Re: Transmitter Cooling Methods

Butch Bussen

Just wondering where you find these thermostats? Only one I could find
was actually made to mount on the ceiling for fire detection and is 130
DG. Would like to find something a little easier to mount and perhaps a
little lower temperature.

Butch Bussen

On Sat, 23 Oct 2004, Mike WA6ILQ wrote:

At 08:37 AM 10/23/04, you wrote:

On Sat, 23 Oct 2004 09:56:38 -0500, Jeff Davis wrote:

I'd like to ask how folks are keeping their link radio finals cool?
Hi Jeff,

I usually use a computer fan, like you, and control it with a small
Klixon thermostat when possible. On the particular radio I'm running
now, there isn't room for the thermostat to fit between the heat sink
fins, so I'm running it continuously until I figure out something
different. Don't forget also that you can run most of those 12V
computer fans on the 5V supply and they will be quieter and still move
pretty good air. I've got 8 fans in my main computer and all of the
case fans are running that way.

Gary - AG├śN
IRLP node 3055
ag0n at arrl dot net
http colon//garymcduffie dot com
Cooling link radios has been an occasional topic on the
repeater-builder yahoogroup. Anyone who is really interested
could go to the archives of that group and do a search on "cooling".
There is also a fan controller article on the
web site.

One thing I did years ago (before computerized repeater controllers)
is to run a fan based on PTT plus some time. The time delay was
generated by a 555 chip and the timing resistor was a thermistor
mounted on the heat sink - the hotter it was the longer the fan run-time.
A Klixon thermostat was also mounted don the heat sink and if it
tripped it did three things (it switched to ground, and three diodes
were used to (1) bypassed the 555 to run the first fan full time,
(2) fired up a second fan, and (3) modified the message sent by
the IDer to add "[space]OT" to the end of the ID (the [space]OT was there
all the time, the IDer just stopped early as long as the over temp
line was inactive).

A variant on that idea is in my writeup on Mitrek link radios at
the repeater-builder web site. Just go to the Motorola page,
then to the Mitrek/MSR page then look for the 40-page article
on Mitrek interfacing. The section on cooling is towards the end,
along with rack mounting.


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