Why does your alarm clock radio still make a crackling noise even when turned off The noise is intermittant and is very low but the noise is a concern and it continues all day?

Answer 1

You didn't describe the type of clock radio or age so the following are just guesses to apply to your situation.

Unplug the radio from the wall. If the noise still persists, it isn't the radio, but something else around the radio.

Is the clock and old fashioned mechanical clock. If so it could be the clock motor.

The radio could still be on when you think it is off. This is possible in some models where the on/off switching is electronic rather than mechanical.

There is something living inside the clock radio. Sound will persist even when unplugged.

There is a strong electromagnetic field in vicinity of radio which is causing a resonance frequency in the radio electronics even when off. Move the radio to another part of house and see if sound changes.