[TowerTalk] RF in the Shack

[Jim Brown]

Hi Doug,

You're right that all of the cables in the shack are antennas. Fair-Rite 
#31 material is superior to #43 below 5 MHz, but #43 is better above 20 
MHz. You're also right that multiple turns through a core make a better 
choke at HF than a single turn. You've badly mistaken that a single turn 
through a core, or even through multiple cores, is useful at HF. My 
tutorial about this is at k9yc.com/RFI-Ham.pdf   About 5 years ago, much 
of it was added to the ARRL Handbook, and I'm currently working on 
expanding on it for the 2018 edition. That tutorial explains how 
ferrites work to kill RFI, and why multiple turns are needed at HF.

KK9A asked about HOW to do grounding and bonding.  Here's the power 
point for a talk I've given several times, including at Pacificon last 
fall. http://k9yc.com/GroundingAndAudio.pdf The concepts were much of 
the basis for N0AX's ARRL book on Grounding and Bonding, which he just 
finished and sent to the publisher. Ward is the editor and principal 
author of the ARRL Handbook and Antenna Book, and for the last dozen or 
so years, has written a monthly piece for QST that is often the only 
thing in the magazine that is technically correct.

There's also advice about grounding and bonding in the chapter I wrote 
for K7LXC's very useful book, "Up The Tower."

73, Jim K9YC

On Tue,3/7/2017 10:25 PM, Doug Smith wrote:
> I was
> careful to inventory what wire diameters would need to be beaded, so that I
> ordered exactly the right number of beads needed to fit over the wires, or
> looped wires, that I wanted to protect.  Looped wires through a bead are
> much better than a bead over a straight through wire.  I put beads on the
> coax between the rig and the amp.  I put beads on the coax from the amp.  I
> put beads on all available locations in the incoming mic input line and the
> incoming earphone input line, both into the u2R and from the u2R into the
> computer and into the rig.  I put beads on the incoming power line into the
> rig, on the theory that the RFI might be entering via the power line.