Reply to thread

yes because it is common mode noise that you are fighting, and this doesnt show on the scope.

[automerge]1743270056[/automerge]

Another good way to get low noise from DCDC is to put it in a metal enclosure.....then have a plane in the PCB which is "chassis plane"....connect the metal enclosure to the chassis plane.....and then also y capacitor connect the chassis plane to the SMPS ground plane.

This gives superb y capacitor coupling of the metal enclosure to the SMPS...and really makes it hard for any noise to escape the SMPS.

Combien it with common mode chokes  from large to small ones with low turns aswell.

Also beware noise escaping from your dummy load...you can similarly shield that off aswell....and have a common mode choke to it.