[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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