So after putting it off for way too long i finally installed a Yaesu FT-7900R in my truck last weekend. Dual band V/UHF which is what i wanted for hitting the local repeaters. The install itself went okay, ran the power leads straight to the battery with an inline fuse like everyone says to do, and mounted the control head up on the dash where i can actually see it.

My question is about the antenna. Right now im using a magnetic mount NMO on the roof which i know isnt ideal but its what i had laying around. Im getting into the repeaters fine but i notice sometimes when i key up theres a little bit of engine noise in the audio, like a whine that changes with the RPM. I grounded the mag mount to a bolt under the dash and that didnt really help. Is this a common thing or did i wire something wrong? Also wondering if its worth drilling the roof for a proper mount at some point or if the mag mount is good enough for just local stuff.

Also the radio itself is great, really happy with it, programming wasnt as painful as i expected once i figured out the menu structure.

The alternator whine is super common and usually comes down to a ground loop somewhere or the power leads picking up noise. A few things worth trying - first make sure your radio's negative lead is going all the way to the battery negative, not just a chassis ground point. Sometimes that alone clears it right up. You can also try a ferrite choke on the power leads close to the radio, those things work surprisingly well for just a couple bucks.

As for the mag mount, honestly for local repeater work it's totally fine. The NMO connection is solid as long as the magnet has good contact with clean metal. The one thing I'd watch is if you're doing a lot of highway driving the wind noise can get into the audio a bit depending on placement. Center of roof tends to be the sweet spot. Drilling is worth it eventually if you plan to keep the radio in that truck for a while, a good lip mount or through-hole NMO is just more solid and you stop worrying about it sliding around at highway speed.

yeah the whine thing got me too when I first set mine up, turned out my fuse holder was right next to the ignition wiring and was picking up noise that way. moved the leads around and it mostly went away. also check where your coax is running, if its near any of the vehicle's computer modules or the alternator wires it can pick stuff up

the 7900 is a solid radio btw, ive had mine for like 4 years in a work van and its taken a beating no problem