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G3OYU > TECH 20.09.03 10:07l 36 Lines 1216 Bytes #999 (0) @ WW
BID : 381072G3OYU
Read: DB0FHN GUEST OE7FMI
Subj: Re: Power supply fan mod?
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From: G3OYU@GB7WSX.#32.GBR.EU
To : TECH@WW
G4EBT wrote:-
> In the ones I've repaired the heat sinks have been dull silver alloy.
> Elementary physics ( black body/non-black body radiation etc), dictates
> that the ideal radiator is smooth, black, and shiny. In the EP925's
> I repaired, the heatsinks had the opposite of these qualities.
I guys
I can add a little here. Back in the early 60's I was working for a
company manufacturing static inverters (oh the days of SCRs) We carried
out an experiment on the dissipation of heat from alluminium heatsinks in
order to ascertain what would get rid of the most heat.
Given that as David says, mount them vertically is best, there is
something you can do to improve the situation.
We tested brush painted with various black paints plus black anodizing.
By far the best finish was a THIN coat of blackboard paint.
Surprisingly vastly better than anodizing!
So if you want to improve the heat dissipation lightly paint the heatsinks
with blackboard paint. BUT if the transistors are mounted on mica
insulation washers DON'T let the paint bridge the insulation - keep it
clear of the transistors as black paint may incorporate carbon.
73
Brian G3OYU
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