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Re: [TowerTalk] tower & antenna project questions

To:, "Tower and HF antenna construction topics." <>
Subject: Re: [TowerTalk] tower & antenna project questions
From: "Roger (K8RI)" <>
Reply-to: "Tower and HF antenna construction topics." <>
Date: Thu, 11 Mar 2010 22:30:25 -0500
List-post: <">>

Jan Wise wrote:
> I am not sure, but I think if you look at the Hand Book It will state that 
> you do not want the tower or anything else to be grounded that goes through 
> concrete. The reason being that a hit from lightning 
I think you might want to rephrase that to "grounded *through* the 
concrete" as you certainly want the tower grounded.  OTOH the tower here 
uses the older method of installing the base in the concrete with the 
legs of the tower base extending through the concrete and into a pea 
gravel/stone bed for drainage. Each tower leg is tied into the ground 
system *above* the concrete base.  The first ground rods are about 
16-18" out from the concrete with the grounding system extending out 
about 80' from each leg and also interconnected.  There is well over 
600' of bare #2 Cadwelded(TM) to 32 or 33 8' ground rods. I think this 
system has taken more direct lightning strikes in the last 8 years than 
all of the other ham stations in the county over the last 50 years with 
17 visually verified hits.  The neighbors just call it the neighborhood 
lightning rod.
> Will cause the concrete to explode. If I am wrong someone please let me know !
>'re going to get a range of answers, but with the tower legs 
extending through the concrete there should be no problem as long as 
they can drain.  There'd be no real reason to run grounding cables 
through the concrete in the first place and that I'd avoid, but the 
tower definitely needs to be grounded.

And as others have said, use conduit that will be only about 50% filled, 
then pick a conduit one size larger to allow for expansion of the 
system. LMR-600 is not terribly expensive, but do you really need that 
many runs. I have two runs for the HF, one for 6-meters, and one each 
for 144 and 440 to the tower from both the house and the shop. The 
system is set up for SO2R with the likelihood of both stations being 
active at the same time.  The same is true for 144 and 440, or 6-meters.

LMR-600 is a fairly easy cable to pull but don't forget lots of "wire 
soap", or wire pulling lube. It's cheap and makes life much easier. And 
important point, particularly with the more rigid LMR cables and 
particularly the larger LMR cables is to use a pair of 45's to make a 90 
degree turn instead of a single 90 which can quickly turn into a real 
bear when it comes to cable pulling.

An additional note, I always leave a double length messenger cable in 
the conduit so I can use it to pull in a cable, yet have enough left 
that I can pull it back.

73 and good luck

Roger (K8RI)
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