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Re: Topband: NCC-2 antenna pattern?

To: "'Kenny Silverman'" <kenny.k2kw@gmail.com>
Subject: Re: Topband: NCC-2 antenna pattern?
From: John Kaufmann via Topband <topband@contesting.com>
Reply-to: john.kaufmann@verizon.net
Date: Sun, 17 Dec 2023 10:31:04 -0500
List-post: <mailto:topband@contesting.com>
If you are going to use the NCC-2 to null a nearby in-band transmitter, I think 
it's very likely that the NCC-2 will get overloaded by the extremely strong RF 
and not be usable.  I've tried this before and found that to be the case.  In 
fact, I designed my own totally passive nuller to get around this problem.  It 
worked and was able to create very deep nulls on an in-band transmitter, but 
turned out to be very impractical because it required constant adjustment to 
maintain a null as antennas were changed or rotated.  

The other thing to consider is that if the interference is coming from the same 
direction as a signal you want to hear, nulling the interference will also null 
the signal. Nulling works best when the interference comes from a very 
different direction than the signal.  It also helps greatly if the interference 
sensing antenna receives the interference much more strongly than the main 
antenna.  This can be done by placing the sensing antenna close to the 
interference source, if that's possible.

73, John W1FV

-----Original Message-----
From: Topband <topband-bounces+john.kaufmann=verizon.net@contesting.com> On 
Behalf Of Kenny Silverman
Sent: Saturday, December 16, 2023 10:05 PM
To: Rick Kunath <k9ao@yahoo.com>
Cc: topband <topband@contesting.com>
Subject: Re: Topband: NCC-2 antenna pattern?

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@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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