My NCE system, as soon as it is switched on , creates large noise on my AM band radio & not so much on the FM band. All locos have been isolated from the track.

Can other NCE users advise what they find with a radio next to their power buss cables please?

Dcc is a 9khz square wave signal modified to pass "words" to the locomotive  and is inherently  noisy, with modern radios and DCC equipment being plastic bodied there is no screening to prevent the radio picking up noise. The electronics to run the display and the tiny  computer inside, along with The oscillator/ clocking system will be running even when there is no output to the track.

:oops:    I found out how the noise is created - one of these which is switched on at the same time

(Click to enlarge)

Yes, switched mode power supplies have an oscillator inside as well, they too are very noisy electronically.