so i finally decided to stop putting it off and just build a simple half wave dipole for 40m. cut both legs to around 33.3 feet each based on the 468/f formula, fed it with some RG-8X i had laying around and a SO-239 connector i pulled off an old radio. hung it up in an inverted V config from a tree in my backyard, apex probably at around 30 feet.

the problem is my SWR at 7.1 MHz is reading like 2.8:1 which isnt terrible i guess but i expected to get closer to 1.5 or better. tried trimming a couple inches off each leg and it barely moved. the resonant point seems to be way up around 7.4 or 7.5 which is weird because i feel like i cut it long enough. im using a MFJ-259 to sweep it and the dip is definitely up higher than i want. also not sure if the inverted V configuration is affecting things — i read somewhere that it changes the effective electrical length? anyway just wondering if anyone has dealt with this and whether i should be adding length back on or what

yeah the inverted V thing is real — when you drop the ends down like that it does effectively shorten the antenna a bit electrically, so the resonant frequency shifts up compared to a flat top. some people add a few percent to their initial cut length to compensate, like maybe start with 72 feet total instead of 66.6. also worth checking your feedpoint connection, a bad solder joint at the center insulator can do all kinds of weird stuff to your readings. what are you using for a center insulator? if you just twisted the wires together and taped it thats probably part of the issue too. the velocity factor of RG-8X is around .82 so that shouldnt be throwing off your measurements on the antenna side, but make sure your analyzer is connected right at the feedpoint when you sweep, not at the end of a long coax run or the readings wont mean much

i had almost the exact same issue with my first dipole, spent like two weekends messing with it. ended up being that my coax was acting like part of the antenna because i didnt have a choke or anything at the feedpoint. threw a few ferrite beads on the coax near the connector and the SWR dropped almost a full point. common mode current on the shield is sneaky and the MFJ wont tell you thats happening, it just shows you a weird SWR curve that doesnt respond to trimming the way you'd expect. might be worth trying before you start cutting more wire off