Hi I'm helping a friend who wants to convert a Sinclair Res-Lok 4 cavity combiner into a duplexer. Basically turning it into a Q2220E I think). As far as I can tell, it should be possible by simply adding a vatialbe cap to the coupling loops. I still haven't found the answers to to two questions.
1. What is the correct length of cable between each cavity? 1/4 wavelength? 1/2 wavelength? Something else? 2. What determines the location of the notch? two cavities will have the notch above the pass band and the other two will have the notch below the pass band. I suspect there's something different about the coupling loops but I don't know what. Thanks Bruce VE5BNC
