[time-nuts] Rubidium Performance

[John Miles]

> 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