In article c49Dg.368$Ji1.130@trnddc05,
Amerigo Vespucci wrote:

Would a heating pad cause RFI ? My wife has intermittent back problems and
when she uses her heating pad it seems I get spikes of RFI on my AM
reciever.

That's distinctly possible. Almost any load on the powerline can
create RFI (either radiated or conducted) if its load-switching
circuits cause sudden current changes on the line.

It's possible to build AC power-switching circuits which minimize
current transients and thus minimize radiated EMI. If I recall
correctly, good ones will switch on when the AC voltage crosses
through zero, and switch off when the AC current passes through zero.

Your wife's heating-pad controller or thermostat may very well have a
cheaper switching circuit which pays no attention to the powerline
phase. If so, it'd probably generate a short spike of noise whenever
the heating current was turned on or off.

You could try plugging the pad into a good AC power-line filter,
and/or using a snap-on ferrite or two on its power cord (wrap the
ferrites in soft flannel :-)

--
Dave Platt AE6EO
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