so I finally decided to stop being lazy and build my first real dipole from scratch instead of buying one of those end-fed things everyone seems to be using lately. cut it for 40m using the standard 468/f formula, ended up with roughly 66 feet total, split in the middle at my SO-239 connector soldered to a small piece of coax and then out to the wire elements.

problem is im getting an SWR of like 2.8:1 right at 7.150 which is where I was aiming. tried trimming a few inches off each side and it barely moved. the resonant point doesnt seem to be where I expected it either, the analyzer shows lowest SWR around 6.9 MHz which is a bit low. antenna is up maybe 25 feet in an inverted-V config, center fed with about 50 feet of RG-8X down to the shack.

I used 14 gauge stranded copper wire from the hardware store which I know some people say is fine and some say causes issues. feed point connections are soldered and taped with self-amalgamating tape. not sure what else to check honestly, been staring at this thing for two weekends now

the low resonant point is actually pretty normal for an inverted-V versus a flat-top dipole. the legs being angled downward effectively makes the antenna act a bit longer electrically, so you'll usually need to trim some compared to what the formula gives you. 25 feet at center isnt super high either which can affect things.

the 2.8 SWR at resonance is the more interesting part. if the antenna is actually resonant (low reactance) but still showing that SWR number, the feedpoint impedance might just be sitting lower than 50 ohms, which can happen with inverted-V geometry — some people see impedances in the 35-45 ohm range depending on the angle of the legs. thats not a huge deal for most rigs with internal tuners, or you could look at using 75 ohm coax as a matching section. but first I'd double check your connector isnt introducing a short or cold solder joint, ive been burned by that before on a SO-239 build where I thought the solder flowed but it really didnt make contact properly.

stranded copper from the hardware store is totally fine btw, I've built probably a dozen antennas with it and never had a problem related to the wire itself. if anything the solid copper is slightly better electrically but the difference is minimal at HF frequencies, its basically a myth that it causes issues.

one thing I didnt see you mention — what are you using at the ends to tension the wire? if the ends are sagging a lot the effective length changes and ive seen guys chase resonance for days not realizing one leg was drooping way more than the other. also your coax run going down to the shack, is any of it running parallel to the antenna elements? that can cause some weirdness with common mode current and mess with your readings. adding a few ferrite chokes or a simple 1:1 choke balun right at the feedpoint usually clears that up and makes the whole thing behave a lot more predictably.