The cheap Datum LPRO-101s coming out of China appear to be capable of great performance, no problems at all getting into the 1E-13s at t=1000 seconds.
(This plot shouldn't be taken seriously beyond t=1000s, and the flattening effect at t=700s might be the Thunderbolt's fault. I haven't run my LPRO-101 long enough to see what it will do at 10000 seconds, but at some point the ADEV curve can be expected to turn upward for real.) -- john, KE5FX > -----Original Message----- > From: [email protected] [mailto:[email protected]]on > Behalf Of Bruce Griffiths > Sent: Tuesday, December 22, 2009 5:27 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Cheap Rubidium > > > Bob Camp wrote: > > 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 > > > > > Figure 7 on the FE5680 page (also on the data sheet) indicates that you > may need somewhat less than 3hours to achieve ADEV ~1E-13. > 0.01C stability should be adequate.however its not necessary to control > the room temperature to this stability if the FE5680 is in an enclosure > with a sufficiently high time constant whilst having a sufficiently low > thermal resistance so as to avoid overheating the FE5680. > > Bruce > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. >
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