Question: Are you exhausting air from the cabinet, or pressurizing the
cabinet? And what is expected to be the intake or exhaust ports?
73
Bob, K4TAX
----- Original Message -----
From: "Tommy" <aldermant@alltel.net>
To: <tentec@contesting.com>
Sent: Friday, May 07, 2004 2:55 PM
Subject: [TenTec] Cooling the Orion
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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