Jim, thank you a lot for the detailed information. I will be able to do some surgery on one of the NanoVna gen111.taobao.com firmware, which I updated to 0.3.0m. I will have to check the schematics for it.
Not that I want to deviate to much for the topic of measuring high impedance of vertical, but to bring back a way to update the old technologies like the OIB meter.
"Is there a reason you need high power for the test?"
When you are one of those blessed with a 50KW AM BC nearby and trying to measure the Z of a top hat loaded vertical or inverted V seems a bit of a challenge. After filtering the BC station a lot, I end up with a 10Watts at the end of the feed. Seems like I need some power to fight back.
Patty.
