so i've been putting this off for like two years but i finally just sat down last weekend and built a simple half wave dipole for 40m out of some 14 gauge stranded wire i had in the garage. cut each leg to roughly 33.5 feet using the 468/f formula, soldered it to a so-239 i had in my junk box, wrapped everything in self-amalgamating tape because thats all i had on hand.

threw it up in an inverted-v config between a tree and my deck railing, apex is maybe 25 feet up which i know isnt ideal for 40 but its what i have. swr is reading around 1.4:1 at 7.150 which honestly surprised me, i was expecting worse. made a few contacts into the midwest from here in the northeast and the signal reports were decent enough.

couple things im not sure about though — i didnt use a balun and ive been reading conflicting stuff about whether that matters for a basic dipole fed with coax. also the feedpoint connection is just soldered and taped, no weatherproofing box or anything, and im wondering how long that'll hold up. this is kind of a permanent install if it works so i want to do it right. any suggestions from people who have actually built a bunch of these?

the 1.4 swr without a balun is probably fine for casual use but you might start noticing rf on the coax braid messing with your radio, especially if you're running any real power. common mode current is a real thing and it can cause weird interference patterns and sometimes just makes your audio sound off. a simple 1:1 choke balun wound on a toroid or even just coiling the coax a few times near the feedpoint helps a lot. some guys argue its unnecessary for a basic inverted-v and honestly for qrp it probably doesnt matter much but if you ever go higher power its worth doing right.

the weatherproofing though, definitely address that sooner than later. soldered connections exposed to the elements will corrode faster than you'd think especially if you get freezing temps. i use those self-fusing silicone tape wraps plus a layer of vinyl tape over it, and then i'll sometimes put a small plastic project box over the feedpoint if i can manage it. some guys just use a pvc cap glued over it. coax seal putty is another option but its messy. your 25 feet inverted-v is actually pretty reasonable for 40, the angle of the legs affects the radiation pattern some but youre definitely getting out if you made contacts already so dont overthink it.

yeah im in a similar situation built a 20m dipole last spring and skipped the balun and never had any issues but i also only run 100w. the feedpoint weatherproofing thing bit me though, mine started acting up around 8 months in and when i took it down the solder joint had some green corrosion on it and the swr had crept up to like 2.8. now i just use a short piece of pvc pipe as a strain relief and wrap everything pretty aggressively with the self amalgamating tape. seems to be holding up better so far anyway