My *first tower* (a 100’ crank-up including the mast) is scheduled to
arrive in mid-October. It will be located 150’ from the base of my house.
The problem is, *my shack is located on the second floor of my house*. So,
all cables that will go to and from the tower first go through the second
floor wall, down the exterior wall (a distance of about 20’) to a central
grounding point.
I just finished reading a technical note from PolyPhaser called “Ham Radio
Station Protection.” It suggested for my situation (i.e., shacks that are
above the basement) that coax, ground strap and rotor cables that run
vertically up my outside wall Might inductively couple some energy from the
tower, if it was struck by lightning, 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.
I can understand this approach for the vertical run up the exterior wall of
my house, 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?
Any help would be greatly appreciated.
Wayne, KK6BT
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
B/T/W, if you are interested in how I currently have my station grounded,
here is a description:
A NEMA-type enclosure is located directly below my shack at ground level.
It contains PolyPhasor surge arrestors that are mounted on a copper sheet
that is connected by 2” copper strap to 3 ground rods. The 3 ground
rodsare 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 RF in my transmissions and never been “bitten” by RF when
using my amp during transmitting.
Thanks for your help.
Wayne KK6BT
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|