subseb wrote:
The Dimmer probably uses PWM or is a equivalent switched mode power
supply, unless it has a pretty large transformer on it. As the name of
this circuit topology suggests the current is switched on and off very
quickly with different mark:space ratios to give you a varying output
current. The switching for these units is typically high in the region
of 1kHZ or more, therefore the noise is actually generated from the
switching itself, and it is inherent in the design.

I would suggest moving the dimmer further away if possible or trying
another type/make.




It's not high frequency PWM, standard light dimmers vary the point in
each half cycle at which the triac turns on and completes the circuit.
This switching occurs at line frequency.