[time-nuts] HP5065B !!!

Magnus Danielson magnus at rubidium.dyndns.org
Wed May 1 09:05:38 EDT 2013


On 04/30/2013 03:38 AM, EWKehren at aol.com wrote:
> I never came to that conclusion. There is enough work out there with
> results. My comment was to that particular paper that did not measure up to the
> work Corby has been doing. Still trying to figure out the purpose of the
> posting.
> Bert Kehren

Well, it is comparing apples to oranges. So many other things changed 
that you can't compare it directly to Corbys work on the HP5065As. What 
you can draw conclusions from is relative changes within a particular 
design limit as you alter the design, draw some conclusions and then 
consider what it could do on another design.

So, it is a relevant thing to discuss, as a possible next step to look 
at, which is not to degrade at all the work being done. It can also turn 
out that for it to pan out as better, it comes at a much higher cost or 
has only marginally improvements, so Corbys change is better bang for 
the buck.

Cheers,
Magnus

>
>
> In a message dated 4/29/2013 6:34:24 P.M. Eastern Daylight Time,
> bruce.griffiths at xtra.co.nz writes:
>
> Since  performance improves as the bandwidth of the "lamp" spectrum
> decreases its  not unreasonble to suggest that a suitable laser source
> may improve  performance further.
>
> The following paper (and theoretical  considerations) indicate that your
> conclusions regarding the potential  performance of a laser pumped
> rubidium standard are  incorrect.
>
> http://tf.boulder.nist.gov/general/pdf/1219.pdf
>
> The  addition of second harmonic traps tuned to the 2nd harmonic of the
> modulation frequency of the resonance interrogation signals should
> improve the performance  considerably.
>
>
> Bruce
>
> EWKehren at aol.com wrote:
>>
>>   I am still sitting here trying to figure out the purpose  of posting  the
>> article on laser diode pumping of the Rb. One look at the  data  and it is
>> clear that Corby’s work far surpasses the data  shown in the paper. All
> it does
>> is distract from Corb’s  accomplishments. Lets be clear, Corby has opened
>> the door of H Maser  performance for those that have a HP 5065A. Not all
> work
>> is  done  but a giant step has been accomplished, the challenge now is to
>>   continue  the work. In simple terms it gets down to keep the A/V slope
> from
>> turning  upward. Work is going on off list to address some  of the issues
> and
>> maybe some  one is willing to contribute. But  what the list at a whole
> can do
>> is contribute  data as to HP  5065A performance. There are quite a few
> 5065A’s
>> out there but   very little data besides HP spec. To better tackle the
>> flattening of  the curve,  aging, temperature sensitivity, barometric
> pressure
>>   sensitivity and even  humidity sensitivity has to be understood. It  is
>> unrealistic to get past 1 E-13  unless this is understood and
> compensated for. Also
>> some of these parameters  will vary from  unit to unit and some degree of
>> tailoring to a particular unit   has to be considered in the design. Some
> tests
>> have to be done by  those members  that have access to a Maser.
>> Also Corby   found out that units with older A3 modules did not get the
>> performance  boost but  replacement of A3 did get the super performance.
> That
>>   confirms my suspicion that  there is room for work on frequency
> generation. PRS
>> 10 does a direct  frequency generation. Somehow  using the  step recovery
>> diode as a mixer obviously works but is  it optimum, or is there a
> better way
>> to generate the resonator  frequency? What is key to get the best  signal
> and
>> S/N  ratio?
>> When previously mentioning aging control, concern was   voiced as to
> getting
>> in to the HP 5065A. Corby’s work gets to the hart  of the  unit, the RVFR,
>> but Corby has gone four for four.   Adding control will only move the two
> C
>> field wires to the analog  board and using 30 mA from the unit. Unit can
>> easily  restored to  its original condition as far as frequency control is
>>   concerned.
>> Obviously the RVFR is the big differentiator in the   HP5065A and I know
> of
>> no commercially available unit that even gets  close but  once the work is
>> complete a look at a FRK may be in  order, I doubt it will ever  be as
> good,
>> but there is room for a  filter and the physics part is considerable
> larger
>> than today’s  units.  Some  other units may be using a filter but the
> physics
>> package is so small that  compromises had to be made and  the goal was
> more
>> cost than ultimate performance.
>> It is up to  the list to turn this in to a Maser like  performance with
> out
>>   mortgaging your home.
>> Bert Kehren
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