[time-nuts] Cheap Rubidium

[Bob Camp]

Hi

If I randomly pick up a FE 5680A data sheet, I find that it's short term stability is 1.4/sqrt(Tau) x 10-11.  Since I never doubt anything I see on a data sheet, this immediately tells me I should get 1.4x10-12 at 100 seconds, and I only have to wait for 10,000 seconds to get to 1.4x10-13. 

Since the temperature performance is at the 1x10-12 / C level, I would need a room that's stable to *much* better than 0.1 C over a 3 hour period to get there. I suspect that 0.01C might not be good enough ... 

So here's the question:

Has anybody run any of the cheap rubidiums (FE or Efratom)  in a *very* stable temperature environment to see how close they get / what the floor is?  I've run through a lot of data on the web, but I haven't really found what I'm looking for.

Thanks!

Bob