Sometime in mid-March 2026, just a few days after working 3Y0K on 40-meter FT8, my Cushcraft D40 rotatable dipole developed high VSWR and became resonant up around 7400 kHz instead of 7100 kHz. I immediately suspected something may have happened to one of the capacitance hats at the ends of the antenna. I looked at SWR curves at various points along the feedline and up on the tower in an attempt to determine if the problem was the feedline or antenna. The problem did not appear to be the feedline. I lowered the antenna a few feet to get a look at the feed point. A visual inspection did not show any signs of the problem. The rods consisting of the capacitance hats were intact but each had been repaired previously and I couldn’t tell if they were good electrically.
I didn’t have to time to take the antenna down so I left it up but I did check it every couple of days. Then on the evening on March 20th, I checked the antenna and it was resonant again at 7100 kHz. I decided I would document the antenna fully with SWR curves at each point of the feedline where there was a splice.