My 2205 has this peculiar behaviour of not showing the correct harmonics. One varies the input level and the f2,3,5 (ref 1Khz) all shoot up/down as if the input to the A/D converter is showing harmonics related to amplitude. No it's anti-aliasing- The input is well below warning exclamation. Whats the reason: poor decoupling on 2205 ?
Other instruments don't have this varying harmonic representation with input level. So in the field it's impossible to get the true picture.