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

Ryan Stasel rstasel at uoregon.edu
Tue Dec 16 13:06:55 EST 2014


It's interesting, but I've actually found the FE-5680 I have will power up, and lock, from just 12v. Sure, takes a bit longer, but it eliminates the need for the 7812 in the box, etc. I know the 5680 FAQ on ko4bb (http://ko4bb.com/dokuwiki/doku.php?id=precision_timing:fe5680a_faq#input_voltage_requirements_spec_is_15_-_18_volts_dc_and_5v_dc) states they'll run as low as 9.96v, but I've always been curious if that was AFTER the 15v lock, or from cold. 

Anyway, YMMV on any particular unit, but it would be interesting to hear if anyone else is just powering them from a standard (linear) 12v wall wart, or are you all just using 15v?

-Ryan Stasel

> On Dec 16, 2014, at 09:54 , 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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