On Thu, 02 Nov 2006 21:35:22 GMT, "John, N9JG"
wrote:

I guess I didn't answer your question. You are quite right that at the
previous QTH, the shack ground rod was not strapped to the AC service rod.

Notice the correlation to:

at my previous QTH the use of an
earth
ground made RF feedback problems worse on some bands.

Hi John,

This is classic ground-loop conditions. One ground may have an
elevated potential over another ground (hard to believe, but it is the
practical reality). Current flows as a consequence. This is Common
Mode current (from a Common Mode potential).

You should in the short space of those three sentences be able to
observe several terms that are bandied about, but rarely understood.
This is because they follow on mysterious problems that defy
shielding, "grounding," and almost any other ad-hoc attempt that
inevitably fails as a solution.

One classic solution for providing ground to a tower is "I let the
coax shield do that!" Rarely does the operator consider that there
could be a huge potential difference between that remote point's
ground, and that at the house. The hidden killer here is when the
operator disconnects that coax (for whatever reason) and in that act
is holding the shield of the cable and some ground. He completes the
circuit, and like a fuse, may blow out.

More often I've heard:
"Look at the sparks I'm drawing!"
as the coax plug's shell is brushed up against the socket mounting
screws. My buddy pointed this out as the current burnt out most of
his ground traces inside his rig. It only cost a couple hundred and 3
weeks down time to provide remote grounding through the coax.

73's
Richard Clark, KB7QHC