EMI on a CRJ-200 had me chasing ghosts for 3 days straight

Down in Tulsa last month, we had a right side NAV display flickering every time the radar sweeper rotated. Replaced the antenna coax, swapped the display, even cleaned every ground strap under the floor panels. Turns out a new HF antenna install from the week before had its feed line running parallel to the NAV coax up in the crown. Fixed it by re-routing with 6 inch separation and re-checking SWR, but the troubleshooting cost us 11 man hours on paper. Anyone else had a recent install screw with an older system like that?

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taraanderson10d agoTop Commenter

Wait, 11 man hours on a paper trail for a ghost that was just a parallel feed line? That's wild, man. You'd think someone would have caught that on the initial HF install, like a quick SWR check or just eyeballing the cable path before closing up the crown. In my experience, those new antenna jobs always seem to bite you weeks later, not right away, so I totally get the frustration. I once spent two days on a comm issue that turned out to be a zip tie too tight pinching a cable, so I feel your pain on the hidden culprit. Take this with a grain of salt, but I'd bet your next HF install gets a little extra scrutiny on the routing before anyone signs off on it.