so i finally got around to building a 40m dipole from scratch instead of buying one, figured how hard can it be right. used some 14awg stranded wire i had sitting in the garage, cut each leg to around 33.3 feet, and threw it up in an inverted V configuration with the apex at about 35 feet tied off to my chimney. center insulator is just a piece of i had laying around from an old CB antenna i scrapped years ago.

heres where im a bit confused though. when i measured with my nanoVNA the SWR at resonance came out pretty good, like 1.4:1 around 7.150, but the feedpoint impedance was reading closer to 40 ohms instead of the 50 i expected. i used RG8X coax running about 60 feet to the shack. not sure if the inverted V configuration is pulling the impedance down or if i did something wrong with the build. also the resonant point shifted down a little from where i calculated it would be, which i kind of expected but wasnt sure by how much.

antenna is working, made a few contacts last night no problem, just want to understand whats going on with the numbers before i call it finished. anyone dealt with this before?

yeah the inverted V angle does that, its pretty normal. when you fold the legs down like that the feedpoint impedance drops compared to a flat dipole, how much depends on the angle of the legs. if your legs are at like 120 degrees or less from each other youll see it pull down toward the 40ish ohm range pretty consistently. 1.4:1 into 50 ohm coax is totally fine honestly, most rigs wont even blink at that and your tuner if you have one will knock it flat no problem.

the resonant frequency shifting lower is also normal with wire antennas, the velocity factor of the wire itself and nearby objects like your chimney or whatever trees you used all affect the electrical length. most guys just cut a bit long intentionally and then trim until they hit where they want. sounds like yours landed in a reasonable spot anyway. id just leave it and work some dx.

what kind of balun did you use at the feedpoint? or did you just connect the coax directly? asking because ive had weird impedance readings before that turned out to be RF coming back down the coax shield and messing with the nanoVNA measurement, a simple 1:1 choke balun made a big difference for me. even just winding a few turns of the coax through a mix 31 toroid near the feedpoint can clean things up a lot. not saying thats definitely your issue but worth checking before you assume the numbers are final.