I could live with 3dB of loss which is about what I would expect per leg. I've ran the UHF notch duplexers "back wards" and they have ran ok, but the insertion loss does go up like 1-2dB.
If you want to get picky you would have to modify each set so that the coupling loops and coaxes are the same, but probably wouldn't be worth the effort. That are modify the coaxes so the low frequency goes through all 6 "low" notch cavities and the same for the "high". The isolator system is the way to go for repeaters, but not desireable for simplex radios. You'd have to split out the seperate RX and TX lines and then have a multicoupler and filter for the receivers and another antenna. On Thu, Jul 15, 2010 at 6:10 PM, <[email protected]> wrote: > At 7/15/2010 13:53, you wrote: >>Maybe a pair of those 6 cavity mobile duplexers with the 5 MHz split >>can be configured as 6 notch sections each to reject the opposite >>frequency. and then combine them with a T to the antenna. > > Even though they're notch duplexers, each side has a very weak pass > response, just enough so that you can't use the "low pass" side as a "high > pass". As a result, trying to use one as a 6-section notch filter by > putting all the notches on the same frequency & using the TX & RX ports as > input & output won't work, as it would have several dB of loss @ 5 MHz > offset, even more @ ~1.2 MHz. > > Another alternative to a full size 2 meter duplexer would be a dual > isolator following by a pass cavity on each TX, then T the cans together > using the correct phase-critical lengths of coax. Might be cheaper if you > happen to have an inexpensive source for 4 VHF isolators. > > Bob NO6B > > > > ------------------------------------ > > > > Yahoo! Groups Links > > > >
