[time-nuts] Measuring Rubidium frequencies

[Jim Robbins]

Hi all,

I have a problem which I am unable to understand and need some help.  I have two M100 Rubidiums, a Racal 1992 counter, a factory standard T'Bolt and a Symmetricom Starloc II.  When I set up either GPSDO as the External Timebase for the 1992 and measure either Rubidium, I get the same reading of 9.99998278.  When I use the 1992's Internal Timebase, I get 9.99999995.  All equipment has warmed up.  The antenna is a Symmetricom HP 58532A on the roof.     On a few occasions I have seen the frequency drift up to 0.00001722.  I would have expected that both Rubies would have read 0.00000000.  Any ideas would be much appreciated.

many thanks,
Jim Robbins