On Sat, 17 Apr 2004 20:22:56 GMT, zeno wrote:
Richard Clark wrote:

MAINSGROUND-------------RFGROUND------------SHACK GOOD
MAINSGROUND----------SHACK-----------RFGROUND BAD

I may still be confused here, not really fuly comprehending the above illustration.

The mainsground comes to the shack anyway in the AC outlets powering the shack,
being the third or ground terminal (although not really connecting to my Kenwood
530 which in this unique case only has a two prong AC plug and internal power
suppy.

I think this ground thing has to do with the "routing" as you indicate, just as the
mystery of ground loops in an old tube hi-fi amp where the correct star grounding
is the way to get rid of hum. As long as my shack RF ground is a short direct route
to the first ground rod of the series, I should be ok then tying the mains ground
to a "later" point in the RF ground rod system. (?)

Hi Bill,

Look again at the illustration. Now think of noise originating in the
Mains and traveling towards RF ground. That current, across
impedance, produces noise voltage. In the "BAD" illustration, think
of the left hand as hot, and the right side as cold. Just like at a
setting of a potentiometer, noise voltage is injected INTO the SHACK
if there are other paths to ground (there always are, you describe
just exactly how it happens above).

Now, repeat the same problematic noise current in the "GOOD"
illustration. It sinks right into RFGROUND and does not proceed on
towards the SHACK.

You will of course have mixed grounds because this vale of tears we
call reality demands that you power your SHACK from the Mains. And if
it weren't that, it would be the 'puter, or the phone, or a battery
charger for the drill (the list is endless and so common that we
become blind to the obvious paths mixing noise into our life).

Most local noise is conductive. That is, it comes from the source and
the sink residing on the same breaker in the panel. The source noise
current injects itself into the sensitive sink side that is sharing
the path. By using an extension cord, you can confirm this by
powering the noise source off another outlet that goes to a different
breaker. That noise that is not conductive is radiative. It arrives
from the source through the air. This can be nipped in the bud by
using a transmission line choke at its entry (generally the feedpoint
of the antenna).

73's
Richard Clark, KB7QHC