Leigh L. Klotz, Jr WA5ZNU wrote:
Chuck,
This device is a pull from a larger system, probably a cell site.
It's clearly designed to be mounted on something, as it has lots and
lots of holes around the edge. I suspect there's some thermal
management that's missing. The FEI sheet gives "typical" data for the
0-50C range, though presumably that's ambient temperature.
I don't want to cool the physics package per se, but I do want to at
least approximate what kind of thermal solution ought to be supplied.
Several years back I bought a 5680A and mine came still mounted on the
original (Lucent?) circuit board. There is a small amount of circuitry
on one end, but most of the large board is just a solid plated area
where the FE-5680A mounts. This is almost 100 in^2 plated on both sides,
so an equivalent would be a sheet of aluminum about 7.25 x 13.5 inches.
I'll let someone else translate that to an appropriate finned heatsink.
Quite a few of these have been sold, and I've gotten good advice from
others on this list about calibration. I'd hoped that someone would
have experience with the thermal management.
So far I've seen
http://www.dd1us.de/Downloads/precise%20reference%20frequency%20rev%200_4.pdf
which shows (but doesn't describe) a heat sink on the bottom.
Leigh.
I never saw that particular pdf article before. It looks interesting.
The 5680A I got was a bit different from most and I never found a way to
program mine. I'll have to revisit the unit and see if the header
connector he used works. I though I looked at that, but it has been a
long time. Worth another attempt, I guess.
-Rex, kk6mk
I'm puzzled. I admit that I don't have a lot of experience with
Rb standards, but I do have a bit of experience with the HP-5065A
Rb standard.
In the 5065A, the entire physics package is enclosed in an oven.
Assuming that your Rb is the same, and I believe it is, your plan
to force the physics package to run at room temperature is just going
to make the oven work harder in its never ending quest to maintain
stable temperature. If you monitor the current draw of the 5680A,
you will probably see that it goes up when you put a fan on it.
Sometimes, you just have to let electronics run hot.
What did the manufacturer suggest?
-Chuck Harris
Leigh L. Klotz, Jr WA5ZNU wrote:
I've attached an SMA connector to my FE-5680A and built an external
linear power supply with a TO-3 7815.
I ran the device today for about half an hour, and used an infrared
sensing thermometer to measure the external case temperature.
It got up to 48 C externally in the physics package area.
I put a muffin fan on top and it brought it down to 38C but I don't
think this is a good plan because I worry about the effects of the
fan's magnetic field on the Rubidium system.
I found in my junk box a finned Aluminum heat sink that's exactly
the same size as the FE-5680A and plan to tap it around the edges
for 4-40 hardware to attach to the many screw holes. Even so, this
heat sink will be on the bottom, so the FE-5680A will have to be
operated upside down for this to help.
Has anybody got good thermal management solution for this device?
This is the one currently selling on eBay in the 25x88x125mm chassis.
Thanks,
Leigh.
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