so i finally got around to building a 40m dipole after years of just using a cheap vertical i bought off amazon. used some 14 gauge stranded wire i had lying around from an old project, cut it to the formula lengths and hung it inverted-V style off a mast in the backyard. center insulator i made from a piece of PVC i had, drilled holes and zip tied the coax through it. pretty proud of it honestly.

anyway my question is about the feedpoint. when i measured SWR it was around 1.8:1 which isnt terrible but i was expecting something closer to 1.5 or even lower since everything online says a dipole should be pretty close to 50 ohms. im using RG-8X to the shack, maybe 60 feet of it. i did NOT put a choke balun or any kind of current balun at the feedpoint, just connected the coax braid to one leg and center to the other. could that be causing current on the outside of the coax messing with my readings? ive been meaning to wind a 1:1 choke but havent gotten around to it yet. the antenna is about 25 feet high at the apex which i know isnt great for 40m but its what i have. just curious if anyone else has gone through this and what you found made the biggest difference, the balun thing or just trimming the legs.

yeah the missing balun is almost certainly part of your problem. without a choke at the feedpoint the coax shield becomes part of the radiating system which throws everything off and can cause weird SWR readings that shift when you touch the coax. i went through the same thing with my first 80m dipole. wound a 1:1 choke on a FT240-43 toroid, like 9-10 turns of the coax, and the SWR dropped and stabilized noticeably. 1.8:1 isnt going to hurt anything but its definitely worth sorting out the common mode problem first before you start trimming because you might end up chasing your tail cutting wire based on a reading thats being influenced by the coax anyway.

also 25 feet on 40m is gonna give you more NVIS-ish radiation which isnt the worst thing depending on what youre trying to do. if youre working regional stuff its actually fine. for DX youd want it higher obviously but work with what you got.

im in the same boat, built a similar thing last fall and honestly just left it without a balun for a while. worked fine, made contacts, didnt overthink it. eventually i did add one and it did clean things up a bit but i wouldnt stress over 1.8. thats totally usable. the zip tie through PVC trick is something ive done too, just make sure you use UV resistant zip ties or theyll disintegrate in a season or two, learned that the hard way lol