the catalog(s), you've got plenty of reading and dreaming material for months. Be aware, though, that high vacuum is like amateur telescope mirror making.. frustrating, tedious, and gratifying when it works. There's a surprising amount of craft in it. (and entirely in keeping with time-nuttery) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
Do we know any thing about the Neuchatel design for Galileo? Bert Kehren In a message dated 8/29/2010 11:05:58 A.M. Eastern Daylight Time, p...@phk.freebsd.dk writes: In message 4c7a6b01.3030...@rubidium.dyndns.org, Magnus Danielson writes: On 08/29/2010 03:55 PM, Attila Kinali wrote: It's a complicated field and several traps to fall into on the way. It is a fairly sizeable project to attempt. Well, as with so much else, it depends what the level of ambition is. If you just want to be able to point to the resonance and say I did that, it is not intrinsically hard and none of the materials are hard to get hold of or particularly poisonous. Few of the problems Ramsey fought in the early 1950'ies are relevante today, for instance, the entire detection issue is trivially solved with USRP/GnuRadio. I would tend to think that $10k in materials would get you pretty close. I think the most recent H-maser design is Neuchatels design for the Galileo GNSS. Building a _good_ (ie: metrology grade) hydrogen maser, sounds like the last significant thing you did in your life, however many years you have left... Poul-Henning PS: And if you even manage to build something which works half the time, and do not suffer from ethics, there is a finite but very profitable market for audiopholery, and I'm sure somebody is willing to eliminate the last traces of jitter in his CD-player for just under $100k... -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
In message 3e227.34d2ee82.39abf...@aol.com, ewkeh...@aol.com writes: Do we know any thing about the Neuchatel design for Galileo? Bert Kehren There are plenty of papers about it. They started out with an active design, and got it inside spec (power/weight) but found that the performance was not worth the extra effort, so they switched to a passive design to further reduce weight/power. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
This is very true. Norman Ramsey built one out of aluminum. It was at least 6 feet in diameter and 8 feet long, at a guess. When I frequented that lab (mid-late 80s), it was too big to get it out the door room so had shelves inside to store equipment. It was inside a giant wooden crate, easily 10' cubial. -John == [snip] The size of the glass-bulb is not a fixed thing, during research and development different sizes glass-bulbs is used to establish the wall-shift aspects in order to adjust for it, which is needed in order to make absolute measurements on the free atom resonance or compensate into that regard. As for reference, there is about one set of books and papers from a handful of journals and a bunch of patents which needs to the read in order to build up the knowledge-base for attempting something like it. It's a complicated field and several traps to fall into on the way. It is a fairly sizeable project to attempt. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
Poul-Henning Kamp wrote: In message 3e227.34d2ee82.39abf...@aol.com, ewkeh...@aol.com writes: Do we know any thing about the Neuchatel design for Galileo? Bert Kehren There are plenty of papers about it. They started out with an active design, and got it inside spec (power/weight) but found that the performance was not worth the extra effort, so they switched to a passive design to further reduce weight/power. there's also the Mercury Ion clock.. the physics package looks fairly simple... ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
jimlux wrote: J. Forster wrote: If you took a modern approach by using factory built test equipment as building blocks (microwave synthesizer, lock-in amp, power supplies, etc) and commercial vacuum components (pumps, valves, fittings, controllers, etc. in Conflat or something like it), you could likely build up most of a system pretty easily. You definitely need a copy of this book http://www.amazon.com/Building-Scientific-Apparatus-John-Moore/dp/0813340063/ref=tmm_pap_title_0/182-2347235-0798235 Building Scientific Apparatus by Moore, Davies, and Coplan It's Davis, as in C.C. Davis of the University of Maryland, my former MS thesis adviser. Its a great book, but very expensive. -Chuck Harris ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
