"ve3..." wrote in message
oups.com...
The device is a Timewave ANC-4 Antenna Noise Canceller. It has
excellent reviews in eham. www.eham.net/reviews/detail/1138

MFJ makes one also. But keep this in mind- it is not magic. The principle is
that it picks up noise on a sense antenna. You match amplitude and invert
the phase of the noise and then add that to the signal+noise coming in from
your RX antenna. Theoretically the noise cancels itself.
This will NOT work with multiple noise sources as the amplitude and phase
will be different for each source. If you have one dominant noise source,
like an arcing power transformer, it may be worthwhile.
Dale W4OP