Larry, That's odd; both the GR1225 and RKR1225 repeaters I am familiar with, which use the R1225 transceiver, have a small thermal switch that is wedged between two of the heat-sink fins. In both repeaters, the fan runs only when the radio gets hot. I am surprised that you have a repeater using the R1225 in which the fan runs continuously. Perhaps this installation is a prime candidate for a thermal switch!
73, Eric Lemmon WB6FLY -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Larry Horlick Sent: Saturday, May 01, 2010 7:13 PM To: [email protected] Subject: Re: [Repeater-Builder] Neat kit for switching repeater devices This is excellent Eric. I have an R1225 repeater in a GR500 case. There is a fan but it runs continuously. The duty cycle is low but because of the nature of the service there are times when it may be very high for extended periods of time. So most of the time the fan is not needed, but I want it there for those rare occasions. I don't recognize the part no. on the fan it looks remarkably similar to the one stock in GR500. This will work very well for me. Thanks. lh On Sat, May 1, 2010 at 8:28 PM, Eric Lemmon <[email protected] <mailto:[email protected]> > wrote: Larry, My first use of this thermal switch was on a solar-powered Motorola R1225 UHF repeater at a commercial site. I simply drilled and tapped two 4-40 holes on a flat portion of the outside fin, and mounted the thermal switch after applying some heat-conductive paste. I used a three-inch low-EMI Panasonic fan blowing right on the fins. This is a 45-watt repeater set for about 30 watts output. It went into service early in 2003, and has been trouble-free ever since. I have attached a picture of what it looks like. 73, Eric Lemmon WB6FLY -----Original Message----- From: [email protected] <mailto:Repeater-Builder%40yahoogroups.com> [mailto:[email protected] <mailto:Repeater-Builder%40yahoogroups.com> ] On Behalf Of Larry Horlick Sent: Saturday, May 01, 2010 11:56 AM To: [email protected] <mailto:Repeater-Builder%40yahoogroups.com> Subject: Re: [Repeater-Builder] Neat kit for switching repeater devices Eric, This is good info. I have an immediate use for this. How have you actually attached this 'stat to the fin? Larry On Sat, May 1, 2010 at 2:36 PM, Eric Lemmon <[email protected] <mailto:wb6fly%40verizon.net> <mailto:[email protected] <mailto:wb6fly%40verizon.net> > > wrote: 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:Repeater-Builder%40yahoogroups.com> <mailto:Repeater-Builder%40yahoogroups.com <mailto:Repeater-Builder%2540yahoogroups.com> > [mailto:[email protected] <mailto:Repeater-Builder%40yahoogroups.com> <mailto:Repeater-Builder%40yahoogroups.com <mailto:Repeater-Builder%2540yahoogroups.com> > ] On Behalf Of na4it Sent: Saturday, May 01, 2010 9:38 AM To: [email protected] <mailto:Repeater-Builder%40yahoogroups.com> <mailto:Repeater-Builder%40yahoogroups.com <mailto:Repeater-Builder%2540yahoogroups.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> <http://www.electronickits.com/kit/complete/elec/ck1614.htm <http://www.electronickits.com/kit/complete/elec/ck1614.htm> > <http://www.electronickits.com/kit/complete/elec/ck1614.htm <http://www.electronickits.com/kit/complete/elec/ck1614.htm> <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
