so i finally got tired of putting it off and just built a proper 40m dipole out of some 14 gauge stranded wire i had laying around in the garage. cut each leg to roughly 33.5 feet based on the 468/f formula, nothing fancy. used a piece of scrap pvc for the center insulator and drilled through it, soldered the coax braid and center to each leg. actually went pretty smoothly all things considered.

the thing is when i threw it up in an inverted V config (apex maybe 30 feet up off a fiberglass painters pole) and checked it with my antenna analyzer, the swr dip was sitting around 6.9 mhz instead of closer to 7.1-7.2 where i wanted it. not a huge deal i know i can just trim a bit off each leg but im wondering if the inverted V shape is pulling it lower like that, or if its just the wire type and environment messing with things. i read somewhere that inverted V configs tend to run a bit long compared to a flat dipole but i wasnt sure how much. also the feedpoint impedance was reading around 38 ohms which felt a bit low to me — is that normal for this config or should i be worried about that

yeah the inverted V thing is real, the angle of the legs affects the resonant frequency and you almost always end up needing to trim some off after you get it in the air. the closer those legs get to vertical the weirder it gets. at a 120 or 130 degree included angle youre usually pretty close to flat dipole territory but below that the velocity factor of the geometry or whatever starts pulling it down in frequency. just trim maybe half an inch to an inch at a time off each leg symmetrically and keep checking, youll find it.

the 38 ohm feedpoint thing is also pretty normal for inverted V. flat half wave dipole in free space is that classic 73 ohms but inverted V with legs drooping like that brings it down, ive seen anywhere from 35 to 50 depending on the angle and height above ground. should be fine with 50 ohm coax honestly, the mismatch is small enough the radio wont care and a tuner can handle it easy if needed. sounds like you did everything right, just needs a little trim.

nice work getting it up. i did basically the same thing last spring for 20m and had almost the exact same experience, dip was too low and i panicked thinking i messed something up. ended up trimming like 3 inches total off each leg and it came right up to where i wanted it. pvc center insulators work great btw, ive been using them for years, just make sure you seal the ends somehow if its gonna be outside, water gets in and does weird stuff over time. i just hit mine with some silicone.