"Larry Rappaport" wrote in message
...
I use a single point grounding system. There is a ground rod driven
at the service entrance to which electrical, telephone, and one of two
satellite systems are connected. I have run #2 copper from that
location to a total of 14 other ground rods each one 5/8" x 8', driven
completely in the earth and spaced at least 10' from each other. My
70' guyed tower is about 80' from this location and connected to the
grounding system. Each guy wire is also grounded. The aluminum plate
where all antennae enter the building on the second floor is connected
to this grounding system with #4 copper (to be replaced this summer
with 4" flat copper ribbon). Inside the building, there is a bus bar
which is connected to the flat aluminum plate where the antennae
enter. All the feedthroughs use gas plug protectors. All coaxial
feedlines are formed into a coil before being connected to the
pass-through plate.

My question: Some radio equipment are also grounded by three prong
plugs. Doesn't that constitute a ground loop? I've never gotten a
satisfactory answer to this question.

Thanks,
--

Larry W1HJF
Email to rapp at lmr dot com

Larry, multiple bonding connections of grounding systems from electrical, RF
systems, antenna masts, etc, are rarely guilty of causing the bad-name
associated with "ground loop"

Equipment which has either defects or is substandard design and which is
daisy-chained in series to a single point ground is a much more likely
culprit of AC hum.

Proper single point grounding means each individual piece of equipment has
it's own individual bonding conductor to the station single point ground.
That is one of the most impractical requirements of proper lightning
protection design, and perhaps a rule that is ignored often in favor of a
convenient bus-bar behind equipment. But sensitive audio equipment in that
daisy-chain, perhaps in concert with an offending radiator bonded on the
same bus-bar, could certainly cause an audible problem.

Once a noise-maker is truly grounded (and grounding happens only in the
earth, not wherever you make connections in the system, that is bonding),
that noise has very little chance of offending the human ear no matter how
sensitive the equipment involved.

Restated:

Earthed system to earthed system bonding does not create ground loops.

Equipment-to-equipment bonding can cause ground loops.

By the way, your system was well described and sounds to be well protected.
But you did fail to mention if you have shield-grounded the coaxial
feedlines at a number of places, including the tower and before the
arrestors. That is a critical part of lightning protection, and arrestors
can fail to provide any protection if up to 4,500v that coax can carry is
fed to their outer case/body, no matter if that arrestor case is earthed.

Best regards,

Jack Painter
Virginia Beach, Virginia