Part of the problem here in the US is that practically all modern computer switching power supplies interfere with the AM band, along with flourescent lights, televisions, rangetop stoves, computer monitors, medical equipment, etc. etc., the list is almost endless. But most nights I can pick up 650 WSM, the Grand Ole Opry, out of Tennesse loud and clear. Best heard on a big ole honkin' console from the 1930's.
Make that "cheap" switching PSUs. If you look in some of them, you might find silkscreening for capacitors that have just wires instead of caps.
Heck, I my PDA on battery generates static if I put it next to a pocket radio.