In article , lsmyer
wrote:

When we moved into this house a few years ago, I was really disappointed
about the radio noise. Someone suggested that a dimmer switch might be
to blame, but this house only had one and it was in the far corner of
the house on a different floor and it wasn't even turned on. But I went
ahead and replaced it with a regular switch, and it was amazing how
quiet our house had instantly become.

Since then, we added cable internet and a wi-fi network with four
computers and two wireless keyboards and now it's nearly as noisy as the
old dimmer switch days.

Usually if the dimmer switch is off or fully on it does not make much
noise. Why you ask? They way they work is to switch a portion of the 60
Hz cycle on and off to the light. When very dim the switching device is
off most of the cycle and is on more of every cycle as you cause the
control to brighten the light. When full on the switching device is on
all the time and when the control is fully off the switching device is
off all the time. It is only when it is between the two extremes that
the switching device turns on and off every 60 Hz cycle. It is that
switching that generates the pulse noise. This square wave pulse noise
is very broadband in nature being composed of many frequencies.

--
Telamon
Ventura, California