[time-nuts] Thinking outside the box a super reference

Tim Shoppa tshoppa at gmail.com
Thu Nov 3 20:55:50 EDT 2016

It would obviously be larger than a homebrew Cs, but why not a homebrew
Hydrogen Maser Frequency standard?

The commercial Cs units always seemed objects of pure miniaturized hi-tech
materials science magic, while the Hydrogen Masers I've seen seem much
larger-scale\ and more a matter of vacuum plumbing. Obviously the materials
cost for the copper microwave cavity will be very large, and I'm sure
Teflon-coating a quartz chamber is an art, but the pumps and magnets are
very familiar from my years in grad school working with plasma kettles and
mass spectrometers.

Tim N3QE

On Thu, Nov 3, 2016 at 4:07 PM, Bert Kehren via time-nuts <
time-nuts at febo.com> wrote:

> Over the past there has been talk about building from  scratch high
> performance references. I think consensus was that it is out of  reach. In
> the mean
> time Corby is reworking an active maser which takes a lot of  know how. But
> let us look at his work on the super HP5065. It is able to  outperform a
> passive maser in the below 100 second range! Long term a proper  GPSDO
> should
> be possible to step in. We are working on it including pressure and
> temperature control. To make full use of it you also need to have the
> capability
> to monitor, record and analyze on a continuous basis preferably with out
> tying  up expensive equipment. We have the pieces in place and looking
> forward
> of  combining all the pieces and compare with Corby’s active Maser. We are
> back to  the GPSDO after being distracted by Tbolt performance. A third
> party
> is working  combining the GPSDO data stream with the data from the unit
> that
> generates  frequency, pressure and temperature data along with time to a
> USB stick, while  also be able to monitor with a PC.
> I know it is considered by some heresy but our lack of a  Maser and in
> Juerg
> ’s case no access to one, we try to overcome it with a GPSDO  tailored for
> Rb and Cs and control our Cs’s C field .
> There was a time that I did have a HP5065A but got rid of  it when I got
> some Cs’s. My best counter was A HP5345 and even with a Tracor 527  1
> second
> performance was not an issue. That changed when Corby introduced me to
> time
> nuts and frankly it was the first  time I learned about ADEV. But the
> HP5065A was gone. Now I have a cell  that Corby has plotted and time
> permitting
> may become a project.
> Let me get to the real issue. There are not enough  HP5065A’s out there and
> not affordable for all time nuts. Most are being kept  and are not for
> sale. But if a combined effort by many time nuts it MAY be  possible to
> recreate
> the guts of the HP5065A. The key word is MAY. 200 time nuts  be willing to
> invest $ 5000 each may get us there. The market does not justify  such an
> effort but time nuts keep bringing up discussions. All the other ideas
> kicked
> around in the past will cost more. There are some among us that know what
> it cost and who can make the key elements like lamps, cells, filters etc.
> Just a  thought outside the box and hopefully may turn in to a limited
> constructive  dialog. We will continue on our path, which include
> FRK/M100, HP5065
> and  Cs.
> We would not be capable to contribute technically on the  physics package
> but I would be willing to contribute financially and with  monitoring
> equipment even if I would not be around when finished.
> Bert Kehren
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