Hi There are papers from the mid 90’s talking about improving the GPS Rb’s. Those parts are as far as I know the best “production” Rb’s out there. The main comment seems to be that phase noise (in it’s various forms) is a major contributor to the stability of the Rb’s….
Bob > On Apr 12, 2017, at 4:55 PM, Bert Kehren via time-nuts <time-nuts@febo.com> > wrote: > > Looking back at the dialog I started on Rb’s and the repeated returns to > that subject allow me to make some comments, observations and > recommendations.. I stayed on purpose away from participating but learned a > lot. It also > resulted in some off list dialogs with members working on the subject off > list. > Rick’s discussion on why to use two frequencies was for me an eye opener > and gives me clear directions on how to proceed on frequency generation. The > single frequency project is dumped. Corby’s work on filters again > influences our future steps. Using a laser diode and its challenges again an > eye > opener and a challenge. We have time nuts that have working systems. > Let’s be honest, we have members with super knowledge but very few have > the appetite to do something with it in the form of hardware. Here is my > proposal that is based on walk before run. > FRK and M100 are next to the HP 5065A the most promising Rb’s in what we > like to do. They are easy to work on specially when you are 75/78 and in my > case have a macular hole. > Optical Filter. Corby actually did insert a filter in a M100 did however > not notice an improvement. When we discussed it come to find out he forgot > to change the time constant so the cell did not control the performance. > This was years ago and like many of us has his hands full with projects. He > decided to pass his M100/FRK to an other time nut and focus on HP and Maser. > We all benefit from these efforts. > Back to filter we have dissected a FRK and a M100 and are convinced that > there is a room for a filter, in case of the FRK, very easy. Corby used a > M100, in my opinion more of a challenge. Will not try it. After discussions > with Corby I now understand that the filter does not filter out a particular > wavelength but most the noise that Rb lamps produce as seen on optical > spectrum analyzers. It improves signal noise ratio after all that is what is > all about. Once we have completed our current projects we may do so. > We are also considering to review the frequency generation using Rick’s > postings as guidance. All this needs measuring capabilities which is what we > are working on. I am fortunate to have access to Corby’s Maser but Juerg > does not have that. We are working on a solution. > There are many FRK/M100’s out there some with low output lamps that would > be a natural for a Laser Diode replacement. The mechanical makeup begs for > a Laser solution. The two units have a cell in size only second to HP5065A > Going to laser would also allow to reduce cell temperature again > contributing to an improved signal noise ratio, > This is way off our expertise but it would be nice if some one would take > the ball and run with it. I am convinced from off list conversations that > $1000 is a reasonable goal. > There is no guarantee that we will do the filter depending what our > results will be on our present work so again maybe some one would carry that > ball. > Both can be a first step for future work. WALK > Bert Kehren > > > In a message dated 4/11/2017 12:02:09 P.M. Eastern Daylight Time, > att...@kinali.ch writes: > > On Tue, 11 Apr 2017 07:31:01 +0000 > Andre <an...@lanoe.net> wrote: > >> Has anyone else either built an atomic clock around a bare Rb lamp > module "core" or attempted >> >> to make a hydrogen maser? > > Building my own Rb vapor cell standard or H-maser is on my list > of Things-I-have-to-do-before-I-die :-) > > If I had to do one of those now, I would go for a Rb vapor cell > with dual-resonance using an external cavity laser diode for pumping. > > The electronics for such a thing are relatively easy, if you are not > afraid of Jiga-Hurts and using these pesky QFN packages. But it isn't > cheap either. There was a discussion started by Bert[1] where I ventured > a rough calculation what I think it wold cost. Though I think I have > understimated the cost of an ECLD (it's more like 1k-5k from what I have > read) > > > Attila Kinali > > [1] search for "thinking outside the box" in the archives > > -- > It is upon moral qualities that a society is ultimately founded. All > the prosperity and technological sophistication in the world is of no > use without that foundation. > -- Miss Matheson, The Diamond Age, Neil Stephenson > _______________________________________________ > 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.