Scott, I must agree that the CK1614 is an extremely versatile timer, with many potential uses. However, using it for fan control is not only expensive, but unnecessary.
A fan blowing on a transmitter heat sink does absolutely nothing immediately after the transmitter is keyed, since the heat sink is likely at ambient temperature. It takes a period of time for the heat sink to warm up, so operating the fan prematurely is a waste of energy- which may be an issue for a solar-powered repeater. IMHO, the most efficient means of fan control is also the cheapest: A thermal switch. My first choice is a Cantherm #R2005015 normally-open thermostat that closes at 50 degrees Celsius, about 122 degrees Fahrenheit. When attached to a heat-sink fin, it turns the fan on when necessary, and keeps it on until the heat sink cools below about 100 degrees F- around body temperature. This particular switch is available from Digi-Key for about $9, as Catalog Number 317-1094-ND. 73, Eric Lemmon WB6FLY -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of na4it Sent: Saturday, May 01, 2010 9:38 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Neat kit for switching repeater devices I have started using this little kit (http://www.electronickits.com/kit/complete/elec/ck1614.htm <http://www.electronickits.com/kit/complete/elec/ck1614.htm> ) for fan control on repeaters. I can also be used as a PTT and Time Out circuit, along with a lot of other uses. Download the pdf on that site and check it out. Scott NA4IT