Any links to reading material, would be nice to learn what they did to get a small package and how small is it? Bert Kehren In a message dated 8/29/2010 2:03:34 P.M. Eastern Daylight Time, p...@phk.freebsd.dk writes: In message 3e227.34d2ee82.39abf...@aol.com, ewkeh...@aol.com writes: Do we know any thing about the Neuchatel design for Galileo? Bert Kehren There are plenty of papers about it. They started out with an active design, and got it inside spec (power/weight) but found that the performance was not worth the extra effort, so they switched to a passive design to further reduce weight/power. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
http://www.spectratime.com/product_downloads/PTTI_FCS_2005.pdf ewkeh...@aol.com wrote: Any links to reading material, would be nice to learn what they did to get a small package and how small is it? Bert Kehren In a message dated 8/29/2010 2:03:34 P.M. Eastern Daylight Time, p...@phk.freebsd.dk writes: In message3e227.34d2ee82.39abf...@aol.com, ewkeh...@aol.com writes: Do we know any thing about the Neuchatel design for Galileo? Bert Kehren There are plenty of papers about it. They started out with an active design, and got it inside spec (power/weight) but found that the performance was not worth the extra effort, so they switched to a passive design to further reduce weight/power. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
The Hahvahd physics dept. has all number of interesting papers. For example there's Humphrey's dissertation:www.physics.harvard.edu/Thesespdfs/humphrey.pdf If you've ever wanted to make your own Rb cell, how about this one?cfa-www.harvard.edu/~dphil/work/coat.pdf http://cfa-www.harvard.edu/%7Edphil/work/coat.pdf%20 On Sun, Aug 29, 2010 at 11:07 AM, Attila Kinali att...@kinali.ch wrote: On Sun, 29 Aug 2010 16:13:21 +0200 Magnus Danielson mag...@rubidium.dyndns.org wrote: On 08/29/2010 03:55 PM, Attila Kinali wrote: Does anyone know whether any of those people collected their results somewhere? And if, where i could find them? The physical package is definitely where most of the effort goes in. I know, that's why i'm asking. The papers i've read sofar all suggest that the difficult part is to compensate for cavity detuning, wall shift and second order doppler effect. Somehow all these papers seem to assume that getting an oscillation at all is so easy that everyone could do it (yes, i know that this is normal with scientific papers). I thought, that if someone build a homebrew H maser, he'd write about the difficulties getting there. Which would be a very interesting reading and teach a lot about the physics (and tool making, mechanics, etc) of these devices. A complicating aspect is the self-tuning stuff for which several strategies may be chosen. I'd start here at getting a cavity that is resonant at the frequency at all. Getting sub-milimeter precision in tooling is quite easy (given you have the tools and knowledge, or can pay someone to do it for you), but if the cavity has to be resonant within a couple of Hz of the 1.4xxxGHz, then you have to get a precission in the range of 10^-9 which basically impossible mechanically. So the cavity would need to have a mechanical tuning system too, but one that doesn't lower the cavity's Q or add any additional resonant modes. You need to balance the rate of the atoms, as both too few and too many kills the oscillation. Or get to the basic requirement of getting a pure H2 source to feed the beam source. The beam source itself, including the dissociator, would be a formidable project to do at home by itself. The size of the glass-bulb is not a fixed thing, during research and development different sizes glass-bulbs is used to establish the wall-shift aspects in order to adjust for it, which is needed in order to make absolute measurements on the free atom resonance or compensate into that regard. Interestingly, i think that the bulb would be the easiest part these days. At least around here, there are a few glas blowers for the chemical/pharmaceutical industry that also do single pieces. Getting it coated would only involve finding a company that does teflon coating (there do seem enough of them). From what i gather it's shape doesnt have to be exactly spherical down to the sub-milimeter range. As for reference, there is about one set of books and papers from a handful of journals and a bunch of patents which needs to the read in order to build up the knowledge-base for attempting something like it. Which papers/books would you recommend reading? And no, i don't think i'd attempt to build a H maser. I'm quite confident i could do the electronics part, but i know that i don't know anything when it comes to mechanics. Much less about handling high vacuum and atomic gas beams. It's a complicated field and several traps to fall into on the way. It is a fairly sizeable project to attempt. Yes, but it's fun to read about it :-) Attila Kinali -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Homebrew H Maser
