[Top] [All Lists]

[TowerTalk] Pushup Pole Installation

To: <>
Subject: [TowerTalk] Pushup Pole Installation
From: (Red)
Date: Mon Jun 2 11:27:46 2003
For 15 years I've used a 35' mast of R-S steel sections supported in one 
plane by the elements of an inverted Vee and in a perpendicular plane by 
guys at about the 2/3 height of the mast.  I can put this up and down 
easily by myself, by adjusting the guys to approximately the correct 
length (leaving them as is when making no change) and walking the bottom 
away from one end of the dipole.  The bottom stands on a short piece of 
treated 2 X 6 with a landscape spike through a hole in the 2 X 6 to 
"nail" it to the ground and to keep the mast in place.  The feedline is 
supported on one of the guys down to the ground and away in a direction 
perpendicular to the dipole, and there is an I.C.E. lightning suppresser 
where it enters the house.  It ought to have a distributed ground system 
at the mast and an inductor across the dipole for better lightning 
protection and to more effectively dissipate precipitation static.  

When I designed this house, I inquired about lightning protection.  The 
best source of information was the books by Uman and the University of 

Lots of lightning rods are the result of busy salesmen.  The State of 
Minnesota fire marshal does not keep useful statistics on either 
lightning induced fires or the effectiveness of lightning rods. 
 Commercial buildings typically include perimeter lightning protection 
in this state.  The U of MO recommends lightning rods on buildings that 
are exposed, that is, on high ground and not sheltered by taller 
buildings, trees, or other objects.

According to Uman, 90% of lightning strikes may be grounded through #12 
copper wire.  The other 10% are the high energy events that typically 
include sustained current exceeding 100 amp between strokes.  This 
explains the survival of many items, including a Hy-gain vertical that I 
watched take a direct hit but on which I could find no damage (the coax 
was disconnected and totally outside the house at the time).  I've also 
observed a direct strike on the commercial tower on which our club's 
repeater antennas are mounted.  The repeater was in use at the time, and 
its antennas were protected by PolyPhasor suppressers.  The strike 
appeared to hit the tower horizontally near the mid-point of the tower, 
not far from where the repeater antennas are.  The transmission of the 
repeater was interrupted only momentarily and not damage was detected.

Another of our club's repeaters suffered serious damage and lots of wood 
in the building housing it was charred by lightning energy that entered 
on an ungrounded phone line.  The ground wire to its suppresser was not 
connected.  Phone connections were welded and charred wood traced its 
path to our repeater cabinet.

I haven't read the current edition of PolyPhasor's book, The Gounds.  An 
earlier version was informative, especially when studied in conjunction 
with Uman's books.  However, I've not read any single source that gives 
the amateur complete guidance for assessing the variables associated 
with a particular station and designing a lightning protection system 
for that station.  I recommend that each amateur study a lot but be very 
critical to try to separate the facts from the myths.  In the end, each 
must decide what risks to accept.  

73 de WO?W

David Greer wrote:

>I've had good experience putting a mast up against a
>two-story home with a bracket at the roof peak. At the
>bottom, I put the bottom of the mast in a bucket
>filled with mix-it-yourself concrete. It was plenty
>sturdy for a VHF beam turned with a TV rotor.
>73, Dave, N4KZ
>--- "Tim, N9PUZ" <> wrote:
>>I have a 40-foot push up pole (4 sections) that I
>>want to use to support a 
>>small VHF/UHF ground plane and the center of an HF
>>inverted "V". This is a 
>>semi-permanent installation for about a year. I
>>would like to minimize 
>>concrete work, etc. but want to do what's necessary
>>to have adequate guying, 
>>etc. to make it through a Midwestern winter and
>>summer of high winds, etc. 
>>There are two options for installation location. One
>>is against the side of a 
>>two-story house, the other is totally free standing.
>>Web searches haven't turned up much in the way of
>>suggested installation, 
>>etc. Anyone with experience to share?
>>Tim,  N9PUZ
>>See:  for "Self Supporting
>>Towers", "Wireless Weather Stations", and lot's
>>more.  Call Toll Free, 1-800-333-9041 with any
>>questions and ask for Sherman, W2FLA.
>>TowerTalk mailing list
>David Greer
>Do you Yahoo!?
>Yahoo! Calendar - Free online calendar with sync to Outlook(TM).
>See:  for "Self Supporting Towers", "Wireless 
>Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any 
>questions and ask for Sherman, W2FLA.
>TowerTalk mailing list

<Prev in Thread] Current Thread [Next in Thread>