[time-nuts] HP5065B !!!

paul swed paulswedb at gmail.com
Mon Apr 29 20:37:42 EDT 2013


I have to agree that the subjects really drifted. I am very excited about
what seems like a reasonable effort to improve the 5065. Since I have one
all the more interest. So I want to hear about the reflectors and
concentrators and how they were added and then how the system may have been
retuned to leverage the change.
Have I accidently gotten on to the wrong thread?? If so can some one please
point me to the correct thread?
Thanks
Paul
WB8TSL



On Mon, Apr 29, 2013 at 6:30 PM, Bruce Griffiths <bruce.griffiths at xtra.co.nz
> wrote:

> 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<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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