so i picked up a used FT-7900R a few weeks ago and spent last weekend getting it installed in my F-150. ran the power leads straight to the battery with an inline fuse on each lead, antenna is a Larsen NMO mount on the roof, coax down through the weather stripping on the door frame. honestly pretty proud of how clean it came out visually.

but now when i key up or even just when the engine is running i get this whine that goes up and down with the RPMs. its not terrible but its definitely there and i know its not supposed to be. ive read a bunch of stuff about ferrite chokes and ground loops but im not 100% sure what im dealing with here. the radio itself is grounded to the chassis with a short strap near where the unit is mounted under the dash. power leads are about 6 feet long running along the firewall.

anyone dealt with this before? is this an alternator whine thing or something else? and is the fix usually the ferrite beads on the power leads or do i need to do something more with grounding

yeah that sounds like classic alternator whine, super common especially in newer vehicles with all their electronics. first thing id try before buying anything is check all your ground connections — the radio chassis ground to the truck body, and make sure the body itself has a solid bond to the battery negative. sometimes thats all it takes.

if that doesnt do it, a good quality noise filter on the power leads right at the radio usually knocks most of it out. the ones from West Mountain Radio or even the cheap ones off amazon actually work pretty well. ferrite chokes on the coax right at the radio can help too if youre hearing it come through the receiver. i had almost the exact same situation in my silverado a few years back and it turned out the ground strap to the engine block was the culprit — added a supplemental ground from the block to the firewall and the whine dropped like 90 percent. worth checking that first before you go buying a bunch of stuff.

oh man i went through this exact thing when i first installed my radio lol. mine was so bad i thought something was broken. turned out my power leads were running too close to some of the truck's wiring harness and that was coupling noise into everything. i rerouted them and it got way better. also the door frame thing with the coax — i eventually moved mine to go through the firewall instead and that helped with a little bit of noise i was still getting. not saying thats definitely your issue but might be worth looking at once you sort the power side out.