After keeping an old EFOS 2 H maser running the last couple or three years here are a few bits of advice. -The triple magnetic shields are VERY important. The first time I removed the top shield to access the RF section the Maser stopped oscillating! Replacing the shield restored oscillations! -The cavity does not have to be machined to super precise levels, in this Maser once the coarse setting (mechanical at factory) is made, the medium tuning is done by adjusting the cavity temperature. The fine is done with the cavity varactor. This cavity is aluminum. -from a cold start it takes about 1 week for the ovens to come up to operating temp.! -this maser has two vacuum sections, an outer that enclosed the cavity and thermally insulates it. This allows the cavity temperature to be regulated to within .001 degree C. The inner chamber keeps the cavity evacuated so all you have in it is the H atoms. -Making a homebrew collimator (at the discharge bulb output) might be hard, google it and you will see it's tricky. -As stated the electronics are pretty easy these days. Main points are a low Insertion loss, high isolation circulator on the cavity output, a low noise figure RF amp and a low noise downconvertor. I have, somewhere, a scan of the two manuals. There is lots of theory and full schematics. Might be a good read if you are serious in trying to homebrew one. I'll dig them up and see if anyone could host them on a website. (Files are quite large!) Corby Dawson 1 Tip for Losing Weight Cut down 2 lbs per week by using this 1 weird old tip http://thirdpartyoffers.juno.com/TGL3141/4c7ac2d3136f9d283cm04duc ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
http://tycho.usno.navy.mil/ptti/ptti2002/paper14.pdf Bruce Griffiths wrote: http://www.spectratime.com/product_downloads/PTTI_FCS_2005.pdf ewkeh...@aol.com wrote: Any links to reading material, would be nice to learn what they did to get a small package and how small is it? Bert Kehren In a message dated 8/29/2010 2:03:34 P.M. Eastern Daylight Time, p...@phk.freebsd.dk writes: In message3e227.34d2ee82.39abf...@aol.com, ewkeh...@aol.com writes: Do we know any thing about the Neuchatel design for Galileo? Bert Kehren There are plenty of papers about it. They started out with an active design, and got it inside spec (power/weight) but found that the performance was not worth the extra effort, so they switched to a passive design to further reduce weight/power. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] homebrew H maser
Chuck Harris wrote: jimlux wrote: J. Forster wrote: If you took a modern approach by using factory built test equipment as building blocks (microwave synthesizer, lock-in amp, power supplies, etc) and commercial vacuum components (pumps, valves, fittings, controllers, etc. in Conflat or something like it), you could likely build up most of a system pretty easily. You definitely need a copy of this book http://www.amazon.com/Building-Scientific-Apparatus-John-Moore/dp/0813340063/ref=tmm_pap_title_0/182-2347235-0798235 Building Scientific Apparatus by Moore, Davies, and Coplan It's Davis, as in C.C. Davis of the University of Maryland, my former MS thesis adviser. Sorry about that... yes.. Its a great book, but very expensive. worth every penny if you're doing this sort of thing.. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Homebrew H Maser
After keeping an old EFOS 2 H maser running the last couple or three years here are a few bits of advice. -The triple magnetic shields are VERY important. The first time I removed the top shield to access the RF section the Maser stopped oscillating! Replacing the shield restored oscillations! As I understand it, not only the intensity of the ambient H-field but its orientation is critical. Sounds like you either pulled the 1,0 - 0,0 transition frequency too far for the control loop to compensate, or the static field was no longer oriented properly with respect to the cavity's TE mode axis. The impression I got from my reading on the subjecct is that tuning an H-maser isn't something you can do incrementally. It's not a conventional RF tank circuit -- there's a list of factors as long as your arm that have to be just right, or you will get nothing at all for your trouble. Getting those factors right seems to require a graduate-level understanding of both the materials and the math. Ars longa, vita brevis. -this maser has two vacuum sections, an outer that enclosed the cavity and thermally insulates it. This allows the cavity temperature to be regulated to within .001 degree C. The inner chamber keeps the cavity evacuated so all you have in it is the H atoms. I imagine the cavity has to be pretty stout not to either collapse from barometric pressure or flex excessively. I'll dig them