[time-nuts] Rubidium Performance

[EWKehren at aol.com]

John
Thank you for your effort. It would be nice if you could confirm the 4 to 5 
 Hz dither that seems to be the loop time constant and long term aging that 
will  influence the GPS/Rb control loop time constant setting. I did see 1 
E-12 per  month which may be unique to that unit.
Bert Kehren
 
 
In a message dated 2/3/2012 10:19:47 P.M. Eastern Standard Time,  
jmiles at pop.net writes:

>  Someone earlier today made the point that for all the talk about the  FEI
> rubes, there hasn't been any real performance info posted.   That prodded
> me to start an experiment I've been meaning to do for a  while.  I have
> samples of all three of the common telco Rb  standards -- Efratom FRS,
> Datum LPRO, and Fe8-5680.
> 
>  Over the next couple of days I'll do measurement runs of each of the  
three
> versus an HP-5065A laboratory Rb (for ADEV), and a Wenzel ULN  (for phase
> noise).  I'll collect long enough to get solid ADEV  out to at least 1000
second
> tau on each unit.  I have the FRS  test running now.
> 
> If all goes well, I'll post the results  early next week.

I'm doing some short-term runs on the ones I have  around here, as well
(FE-5680A, PRS-10, LPRO).  Will be interesting to  see how close ours are. 

So far, the FE-5680A is doing well in the ADEV  department, but its AD9832
DDS chip adds some substantial noise and spurs  to the 10 MHz output.  Does
yours have that chip?  I understand  that some of them didn't.

The overall SSB C/N ratio I'm seeing between  1 Hz - 100 kHz is pretty much
in line with Analog Devices' data sheet, as  are the spur levels.  

--  john



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