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Old April 8th 11, 11:52 PM posted to rec.radio.shortwave
RHF RHF is offline
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Default Living with Static {RFI 'Noise'} & Basic 'Outside' Vertical Noise{Sense} Antenna & Placement of a Vertical Noise {Sense} Antenna

On Apr 8, 8:09*am, bpnjensen wrote:
On Apr 8, 5:23*am, dave wrote:









On 04/07/2011 10:26 PM, bpnjensen wrote:


* * p


Hmm - do you have QRM at your cabin? *My guess is that, the more rural
(and QRM-free) the setting, the less useful a set of phased antennae
would be. They don't work on atmospheric/QRN noise very well. *MFJ and
Timewave says they work on things like lightning crashes, but you'd be
very hard-pressed to twiddle those knobs fast enough to use it for
that purpose.


Having said that, two DX-Ultras phased together for noise abatement
might be just dandy, and they don't require grounding for exemplary
results.


Bruce


It depends. If all the QRM is coming from one t-storm cell, or a line
500 miles away, you don't have to adjust that much. I've always lived in
a neighborhood and have had excellent DX catches in spite of the power
lines and dimmers. The reason I use verticals is that they have reduced
response to things below about 15 degrees elevation.


The MFJ-1056 is handy for steering a null toward a single noise source
and doesn't require a full size "noise' antenna. That's why the "noise"
antenna has a preamp. My "noise" antenna is actually farther from
Dewey's RV than my "main" antenna, but it still does its job.


True, Dave, but the closer the noise antenna is in general electrical
characteristic to the main antenna, I believe, the better phasing
ability you'll get. For awhile I used the tiny noise whip that came on
the 1026, and it actually worked better than one might expect,
especially on 60 meters - but the few antennas I have had since than
have progressively improved on that, and less preamping I need to use
on the noise antenna, the better the results seem to be.

The vertical idea is very intriguing. *I have heard, maybe
erroneously, that verts capture more QRM due to its inherent polarity;
but I can imagine that two verts pumped through a 1026 might be a
really great set-up if the sources of QRM are limited.

Bruce


*IF* Your main RFI/EMF Noise Sources are External
to your House an 'Outside' Vertical Noise {Sense}
Antenna usually works better than the Built-in Whip
Antenna.
-however- *IF* Your Your main RFI/EMF Noise Sources
are Internal to your House the Built-in Whip usually
works well as the Vertical Noise {Sense} Antenna.

Basic 'Outside' Vertical Noise {Sense} Antenna :
Connecting a "Snake" {50 foot Coax Cable} Antenna
that ends in a Vertical Section with a Bottom 5-12 Feet
of Coax Shield and a Top 5-12 Feet of Inner Conductor
to the MFJ-1026's Rear SO239 AUX ANT Jack.
http://www.universal-radio.com/CATAL.../3542rear.html
[Total 10~25 Foot Vertical Noise {Sense} Antenna]
Place a Clamp-On Ferrite Bead at the Base* of the
Vertical Section. * Very Near Ground Level

Relative to your Main SWL Antenna your Vertical Noise
{Sense} Antenna can be moved around to find the best
location where it picks-up the most Noise to do it job :
Right-Side [Out=L/2] Center; Left-Side [Out=L/2] Center
Far-End [Out=L/2]; Near-End [Out=L/2]
-if- You have an Identifiable 'Outside' Noise Source having
the Noise {Sense} Antenna Closer to the Noise than the
Main SWL Antenna can make it more effective and produce
better overall results.

-note- Out=L/2 : Try to get the Vertical Noise {Sense}
Antenna "Out" and Away from the Main SWL Antenna
by about Half-the-Length "L/2" of the Main SWL Antenna
or at least Half-Way between the Noise Source and
the Main SWL Antenna; that is within the confines of
your property. -better- "Out" and Away is "L=1"

iane ~ RHF


 
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