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Re: Topband: improve the lightnings charges protect for my equipment 160

To: topband@contesting.com
Subject: Re: Topband: improve the lightnings charges protect for my equipment 160m
From: "GeorgeWallner" <aa7jv@atlanticbb.net>
Date: Wed, 22 Jun 2011 04:29:53 -0400
List-post: <topband@contesting.com">mailto:topband@contesting.com>
Gentlemen,

I have a 31 meter tall bottom fed vertical in Florida that 
is located right on the edge of the water. It gets hit two 
or three times a year (not always directly). I used to 
suffer serious damage until I installed the following 
lightning protection:

1. Whenever I switch the power off to the transceiver, a 
"linear actuator" automatically grounds the bottom of the 
vertical via a 5 cm (2") wide ground strap (to a 
substantial ground). The linear actuator is a surplus from 
a boat, where it was used as a trim-tab actuator. It has 
about a 10 cm (4") throw, so it does not cause any stray 
capacitance when in the retracted position. An alternative 
could be an old Satellite TV dish actuator. You can often 
see them cheap at hamfests.

2. At the same time a 20 kV normally open vacuum relay 
dsiconnects the coax center conductor.

3. At the shack end the coax is rolled into a .7 meter 
(2') diamter, 6 turn coil. At the entry point, the braid 
of the coax is grounded to large ground bar and a ground 
system of four 2 meter ground rods. Another vacuum relay 
disconnects the center conductor of the coax going into 
the shack and grounds it (i.e. the PA output gets 
grounded).

4. On the 240 VAC power side, I have installed three 
60,000 A varistor type surge absorbers connected in a 
delta configuration (i.e. one arrester each from L1 and L2 
to ground, and one between L1 and L2.) I have also 
installed the same on the main AC panel, where the AC 
service enters the house. That surge arrester group uses 
the utility ground.

While all the above sounds excessive and a big job, it 
took that much to be able to survive hits without damage 
or the need to disconnect equipment all the time. Earlier, 
I have tried gas discharge surge arresters, etc., but 
nothing really worked 100%. Since I have installed the 
above system I had no problems. (But I had to replace the 
grounding strap once, as it partially melted during a big 
strike.)

GL,

George, AA7JV
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UR RST IS ... ... ..9 QSB QSB - hw? BK

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