so i picked up a used FT-7900R a few weeks ago and spent last weekend doing the install in my Tacoma. overall pretty happy with how it turned out but i have a few things bugging me.

first the power wiring - i ran it direct to the battery with an inline fuse like everyone says to do, but the run was kind of long so i used 12 gauge wire. at 50 watts is that going to be okay or should i have gone heavier? i feel like i read somewhere that 10 gauge is better for anything over 30 feet but im not sure i remember correctly.

also the antenna situation. i have a Tram 1185 on a lip mount on the trunk lid. works fine but i get some engine noise when i rev up, kind of a whine that changes with RPM. ive been poking around forums and it sounds like a grounding issue but i cant figure out where the noise is coming in. the antenna feedline is just the stock one that came with the radio, maybe 18 feet. tried a ferrite choke near the radio and it helped a little but didnt totally fix it.

otherwise the radio sounds great on the local repeaters and i made it into a linked system about 60 miles out last night which was pretty cool for my first real mobile contact. just want to get the buzzing sorted out before my wife starts complaining that it sounds broken lol

congrats on the first install, that's always a satisfying weekend project. for the wire gauge question, 12 gauge is honestly right on the edge for a long run at 50 watts. the FT-7900 can pull close to 10-11 amps on transmit at full power, and if you're pushing that through 30+ feet of 12 awg you're going to see some voltage drop. not dangerous but the radio might not be super happy. if you ever notice it acting funny on transmit or the power output seeming low that's probably why. worth upgrading to 10 gauge when you get a chance, it's not a huge job if you leave the fuse holder in place and just swap the wire.

the alternator whine is a classic problem and the ground is almost always the culprit. thing people miss is that the antenna mount itself needs a really solid RF ground to the vehicle chassis, not just the coax shield. lip mounts can be tricky because they're sitting on painted metal. try running a short braided ground strap from the mount base directly to a chassis bolt nearby and see if that changes things. also check where your radio's negative lead is going - if it's on the battery negative and the radio chassis isn't grounded separately that can cause issues too.

yeah the alternator whine thing drove me crazy on my first install too. for me it turned out the coax was running too close to the power wire for like half the length under the carpet and that was basically acting like an antenna picking up all the electrical noise. once i rerouted them on opposite sides of the car it mostly went away. might be worth checking if yours are bundled together anywhere.

also 60 miles on a linked repeater from a mobile is pretty solid honestly, those linked systems are addictive once you discover them