so i spent most of saturday running coax and getting my FT-7900 bolted under the dash and honestly the install looks pretty clean if i do say so myself. ran the power leads direct to the battery with an inline fuse which i know some people skip but i wasnt gonna do that. antenna is a NMO mount i drilled through the roof which was terrifying by the way, first time i ever drilled into a vehicle roof.

anyway everything powers up fine and i can hit the local repeater no problem on 2m but when i checked SWR on the 70cm side its sitting around 2.5 which seems high. the antenna is a Diamond MR77 which i thought was supposed to be a decent dual bander. coax is about 12 feet of LMR-240 with PL-259 connectors that i soldered myself. im wondering if maybe i messed up one of the connectors or if the antenna needs some kind of tuning which i didnt think it did. havent had a chance to pull the antenna off and check the connection at the mount yet. anyone dealt with this before

first thing id check is that NMO adapter connection at the base of the antenna — those can look fine and still have a bad connection. also how big is your ground plane? if you mounted it off center or near the edge of the roof it can mess with the radiation pattern and affect SWR especially on the higher frequencies. 70cm is way more sensitive to that stuff than 2m is. my first mobile install i had a similar reading and it turned out the center pin on one of my PL-259s wasnt fully seated into the SO-239 on the radio. just wiggle the coax near each connector end while watching the SWR and see if it changes at all, that usually points you right to the problem.

yeah 2.5 on 70 is annoying but honestly your radio will probably survive it for now while you track it down. i had a Diamond NMO antenna a while back that was just slightly loose at the base plate and that was enough to throw things off. the LMR-240 with hand soldered connectors is usually fine but 70cm doesnt forgive sloppy connectors the way 2m does. if you have access to a cheap antenna analyzer even a NanoVNA you can sweep it and see exactly where its resonant which makes finding the problem way faster than just poking around. good luck with it, clean installs like that are worth getting right