-----Original Message----- >From: wb6ymh <[EMAIL PROTECTED]> >Sent: Nov 2, 2007 10:28 AM >To: [email protected] >Subject: [Repeater-Builder] Re: UHF Radio recommendations ?? > >--- In [email protected], George Henry <[EMAIL PROTECTED]> >wrote: >> >> And the Mitrek is just about the easiest radio to convert... snip >two diodes, jumper your channel elements hot full-time, disable the >T/R relay & add a 2nd antenna connector, controller of your choice, >and duplexer. And already in a nice, RF-tight enclosure, to boot! >> >> I picked up a 55-watter on E-Bay recently for $10 plus $10 shipping! > I don't see very many MASTR II's pop up on E-Bay, though. > >Yup Mitreks are great, but please don't imply that a 55-watter will >last in repeater service at anywhere near 50 watts. (They are actually >spec'ed at 50 watts, but mine did 80+ full tilt). >
I was really just commenting on the price, not recommending any particular power level. >The 30 watt version is a better radio for repeater service since all >solid state transmitters are very inefficient when run below their >designed output. A 30 watt Mitrek running at 15 watts will probably >last forever, but a 50 watt Mitrek running at 20 watts gets way too >hot for my tastes. It would probably be ok with a fan, but I really >didn't want a fan for numerous reasons. > >Since I'm using mine to drive an Micor PA I bypassed the finals and >driver transistor and got 10 watts out with about 2 amps in. In that >configuration it just barely gets warm. Since the Micor amp only >requires about a watt drive I have the power output turned all the way >down. > >73's Skip WB6YMH > I am adding a generous amount of additional heatsink material to mine, as well as 2 brushless fans (one PTT-triggered with a 5 minute run-on after last key-up, and one thermostatically controlled), and will be running it at 30 watts (I was told by a local Motohead to never run them at less than 60% design power). If I find that it gets too warm, I have a couple of outboard PA options available, but due to space considerations where I am hoping to get this sited, I'd like to keep it as self-contained as possible. George, KA3HSW / WQGJ413
