[time-nuts] Connections for FE-5680A rubidium sources

Bob Camp kb8tq at n1k.org
Tue Dec 16 18:06:20 EST 2014


What ever you do, take the extra step of checking the baseplate temperature once you have things up and running. The Rb’s will *work* over a wide temperature range. The region over which they will last a long time is a bit more narrow. I seem to have spent a lot of time demonstrating that. Keeping the baseplate below 40C (and above 10) does indeed extend their lifespan. 


> On Dec 16, 2014, at 12:54 PM, Clint Turner <turner at ussc.com> wrote:
> Hello,
> I've mounted both my LPRO-101 and FE-5680 in Hammond 1590-type cast aluminum boxes, bolting the rubidium unit to the lid of said box, and found the heat sinking of the entire arrangement to be entirely adequate.  In each case there is a (well filtered!) switching regulator present that contributes little to the overall thermal load as well as allowing them to run directly from a standard "12 volt" equipment bus.
> If you run the units at their minimum allowed voltage (19 volts for the LPRO-101, 15 volts for the FE-5680, IIRC) they will dissipate much less power as the regulators contained therein are linear type.  It struck me that at the lower limit voltages that they take slightly longer to warm up and come online, but still somewhere around the 3 minute mark for a "Physics Lock."
> Details may be found at:
> http://www.ka7oei.com/10meg_rubidium1.html   - For the LPRO
> http://www.ka7oei.com/10_MHz_Rubidium_FE-5680A.html  - For the '5680, of course!
> 73,
> Clint
>> On 16  December 2014 at 12:16, Bob Camp<kb8tq at n1k.org>  wrote:
>>>  Hi
>>> One fairly important issue - the unit needs to be on a heat  sink. If you
>> run it without cooling of some sort, it will not run for very  many years.
>>> Bob
>> I do realize that, but how big?  Normally "the bigger the better" is
>> not an unreasonable rule on heatsinks,  but I have heard that cooling
>> these too much is bad. I have here a heatsink  about 600 x 300 x 150
>> mm, although I think that is a bit OTT  !!
>> Dave
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