I purchased a NanoVNA-F a few weeks or months after first buying a 2.8 inch NanoVNA. I wanted the -F for its MUCH better screen - I could not read the screen of the first, smaller unit while outdoors testing and adjusting my antenna. I had to connect it to the 'in-the-shack' end of the antenna cable and go inside and to the far end of the house to see if I adjusted the antenna correctly. Then back out for the next re-adjustment.
Operation of the -F and -H is nearly the same, and it's easy to switch between them. I do still use my 2.8 inch -H while I'm in the ham shack checking an antenna that's standing out in the yard or strung up in the nearby trees.
I have not seen the screen of the -H4 and can't really comment on its usefulness, but I DO consider the -F to be definitely the best choice. If I lost mine and had to replace it, I would certainly get another -F. If you use your Nano outdoors, you'll be glad you got the -F.
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Doug, K8RFT
