> But from the lightning and RFI viewpoints, it is highly *un*desirable to
> cross-connect the mains and RF grounds at the shack. If you do, you are
> creating an alternative pathway for lightning and RF currents - a
> pathway that now goes right *through* the building wiring, and probably
> through your electronics.
Unless I'm not following something, I don't know why that would be true. I
don't isolate or choke the ground leads outside equipment and would never do
that.
I bond the safety ground of all power mains to the shack grounds inside the
shack where all wires enter.
Of course I bond the main grounds to all building entrance grounds at the
building entrance point also.
I can't understand the reason for choking a ground lead inside a boundary
like a room entrance. The only place I can think of where a common mode
choke is useful would be on shielded leads that go between ground points or
isolated devices at a point of potential ingress or egress, not inside a
system. For example I normally totally float the antenna signal grounds of
Beverage antennas from feed cable grounds near the antennas (using an
isolation feedpoint transformer also), but I'd never float the ground at the
entrance panel.
I also might toss a few beads over the coax between phono jacks on receivers
and my receiving amplifier and switching panel, but that's only because I
don't want common mode currents flowing over those cables where the finite
shield connection resistance at the ends might allow signal ingress into
cables.
As another example my audio lines, both transmitting and receiving, have
isolation transformers that prevent ground loops on cable shields of both
headphone and microphone leads, to prevent hum from ground loops. The
grounds of actual terminating devices like headphones or microphones all
float.
But the power entrance mains safety grounds are firmly bonded to the "shack
ground" and the power line and shack grounds remain unimpeded up to the
equipment busses. I *want* ground loop currents to flow between cables at
the entrance, and not through the gear. I'd never dream of adding any choke
in the station ground leads at any place. I add ground impedance only on
cable shields (or two wire headphone or audio circuit grounds) and only then
in limited applications or locations where it prevents ground loops through
cable grounds between terminating devices inside the shack or outside at
low-noise low-level antennas.
73 Tom
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