Hi all. Installing a 2m repeater back into a higher/better location. The duplexer, (Wacom 641), was tuned and seemed to be operating perfectly. When moved to the new location, there was a lot of TX noise and desense introduced into the system. With a weak and STABLE portable station transmitting into the input frequency, and listening on an HT connected through the RX side, I noticed a fair amount of attenuation. (Signal straight from antenna was full scale, thru duplexer was about a 7). SO, I (by ear and signal) retuned the RX band pass filters to get an almost full scale signal. When the repeater was put back on the air, The densense problem was better, so I listened to the noise level on his signal and carefully adjusted each band=pass filter for minimum noise. This seemed to help the desense problem. When I adjust transmit power from 0 watts to 35 watts, I hear no audible noise added. At 40 watts, noise begins to enter the received signal.
Now, I'm concerned about WHY this happened, mechanical changes, impedance mismatches, etc., and if I could have messed anything else up by doing this "by ear". Also, I'm thinking I could do the same with the TX pass filters, but I also know I could really mess up VSWR and other things without having proper field test equipment. Any thoughts? Should I leave it as is, or could I possibly do some tuning to make the duplexer better? Repeater is 35 watts out, and currently pretty well "balanced" I think.. If a station can hear it decently with a 5 to 7 S-meter reading on a moble, 1/4 antenna, they can get in with a slight bit of noise at 5 watts. Is this suitable, acceptable, or should there be more receive? Thanks, 73 Jeff - N5VAV
