On Mon, 26 Apr 2010 23:49:12 -0500, Duane Calvin wrote:
>ANC-4 along with the MFJ noise eliminator.
Several thoughts. First, the concept is great -- for ONE noise source. If you
have more, it won't help much. Second, the ANC-4 can be a very nasty key-
click generator. I used one in Chicago, and sometimes it helped, so I brought
it with me to California. Soon after I moved in, I got a friendly call from
my neighbor, who said I had clicks 5kHz away from my carrier. It took only a
few minutes to figure out it was the sensing circuit for the carrier-operated
relay. That was the end of the ANC-4 at this QTH, at least on the TX antenna.
I've heard that the MFJ is nicer. It has the same limitations as the ANC-4 --
it only works on once source.
I have used the ANC-4 on a dedicated RX antenna, also using a sense antenna,
and that works without creating clicks. The noise cancelling concept is
solid, but it has that fundamental limitation that you can only null one
source at a time. Why? Simple -- cancellation can only occur with the two
signals are equal in level and 180 degrees out of phase, and 99% of the time,
it's only possible to do that for one noise source (or for multiple sources
that were VERY close to each other).
73,
Jim K9YC
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