Ken,
The main thing to avoid RF in the shack is to make sure the distance to the
outside earthing point is not a quarter wave total of conductor on any band
you use. If so, it makes a high impedance and not a good ground.
That goes for odd multiples of quarter wave as well. For example, 8 feet at
10m is a quarter wave and the rig would be subject to RF on the chassis.
Also, if your earth is a poor RF conductor, you are better off using
balanced, center fed antennas, or dipoles vs. quarter wave verticals, or off
center fed wires, etc.
Another trick for poor RF ground situations, is to hook a quarter wave
counterpoise wire for each band you use to the ground screw of the rig. lay
these insulated wires out around the baseboards, or run them out of the
shack to outside.
Ground rods are for static discharge, and do not automatically make an RF
ground. They are for lightning protection, and coupling a surge to earth,
not for keeping RF off the rig. Earth is usually a lousy RF conductor, thus
elevated vertical dipoles are the best vertical compared to a quarter wave
pole operating against ground, with on the ground radials. Another RF in
the shack factor is how far is it from the antennas, and how long are your
electric supply lines compared to RF quarter waves at the bands you use?
Hope this clarifies grounding considerations.
Stuart K5KVH
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