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

Eric Scace eric at scace.org
Thu Nov 3 18:05:27 EDT 2016


> On 2016 Nov 03, at 16:07 , 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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