Several years ago, when I was an active ham repeater builder, I was always in the market for cavity duplexers. They are an essential component of almost all repeaters. Unfortunately, inexpensive used cavities and duplexers are often hard to find.  So I undertook what many of my ham friends told me was impossible, to build my own. To my delight, and despite the dire

At that time I also began to write a book to describe my experiences, that you may access to the left. I wanted to be of assistance to other hams who might want to duplicate my efforts, or at least better understand the duplexer(s) that they already owned.

I never totally finished the book. So rather than continuing to pack the unpublished manuscript around with me, I offer it here in its unfinished state. I'm sorry that there is nothing still existing, diagrams, plans, etc., than what you find here. 

John Portune W6NBC