I do not recommend this mod as there is no engineering/technical justification
for it, however it is my personal choice to do so.
Having been a microwave circuit design engineer and having designed several
integrated circuits in my career, I have an 'obsession' about keeping heat out
of solid state devices. My Orion has the Ten Tec fan on the heat sink. The
Orion sits in a custom shelf, open in the front, back, and both sides. It sits
with the bail up and about four inches clearance on the top in front, and
about seven inches clearance on the top, in the back.
During normal operations, meaning with it running all day, I observer the top
of the case getting, not hot, but very warm to the touch. (It is most likely
designed to withstand this (small) heat build-up, but I just don't like it. A
digital therometer just placed on top of the Orion, shows a 15 to 20 degree F
temperature rise above ambient during normal operation (primarily CW).
The Orion has one of the best sounding internal speakers I've ever heard on a
Ten Tec piece of equipment, however I use either headphones or an external
speaker. Dead PC power supplies normally have a 12 vdc fan in them that seldom
go bad. The PC pwr supply fans I have in my junk box have mounting hole
spacings of 3 1/4 inch. Remove the Orion top cover and the internal speaker has
mounting holes that are spaced 3 1/4 inches. The depth of the internal speaker
is deeper than that of the pwr supply fans.
VERY BASIC
Remove the speaker plug from it's socket in the top of the Orion. Remove the
speaker bracket, then the four screws holding the speaker to the custom
bracket.The holes in the speaker bracket are tapped, so find some mounting
screws that will fit in the tapped holes. (Do not use a washer/nut on the upper
side of the speaker bracket as the top cover would no longer fit on the Orion.)
Select the length of the fan mounting screws so that with the fan mounted, the
end of the screw is at least 1/16 inch below the rubber vibration pad on the
speaker bracket.
The old PC pwr supply fan is noisy when run at 12vdc. I added a 100 ohm
resistor in series with the +12vdc wire going to the fan. (If you do this,
don't forget to put heat shrink tubing over the resistor and the soldered
leads.) The points I selected to obtain +12vdr is the very same point where the
rear +12vdc RCA connector obtains it's voltage and the ground connection is the
same point on the vertical PC board in the rear of the Orion that is used for
the +12vdc RCA connector shell. I very carefully soldered the + and - fan dc
supply leads to those two points. I ran the fan wires along the vertical
aluminum panel on the right side, internally, of the Orion and I used
'spot-tie' to hold it snuggy to the other wires along that same location.
RESULTS
Not earth-shattering -- doesn't improve/degrade performance the least bit --
but now there in no temperature rise with the digital therometer sitting on
top of the Orion for a full day's operation. The top cover remains at ambient
temperature all day. The main thing that may be gained by doing this is some
help in possibly preventing long-term failure problems due to sustained heat
environment in the Orion.
As I said, I'm kinda obsessed with keeping all solid state devices as cool as
possible. Took about 2 hours to complete.
Tom - W4BQF
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