[time-nuts] HP5065B !!!

Tue Apr 30 14:03:27 UTC 2013

Look forward to your test results.
Bert Kehren

In a message dated 4/30/2013 4:27:38 A.M. Eastern Daylight Time,  
Paul.Reeves at uk.thalesgroup.com writes:

I rather  agree with Bruce. What I have seen on recent improvements on 
laser diode  accuracy/stability results seem to imply a rather large improvement 
is  possible - and, as the HP5065A is a rather rare beast indeed on this 
side of  the Atlantic, the excellent work done by Corby is not of direct 
relevance  (except to prompt much experimenting......). Trying a stabilised laser 
diode  source (and sacrificing one of my 'definitely not HP level' Rb 
units), in my  particular case, seems like a very good alternative line of 
enquiry - even if  I don't get quite as good results it will be  fun!

regards,
Paul
G8GJA

-----Original  Message-----
From: time-nuts-bounces at febo.com  [mailto:time-nuts-bounces at febo.com] On 
Behalf Of paul swed
Sent: 30 April  2013 01:38
To: Discussion of precise time and frequency  measurement
Subject: Re: [time-nuts] HP5065B !!!

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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