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 !
>
Wellll...you'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)
> -----Original Message-----
> From: towertalk-bounces@contesting.com
> [mailto:towertalk-bounces@contesting.com] On Behalf Of ke2d@comcast.net
> Sent: Thursday, March 11, 2010 3:44 PM
> To: towertalk@contesting.com
> Subject: [TowerTalk] tower & antenna project questions
>
>
>
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