so i finally got around to building a proper dipole for 40 meters instead of just using the random wire ive had strung up for the past two years. cut two legs at roughly 33.5 feet each, used some 14 gauge stranded copper i had in the garage, and threw together a little feedpoint out of a piece of PVC and a SO-239 i pulled off an old radio. center insulator isnt pretty but it works.

anyway i got it up in an inverted-V config, apex at about 30 feet which i know isnt ideal for 40 but thats what the tree lets me do. fed it with about 50 feet of RG-8X down to the shack. SWR at resonance came in around 1.4:1 which honestly is fine but it peaked lower than i expected, like around 6.9 MHz instead of right at 7.1. i trimmed a bit off each leg and got it closer to 7.05 which is where i mostly hang out anyway.

my question is about the feedpoint connection itself. i just soldered the braid and center to the legs, no balun, and ive been reading conflicting stuff about whether i really need one for a basic dipole. common mode current is a thing i understand in theory but im not sure if its actually affecting my signal or just something people worry about. anyone running a simple dipole without a choke balun and noticed RF in the shack or other weirdness?

the short answer is you probably wont notice anything until you do, if that makes sense. i ran a dipole without any kind of choke for probably three years on 40 and 80 and never had issues. then one day my audio started sounding funny on transmit and somebody on the repeater told me i had a weird buzz. turned out the coax shield was radiating and picking up noise from my switching power supply. slapped a ugly balun on there, like 8 turns of coax through a FT-240-43 toroid, and it cleared right up.

your SWR situation sounds totally normal by the way. the inverted-V configuration does pull resonance down a bit compared to a flat-top dipole, and 30 feet of apex height on 40m means the legs are at a fairly steep angle which affects the feedpoint impedance too. 1.4:1 at your operating frequency is completely workable, most rigs wont even flinch at that. if you want to get nerdy about it the feedpoint impedance on an inverted-V with that kind of angle is probably somewhere in the 50-65 ohm range which is pretty much a natural match for coax, so a 1:1 choke balun is all you'd ever need there, not a transformer balun.

yeah i had the exact same resonance issue when i built mine, kept coming in low. for me it was partly because i measured the wire before stripping the insulation and the insulation adds a little to the electrical length, like the velocity factor thing. probably not huge but when you're trying to nail a specific frequency it adds up. might be part of what you saw.

as for the balun question i just wound 10 turns of my feedline coax around a section of 3 inch PVC pipe and called it a day, its not the prettiest solution but its free and it works well enough for casual operating. i dont do anything serious enough to care that much honestly