How do I tell a bad jumper from a bad antenna or feeder?

Work from the radio down, changing one thing at a time: 1. Look first: crushed or kinked jacket, water in the connector, green or dark center pin, loose coupling nut, missing weatherproofing. 2. Sweep the whole run (radio port to antenna port) and note the problem distance with DTF. A spike near the start of the run points to the bottom jumper, near the end to the top jumper or the antenna. 3. Break the run at a connector and sweep each section with a known-good load on the end. The section that fails holds the fault. 4. Replace the suspect jumper with a new one (not one lying in the truck) and sweep again. If the result changes, you found it. 5. Re-torque connectors to spec and re-weatherproof before you close out. Never judge a jumper by looks alone: a jumper can pass a quick return-loss check and still fail PIM. — CrewRating Team. General guidance, not a substitute for your company safety program, manufacturer instructions or the carrier’s scope of work. If this conflicts with them, follow them and tell us so we can fix it.