One point I meant the make was that while each individual component of
a 'system',
such as a typical PC, may meet FCC class B regulations, and in fact,
each component
may not be a serious RFI source.

But when all the individual components are connected, the combined RFI
will almost
always be be much higher then might be expected.

The same issue applies to 'home theaters' systems. Each component will
likely meet
the Class B requirements but when interconnected will almost always be
significant
RFI sources.

Telephone answering machines combine a power supply, a logic control
system, and
bridges two sets of conductors, the AC mains and the telephone line,
and are often an
overlooked significant RFI source.

A coworker mentioned the new refrigerator he just bought has a
variable speed compressor
for greater efficiency, and an electrician friend says that he just
received some Panasonice
window Air Conditioners that have variable speed compressors. I would
guess as the
technology matures, we can expect to see variable speed drives for
many motors.

Since these variable speed drives all rely on the same basic single
phase to three phase
conversion, they will all be strong contenders for RFI source from
Hell.

Home Ethernet networks are very high on the potential RFI problem
list. The fact that they
are connected to a hub that derives power from the AC mains, and are
connected to PCs
and have significant cable runs all conspire to produce a system that
can be very problematic
to mitigate. We went with WiFi because I don't care about RFI at
2.4GHz. I am willing to
trade LW/MW/SW RFI for microwave RFI .

Bug Zappers are a major RFI source and are ineffective in controlling
mosquitoes, instead
the kill insects that pray on mosquitoes.

Terry