Topband: NCC-2 antenna pattern?

[Jon Zaimes, AA1K]

 I use NCC-1 and NCC-2 boxes for phasing numerous receive antennas, mostly on 160. My property is heavily wooded, with antennas among loblolly pines, oak, maple, gum, etc.

For in-band listening while transmitting on 160, I have a pair of 34-foot verticals (self-supporting aluminum elements) placed about 1000 feet from my nearest transmit array, roughly on a line toward Europe (the RX antennas are closer to Europe). Spacing is 1/4 wave. To get maximum end-fire null, they are lined up on a heading of 29 degrees. The beamwidth is broad enough to hear many Eu signals while transmitting. Equal RG6 feedlines run to an NCC-1 in the shack, and I am able to listen within a few kHz of my transmit signals 

The quality of the transmitter signal and the receiver are major factors allowing in-band listening. There was a quantum leap years ago when I upgraded my K3's to the newer synthesizer boards (or a K3S). 

When I change directions of the transmit array, I usually have to tweak the null on the NCC-1.

I also have used a broadside/endfire set of 560-ft Beverages that have the TX array off the rear for in-band listening and their null is deep enough for this to work. I use an NCC-1 to phase the two pairs of Beverages. The closest feedpoint is about 550 feet from the nearest TX array.

I have two sets of broadside-endfire short verticals (four 34-foot wire elements hung from trees). These have the two forward and rearward element feedlines coming together at tees (no matching) and then separate feeds run to an NCC-2 in the shack. Performance of these can equal or exceed that of the numerous phased Beverages we have.

A few of my stagger-phased Beverages have separate feedlines going to an NCC-1. This allows adjusting the rearward null for optimum. 

While the exact phase setting isn't known, the settings achieved experimentally are repeatable. I use several BC stations in the 1600-1700 range for reference.; An S-9 plus signal often will drop out entirely when I reverse the phase on the NCC-1 (or -2).

The charts of phased arrays in the ARRL Antenna Book and ON4UN's Low Band antennas book are useful in positioning of the various arrays for placing the null in a desired direction.

73/Jon

Jon P. Zaimes, AA1K
Tower climber for hire
Felton, Delaware
http://www.aa1k.us/


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     On Saturday, December 16, 2023 at 10:05:41 PM EST, Kenny Silverman <kenny.k2kw at gmail.com> wrote:  
 
 Rick, my application is for an in-band RX antenna, but on a higher band. I 
just thought the guys here might know more about the NCC-2, MFJ or QRM 
eliminator than most others.

One thought was to create a 2 ele phased vertical array for the RX antenna 
with a known pattern and put the null towards the TX array, along with 
physical separation to allow in-band receiving.

But I was thinking an adjustable phasing system may produce a better null. 
But I wouldn’t want the adjustable unit to create a clover leaf pattern for 
example. One null might take out the interference but another null towards 
the desired receiving direction might be created and is not desired.

I hope I’m explaining this well.

Regards , Kenny K2KW

> On Dec 16, 2023, at 9:47 PM, Rick Kunath <k9ao at yahoo.com> wrote:
>
> What's your application Kenny and what would you be feeding the antenna 
> output of the phaser into?
>
> Rick Kunath, K9AO
>

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