We had an ongoing problem on one of our repeaters for quite a while that eventually turned out to be a bad cable between the duplexer and the repeater. We purchased new cables from a local 2-way radio supplier and they provided what appeared to be commercially made mini-hardline cables. These were worse than the ones we replaced! It turned out that the supplier had cut off the factory connectors and soldered on PL-259's. I made up some cables using Belden 9913 with it's 100% shielding, and that temporarily cured the problem until we could get some new commercial cables with factory connectors.
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