The simplest would be to mount a thermal switch on the heatsink. When it closes fire a GPI. Something like this at the temp threshold that you want to alarm: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=3455RC%2001... Find out the temp were it's failing now, and select a switch maybe 5 or 10 degrees lower. For the room temp, maybe a plain old thermostat tripping a different GPI. Using one for AC/HEAT would give you high and low trip points. This would at least give you some alarms. Bob WB3AWJ      ----- Original Message ----- From: "Scott Weis" <kb2ear@kb2ear.net> I am having a problem with the hot weather shutting down a repeater. I would like to know if anyone has any way of monitoring the ambient temperature in the room as well as the surface of a heat sink and then triggering an event in app_rpt when they exceeded a certain threshold.