Well look at it has good result it's just not the one you wanted.!! . . Good because you know the cause and not ending not knowing the reason.

The fact the bob works with bench supply shows it's working so PSU would be my first choice.

The drives affecting radio is a little concerning because shows dirty system (or Crap drives) so i'd be looking at this while i'm at it. Personanly it's no brainer to me I'd dump the SMPS and go with toroidal setup. 15mins work to man of your calibre.!!