[time-nuts] Re: Creating a D.I.Y Rubidium Atomic Clock

[Magnus Danielson]

Hi,

I agree with Rick and was about to make more or less the same comment.

The glas package is the hardest thing to do, and there is also a certain 
magic to mix the buffer gas just the right way to frequency compensate 
the wall shift. Already there comes the aspect of knowing what wallshift 
you will get, so you need reasonable reproduceability in both the glass 
and pressure and mix in gases. To put that in other words, I am not THAT 
crazy, yet.

Next level is the cavity you put the glas-ware into. The Q of that 
resonator is not irrelevant, so you want to handle that.

There is a certain magic to the temperatures of the rubidium lamp and 
that of the rubidium filter. This has consequences on how the physical 
package is built. Some of this can be avoided today by using diodeds, 
and that may even open up for avoiding the tuned resonator, but brings 
in it's own set of issues.

Achievable engineering challenges, but maybe hard to do as a hobbyist. 
The remaining temperature controls, FLL-lock of oscillator, synthesis 
have become more and more achieveable over the years. That has become 
hobbyist achieveable for sure.

However, just *attempting* to study up on a subject like this forces you 
to learn alot, so even if you do not do a single soldering, you can have 
improved your knowledge.

I would consider recycle an existing physical package that works and 
make modern electronics for it. That should be plenty of challenges and 
quite achieveable.

Cheers,
Magnus

On 2023-06-07 02:26, Richard Karlquist via time-nuts wrote:
> In a former life, I was on the design team of a mini rubidium standard
> at Hewlett-Packard.  We built some working prototypes before it was
> cancelled.  It was going to have the model number 10816.  I was the RF
> person, but I worked very closely with the other team members.
> Remembering what we had to go through to make "glassware", it is
> inconceivable that you could do that as a "home brew" project.  And this
> was the same HP facility that already made the 5065 rubidium standard.
> The best you could hope to do is to start with a commercial "physics
> package" as we called it, and make your own electronics for it.  Reading
> books about how rubidium standards work, etc is fine, but again, you
> can't home brew the glassware.
>
> ---
> Rick Karlquist
> N6RK
>
> On 2023-06-06 15:39, Tom Van Baak via time-nuts wrote:
>
>> Hi Leo,
>>
>> That sounds like a fun project. Here are some extremely informative resources:
>>
>> "Introduction to the Rubidium Frequency Standard"
>> by Michael Parker, 358 pages
>> http://www.leapsecond.com/u/parker/ParkerIntroRFS-PPCP.pdf
>>
>> "Rubidium Frequency Standard Primer"
>> by Bill Riley, 163 pages
>> http://www.wriley.com/Rubidium%20Frequency%20Standard%20Primer%20102211.pdf
>>
>> "Selection Criteria for Rubidium Frequency Standards"
>> by Bill Riley, 51 pages
>> http://www.wriley.com/Selection%20Criteria%20for%20Rubidium%20Frequency%20Standards.pdf
>>
>> Also read service manuals for commercial Rb products. Didier's site has a nice collection. Search by product number (e.g., 5065a) or by title (e.g., rubidium):
>>
>> http://www.ko4bb.com/getsimple/index.php?id=manuals
>>
>> /tvb
>>
>> On 6/6/2023 12:25 PM, Leo Ahluwalia via time-nuts wrote:
>>
>>> Hello, my name is Leo, and I was wondering about the feasibility of
>>> creating a simple rubidium atomic clock at home, and good places to source
>>> parts for this sort of project. I was also wondering what instruments and
>>> specialized knowledge would be required depending on how pre-built the
>>> parts are, for example, the prerequisite knowledge for creating PLL(s) for
>>> both frequency division to provide an output and also to modulate the input
>>> of the microwave oscillator. Any good resources or PDFs would be greatly
>>> appreciated, as I am very new to frequency analysis and phase manipulation
>>> in general. I was also hoping to keep the cost of the project soft-line
>>> below 500$, though that would be assuming a decent level of precision and
>>> already possessing basic equipment (oscilloscope, multimeter, etc...). Safety
>>> is also a major concern, as I know while the intensity of the EM waves
>>> involved is low, the power source may or may not be. This is all of course
>>> assuming a basic design, where my assumption is that it will involve the
>>> microwaves being shot at a rubidium vapor cell which is directed towards a
>>> photodetector. This would then be connected up to the PLL and circuitry to
>>> both provide a stable standard while also modulating the microwave
>>> oscillator to offset any external environmental factors. I don't have a
>>> clear vision of what would truly be the best design for both simplicity and
>>> cost, though this is what I've found to be a common design in what I've
>>> looked at online.
>>>
>>> Thanks, Leo
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