[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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