Topband: Looking for 160m narrow beam RX advice - aninteresting com

[Tom W8JI]

Actually you could go back and forth with the two boxes, like nulling a 
phasing SSB rig that has two balanced modulators, and have it work in most 
cases under the criteria given.

The reason this would likely work is there are two sense antennas, each one 
close to an independent source. Each independent sense antenna must be 
significantly closer to each independent source, and if we do that, it will 
likely work.

With a single nuller, it will almost certainly not work because each  noise 
source has a different phase shift and level to the main antenna. There MUST 
be a way to independently set level and phase for each sense antenna.

----- Original Message ----- 
From: "Rob Atkinson" <ranchorobbo at gmail.com>
To: <topband at contesting.com>
Sent: Monday, January 12, 2015 12:39 PM
Subject: Re: Topband: Looking for 160m narrow beam RX advice - aninteresting 
com


> >1. I can see the case for an array of loops. However, wouldn't it be less
>>time-consuming --not to mention less expensive-- to just get an additional
>>MFJ-1026 to effectively null the second noise source? Null out one noise 
>>in
>>the first 1026, and then null out the second noise source in the second
>>1026? (If not in this case, then in other situations?)
>
> That won't work.  Think about it.  You null noise source 1 with one
> box and feed that to the second box and you use that box to null noise
> source 2, but noise source 1 is going to come in on the noise source 2
> pickup antenna and appear in the receiver front end.  The only
> effective method is to use loop stick antennas oriented so as to null
> one noise source then use the phase-shifting-nulling network to null
> the second noise source.  If you have three noise sources you are
> sunk.
>
> We may as well face it--we're screwed.  Unless you reside in the
> sticks with about 500 feet all around your antennas, 160 is no longer
> a weak signal band for you.  You can still operate it, but you won't
> be able to work anyone unless they have a strong signal.
>
> 73
>
> Rob
> K5UJ
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