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RE(1): [TowerTalk] Lightening question

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Subject: RE(1): [TowerTalk] Lightening question
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Date: Sat, 12 Apr 1997 17:17:52 -0500
W4>1.  All coax comes through an aluminum bulkhead that is grounded.

            Use coaxial lightning protection devices at the bulkhead,
best on the outside of the building penetration bulkhead. Make sure they
are rated for the frequency and RF power levels you intend to use. Make
sure the lightning protection devices  will pass DC, where required, for
the mast mount preamplifiers and other antenna switchers.

W4>2.  All gear is grounded to a copper bus bar with 1" strap and each side of
W4>the bus bar is grounded to an 8' copper ground rod.

            I hope the ground rods are all tied together with either a
copper ribbon           or at least a #4 copper jumper. Do not use
copper braid or tinned copper braid ourtside, it deteriorates quickly
when exposed to the elements.

 W4>3.  Each tower has 3 8' ground rods on each leg of the tower.

            I hope the 8' ground rods are separated at least 8' from one
another....             and bonded with a 4" copper ribbon or even
better with 8" wide . Bond the ground rods to each other and to the
tower leg.

W4>4.  Every antenna is fed with hardline that runs underground.  On the
W4>tallest tower, each piece of hardline is grounded (common) at the base of
W4>the tower to an 8' ground rod.

            Add a coaxial lightning protection device at the base of the
tower for each          coaxial cable coming down the tower. Bond these
lightning devices with copper ribbon to the ground system.  If you are
using additional 8' ground rods for each coax coming down the tower,
ensure all components of the        grounding system are bonded
together.     The copper ribbon I use is "1 oz copper flashing" either
4" or 8" wide and commonly available from either THE HOME DEPOT or any
other building supply house.

             W4>5.  Each bands antennas are controlled by at least one
Ameritron RCS8V W4>remote antenna switch.  10, 15, and 20 have two
RCS8V's.  One for switching W4>the stacks and the other for selecting
antennas.  The switches will be W4>powered off remotely when the station
is not in use.  When off, all W4>connections are grounded I believe.

            make sure to use lightning protection devices on all control
lines to the            remote coaxial switching boxes, both at the base
of the tower and at the  building penetration bulkhead.

W4>6.  At the bulkhead I will install some kind of lightening arrestor.  Any
W4>suggestions to brand and type?

            The most cost effective I have found are the ICE devices.
Call 1-800-423-2666 for the manufacturer or     1-800-950-9273 for
RADIOWARE, an ICE distributor..

 W4>7.  I will install protection on each of my rotor & control cables
before W4>they enter the shack.  So far no problems, but I'm leaving
myself wide open.

            Use an ICE device for all control cables too.

W4>8.  High quality surge protection on AC lines & on telephone line already in

            High quality is important. MOV only devices may fail open or
dead shorted.           you must test the MOV's at least annually to
determine their effectivity, or simply replace.

Poorer quality surge protectors may dump the transient to  ground
(electrical safety ground, ESG) and  may radiate and degrade your
receiving system performance....

 W4>9.  Electrical and phone lines are underground for 1500' before
going above W4>ground.

            GOOD planning, in conduit with spares and room for many
additional cables AND a pull rope....

 W4>OK... What am I forgetting?  Any suggestions?

            How about the ground screen under the antennas and extending
multiple    wavelengths beyond the antennas???

Many very high hills may be rock which typically has poor electrical
conductivity. ground rods may be difficult to drive in vertically.
Alternative is to make sure everything is electrically bonded together;
metal tower, electrical safety ground, metal shelters, metalic plumbing
and metalic electrical conduits, station single point ground system,
building penetration    bulkhead,  etc, etc.  Objective is to provide an
"equal potential" everwhere         during a lightning event.  If the
remote site is fenced, make the fence posts and chain link part of the
grounding system also..  Consider the effect of using dissimilar metals
in your ground system. Avoid situations where a high galvanic potential
is present between different metals.

Stan, WA1ECF          Cape Cod,  MA        FN41sr

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