I agree that timers for fans are a waste of time, effort and money. If you can stand a little waste of power, I like to simply key the fan with a relay driven by PTT. Sure, it starts the fan before it's needed, but to me it's no big deal. Once the repeater stops transmitting, so does the source of heat - it won't get hotter, but will cool down slowly on it's own (just like turning the burner of your stove off - the pan starts to cool right away).
Chuck WB2EDV ----- Original Message ----- From: "Eric Lemmon" <[email protected]> To: <[email protected]> Sent: Saturday, May 01, 2010 2:36 PM Subject: RE: [Repeater-Builder] Neat kit for switching repeater devices > 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: [email protected] > [mailto:[email protected]] On Behalf Of na4it > Sent: Saturday, May 01, 2010 9:38 AM > To: [email protected] > 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 > > > > > > > > ------------------------------------ > > > > Yahoo! Groups Links > > > -------------------------------------------------------------------------------- No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.814 / Virus Database: 271.1.1/2847 - Release Date: 05/01/10 02:27:00
