Ron; Thank-you for your comments and suggestions.
I didn't get around to trying to tune then with just the audio of a receiver to go on; fortunately I got the Sweep/Marker Generator and Oscilloscope setup to work. I really like how the display output is linear (vs log.); I think that it makes it easier to read/adjust. I didn't have the problem you described with the narrow notch. I'm not sure if it is because of the linear (vs. Log.) display, or perhaps the cavities I was using. It might also be because I tuned each cavity individually first, before looking at them in series. Either way, it seemed to dial right in. I haven't done the final tune (of the entire duplexer system) yet; as I am still trying to get the interconnecting cables cut just right. Perhaps the situation you describe might show up more notably during the final tune when the pass and reject behavior is more pronounced (e.g., narrower BW,...). Either way, I'll keep my eye out for it. Another Ham here asked me about reading the "actual bandwidth" of the cavities (referring to a 3db or 6db point, or something like that). To be honest, I wasn't quite sure what he meant or how I might do it; but I suspected that it is just the width at a certain number of DB from the peak (of the pass or notch). The Sweep/marker generator does seem to have data to indicate the signal strength (in db); so I am guessing that I can actually do it if I was more familiar with the Wavetek 1080 and how to read the vertical display it generates (I'm still looking for the manual). <<< vern >>>
