Wow, so I just did a simple test after getting my new unit. I updated the firmware (took <5 minutes) and downloaded and ran the Nanovna-Qt application. Then I 1-port calibrated and tested 4 dummy loads (well, one was the calibrator) as a way to test units. I haven't read the doc yet (my bad).

Three of the loads looked virtually perfect - which is great confirmation of the unit.

One of the loads (bought via Amazon) was interesting. I'm including the flat-line (one of 3 of them) and the not-flat-line. Wow this unit rocks. There's very little noise showing and the fact that all three loads matched up so flat is just really impressive as an out-of-the-box experience.

Mark