I am a fan of old portable radios. Early radios of that time didn't come with a power supply, you had to power them with batteries. I do not want to use batteri

I am a fan of old portable radios. Early radios of that time didn't come with a power supply, you had to power them with batteries. I do not want to use batteries yet pretty mich every power supply I use these days causes either bad rf via the device itself feeding into the antenna or via the power wire. Any advice for a stable low-cost stabilized dc swotching power supply which does not exhibit this terrible behaviour?