The linear power supply is not efficient but it does not create large amounts of RF interference. The cheap SMPSes leave out the inductors and capacitors that filter out the RF interference, making them cause any receiver to receive “hash” – constant noise that blocks reception.
I put a power line filter at the power input of a 30V, 10 amp adjustable power supply and it dramatically reduced the interference it was causing. It’s all about money. They cut corners to make it cheaper and the result is your AM and other radios can no longer receive distant stations and local stations are affected too.
Switch Mode Power Supplies Cause RF Interference
