I have a note in my file that I do not recall where it came from relative to cable length between the duplexer and the TX or between the duplexer and additional filter. Length = (30)(32.785)(vf/freq). 30 is for 30 degrees, vf is velocity factor, freq is the average of the pass and reject frequencies. If too short add 180 degrees. Don't know if this is good info or not. The article would be appreciated. Sid.
--- In Repeater-Builder@yahoogroups.com, Nate Duehr <n...@...> wrote: > > > On Aug 5, 2010, at 11:20 AM, Kevin Custer wrote: > > > Allan Crites and I are currently in discussion which will be used as the > > basis of a RB web article that will explain exactly what is happening, why > > it happens, and why an 'optimized' cable length can be used to transfer > > power ending up with the stated loss of the duplexer and have little > > reflected power toward the transmitter - so long as the duplexer is tuned > > properly and exhibits good return loss on the frequency it's designed to > > pass. > > There's already a great book on that topic, it's called the ARRL Antenna > Handbook, and the chapter on transmission lines covers it in more detail than > anyone will ever need to know in the real-world, who's not a practicing RF > Engineer. > > That book if read cover-to-cover, is also damn good for insomnia. Or at least > it'll keep you distracted while you can't sleep! :-) > > -- > Nate Duehr > n...@... > > facebook.com/denverpilot > twitter.com/denverpilot >