up and see if anyone could host them on a website. (Files are quite large!) It would be great if you could upload these to the Manuals page at www.ko4bb.com. I've looked over the Symmetricom maser's manual but it's pretty terse. Building Scientific Apparatus by Moore, Davies, and Coplan It's Davis, as in C.C. Davis of the University of Maryland, my former MS thesis adviser. Sorry about that... yes.. Its a great book, but very expensive. worth every penny if you're doing this sort of thing.. The current edition is $70 at Amazon, not too bad by textbook standards. It's a good book, but often more valuable as a pointer for further reading than as a practical, up-to-date handbook. Seems like a good overview of vacuum technology. The book you really want to start with is Major's The Quantum Beat, IMHO. In thinking about it, it would be a terrific project to run with LabView! Rubbish, LabView would _never_ be able to do that. (Shrug) PLLs are PLLs. I don't see a role for a PC in the cavity tuning or oscillator disciplining loops, but that's a very small part of the overall control picture. Most of the actual software work would involve UI design for monitoring (and ideally graphing) the dozens of operating parameters over time. It would probably make the most sense to use either analog or microcontroller-based controls for the realtime (RF) loops, and use Labview or another instrumentation package to monitor everything. There are also various high-latency thermal loops that could be controlled as well as monitored by Labview-like software on the PC. -- john, KE5FX ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Homebrew H Maser
I'll dig them up and see if anyone could host them on a website. (Files are quite large!) It would be great if you could upload these to the Manuals page at www.ko4bb.com. That would be great. If the files are really big (over 100MB) and if your internet access is not truly broadband, you may find it more convenient to put them on a CD/DVD and snail mail them to me if you prefer. Either way is fine with me Didier KO4BB Sent from my BlackBerry Wireless thingy while I do other things... -Original Message- From: John Miles jmi...@pop.net Sender: time-nuts-boun...@febo.com Date: Sun, 29 Aug 2010 16:39:42 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Homebrew H Maser After keeping an old EFOS 2 H maser running the last couple or three years here are a few bits of advice. -The triple magnetic shields are VERY important. The first time I removed the top shield to access the RF section the Maser stopped oscillating! Replacing the shield restored oscillations! As I understand it, not only the intensity of the ambient H-field but its orientation is critical. Sounds like you either pulled the 1,0 - 0,0 transition frequency too far for the control loop to compensate, or the static field was no longer oriented properly with respect to the cavity's TE mode axis. The impression I got from my reading on the subjecct is that tuning an H-maser isn't something you can do incrementally. It's not a conventional RF tank circuit -- there's a list of factors as long as your arm that have to be just right, or you will get nothing at all for your trouble. Getting those factors right seems to require a graduate-level understanding of both the materials and the math. Ars longa, vita brevis. -this maser has two vacuum sections, an outer that enclosed the cavity and thermally insulates it. This allows the cavity temperature to be regulated to within .001 degree C. The inner chamber keeps the cavity evacuated so all you have in it is the H atoms. I imagine the cavity has to be pretty stout not to either collapse from barometric pressure or flex excessively. I'll dig them up and see if anyone could host them on a website. (Files are quite large!) It would be great if you could upload these to the Manuals page at www.ko4bb.com. I've looked over the Symmetricom maser's manual but it's pretty terse. Building Scientific Apparatus by Moore, Davies, and Coplan It's Davis, as in C.C. Davis of the University of Maryland, my former MS thesis adviser. Sorry about that... yes.. Its a great book, but very expensive. worth every penny if you're doing this sort of thing.. The current edition is $70 at Amazon, not too bad by textbook standards. It's a good book, but often more valuable as a pointer for further reading than as a practical, up-to-date handbook. Seems like a good overview of vacuum technology. The book you really want to start with is Major's The Quantum Beat, IMHO. In thinking about it, it would be a terrific project to run with LabView! Rubbish, LabView would _never_ be able to do that. (Shrug) PLLs are PLLs. I don't see a role for a PC in the cavity tuning or oscillator disciplining loops, but that's a very small part of the overall control picture. Most of the actual software work would involve UI design for monitoring (and ideally graphing) the dozens of operating parameters over time. It would probably make the most sense to use either analog or microcontroller-based controls for the realtime (RF) loops, and use Labview or another instrumentation package to monitor everything. There are also various high-latency thermal loops that could be controlled as well as monitored by Labview-like software on the PC. -- john, KE5FX ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Homebrew H Maser
