[time-nuts] Antique Rb Standard - Thanks, Pictures, Parts Request, Question

Magnus Danielson magnus at rubidium.dyndns.org
Sat Apr 28 23:37:17 UTC 2012


Hi Ed,

On 04/28/2012 08:43 PM, Ed Palmer wrote:
> First, I'd like to thank Magnus, Joe, Paul, and Ed for taking the time
> to provide answers, ideas, and challenges to my assumptions. It has all
> been very helpful. I'm still working on it so I don't have a resolution
> yet.

Happy to help, while not tossing you necessarily the solution, we have 
to read up and we all learn in the process... which was kind of the 
point with the exercise.

> Second, pictures. If anyone is interested, check out
> http://s701.photobucket.com/albums/ww18/edpalmer42/Tracor%20304-B/ .

Nice photos. Thanks. GAS building up.

> Third, I'd like to build an extender board, but I can't find the
> connectors. The contacts are called Varicon and are used both on circuit
> boards and in connectors. The connector version is available, but I
> can't find the board version. The last picture in the above gallery
> shows a close-up of the connectors. They were available in regular and
> mini versions. I need the regular ones that stand about 4.3 mm high. The
> minis are about 3.5 mm high and won't mate with the regular ones. New
> ones could be loose or spaced out on a plastic strip to make
> installation easier.
>
> Fourth, I'm currently working on the cavity tuning. Does anyone know of
> a document or research paper that discusses cavity sizes for Rb
> standards - preferably with equations? I found this document:
>
> http://www.alcatel-lucent.com/bstj/vol25-1946/articles/bstj25-3-408.pdf

Good article. Thanks for the reference.

> that talks about cavities in general, but the calculations don't work.
> I'm guessing that the Rb cell is changing the resonant frequency of the
> cavity.

The glass pulls the cavity resonance somewhat, yes. A TE111 resonance 
mode is typically used, allowing light to enter and leave at the ends of 
the cylinder.

TE011 was used before, but it much larger.

Todays modern cells use a "loaded" cell (dielectrum added) to move the 
resonance frequency down, which allows much smaller physical cells.

W.J.Riley "Rubidium Frequency Standard Primer" is a good starting-point, 
but following the references should help.

I think just searching for "TE111 mode rubidium" cranks out a few 
interesting things, such as:

http://dspace.thapar.edu:8080/dspace/bitstream/10266/968/1/Satyendr_Thesis.pdf

Cheers,
Magnus



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