[Antennas] Common Mode Choke

2003年3月09日 18:39:06 -0500

On Sun, 9 Mar 2003 17:49:40 -0500
 "Ed" <[email protected]> wrote:
> OK, I'm confused. I looked at one commercial site and they say to
> isolate
> the tuner from ground, the other commercial site says to use the
> tuner for
> the common ground point if you are going to use a common mode choke.
> Which
> is right and what do you do if you do not use a tuner ?? I need to
> get RF
> out of the computer, but !!! 73..

Dear Ed,
Admit it, you have to look with great suspicion at anyone who would
tell you to isolate a tuner from ground. On the other hand, the tuner
is also not the best single point ground. The best single point ground
is the center of an array of ground rods driven at 4' intervals over as
many square feet as you have available.
Another point is that there are balanced tuners that are entirely
isolated from the chassis they reside in, and then there are the single
ended CLC tuners that are intended for coax in and coax out. All of
these things have influence over your options. 
If I am constrained to install a rig highly elevated above earth, I
would consider grounding my balanced tuner to the nearest, heaviest
cold water pipe and put up a balance feed line to a balanced antenna.
Anything less is asking for RF in the shack or lightning in the shack -
take your pick!
73 de W9DMK (Bob Lay in Dahlgren, VA)
http://www.qsl.net/w9dmk