At 12/30/2004 03:39 PM, you wrote: >Is the best way to have a mobile repeater up and running with two mobile >radios and a duplexer? Looking for a way to be able to run a couple of >repeaters, one VHF, one UHF for a mobile communications van. Can anyone >recommend ways to cut down on weight and space? >Thanks >Dakota
I suggest using commercial equipment. A single G.E. MVP radio will run duplex & probably take up less room than 2 amateur grade mobiles. The ham gear, although synthesized, will require more isolation due to the receiver not being designed for high RF environments. I use MVPs for my UHF repeaters mainly because of the small size - I'm space-constrained at most of my sites. They work very well in high RF environments & their TXs can run continuous duty by adding a fan and/or heat sink to the back of the radio. They can duplex on a single antenna using just a small 6-section flat-pack mobile duplexer. The one minus is that the stock RX is a bit deaf (spec is 0.35 uV for 12 dB SINAD, mine are a bit worse probably due to the helical resonators being a bit out of spec'd 450-470 MHz range). The G.E. "UHS" preamp brings it down to below 0.2 uV but for best performance use a GaAsFET preamp from Angle Linear or ARR. The VHF MVP works great too & generally doesn't need a preamp. In metropolitan areas the receiver's noise temperature is comparable to that of your antenna at 2 meters. Of course for 600 kHz splits you're going to need a rather "unportable" duplexer. An alternative to the big duplexer is to run a wide split & use a VHF mobile duplexer carefully tuned down to ~2.5 MHz spacing; there are many 6-section units that will just make it down to this split. Here in SoCal we have a special pair in the bandplan just for these portapeaters: 147.585 input, 144.93 output (+2.655 MHz split). See the articles at <http://www.repeater-builder.com/ge/mvp/no6bmvpconversion.html>, <http://www.repeater-builder.com/ge/mvp/mvpstepbystep.html> & <http://www.repeater-builder.com/ge/mvpconversion.html> for info on "repeaterizing" these nice radios yourself or by the list owner. Bob NO6B Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
