[time-nuts] LPRO-101 Heatsinking

[Michael Baker]

Hello, Timenutters--

I only have experience with four different LPRO-101
units, but with respect to heatsinking, all 4 behaved
identically during my testing of them.

It appears that the LPRO-101 units do not require
much heatsinking.  I experimented with a variety
of heatsinks and discovered that just bolting them
down to a 1/8" thick flat sheet of aluminum roughly
8" x 10" (no fins, just a flat sheet) kept the
case of the unit and the aluminum sheet below
105 deg F.  That is relatively quite cool as far
as electronic circuitry is concerned-- only
slightly warm to the touch.

The 4 units I tested were powered by a regulated
24VDC supply and the aluminum sheet was kept vertical
and had good air flow around it.

I also experimented with a heat sink that is very
nearly the same size as the base plate of the LPRO
units but only has ten 1/2" tall fins that are
quite wide spaced on it.  With that particular
very minimal heatsink the highest temp reached after
4 hours was only 97 deg F.

I put a teeny 12 volt CPU fan about 2" from the fins and
ran it on 6 volts DC to keep the blade speed waaaaaaay
down (and essentially silent).  After two hours had
elapsed, the heat sink and case were still only
ever so slightly above room temperature. 

Bottom line seems to be that the LPRO units must have
at least some minimal heatsinking but they do not
require much.  The four units I tested came to me
with their base plates covered with a very thin layer
of some sort of a pale green heat transfer material
so I did not need to apply any of the typical
messy white "moose-poop" zinc-oxide and silicone grease
heat transfer paste.

Mike Baker
WA4HFR
Gainesville (Micanopy) Florida
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