[RFI] Ladder Line and RFI/Noise

[Howard Lester]

On Tue, Oct 19, 2010 at 1:31 PM, Jim Brown <jim at audiosystemsgroup.com>wrote:

>



>  100 years later, we use parallel wires for speakers and power wiring. El
> dumbo grande. Replacing them with twisted pair solves a LOT of noise and
> RFI problems. And ladder line is a TERRIBLE idea if you have neighbors.
> Or any noise generators in your home.
>
>

Thanks Jim. In my case I'm 1000 feet from the nearest neighbors, so my
ladder-line fed dipole isn't an issue in that regard. Many years ago,
however, I lived in a townhome where I installed a 50' dipole on the roof,
fed it asymmetrically (I had no choice) with ladder line running toward her
unit, and wreaked havoc with my poor next door neighbor's phone system.
(Part of the problem was her add-on wiring installation done by someone who
was not a phone tech. He simply created a rat's nest of non-twisted pair
wiring to give her a second phone line for her business.)

Had I been aware of the dangers of using ladder-line in that installation, I
would have made a single-band dipole and fed it with coax. Maybe that would
have made our lives easier. Of course I could have cut the power way down,
too, when I knew she was home. (The neighbors on the other side of me,
however, had no RFI problems at all.)

Howard N7SO