[time-nuts] Re. DIY atomic "resonator"
Bob kb8tq
kb8tq at n1k.org
Wed Apr 12 19:19:55 EDT 2017
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 at 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,
> attila at kinali.ch writes:
>
> On Tue, 11 Apr 2017 07:31:01 +0000
> Andre <Andre at 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
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