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

EWKehren at aol.com EWKehren at aol.com
Wed Apr 12 16:55:35 EDT 2017

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 
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 
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 

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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