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

Ed Palmer ed_palmer at sasktel.net
Sun Apr 29 11:46:41 EDT 2012

Hi Magnus,

On 4/28/2012 5:37 PM, Magnus Danielson wrote:
> 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.

What does GAS mean?

>> 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.

This unit is TE011  No dielectric, plain brass - not silver-plated, 
2.495 inch diameter @ room temperature, length tunable from ~0.9 to 1.07 

> 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 
Thanks for that link.  I have been searching, but it's like panning for 
gold - lots of sand and dirt and a very few nuggets of gold.


> Cheers,
> Magnus

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