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

Bob Camp kb8tq at n1k.org
Thu Nov 3 20:59:46 EDT 2016


Ok, how many full performance Hydrogen Masers can you build (size is not an issue) and 
deliver for < $10,000 (2X Bert’s number) ?  


> On Nov 3, 2016, at 8:55 PM, Tim Shoppa <tshoppa at gmail.com> wrote:
> 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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