> Has anyone used the ANC-4 antenna noise canceller.....does it REALLY
> work?
The ANC4 as well as the MFJ1025 noise canceller might work.
These units are really variable phase shift networks with amplitude
controls and a combiner. What they do is combine the signals from
two input ports after one channel is shifted in phase.
What you do is install a noise antenna as close to the noise
source as you can, and phase it against your main antenna. You
can also use this unit to phase two antennas together for receiving,
and add desired signals to make them stronger or null unwanted
signals.
If you hear the same noise bothering you on your main antenna
clearly on the noise antenna, you can get a real deep null. 50-60
dB is not unusual for the null of a groundwave signal.
If noise or QRM comes from multiple sources, or changes
directions or angles, the nulling effect can be much less dramatic.
The MFJ is certainly the better unit of the two. The MFJ unit has
much better amplitude stability when you adjust phase, and more
phase adjustment range. I used a homebrew enhanced version of
the MFJ for years to phase receiving antennas, and to tell the
direction of incoming signals.
73, Tom W8JI
W8JI@contesting.com
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