so ive been messing with this 80m dipole for about three weekends now and i cant figure out what's going on. cut it to roughly 130 feet total according to the standard formula, center fed with RG-8X running about 65 feet down to the shack. the swr dip is showing up around 3.4 MHz instead of where i want it which is closer to 3.7 or so for phone. i trimmed it back a little thinking maybe i'd cut it long by accident but the resonant point barely moved, like maybe 20 kHz which doesnt make sense if i took off a foot on each side.

the antenna is basically an inverted V with the apex at about 35 feet off a pushup mast and the ends are only maybe 8 feet off the ground, which i know isnt ideal but thats what i can do in my yard. wondering if the low end height is loading it and pulling the resonance down? also have a 1:1 balun at the feedpoint that i built from a type 31 core, dont think thats the issue but who knows.

any ideas before i start over from scratch, which at this point im tempted to do

yeah the low end height is almost certainly your problem. when the ends are that close to the ground, the ground loading effectively makes the antenna look electrically longer than it actually is. 8 feet is pretty much in the dirt as far as RF is concerned. ive seen dipoles shift 200-300 kHz just from raising the ends from 8 feet to 15. if you can get them even up to 12-15 feet you'd probably see the resonance climb up toward where you want it without touching the wire length at all.

also worth checking if there's anything running parallel to the antenna close to it, like a fence or a gutter. those can do weird things. the fact that trimming barely moved it is a bit odd but low end height is still my first guess.

had almost the exact same thing happen with mine last fall. turned out my coax was picking up common mode current and basically becoming part of the antenna. the balun wasnt doing much because i hadnt wound enough turns, i think i had like 8 on the core and went to 12 and it helped a lot. not saying thats your issue but might be worth checking with a current probe or just temporarily clamping some ferrites on the coax right below the feedpoint to see if anything changes. probably still the height thing like the other guy said though