Microwave test gear and plumbing is very significantly harder to get at 24 GHz than at 1.4 GHz.
At a guess I've seen easily 100 times more stuff available at 1.4 GHz. FWIW, -John ============ > That's a great article. It almost makes the job seem doable. > > It is going to be expensive, though. If someone can build a working maser > for less than $10K in materials and bespoke fabrication services alone, > I'll > be impressed. An obvious question is, what's the so-called "minimum > viable > product" that can actually produce a population inversion in a cavity and > demonstrate maser action? Do you need any magnetic shielding at all, > beyond > a couple of Helmholtz coils? Maybe not. Do you need to coat the bulb at > all if you don't care about line width? Maybe not. How exotic does the > collimator need to be if you don't care much about service life? Probably > not very. You definitely don't need a multilayer vacuum system. What > corners can be cut to get a rough prototype running? > > Control electronics is trivial, and not even worth thinking about until > the > physical details are nailed down. > > Once you start talking about cutting corners just to get a maser up and > running, though, there's another obvious question worth considering: what > about starting with an ammonia maser? This was the first molecular > oscillator. Experience optimizing the (numerous) operating parameters in > an > NH3 maser would no doubt be helpful in later work with an H maser. > > Ammonia molecules have a dipole moment and can be state-selected > electrostatically. There is no need for either a dissociator or a storage > bulb, just a basic electrostatic lens and cavity in a vacuum. Townes's > original 1954 paper makes no mention of magnetic shielding. But at 24 GHz > a > high-Q cavity is small and manageable, so if you do have to enclose it in > mu-metal it's not going to cost a fortune. > > Further, with stabilities in the 1E-12 range, a 5065A-class rubidium > standard or a well-optimized GPS clock can be used as a reference for > tweaking and debugging an NH3 maser. If you do manage to build a hydrogen > maser, OTOH, you are going to need to build at least two of them to get > any > idea where your performance floor is. > > Just one possible thought... > > -- john, KE5FX > > >> -----Original Message----- >> From: [email protected] [mailto:[email protected]]on >> Behalf Of Bruce Griffiths >> Sent: Tuesday, August 31, 2010 1:23 PM >> To: Discussion of precise time and frequency measurement >> Subject: Re: [time-nuts] homebrew maser >> >> >> PTFE wall storage bulb wall coatings haven't been used for some decades, >> FEP (or the Russian fluoropolymer ) is better in that a smoother coat is >> achievable see: >> http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&; >> AD=ADA509340 >> <http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf >> &AD=ADA509340> >> >> A sual hexapole state selector is probably a little more effective than >> the cruder method used in the Russian masers. >> >> Bruce >> >> Mark Sims wrote: >> > Same general idea, but an image intensifier plate would >> probably not work well. They are usually thinner and are cut at >> a bias so the electrons ricochet along its length. You might be >> able to mount one so that it cancels the bias angle. >> > >> > They are made by stretching a bundle of hollow glass tubes that >> have been filled with solid glass rods of a different >> composition. The original bundle can be very large (like over a >> meter) and is shrunk down to like 100 fibers per millimeter. It >> is then sliced and polished. Often the slices (or the pulled >> bundles) are joined into a bigger plate. Then the inner solid >> glass is dissolved out with a strong alkali. The hollow tubes are >> coated with a photoelectric material. >> > The image from the tube is inverted using a "twister"... a >> coherent fiber optic rod that has a 180 degree twist. >> > >> > --------------- >> > Do you know if the collimator is made from an uncoated >> microchannel plate? >> > If so, an old, broken Gen II image intensifier might be a viable >> source. >> > >> > >> > _______________________________________________ >> > time-nuts mailing list -- [email protected] >> > To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> > and follow the instructions there. >> > >> > >> >> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
