[time-nuts] Cheap Rubidium
Bob Camp
lists at cq.nu
Wed Dec 23 03:23:53 UTC 2009
Hi
I agree that if you simply bolt the rubidium to an old engine block and toss a blanket over it, you might get some pretty good thermal stability in the "hour to couple hours" time period. That's certainly a better approach than putting some kind of DC heater (and it's varying magnetic field) near the rubidium.
I'm still wondering if they do indeed hit 1x10-13 (as in almost 1x10-14) or not. I suspect not. I'm sure that they do indeed get into the 1x10-13's, just not sure they get to the bottom of that region.
Bob
On Dec 22, 2009, at 8:26 PM, Bruce Griffiths wrote:
> 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 -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
More information about the Time-nuts_lists.febo.com
mailing list