so i've been putting off doing a proper mobile install for like two years now and this past weekend i finally got around to it, ran the coax through the firewall, mounted the radio under the dash on one of those cheap bracket things from amazon, and got a mag mount antenna on the roof temporarily until i figure out where i want to drill for a permanent mount

problem is on 2m the SWR is reading like 2.1 or so on my meter and im not sure if thats the antenna, the coax, or if i just did something dumb with the connections. the antenna is a diamond MR77 which i thought was supposed to be pretty decent for a mag mount. UHF seems fine actually, reads closer to 1.4 which doesnt bother me

anyone run into this with the MR77 or should i just start checking connectors first? i used PL-259s throughout which maybe wasnt the best choice but thats what i had

first thing id check is the PL-259 to SO-239 connection at the radio end, ive seen that cause weird SWR readings before where UHF looks okay but 2m is off. the other thing with mag mounts is where exactly you have it sitting on the roof makes a difference, if its too close to an edge of the roof or near a lip it can mess with the ground plane. 2.1 isnt terrible honestly and depending on your radio it might not even notice but if youre running 50w into it continuously you probably want to track it down

also the MR77 is a solid little antenna, doubt thats the problem

i had basically the same thing happen when i did my first mobile setup, turned out i hadnt gotten the PL-259 on all the way at the antenna base, like it was hand tight but not actually seated properly. took me forever to figure it out because everything looked fine visually. might be worth borrowing an analyzer if anyone in your club has one, way easier than guessing with an SWR meter