At 3/9/2010 16:29, you wrote: > > Here's the idea. This is a remote RX site. The idea is > > to run something like a beefed up X500 dualbander at tower > > top, then 7/8 hardline 100 feet down to the receivers. > > Both receivers will have one or two bandpass cavities > > inline before the T. Would a duplexer be necessary in > > this case. Or could it be done with proper cable lengths > > and a T? > >Doesn't even need the special cable lengths....
It most certainly does. Try random length cables from the cavities to the T instead of 1/4 wavelength (like one local did several years ago) & watch your sensitivity drop by over 20 dB if you're unlucky (as he was). That mistake literally killed off a local radio club, as few of the members were able to use the repeater following the addition of the T & wrong cables. >but there is >a reason for doing everything and here comes questions 101. > >Will the receivers stay on one frequency as in a repeater >receiver or do you need to move around each band a bit? If he's got bandpass cavities in front of the RXs already, they're very likely not frequency-agile. >How much other RF is around? ... does the site have a lot >of transmitters and are any of the high power monsters as >in the case of paging or broadcast? > >If you don't have a lot of adjacent frequency operation >going on there are two other options to consider. One is >the Diamond or Comet type of band splitter, which actually >would take the place of your T and be much better. That would be my choice, but if he's already got the cans, a pair of 1/4 wavelength cables will be much cheaper. I'd stay away from using a broadband isolated power divider (splitter), as you'll lose 3 dB in the split. The frequency-splitting options lose virtually no signal. Bob NO6B
