Topband: QRM Canceling Experience

[VE6WZ_Steve]

Hi Bill:

All 4 of my staggered beverage pairs are phased with the NCC-1.  This is my 
second season with the system.
Each beverage in the pair has its own coax line to the shack and is phased 
with the NCC-1.  Actually, there are only two lines to the shack, and each 
wire is relay switched in the field.
I also use a stable "local" source using a homebrew 1.843mHz oscillator 
circuit located behind each pair, and can achieve incredible nulls......from 
s-9 +20 to almost zero.  I use this "tune-up" method to mark out the 
controls on the NCC-1 for approximate settings....both phase and gain.
On air, I will often use N7UA, N6TR or W7LR who  vary, but are close to off 
the rear off my EU pair and W1AW which is almost off the back of the JA 
pair.  It seems to depend on conditions, but the null is NEVER quite as deep 
and complete as using the local source.  On some evenings, I suspect because 
of wave-angle arrival the nulls can be very poor, but on other nights they 
are exceptional....from S-9+10 to S-3 or 4.
Prior to the NCC-1 I was also using a "fully modified" MFJ unit, and did not 
notice any big difference regarding null or pattern development between 
units.  The biggest difference with the NCC-1 is it has a noticeably lower 
noise floor.

My city QTH is a compromise location for Beverages, and therefore, each pair 
is very irregular.  The wires in a pair although will follow the same 
"general direction" often change in height and spacing along their length 
(depending on tree location), and therefore could not be considered 
"identical".  I think this is where using a phase box in the shack is 
superior to field phasing the pair in the traditional end-fire (cross-fire) 
method.  The ability to adjust (correct) the gain (current) on each wire to 
maximize the pattern is essential.  I'm pretty sure if I phased any one of 
my pair "as per the book" in the field, the pattern would be rather poor 
because of the variability between each wire.
It is also very nice to be able to adjust the phase in the shack to move the 
null around as needed. .  Sometimes, I will need to rotate the null to 
remove a local man-made noise, and I have the ability to phase ANY of my 8 
wires together....not just the pairs, which then can be a very effective 
noise cancelling effect.
 I also use the NCC-1 to phase together each element of my 80m Yagi at 100' 
to yield a rotatable 160m RX yagi.  Surprisingly, this models rather well 
and on air performs well.  There are times when it will out-copy the 
beverages, but most of the time is slightly behind or equal....probably 
depending on arrival angle since the wave angle is much higher using dipole 
elements this low.

73, de steve VE6WZ
http://www.qsl.net/ve6wz

>         If anyone is using an NCC-1  **with Beverages**  (i.e. not
> verticals), I'm especially interested in how much rejection you can
> achieve on real signals?
>
>                                                                  73,
> Bill  W4ZV