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
