[TowerTalk] Need Help Grounding My Shack & Tower

[Wayne Willenberg]

In the past few months, in preparation for my first tower, I asked on this
reflector about the best way to run coax, AC power, and control
lines(rotator, coax switch) from the shack to the tower.  The 100’
tower is
about 150’ from the base of my shack.

What I failed to explain in my post is that my shack is on the *second floor
* of my house.  So, all cables that will go to and from the tower first go
through the wall, down the exterior wall (a distance of about 20’) to a
central grounding point.

The NEMA-type grounding enclosure contains my surge arrestors that are
mounted on a copper sheet that is connected by 2” copper strap to 3 ground
rods.  The 3 ground rods are connected by 2” copper strap that terminates
at the ground rod used for my electric and phone utilities into the house.

Each piece of equipment in my shack is grounded, using 1” copper strap, to
a copper ground buss behind the bench (each is a “home-run”).  2” copper
strap runs along the outside wall from the buss to the central groundingpoint.

This technique seems to have worked well in the sense I have never been
bothered with reports of RF in my transmissions and never been “bitten” by
RF when using my amp during transmitting.

I just finished reading a technical note from PolyPhaser called “Ham Radio
Station Protection.”  It suggested for my situation that coax, ground strap
and rotor cables that run vertically up my outside wall might inductively
couple some energy from the tower to the shack.

The article suggested having all of the cables go through surge protectors
at the base of the tower and then run through EMT (electrical metal tubing)
that is grounded to the tower base *only *and runs all the way from the
tower base to the second floor shack.  The article says the EMT will act
like a Faraday shield for the cables inside.  This seems to imply the EMT
would not be grounded at the central grounding buss at the base of my house.

I can understand this approach for the vertical run up the exterior wall of
my house (the cables and tower are parallel to each other), but does it
make sense to use EMT all the way from the tower?  How about the 2” ground
strap that will run from the ground protection system around the base of
the tower to my shack.  Following this logic, shouldn’t it be inside the
EMT?

Thanks for your help.

Wayne KK6BT