[TowerTalk] Questions from the unwashed on a small project.

[K8RI]

On 7/29/2013 9:52 PM, Stan Labinsky Jr. wrote:
> Gentlemen, ladies, I'm in the process of repairing my standalone garage
> (replacing some of the Dutch Lap siding and of course, painting) to use
> as the upper support (by wall bracketing) for about 40 ft of 25G.
>
> Rohn says that 40 ft of it can stand unguyed, but probably with not too
> much of an antenna.

and a good base.
>
> My plans are for a TA-33 and maybe a smaller six meter beam above it.
> Would stand thirty feet above the roofline.
>
> The upper bracket would attach to the tower just below the first to
> second section joint.

How high is the roof line?
That sounds pretty low for a bracketed tower, or will you be using guys?

   That I've drawn up a bracket made out of Unistrut,
> which to me, looks to be more substantial than the factory offering for
> far less cost. If curious, I can attach a jpg of it to a follow-on note,
> just don't know if the reflector will pass it.
>
> Question(s):
>
> I have the choice of using a base plate (all this courtesy of an SK
> estate sale) listed in the catalog as the BCP25G, but planning rest it
> on the ground with an 8 foot ground rod set as the pier pin.

If you use the rod as a pier pin, it will need "ears' welded on.  The 
rod alone will not offer enough resistance to keep the tower base steady,

  I know
> that galvanized on earth is not a good plan and would probably coat it
> with some sort of undercoating as a protectant.

I've buried tower bases for years. Some were galvanize and some were 
painted. http://www.rogerhalstead.com/ham_files/Dirt_Base.htm

>
> Or, I can build another wall bracket and attach the lower end of the
> tower to the wall as well, set at about a 1/2 foot above ground level,
> the tower legs setting on some concrete pavers.

Normally the pier pin approach keeps the base from moving, but prevents 
the tower from twisting in the wind. A bracketed or self supporting 
tower needs the base held rigidly in a sturdy base. Larf=ger for the 
free standing.

>
> My concern would be, using only option two, that the two point leverage
> against the wall might be excessive where using just the pier pin and
> upper support would put less twisting stress on the wall.

That's one of the reasons for the rigid base on a bracketed tower.

>
> Or, I could use both at the tower bottom, but see that as over-kill...
> either-or.  Also, suggestions on an on-earth undercoat for the base?
>

Depends entirely on the soil and moisture content.
I've never had one rust, but a friend who lives less than two miles from 
me had two legs on a tower fail.  Completely rusted through.

73

Roger (K8RI)