[time-nuts] Re. DIY atomic "resonator"

Bob kb8tq kb8tq at n1k.org
Tue Apr 11 12:50:09 EDT 2017


If you are going to do a Rb, probably the best place to start is with a salvaged physics
package out of one of the telecom Rb’s. That would let you get the “easy bits” worked
out on your side of the design. It would also let you lear how to address  a few of the 
more complex items sorted as well. Since the salvaged physics package performance 
is likely better than what you would build in a basement, the performance of your device
would not be impacted in a negative way. Indeed it’s “cheating”, but it’s about the only
way to move the project forward.

I agree with Rick that Rb is by far the easiest one of the atomic devices to address. The complexity
of the device / design precision goes up quite a bit for the other candidates. To the degree 
that Rb is complicated, it’s quite easy compared to the others. One way to view this is to
take a look at the minuscule size of the resonance response above the noise floor on even
a well made standard ….


> On Apr 11, 2017, at 11:54 AM, Richard (Rick) Karlquist <richard at karlquist.com> wrote:
> On 4/11/2017 12:31 AM, Andre wrote:
>> Has anyone else either built an atomic clock around a bare Rb lamp module "core" or attempted
> Not a DIY project, but I was the RF designer on the HP 10816 rubidium
> standard, which never made it to product introduction (a half dozen
> working pilot run units were built in 1982).  I would say this task is
> probably beyond the scope of a DIY project, at least for most
> time-nuts.  The Rb lamp drive circuit (particularly getting the
> lamp to light up) is very challenging.  The step recovery diode
> multiplier is very challenging.  The photodetector and loop
> integrator is non trivial.  The synthesizer is the one thing that
> is easy in 2017.  The oven is also no simple thing to get
> low tempco.  Unlike a crystal, you have a lot of heat being
> generated by the lamp, etc. The lamp needs to be at a different
> temperature than the other cells.  You have to keep the tip
> off at the lowest temperature to keep the Rb in place and not
> "flood" the cell and block the light.  Etc., etc.
> This is in the category of projects where if you were qualified
> to do it, your time is far too valuable to do it for the amount
> of money you would save.
> Rick N6RK
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