I agree with Fred in that there is no one system or method that "fits
all". In general I view station grounding approaches as 4 different
systems, all which should be implemented.
(a) All driven grounds must be bonded to each other an to the AC Mains
ground and this should occur outside of the structure or house. I find
no exception to this practice unless a tower is 200 ft or more from the
structure at which point a ground system should be located at the base
of the tower.
(b) Third pin green wire or safety ground for equipment must always be
in place and not "cheated" with an adapter.
(c) All lightning protection should occur before any feed line or rotor
control enters the building. Its ground attachment should be part of
the driven ground and bonding system. Towers should have a ground from
top to bottom and not relay solely on the structure alone. Don't forget
to bond the rotating mast out the top of the tower to the tower itself.
(d) Certain type of antennas do require a specific ground system which
I refer as RF Ground. A few driven ground rods do not make a RF
Ground. Those being, but not solely inclusive, verticals, slopers, end
fed Zepps, long wires and such as examples.
As to running a ground from the operating position to the outside ground
system, I've never found this necessary with proper antenna
installation. In many cases, the length of the ground conductor becomes
or acts as an antenna system and actual picks up RF from the
transmitting antenna thus placing the station above RF ground. {Opinions
will vary on this point.} I view if one has RF on the equipment, don't
run it to ground. Change the antenna and / or feed system to get the RF
to the antenna where it will do some good and thus not just warm the
earth worms.
73
Bob, K4TAX
K3S s/n 10,163
On 9/27/2015 3:20 PM, Fred Townsend wrote:
erry there is NO one size fits all grounding solution. As Don suggests you
are really dealing with four grounding systems. Your RF or rig ground, a
lightning ground, your NEC or house power ground (neutral), and finally the
safety ground (green wire) ground which is really part of the NEC ground.
Often the requirements of one system will be at odds with other grounding
requirements. For instance you generally want a high impedance for RFI
issues and a very low impedance for lightning grounds. One system defeats
the other so they really need to be separate systems.
Your NEC and lightning grounds have very serious safety issues so running
your proposed wiring changes by your local power company can often be very
helpful. Most power companies have an expert on such issues although the
existence of such a person is often a closely held secret.
73
Fred, AE6QL
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