so ive been running a little rubber duck on a handheld forever and finally decided to do something real. built my first dipole for 40m, cut each leg to roughly 33.5 feet based on the 468/f formula, used 14 gauge stranded copper i pulled from some old romex i had sitting in the garage. center insulator is just a piece of pvc i drilled holes through and zip tied everything. coax is RG-8X, about 50 feet of it running back to the shack.

problem is when i tune it up the SWR is sitting around 3.2:1 at 7.150 and i cant get it below like 2.8 anywhere in the band. i expected it to be a little off but not this bad. the thing is i dont have an antenna analyzer, just watching the SWR meter on my ic-7300. the antenna is only about 18 feet high which i know is low for 40m but i figured itd at least resonate somewhere reasonable.

my feedpoint connection is where im not sure i did this right — i just stripped the coax, soldered the center conductor to one leg and the shield to the other, then taped the hell out of it with self amalgamating tape. no balun or anything. could that be the problem? or is 18 feet just too low and im seeing ground effects messing with the resonant point?

yeah the no-balun thing is almost certainly part of your problem. without a choke or 1:1 balun at the feedpoint the shield is radiating and the pattern gets all weird, and it also messes with your SWR reading because current is coming back down the outside of the coax. easy fix is just winding a few turns of the coax into a coil right at the feedpoint — like 6-8 turns about 6 inches diameter — that acts as a decent air core choke and costs you nothing. it wont be perfect but it'll be way better than what you got now.

also 18 feet is low but it shouldnt push you that far off resonance by itself. id try the choke first then retrim the legs. cut a little at a time, like an inch per side, check SWR, repeat. going up even a couple more feet would help a lot too if thats an option.

the romex wire thing caught my eye — is it solid conductor? solid copper can be a bit different to work with for antennas that move around in the wind, it'll work fineelectrically but it gets stress fractures at connection points after a while. just something to keep in mind down the road. for now your bigger issue is probaly what the other guy said about the balun, that'll fix a lot of weirdness at the feedpoint.