Most likely the reason the noise changes when you switch
your light on is there is a small line voltage drop. This
would cause a free running oscillator such as used in
switching power supplies to shift frequency. I think that
because your light changes this that the problem is very
close to that circuit if not on the same one.
You simply need to turn off all the breakers in your house
and see which one stops the noise. There are hundreds of
things this could be. Do you turn on the light in a fish
aquarium in the eve. Do you have a touch light in a china
cabinet that gets turned on? Do you have a programmable
temperature on your water heater, the list goes on and on.
A small BC band radio and turning off your breakers will be
very informative. Barring finding anything atyour house you
need to do the same thing at your neighbors. Do you share
a power transformer with any of them?
Lee K7TJR OR
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