Topband: MFJ-1026 question

[w2pm at aol.com]

W2IRT Writes:


-----Original Message-----
From: Peter Dougherty <w2irt at comcast.net>
To: topband at contesting.com
Sent: Tue, 25 Dec 2007 11:03 pm
Subject: Topband: MFJ-1026 question

Hi all,

I'm just starting to play with my 1026 and I have a question or two.
I'm using a 20' vertical wire as my sense antenna and my K9AY loop as
my main antenna and I'm finding that I can't use the preamp at all if
I'm to get any cancelling on the 1026. My settings arey 7-10-10 with
the invert switch out. I can get rid of the AC line noise on 80 with
it to a pretty good degree but not entirely. adjusting the levels
doesn't do much beyond that point. Is there a way I can use the
preamp and still get noise cancelling out of this?


W2PM Replies:

The noise nulling is no way standardized and the settings completely 
unique to your conditions.  Amplifying the noise is only required when 
the level is too low vs the main antenna signal level - which sometimes 
you can adjust by attenuating the main sig level and sometimes by 
amplifying the noise - whichever method works is the method you go 
with...  The biggest issue I have found with noise nulling is the 
placement of the sense antenna relative to the "main antenna". The 
sense antenna should be fairly close to the main one in order to get a 
similar "copy" of the noise. Finding the noise null is very crtical on 
these devices - you just have to experiement and find what works.  Im 
wondering which preamp you are using by the way?  The one on the 1026 
is typically wired for the whip antenna on the set - which is 
essentially useless.  I beleive there is a jumper option to use the 
preamp on the external sense antenna. Here I use a 1025 which doesnt 
have the preamp - and sometimes I use an external preamp for the sense 
antenna but most times I don't need it.  73 Pete W2PM
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