[time-nuts] Connections for FE-5680A rubidium sources
kb8tq at n1k.org
Tue Dec 16 20:48:55 EST 2014
> On Dec 16, 2014, at 4:36 PM, Brian M <brayniac at gmail.com> wrote:
> I just power mine off an old 19vdc laptop supply dropped with a linear
> regulator (and filtered) to provide ~17vdc
I think that keeping the internal regulators running is a good idea. The more stages of stabilization and clean up, the better.
> No 5vdc supply required for
> mine. I recall reading that some have an internal 5v regulator. I believe
> the way to check is if the lock pin signals and PPS is present without
> external 5vdc supply. Mine does. Your experience might vary - but that was
> my experience with my copy.
> I also didn't have serial connected on mine. Had to mod it to bring out
> serial. Anybody else face that?
From what I’ve seen, if there are 8 basic features on these Rb’s then there is a unit out there with each of those features either present or absent. We only have seen the most popular 32 out of the 256 that are running around.
Don’t bother to bug the manufacturer for info. They all appear to have been OEM custom models. I’m amazed that they could find that many customers and slots for them ….
> - Brian
> On Tuesday, December 16, 2014, Ryan Stasel <rstasel at uoregon.edu> wrote:
>> 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 (
>> 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
>>> 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!
>>>>> One fairly important issue - the unit needs to be on a heat sink. If
>>>> run it without cooling of some sort, it will not run for very many
>>>> 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 !!
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