Dave, I am not sure what your intended use of the repeater is, but you have gotten lots of good advice. If you are looking for something to use at your or a buddy's house, you can get by with a lot less investment than if it is going up on a mountain top somewhere.
As was mentioned UHF or 900 MHz is a lot less costly to get started with and you might be able to find a frequency. Duplexers cost penny's on the dollar when compared to a VHF unit. For simplicity if you are wanting to use a pair of mobiles, I would recommend Motorola SM50, SM120 or GM300 radios. With the 16 pin plugs, they are a direct plug-in to any of the ham controllers, or use one of the cables available on EBay between them and you don't need a controller, if you are just doing a back yard thing. A lot of people are particular about antennas when used with a duplexer and for good reasons. A duplexer can present certain challenges for the antenna system and feedline that do not show up under normal base station use. The other concern is how well the radio's transmitter performs into a hi-q circuit like a duplexer presents to the transmitter. Not all transmitters are happy transmitting into a duplexer directly, that is where a circulator or isolator comes in, it presents a nice 50 ohm load to the transmitter. As was also mentioned, heliax or good double shielded silver plated braid for cables and silver plated connectors and adapters are a must, especially for UHF and 900 MHz and above. Good tight mechanical connections on all antenna mounting hardware and tower/mast is a must. Loose or rusty and corroded metal parts, nuts bolts..etc on the tower or mast can produce noise and possibly desense with a duplexer. I mention this again, because this is where I find 90% of problems with amateur repeaters that are performing poorly or not at all. Good luck with your project. Joe - WA7JAW --- In Repeater-Builder@yahoogroups.com, Dave Gomberg <[EMAIL PROTECTED]> wrote: > > I have long considered building my own 2m repeater out of 2 Icom 2100 > or 2200 back to back thru a repeater controller, using a good > duplexer and a Comet or Hustler antenna. Here are my questions: > > 1. Nobody seems to like the Comet or Hustler antennas. Why? I > have no ice here, lots of wind tho. > > 2. Why is a 50w 2m transceiver, derated to 25w and driving a power > amp a bad choice? Or is it OK? > > 3. Any suggestions on how to keep the duplexer cavities affordable? > > 4. Which repeater controller? Or is that a religious question? > > Anything else I should be wary of? > > > -- > Dave Gomberg, San Francisco NE5EE gomberg1 at wcf dot com > All addresses, phones, etc. at http://www.wcf.com/ham/info.html > ----------------------------------------------------------------- >
