so ive been trying to build my first real dipole from scratch for 40m, just plain old 14 gauge stranded copper wire i had sitting around from some old lamp cord, cut each leg to roughly 33 feet based on the 468/f formula. coax comes up from the shack, i soldered the center conductor to one leg and braid to the other, taped it all up with self-amalgamating tape pretty well i thought.

the issue is my swr is sitting around 2.8:1 at 7.150 and i cant seem to get it lower than that no matter what i do. tried trimming a bit off each side but its just not behaving like i expected. the antenna is about 20 feet up, inverted V config, apex tied off to a tree. im using a ft-891 and a basic swr meter in line.

not sure if its the height, the wire type, the coax length, something with the feedpoint... honestly i dont know where to start. any ideas what the usual culprits are for this kind of thing

2.8 isnt terrible for a first build honestly, could be a bunch of things. height is definitely a factor — 20 feet is kinda low for 40m, you want at least a quarter wave up if you can manage it, and an inverted V with that low an apex is gonna have the ends pretty close to ground which affects resonance and pulls the impedance all over the place.

also lamp cord wire — is it stranded? stranded wire has slightly higher velocity factor than solid and that can shift your resonant point a bit, usually means you need the legs a touch longer not shorter. i'd stop trimming for now honestly.

the coax length can also matter more than people think when you dont have a choke balun at the feedpoint. RF can ride back down the outside of the coax shield and mess with your readings. try winding about 8-10 turns of the coax into a coil right at the feedpoint — cheap and easy air core choke balun. that alone might change your swr reading noticeably.

yeah what he said about the balun is real, i had almost the exact same problem with my first dipole and adding even a crappy air choke dropped my swr like half a point. also just double check your solder joints at the feedpoint, i once had a connection that looked fine but was actually just barely touching and gave me weird readings for like two weeks before i figured it out