You are right ff ... I forgot and it was a stupid memory blank for me as I have tested some of those units right here (on a dummy load of course... yes really a dummy load... honest... I wouldn't kid you... <sigh>).
I was amazed at the overall frequency coverage and my stomach kinds sorta turned over when the thought passed that some evil person could raise hell with these devices.
I had 2 identical units just by chance , one was relativity clean but the one was dirty as all get out. Same design, board, parts, layout, power supply, etc... so the only thing that could be different were the active component quality... voltages seemed the same but... something was wrong.

Lacking a full lab I never wrote this up. Maybe someone with a complete lab could try this same experiment...

Oh well, I'm too old and worn out to enter into such matters

Later and thanks for giving my memory a much needed kick