so i've been running my FT-7900R in the truck for about three weeks now and i thought i had everything sorted out but theres this weird buzzing noise that comes through the speaker whenever i transmit, kinda sounds like engine noise or alternator whine or something. it gets faster when i rev the engine so im pretty sure its related to that.

i ran the power cable direct to the battery which i thought was the right way to do it, and the antenna is a mag mount on the roof right now until i can figure out where to do a proper mount. the ground wire for the radio goes to a bolt under the dash which seemed convenient at the time but maybe thats the issue? i dunno. everything else works fine, reception is good, people can hear me okay i think but i havent really asked anyone to give me a signal report while driving.

anyone dealt with this before? im in a 2019 F-150 if that matters

yeah that's almost definitely alternator whine, classic symptom when the pitch changes with engine RPM. the ground to the dash bolt is probably your culprit honestly. those points under the dash are usually not great for RF ground and you can get all kinds of noise coupling in from the vehicle electronics.

what i'd try first is running a dedicated ground wire from the radio chassis directly to the battery negative, same as you did with the positive. keep both runs together and as short as practical. if that doesnt fully fix it you might need a ferrite choke on the power leads or even an inline noise filter, but try the ground first because that's usually 90% of the problem. also worth checking that your coax shield has a solid ground path too — mag mounts can be iffy on that depending on the truck's paint and contact surface.

had the exact same thing in my Silverado when i first put my 2320 in. drove me nuts for like a month lol. ended up being the ground like the other guy said but i also had to move where my coax was routed because it was running too close to some of the truck's wiring harness and picking up noise that way too. took a while to sort out but its dead quiet now. mag mounts on modern trucks can be a pain because the roof isnt always making great contact through the paint