Hi Dave,
Here's the text of a message I sent to another ham who was looking for
similar information. It addresses some of what you're looking for and then
some.
I will send some pictures of my attachments and process to you directly.
Someday I'll get a web site up to put these photos online.
------------------
There's nothing like doing the job right if we have the money to afford it.
But sometimes, as we hams know quite well, we like to "roll our own" for
less when possible. Here's some info I gathered/used when I installed my
grounding system.
I have read and adhered to as much of the polyphaser guide as possible. I
decided the best way to go was with copper strap and exothermic welds.
However, Polyphaser's cost on some items was more than I could afford. I
went shopping at the local metal scrap yard. I found copper strap left over
from commercial radio installations.
The size of the very inexpensive copper strap I found was a little off from
the size of commonly available exothermic welding molds. So I bought my mold
and exothermic weld cartridges from Alltech in Asheville , NC, Ph.
828-646-9290.
They were very helpful in getting the proper size mold for the strap sample
I sent them. The mold was sized for 5/8" ground rods. The mold is reusable
and cleans out very nicely after each weld. I made 24 welds and then sold
the mold and unused cartridges to another ham. I knew nothing about this
process before I started and it all went very smoothly.
Cadweld OneShots manufactured by Erico are also available to attach copper
cable to ground rods if you're not using "copper strap". Joel at RF
Connection can supply the product. If you're using strap and you want to use
Cadwelds I believe you have to go to Erico for product information.
You can also purchase strap from:
Metal & Cable Corp
Twinsburg Ohio
Ph. 330-425-8455
Attaching the ground radials to the tower depends on the type of radial you'
re using. Most towers are galvanized so you must protect against oxidation
at the connection point caused by the copper to galvanized contact area. My
radial attachments were accomplished by sandwiching the copper strap in
between 2 pieces of stainless flashing and an aluminum plate (also from the
scrap yard). If you use copper cable, as opposed to strap, you can wrap the
leg with a piece of stainless steel flashing and use a stainless hose clamp
to hold the copper cable to the tower leg. I also used a little
anti-oxidizing compound under the flashing.
I also made my own coax grounding clamps to bond all feedlines at the top
and bottom of the tower. I fashioned the clamps from the same copper strap I
used for grounding.
-----------------
Joe - KC2TN
"If you're sure of everything,
and it still doesn't work,
one of the things you're sure of is wrong!"
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com]On Behalf Of Dave Anderson,
K4SV
Sent: Monday, March 14, 2005 10:01 PM
To: TowerTalk@contesting.com
Subject: [TowerTalk] Getting a GOOD ground on a Tower
Hi guys,
Just moved to my new QTH with lots of land and no real
restrictions. I live ON a hill so my towers could be
subject to potentially more hits than normal.
Have a 90 foot crankup and two 5 foot crankup towers
up. Want to keep the lightning energy mostly
dissipated at the tower. I plan at least 5 ground
radials for the 100' and 4 for the 50' footers.
Looking for a good way to ground the tower to earth.
Without the gory details on all the common grounding
to and from the shack I want to know what works well
for you at the tower.
I have read the Polyphaser lightning manual and
everything else I could find. So here is my question.
When grounding a tower, assuming 8 foot ground rods on
the ground radials every 16 foot, what should I use
for the conductor.
I see Polyphaser recommends flat copper strap 1.5 or 3
inches in width using their copper compression device
allowing connection of the strap to a 5/8" copper clad
rod. I would use the polyphaser stainless steel
special hose clamps to interface the copper strap to
the galvanized tower legs making a clean low
inductance path directly to ground with no corrosion.
An alternate method my buddy tells me is to use 3/0
bare stranded copper cable Cad welded to the rods with
the same rod spacing. A problem arises on how to
connect the cable to the tower using Bronze
terminals??
The cost is about a wash so I am interested to know if
you have experience with this situation how would you
do it. Lightning is coming, I need to ground the
stuff soon.
Thanks in advance,
Dave...
Dave...
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See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
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questions and ask for Sherman, W2FLA.
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_______________________________________________
See: http://www.mscomputer.com 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.
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