so ive been putting off doing a proper mobile install for like two years now and i finally bit the bullet last weekend and got my ft-7900r mounted in my f150. ran the power cable directly to the battery with the fuse right at the battery like everyone says to do, antenna is a tram 1185 on a mag mount sitting on the roof.

thing is im getting this kind of raspy buzzing noise that goes up and down with the engine rpm. its not terrible but its annoying enough that i notice it on every qso. ive already tried moving the radio around a bit and grounding the antenna mount with a small wire to a nearby bolt but nothing really changed. wondering if anyone has dealt with this and knows what the actual fix is. i feel like its coming from the alternator maybe? or could it be something with the ignition system

yep that sounds like classic alternator whine, the rpm-following noise is the giveaway. a few things that usually help - first thing id check is whether your power leads are routed anywhere near the vehicle's ignition wiring or anything with switching noise. sometimes just rerouting the cables fixes it.

the bigger thing though is your ground. even if youre going straight to the battery on both leads thats usually the way to go, but a lot of guys find that adding a ferrite choke on the power leads right at the radio cleans things up a lot. you can get a snap-on type for a couple bucks and just put it on the cable near the radio chassis. also make sure the coax braid is making good contact at the antenna base - mag mounts can be iffy for ground depending on the paint situation under there. some people strip a small patch of paint under the mag mount to get better contact to the body metal.

if none of that works a noise filter inline on the power lead is the nuclear option and usually solves it.

had the exact same problem in my tacoma with a similar setup. turned out the mag mount just wasnt grounding well through the roof paint and once i stuck a piece of copper tape under it and scratched through to bare metal it went almost completely away. the ferrite choke thing the other guy mentioned is also worth doing, i did both and now its dead quiet even when i rev it up sitting still.