[time-nuts] Next upgrade

EWKehren at aol.com EWKehren at aol.com
Fri Nov 24 06:58:56 EST 2017

A few comments I forgot.
Most Rb's can use a clean up loop, we are experimenting with Wenzel's 600  
second loop recently posted here. Exceptions are the HP 5065 the optical 
unit is  the source of the performance, Corby experimented with different OCXO, 
 performance remained the same. Loop time constant is 0.01 second. There is 
also  no way to improve PRS 10 performance it will stay at 2 E-12 because 
of DAC  resolution.On related subject Corby and I community regularly and he 
mentioned  in all his 5065 work he has never experienced a bad lamp!!
We focus our Rb work on FRK/M100 because next to the 5065 it has the  
largest cell and it is easy to work on. Focus right now is OCXO and reducing  
time constant. If positive results we may look at inserting an optical filter,  
Corby did experimented with it but forgot reducing the time constant. 
Bert Kehren
In a message dated 11/22/2017 7:26:57 P.M. Eastern Standard Time,  
k8yumdoober at gmail.com writes:

For the  most part the SRS-10 is a nice choice, although I'd always be wary
of  buying a
used one.

My only real beefs are that the tuning  granularity is rather coarse, about
2E-12, and the
disciplining loop  seems to be a bit aggressive so that the poor oscillator
gets  jerked
around quite a bit by the GPS.  This makes for rather  ugly-looking plots of
time error
over time.

The above comments  are derived from about 3 years of operating one as a hot
emergency spare at  the Arecibo Observatory against the day when the H-maser
crashed  abruptly.  In this case the SRS-10 was embedded in an FS725 which  
bought new.


On Wed, Nov 22, 2017 at 4:16 PM,  Jerry Hancock <jerry at hanler.com> wrote:

> Three  questions:
> 1) Now that I’ve split my Lucent RFTG-U into a REF0  and REF1 unit with
> both supplying 10Mhz and 1PPS, is there a way to  combine the outputs or
> some other technique to improve the short  and/or long term performance?
> 2) I’ve become interested in  Rubidium Disciplined Oscillators recently 
> was now thinking of  purchasing one of the PRS-10 that I see on Ebay. If I
> did that and  replaced one of the DOCXOs from one of the Lucent boxes, 
> impact  would this have on the overall performance both with and without
> (when  in hold-over)?  Basically, is it worth the money to upgrade one  of
> the boxes to a Rubidium disciplined oscillator assuming the GPS  signal is
> rarely lost?
> 3) Figuring the PRS-10 will  cost around $250 when all is said and done, 
> there a better option  to improve my GPSDO system?
> I basically use the GPSDO as a  reference for any equipment that takes an
> input. I have no monetary  need for a reference, just an interest.
>  Thanks.
> Jerry
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