[time-nuts] HP5065B !!!
EWKehren at aol.com
EWKehren at aol.com
Tue Apr 30 11:06:00 UTC 2013
Bruce
Thank you for the second paper. It addresses also the generation of the
microwave signal, critical to those of us that do not have the late A3 module.
I do not want to discourage any one to experiment with laser diode
pumping, but in the meantime it would be nice to work on flattening the curve on
the Super HP5065A. There are at least fifty units in the time nuts
community.
Bert Kehren
In a message dated 4/30/2013 2:05:40 A.M. Eastern Daylight Time,
bruce.griffiths at xtra.co.nz writes:
That paper appeared to describe how a laser is used to replace the
rubidium lamp more completely than later papers that achieved better
results.
I should have also included links to later papers that better illustrate
the performance that can be achieved.
Bruce
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
>
>
> 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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