Topband: Slightly OT - amplifier noise

[Richard (Rick) Karlquist]

I am trying to understand what these noise cancelling
schemes do that couldn't be done with a simple loop
(rotating the loop until the noise drops into one of
the null directions).  You can easily prove to yourself
with a hand held AM BCB receiver equipped with a ferrite
bar antenna that even the worst power line noise can
almost always be greatly suppressed by properly rotating
the receiver.  Similarly, I have had good luck with
small tuned loops (10 feet perimeter) nulling power
line noise.  Smaller loops seem to have deeper nulls.

It is critical to keep loops away from your other antennas
and power wiring.  Otherwise, they will not exhibit a
good null.

Rick N6RK