so ive been running a TM-V71A in my truck for about 6 months now and i keep going back and forth on where to mount the antenna. right now i have a NMO mount drilled through the cab roof near the back and it works okay but i feel like im losing something compared to when i had it on a magnetic mount sitting on the roof. which i know sounds backwards because the NMO should be better grounded but something just feels off.

truck is a 2018 F-150 with the aluminum body which i know complicates things a little bit. running a Larsen NMO150/450 dual band whip. on 2m i hit the local repeater just fine, maybe 35 miles out, but on 70cm it just feels weak. a buddy of mine who runs the same radio in his Tacoma with a trunk lip mount says his 70cm is noticeably better and i cant figure out why that would be.

has anyone done a NMO on aluminum body trucks and had issues? wondering if the ground isnt as solid as i think it is. i did use the star washer and made sure the paint was scraped clean but aluminum is aluminum i guess. anyway open to hearing what placements have worked for people, especially on the newer trucks with all the weird body panels

the aluminum thing is almost certainly your problem. you're not getting a great RF ground through that body even with the star washer. a lot of guys with the newer F-series trucks have moved to a lip mount on the bed rail or even a hitch mount setup with a ground plane plate. it sounds janky but the RF doesn't care what it looks like, it just wants a solid counterpoise.

what i'd do is grab a cheap SWR meter and actually check it on both bands, wouldnt be surprised if your 70cm SWR is running kinda high and robbing you of power before it even gets to the antenna. the Larsen is a good antenna but its only as good as its ground. also worth checking the coax connection at the mount itself, ive seen a surprising number of NMO installs where the center pin wasnt making great contact and it was fine on 2m but fell apart on 70cm

yeah dont feel bad about this one, aluminum trucks are kind of a pain. my neighbor went through the exact same thing with his Silverado -- wait that might be steel still, nevermind. but anyway i run a mag mount on my SUV and honestly for just hitting repeaters around town its been totally fine. i know purists hate mag mounts but if it works it works right

what repeater are you trying to hit on 70cm? just curious if maybe the repeater itself is the issue and not your setup