The duplexer design I am working on will use 1/2" solid rod Copper, Brass or Invar 36 with 6-8 inches for 2 meters tapped with fine threads at the top, and a bolt soldered to it for the tunning plunger. The tunning rod will be supported at the bottom by a teflon disc
When using Invar the tunning bolt to the actual tunning plunger contraction/expansion can be avoided. Outer jacket will be 1 1/4" copper "L" pipe, Avalible at any home depo. The coupling loop I am still working on but basicly there is a "BNC" on the side of the can about 1 3/4" from the top. A strip copper will "L" from the connector and come to the notch capacitor on the top of the can. This capacitor is cheaply salvaged from a GE MASTR-II ICOM. I originaly came up with the concept after my 220 Interdigital band pass filter exhibited 12dB of loss, but 117 dB of isolation. Oddly the aluminum bar is more expensive then the copper. And it is also harder to work with Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
