Ben, I believe that the best solution is to use a normally-open thermoswitch mounted to one of the heatsink fins. My choice is Digi-Key 317-1094-ND, about $7, which closes at 50 degrees Celsius (122 degrees Fahrenheit). This setting ensures that the fan does not run needlessly, but will kick in long before the radio gets hot enough to affect its health. I drilled and tapped a couple of 4-40 holes, and mounted the switch with some heat-sink compound under it to get good heat transfer.
73, Eric Lemmon WB6FLY -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of wqjf348 Sent: Saturday, October 11, 2008 11:39 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] GR500 Cooling Fan Control I am setting up a GR500 with the R1225 radio. It is in the wall mount box. The cooling fan that came with the box runs non-stop. I would like to be able to control the fan either by slowing it down or making it switched by temperature or PTT of the repeater. Can anyone here offer some suggestions? It is currently wired straight from the power supply. Thanks in advance! Ben WQJF348 West Jordan, Utah
