So ive been messing with this install for about three weeks now and its mostly working but something is still off. Running a Yaesu FTM-400 in my F150 and the antenna is a Tram 1185 on a mag mount right now, center of the roof. SWR on 2m reads around 1.3-1.4 which i know isnt terrible but on 70cm it jumps up to almost 2.1 near the top of the band and i cant figure out why.

The coax run is about 12 feet of RG-58 going through the door jamb rubber seal, which i know isnt ideal but i dont want to drill. The radio itself is mounted under the dash on a RAM mount and everything looks clean to me. Power is going straight to the battery through an inline fuse.

I tried adjusting the antenna tip but it barely changed anything. Anyone dealt with this with that antenna specifically or with mag mounts in general? Part of me is wondering if its the coax routing through the door seal thats pinching something but i cant really see any damage. Really just want to get this dialed in before the club's simplex net on Saturday.

That SWR on 70cm with a Tram 1185 honestly sounds about right for a mag mount with RG-58 going through a door seal. The 1185 is a decent antenna but its pretty sensitive to what its sitting on and how the coax exits — if the cable is getting kinked or compressed anywhere at that door jamb it can definitely mess with the impedance match, especially up at 440 where everything is more fussy.

If you can, try routing the coax out differently even just temporarily, like hanging it out the window with the glass down just to test, and see if the 70cm SWR changes. If it does, thats your answer and you might want to look at running the coax through the firewall or finding a flatter coax profile for that door seal. Some guys use LMR-240 ultraflex for exactly this reason. Also worth checking if your PL-259 connection at the antenna base is fully seated, I once chased a high 70cm SWR for two days and it turned out the connector wasnt quite tight.

yeah the door seal thing is probably it, i did basically the same install in my Tacoma and had to switch to a thinner coax to stop the squishing. 2.1 on 70cm isnt gonna hurt anything though tbh, the radio will just back off power a little. good luck on the net saturday