so i finally stopped procrastinating and just built a proper half wave dipole for 40m instead of using that crappy end-fed that never sat right with me. used 14 gauge stranded copper from the hardware store, got some egg insulators off ebay, and cut each leg to around 33.3 feet based on the 468/f formula. center feedpoint is a SO-239 chassis connector i had in the junk box mounted through a PVC end cap which i know isnt the most elegant solution but it works.

anyway my question is about the feedpoint connection itself. im getting a bit of moisture in there i think because the SWR has been drifting when it rains. i wrapped it in self-amalgamating tape but maybe not well enough. is this normal or am i missing something obvious. also my SWR at resonance is sitting around 1.4:1 which i read is fine but i kind of expected closer to 1:1 since its a dipole at half wave. not sure if thats the feedpoint impedance being slightly off from 50 ohms or if my legs arent quite equal length or what. the antenna is in kind of an inverted V config maybe 30 feet at the apex.

overall really happy with how it went though, the wire antenna is already outperforming the end-fed on receive which i wasnt sure would be the case

the moisture thing is almost certainly your issue with the drifting SWR, self amalg tape is good but you really need to start from the connector itself and work outward, make sure theres no gaps where water can wick in along the coax braid. some guys use a blob of silicone sealant inside the cap first before taping. i had the same problem with a 20m dipole i hung a few years back and once i properly sealed it the SWR stopped moving around at all.

as for the 1.4:1 — totally normal for an inverted V. the angle of the legs changes the feedpoint impedance, a flat dipole is closer to 73 ohms which is already not 50, and once you drop the legs down in that V shape it goes lower, around 50-60 ohms depending on your angle. 1.4 is honestly fine, you wont even notice the difference in transmitted power. if it really bugs you you can try adjusting the leg angle or trimming a tiny bit but id leave it alone.

yeah the inverted V impedance thing is what gets everyone the first time. i spent way too long trying to get a flat 1:1 on my first one before someone on here told me to just stop worrying about it lol. 1.4 into most rigs is a non issue.

one thing i did on my feedpoint that helped a ton — i drilled a small weep hole in the bottom of the PVC cap so any water that does get in has somewhere to go instead of just pooling on the connector. sounds counterintuitive but it made a real difference. still seal everything up top but that little drain hole at the bottom saved me