> I have my computer monitor setting just above my amplifier, and
> when I turn the amp on, I can see the 60 cycle vibrations on the
> screen. Somehow the power transformer is interfering with the
> monitor so guess the magnetic field must be getting through the
> case somehow. 73
Skin depth is pretty thick in most materials at 60 Hz, that why
effective shields on low frequencies are generally ferrous materials,
to divert the magnetic flux. The amp probably was not designed to
shield 60Hz, but rather to shield 1.8 MHz and higher, so the
cabinet material might be aluminum or thin steel.
A time-varying magnetic field won't pass through conductive
materials more than several skin depths thick, but of course skin
depth increases with decreasing frequency.
73, Tom W8JI
W8JI@contesting.com
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