as example:
http://www.kf8kk.com/wi0ok/sixduplex.html
http://www.lewczuk.pl/phocadownload/artykuly/6meterheliaxduplexer.pdf
Remember that these are NOTCH ONLY stubs.
If you have a strong local 'out of band' signal that you need to reduce you would have to determine the frequency of that and build a stub to drop that signal down.
http://www.kf8kk.com/wi0ok/sixduplex.html
http://www.lewczuk.pl/phocadownload/artykuly/6meterheliaxduplexer.pdf
Remember that these are NOTCH ONLY stubs.
If you have a strong local 'out of band' signal that you need to reduce you would have to determine the frequency of that and build a stub to drop that signal down.