so I've been putting this off for way too long, always figured I'd just buy a commercial antenna but after pricing out some of the decent ones I figured why not just build one. ended up cutting a 40m dipole from some 14 gauge stranded copper wire I had laying around in the garage, fed it with some RG-8X I had from an old project. center insulator is just a chunk of PVC I drilled through and sealed with some silicone.

got it up in an inverted V config about 28 feet at the apex which I know isnt ideal but thats what my tallest tree will give me. SWR is sitting around 1.4:1 at 7.150 which honestly surprised me, I was expecting worse for a first build. I did trim it a few times to get there.

my question is about the feedline length — ive been reading about the whole thing where certain feedline lengths can cause issues depending on the impedance and I'm not sure if my 35 feet of coax is going to cause any weirdness. also wondering if I should bother with a 1:1 choke balun at the feedpoint or if that's overkill for casual HF use. I have a tuner on the rig but haven't needed it yet at 7.150.

congrats on getting it up, 1.4 on your first trim is pretty solid honestly. on the feedline length question — for a coax fed dipole you dont really need to worry about specific lengths the same way you would with ladder line or open wire. the coax shields it from that kind of interaction. what you DO want is a choke balun or at least a few turns of coax wound into a coil at the feedpoint, not because youll notice it right away but because without one youre basically using the outside of your coax shield as part of the antenna. that can pull RF into the shack and cause weird SWR readings that change when you touch things. I built a simple ugly balun with about 8 turns of the coax itself on a 4 inch diameter form and it cleaned up some noise I was getting on receive. doesnt have to be fancy.

the inverted V at 28 feet is totally workable for 40m, your angle of radiation will be higher than a flat top but for domestic contacts and general ragchewing its fine. if you ever want to try DX you might notice it, but dont let anyone tell you its not a real antenna because it absolutely is.

yeah im basically in the same boat, built a 20m dipole last spring and went back and forth on the balun thing for a while. ended up just winding one from a piece of mix 31 ferrite I ordered, worked out fine. your swr sounds good though. one thing I noticed with my inverted V is the legs want to droop more than I expected over time especially with any wind, worth checking your wire tension every few months if the ends are just tied off to stakes or something low.