[600MRG] Noise Reduction: Tuned & Shielded Magnetic Loop

[Bill Cromwell]

Hi Joe,

I have had dramatic results using the tuned "mag-loops", too. Some of 
the people (at least two) who have reported the most severe noise 
problems have stated the noise is coming at them "from all duerections". 
They did not say how they determined that but they simply asserted it. 
Maybe. Maybe not.

The directional nulls of those loops can be very helpful - unless of 
course the desired signal lies in the same direction as the nulled 
interference. No single thing is going to cover *every* situation. Some 
other hat trick will be required to pry that codirection signal out of 
the noise. Overall those loops have made a lot of signals useable with 
much less operator fatigue from all those nasty grinding, growling, 
hammering, buzzing, sweeping noises. I think the return on invested time 
and money for the mag-loops is well worthwhile.

Now somebody is going to tell us how much better the beverage antenna 
is. Lets see now, this is the 600 meter list. How many beverages for 
this band will fit in a 30 by 100 foot space? Enough to cover just the 
cardinal compass points? Or maybe none.

So Joe, I have made mine with half inch, soft copper tubing. One is 18 
inches diameter and nicely covers 40 meters an down through 15 meters I 
operate on 40, 30, and 20) and I have also been using it to transmit 
with up to 10 watts of output. I don't know how much higher power it 
will take but probably not very much. I see them as a receive antennas. 
The second one is 5 feet in diameter and gets me nicely down into the 
160 meter band. I have not successfully tuned it to 600 meters and up - 
yet. The problem is getting the tuning capacitance to cooperate. I might 
reconfigure my 100 foot circumference (25 X 25) horizontal loop to get 
me up there on the longer wavelengths - down to at least 190 kc for NDB 
hunts. Do you turn and tune your loops by hand - indoors or have you 
built the enclosur4es and remote controls for outdoor use?

In my case I don't think the electric utility is causing much trouble in 
my area. Noise becomes a problem on weekends and holiday weekends when 
there are more weekenders and tourists here. The really severe noise is 
a couple of miles to the east where many of the local "tourist traps" 
are. I turn off the car radio when I drive down that strip of the beach.

I also have several transistor, AM broadcast receivers with the 
so-called loopstick antennas inside. Those antennas do a remarkable job 
and can get rid of strong, local stations and instead pull in far 
distant DX just by turning the radio! I have noticed their frequency of 
operation is not so very far from 600 meters. I wonder might be done 
with something like that. I'm sure I wouldn't try pumping ten watts of 
RF into one but it might help a receiver an awful lot.

73,

Bill  KU8H


On 12/09/2014 10:34 AM, Joe K I 5 F J wrote:
> Folks,I have read most comments about those with noise problems.A have used a tuned home-brew Magnetic loop. The narrow bandwidth lets in less noise. I rotated it to null (minimize) the local noise.
> I also have had success reducing Power Line BUZZ (120 Hz) bydocumenting the problem by photos. I then emailed the .pdf to the local electric company. Their engineer is equipped with ultra-sonic big ear, a V/UHF yagi and RFI receiver.
>   Some photos of the IC-756P3 spectrum scope and some screen captures of spectrum view did the trick. Once the power company was able to scheduleabout six crews with tall bucket trucks it only took them two days.
>   I have been blessed with low or no PL Buzz for the past 3 years. I also have been very pleased with the MFJ-1026 using an external sampling antenna.I would be glad to share more info, my email is good on qrz.com.
> 73Joe ONNNN
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