[CQ-Contest] RE: Inter-station interference

Tim Duffy tduffy at sygnet.com
Thu Aug 31 23:21:25 EDT 2000

Bill Coleman wrote:

> Huh?
> In the November 1998 issue of CQ Contest, K3LR wrote an article about a
> 3-high remote stack switch.
> Tim talks about using current chokes on all his antenna feedpoints,
> another choke at the remote antenna switching box, and a third where the
> feedline goes into the wattmeter at the shack. These chokes serve to
> isolate the sheild of the feedline.
> His comment, "It is amazing what the installation of these
> high-performance chokes has done to decrease interference and noise
> issues at my multi-multi contest station."
> Tim used a W0IYH design, which certainly uses Ferrite beads.
> Has Tim changed his mind?

Hello Bill!

I use the W0IYH current chokes at each of my main tower mounted (and
isolated from tower ground) stack switch boxes and just prior to the
wattmeter at every operating position in my shack.

I have recently replaced the problematic (and lightning altered) CHO SORB
beads at each antenna feed point with air wound, single layer RG213 current
chokes. The combination of the airwound current chokes and the W0IYH ferrite
bead (100 beads per choke) current chokes makes for a very quiet, non
radiating antenna feedline system.

Again, please remember that my installation design requires that I am
extremely careful about where earth ground is introduced into the feedline
system. My system works great for my application, but it may not perform
well for your situation.

Tim K3LR

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