Stick a fork in her boys, she's done.
I've been getting increasingly erratic readings from my NanoVNA over the last month. I initially chalked it up to a bad connector or cable, because I'm hell on RG316, and it's been pretty intermittent. So I cut off and replaced every BNC in the county over the last 2 weeks and even updated the firmware just in case. But the nanoVNA would still work just enough to make me think that it might not be the issue.
Well, I'm calling it after today. It kept giving me nonsensical readings while setting up my new 6m omni. I checked the balun to make sure it was good, and it showed only 6db of common mode suppression, while I know it from past experience that it's good for 25-ish db.
So I ran an SWR sweep on a known-good 40-10 EFHW, and it gave me the the results in the pic above. I guess now I gotta decide if I want to get another NanoVNA or a RigExpert.
R.I.P. Aursinc NanoVNA-H, 2023-2026. We hardly knew ye.