so i've been running a ft-7900r in my truck for about 3 months now and i think i finally have it mostly dialed in but there's a couple things still bugging me. the radio itself is great, no complaints there, but i'm still not 100% happy with the antenna situation. right now i have a nmo mount drilled through the roof near the rear passenger side and im using a diamond mr77 which is a decent dual band whip but i feel like im losing some signal compared to when i had the same radio in my old car with a mag mount stuck on the trunk lid.

i know mag mounts arent ideal but the ground plane on that trunk lid must have been better than i thought? or maybe the roof mount placement isnt great idk. the nmo connection looks solid and the cable run through the headliner seems fine, no sharp bends or anything. swr on 2m is like 1.4:1 which im not thrilled about but i read that's acceptable.

also been thinking about adding a 70cm antenna separately for aprs since i run a mobilinkd connected to my phone but not sure if that's overkill when the mr77 already does dual band. anyone done a dedicated aprs antenna just for 70cm? or am i overthinking this

1.4 on 2m is totally fine, honestly anything under 1.5 and you're not losing meaningful power. the mag mount thing is interesting though — roof center is actually better for ground plane coverage in theory but real world can vary depending on vehicle geometry. if your roof mount is near the edge or off center it can get weird. also worth double checking your pl-259 or whatever connector you used going into the radio, even a slightly loose connection will mess with readings and perceived signal.

on the aprs question, i wouldnt bother with a separate 70cm antenna unless you're having actual decode problems. the mr77 is perfectly capable for aprs use, i ran one for almost two years doing exactly that. save the second antenna port for something you'll actually notice a difference on, like if you ever want to run a separate uhf talk-around channel or something.

i had almost the exact same setup last year, ft-7900 and mr77 on a nmo roof mount. one thing i found out the hard way is that the cable run matters a lot more than i expected. i had a tiny kink in my rg58 going through the b-pillar and it was causing weird swr readings and the audio on receive sounded a little off on weak signals. once i rerouted with lmr-240 and was more careful with the bends everything got noticeably better. might not be your issue but worth checking if you ever pull the headliner back for something else anyway