Topband: Vertical array

Tod -MN tod at
Thu Dec 13 18:35:02 EST 2007

> This is a perfect application for a box like the MFJ "noise 
> canceller" 
> or the DX Engineering "Noise Canceling Controller" with a pair (or
> three) active antennas.  

> Three antennas (one common, the 
> other two at 90 degrees - say in a corner of a lot) wood 
> allow reasonable "null steering" around the compass using the 
> active phasing control of the MFJ or DX Engineering boxes. 


Have you actually tried this or is it a thought that ought to work?

If you have tried it I am curious to know how you handled the injection of
signals [from the choice of three]. I own the NCC-1 {DXE} and have owned the
1026 {MFJ}. On my web site I have posted some results for noise cancellation
using the 1026 including a couple of .wav files that provide an A-B example
of noise cancellation on 80 meters. For those examples I used the TX
vertical as the sense antenna [for the noise] and then adjusted the MAIN
antenna to have minimum noise when listening on K9AY loops. 

This year I installed a pair of active vertical whips and acquired the NCC-1
to permit phasing of the signals from these RX verticals. The signal levels
are higher than the signals from my two K9AY loops. [there is some mixing
from local BC stations which appears in the 160 meter band however -- even
though the local BC stations are not running particularly high power].

I can indeed hear the effect of changes in the phasing control settings.
There are significant nulls /significant peaks. The nulls are not as easy to
quickly select as the nulls from the K9AY loops, but then the nulls cannot
be 'steered'. In the recent ARRL 160 meter contest I found that I used the
K9AY loops most of the time in preference to the phased verticals. I am sure
that this was in part due to the fact I did not have more than a couple of
seconds to switch between RX choices when trying to hear someone calling and
adjusting the NCC-1 phase control was not as fast as turning the rotary
switch on the K9AY control box.

I have a hunch that for contest applications it might be wise to use the
phasing control to determine the phasing for a particular direction [null or
boost] and then implement those values using fixed components that are
switched rather than adjusted. At this point I am sorry that I parted with
my 1026 because it would be interesting to see if the output of the NCC-1
could have noise removed by the somewhat less expensive 1026. I found both
units quite functional, the NCC-1 is somewhat smoother. I have not yet
managed to 'calibrate' mine so that I know what the settings for various
directions should be. I put the unit [and the active verticals] into service
about November 1, 2007. 

I would very much enjoy hearing from someone who has more experience with
this system than I do at present.

Tod, K0TO

More information about the Topband mailing list