Yes and no. I watched while a cryogenic MASER experiment was done at Harvard. First off, a H MASER built at Smithsonian Astrophysical Observatory, was set up and a GPS set up as a comparison. This was late 1980s. That MASER was used as a reference for a synthesizer which was swept a Hertz two around the 1421 MHz frequency to excite the cavity. The cavity was peaked with a reflectometer using a narrow sweep and then H was added. Parameters were adjusted while the cavity microwave field monitored. The RF field was pulsed, as I remember, and they watched as the RF decayed in a damped exponential. You could see what was happening to the gain of the medium, the decay took longer, and parameters were slowly adjusted to the point where there was enough gain to oscillate and thing took off. Fun stuff, if you have lots of time. Best, -J0ohn == The impression I got from my reading on the subjecct is that tuning an H-maser isn't something you can do incrementally. It's not a conventional RF tank circuit -- there's a list of factors as long as your arm that have to be just right, or you will get nothing at all for your trouble. Getting those factors right seems to require a graduate-level understanding of both the materials and the math. Ars longa, vita brevis. -this maser has two vacuum sections, an outer that enclosed the cavity and thermally insulates it. This allows the cavity temperature to be regulated to within .001 degree C. The inner chamber keeps the cavity evacuated so all you have in it is the H atoms. I imagine the cavity has to be pretty stout not to either collapse from barometric pressure or flex excessively. I'll dig them up and see if anyone could host them on a website. (Files are quite large!) It would be great if you could upload these to the Manuals page at www.ko4bb.com. I've looked over the Symmetricom maser's manual but it's pretty terse. Building Scientific Apparatus by Moore, Davies, and Coplan It's Davis, as in C.C. Davis of the University of Maryland, my former MS thesis adviser. Sorry about that... yes.. Its a great book, but very expensive. worth every penny if you're doing this sort of thing.. The current edition is $70 at Amazon, not too bad by textbook standards. It's a good book, but often more valuable as a pointer for further reading than as a practical, up-to-date handbook. Seems like a good overview of vacuum technology. The book you really want to start with is Major's The Quantum Beat, IMHO. In thinking about it, it would be a terrific project to run with LabView! Rubbish, LabView would _never_ be able to do that. (Shrug) PLLs are PLLs. I don't see a role for a PC in the cavity tuning or oscillator disciplining loops, but that's a very small part of the overall control picture. Most of the actual software work would involve UI design for monitoring (and ideally graphing) the dozens of operating parameters over time. It would probably make the most sense to use either analog or microcontroller-based controls for the realtime (RF) loops, and use Labview or another instrumentation package to monitor everything. There are also various high-latency thermal loops that could be controlled as well as monitored by Labview-like software on the PC. -- john, KE5FX ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Homebrew H Maser
On Sun, Aug 29, 2010 at 7:56 PM, Didier Juges did...@cox.net wrote: I'll dig them up and see if anyone could host them on a website. (Files are quite large!) It would be great if you could upload these to the Manuals page at www.ko4bb.com. That would be great. If the files are really big (over 100MB) and if your internet access is not truly broadband, you may find it more convenient to put them on a CD/DVD and snail mail them to me if you prefer. Try the old DjVu Solo 3.1 program that you can download from here: http://djvu.org/resources/ I've seen it turn 100M page scans into 100K files. If you want to turn the DjVu into a PDF, use the Print command to a PDF driver, such as GhostScript, or Acrobat. -- http://blog.softwaresafety.net/ http://www.designer-iii.com/ http://www.wearablesmartsensors.com/ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.