Dan, My guess is that the duplexer tuning was disturbed when you took it apart. Most likely, the notch for the RX frequency on the TX side is not exactly tuned to notch out the TX carrier, leading to major desense of the RX. Unless you have a network analyzer, or a good spectrum analyzer with tracking generator and a return-loss bridge, you might consider sending the duplexer to Telewave for repair and tuning. Although almost any duplexer manufacturer can rework Wacom cavities, Telewave also has spare parts on hand. (Commercial-interest disclaimer applies).
Ensure that the jumpers connecting the RX and TX to the duplexer are double-shielded, and that the connectors are clean and tight. The desense can be caused by any leakage from the TX into the RX, and jumpers are always a suspect. Regarding the other stuff like cables and connectors, I strongly suggest that anything that was submerged be discarded. Water can wick into spaces that are not visible and cause problems over time. Besides, flood water is nasty stuff, and may contain bacteria and/or chemicals that are not nice. 73, Eric Lemmon WB6FLY -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Dan Cation Sent: Saturday, September 29, 2007 5:15 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Duplexer and noise question Hi everyone - new to the group looking for help on a strange problem. I've been involved with two repeaters in Southeast Kansas (Humboldt - 147.18 and 442.900) for over 30 years and work in electronics, although not in radio. A couple months ago we lost both repeaters when we had a flood in this area - I took the Wacom duplexer apart and cleaned any obvious corrosion or such and assumed it would be fine - it tuned up without any trouble and there was almost no corrosion. I replaced as many of the T connectors as I could and carefully cleaned any that remained and made new cables of the correct length. I have built a new repeater but am now having a problem with intermittent buzzing sometimes when the transmitter is up - it will hold the receiver open and cover any signals that aren't pretty strong. Comes on whenever the transmitter comes up but not always - sometimes it is fine. I have tried 3 different transmitters - a Midland 3400, a Midland 340A and even a couple Icom rigs - makes no difference. Same for receivers - makes no difference. Never shows up unless the duplexer is hooked to an antenna - works fine on a dummy load. Tried two different antennas as well. The noise sounds like bad line noise, but I can't hear it except on the repeater. The repeater is at my house right now, but I intend to haul it back to the site to see if it shows up there as well when I can get time to do it. Anyone else ever ran into this kind of thing?
