Excellent. Thanks for the info. This is going to be my first repeater and so I'm still learning. Thx. Thanks,
Michael H. Cox michaelh...@gmail.com -----Original Message----- From: "Daron Wilson" <daronwil...@yahoo.com> Date: Sun, 3 Jan 2010 22:22:05 To: <Repeater-Builder@yahoogroups.com> Subject: RE: [Repeater-Builder] Mastr II mods and parts >Any reasons? First, it could be used as a duplexer, however you don't get all the benefit you would get from a BpBr duplexer. The one in question is a notch only duplexer, the cavities are designed to notch the two frequencies in use. While it can work, you generally cannot get the required isolation for a fairly sensitive repeater with much of a power output. A more typical duplexer would have band pass cavities, or better yet, band pass band reject cavities. There is a wealth of information on the web regarding the theory and design of duplexers. In short, with a BpBr duplexer, you get two cavities that ONLY pass the receive frequency, and they also notch the transmit frequency. On the transmit side, you get the same double action. This yields more isolation and protects the front end of the receiver a bit from adjacent channel signals by only 'passing' the correct signal. With the notch only duplexer, there is no front end receive protection provided, simply a notch where the transmitter is. If there are other nearby signals they could very well interfere with the receiver. Do the right thing and get a Band Pass Band Reject duplexer, you'll be much happier. 73 Daron N7HQR
