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Re: [TowerTalk] new member with tower question

To: towertalk <>
Subject: Re: [TowerTalk] new member with tower question
From: "Patrick J. Jankowiak" <>
Date: Thu, 29 May 2008 21:43:06 -0500
List-post: <">>
I was also thinking about water piling up in the tower legs. I have seen 
bases for Rohn towers that sit on top of the concrete foundation, and I 
suppose the water if any runs out the bottom there?

The tower will be more than its height away from any lines. I have room 
for about 2X. If the tower went towards the lines, it would land on the 
house first. What I have is a 50x150 lot with power lines at the very 
front, and the possibility to put the tower about 55FT from the back of 
the lot. The "shack" is a 30x40 building at the back of the lot.

Here's my deal:

I really -need- a dipole of about 100FT length. The guys tell me it 
needs to be 40FT high at the center and at least 20-30FT high at the 
ends for the kind of propagation I can live with.

I really -want-:
stacked 6M beam, 2M beam, 440 beam
225-400MHz discone,
108-140MHz discone.
- and I don't think I can put those on the center pole with the dipole!  
But they need to be up at least 25-30FT and that would be mediocre 
because my site is in a slightly low lying area with alot of trees. Some 
of the trees are going to be whacked soon. Of course I could put up a 
small pole farm, and get away with alot of this, not sure about the 
beams on a push up pole with a rotor, that is a bit heavy.

My total budget is about $1500 (less the antennas, co-ax, etc)


Jim Hoge wrote:
> Patrick,
>   There is another issue you must contend with- drainage of water and 
> condensate from the tower legs of any tubular tower. I am a tower monkey in 
> the DFW area and I cannot begin to tell you how many freeze splits I have 
> seen in the tower legs because of inadequate drainage. I removed one Rohn 25 
> tower that was very similar to what you have proposed. The tower base was dug 
> down about 2 1/2 feet until the caliche was hit. The tower legs rested on the 
> caliche rather than a bed of gravel and the concrete was poured. The freeze 
> split on one tower leg was 4 1/2 feet above ground, far above the normal 1 
> foot I see in the area. Rohn specifies a gravel bed for drainage for this 
> very reason. By only digging down until you hit the caliche, you are 
> compromising the mass of the base and if you put in the gravel, even more so. 
> The caliche can be dug out with effort, something you will need to do for the 
> guy posts anyway. A hammerdrill can be used to to start a hole and once you 
> have an
>  area to break off the  caliche into, it will break. One step up the tool 
> ladder is a demolition hammer. The bottom line is don't cut corners on the 
> installation. Follow the manufacturer's specs. They are there for a reason. 
> If you can't make it work, don't guess, get a engineer involved. BTW, do you 
> have overhead powerlines or a drop nearby? My personal safety factor is 2 
> times the height of the tower to the nearest line.
>   73 es gl,
>   Jim W5QM
> _______________________________________________
> _______________________________________________
> TowerTalk mailing list

kind regards,

Patrick Jankowiak
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