On Tue, 2007-01-09 at 18:11 -1000, Ken Brown wrote:
> > Doesn't a good earth ground help remove stray RF from the shack? along with
> > ferrtie cores etc...
> >
> No. Any conductor carrying RF currents, not having another in close
> proximity with equal and opposing RF currents, as in a transmission
> line, produces RF radiation. A lead to a "good earth ground" carrying
> significant RF current, will produce significant RF radiation. The key
> to minimizing RF in the shack is to have all your transmission lines
> working as transmission lines should, with equal and opposite RF
> currents flowing in the two conductors (whether it is the coax center
> conductor and shield, or the two wires in parallel wire line) so that
> they are transmission lines and not antennas. There are various details
> that need to be attended to to accomplish this. With good connectors, a
> properly working transmitter, properly built cables and either a
> non-radiating load (not very useful for communications, yet an essential
> piece of equipment in every shack), or an antenna far enough away from
> the shack and properly fed so that it does not induce unequal RF
> currents into the two conductors of the feedline, there is no reason
> that there would be RF in the shack. It is only when one or more of
> those conditions is not met that there is a problem. Adding another path
> for RF currents to flow, such as a ground wire, is probably just as
> likely to make the problem worse as it is to make it better.
>
> DE N6KB
>
End fed wires, off center fed windoms, and verticals are the worst
antennas at inducing RF in the shack.
Quarter wave counterpoise wires hooked to the rig and open at the other
end do act as a RF connection to earth when its much closer than the
antenna to reduce RF voltage on the radio cabinets.
73, Jerry, K0CQ
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