There were a couple of designs that used copper circuit boards to form square boxes for the outer jacket of the duplexer.
Size maters as the inner to outer diameter ratio effects the impedance of the cavity. It is my understanding that the optimum impedance for a cavity is approx 70 ohms. Not sure if this is true for cavities, but with helical resonators square shields have higher Q than round ones. You would also probably be better off using a BpBr style design, as I remember W1GANs was for pass cavities which would require 6, BpBr can get away with use 4, they would be similar but only have 1 coupling loop that has a high quality trimmer capacitor such as a johansen or a coaxial gimmic in the ground leg of the loop to set the notch frequency. On Fri, Apr 24, 2009 at 4:19 AM, cruizzer77 <[email protected]> wrote: > Hi > > Most of you who are into duplexers will know W1GAN's old QST-article "A > Homemade Duplexer for 2-Meter Repeaters". > > His design uses 4" copper tubes, but today many duplexer manufacturers use > square aluminium profile as duplexer bodies, i.e. Sinclair but others as > well. Now I wondered if W1GAN's design could be used for building such an > aluminium square tube duplexer as well and if it would work equally well. > Does anybody know? > > Instead of the 4" round tube, would a 4" square tube be used, or does the > circumference matter? > > Kind regards > > Martin > > > > ------------------------------------ > > > > Yahoo! Groups Links > > > >
