To give the nanoVNA a tougher test I tried measuring the Q of a small 50uH inductor across LF to 3MHz. In the plot below it struggles to indicate the Q as the data is very noisy and uncertain. The measurement would benefit from some averaging but it indicates a peak in the Q somewhere around 450 at about 700kHz. Clearly this inductor is at its best across 300kHz to just over 1MHz where it delivers an impressive Q factor. I think the nanoVNA is doing very well here although it would be best to measure the Q using a decent Q meter or by using the nanoVNA in a different way to measure Q.
