Compared shielded vs unshielded twisted pair on a King Air install yesterday

I was wiring up a new Garmin GPS 175 in a 1980s King Air C90 at the hangar in Wichita. The old harness had unshielded twisted pair throughout and I figured I'd save time by just matching it. But after fighting with intermittent noise on the audio panel for two hours, I pulled the whole run and swapped to shielded Belden 8723. Night and day difference. Ground loop gone, signal clean on the first power up. Has anyone else had a similar experience swapping to shielded on older airframes or is it just me chasing magnetic fields in my sleep?

3 comments

3 Comments

amy97510d ago

Funny you mention that buzzing sound. I was helping a buddy swap out a old furnace blower motor last winter and the capacitor he grabbed from the junk drawer was bulging on one side. He plugged it in and that thing hummed like a angry hornet for ten seconds before the whole motor seized up. We ended up having to pull the whole assembly and replace the capacitor and bearings. Ever since then I check for bulging caps on anything with a motor before I even turn it on.

jamiekim11d ago

Yeah, it's like how cheap extension cords always buzz with cheap phone chargers.

michael_craig10d ago

Man literally told me last week his $10 charger melted the side of his phone. That buzzing sound is straight up your stuff telling you its gonna die soon.