Can a Rohn 25G be safely self-supporting at ~ 40' with a house bracket at
15', or must it be guyed? The beam will be a 10 lb. Mosley 3el mini-beam
with only 2.5 sq ft of wind surface area.

Is a concrete base essential under these circumstances? I'm planning on
erecting one in the spring and want to plan properly, but don't have much
room for guy wires unless it's unsafe not to use them.

Thanks & 73s

Dave - W5GT

W5GT wrote:
Can a Rohn 25G be safely self-supporting at ~ 40' with a house bracket at
15', or must it be guyed? The beam will be a 10 lb. Mosley 3el mini-beam
with only 2.5 sq ft of wind surface area.

My "25G Bracketed Towers - No Ice" chart shows 7.7 Sq Ft at 90mph for a
bracketed 40 ft tower. It lists two brackets, one at 30 ft and one at
15 ft. It is not clear to me whether this is an either/or situation
involving one bracket or a two-bracket configuration. It's Rohn DWG#
A871302R1 dated 3/17/88
--
73, Cecil http://www.qsl.net/w5dxp



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Can a Rohn 25G be safely self-supporting at ~ 40' with a house bracket at
15', or must it be guyed? The beam will be a 10 lb. Mosley 3el mini-beam
with only 2.5 sq ft of wind surface area.

Is a concrete base essential under these circumstances? I'm planning on
erecting one in the spring and want to plan properly, but don't have much
room for guy wires unless it's unsafe not to use them.


Go here and look in the ON LINE Catalog;

http://www.rohnnet.com/

Look under the GT series of towers.

Dave,

I would think it should work. I have an old Wilson 40 foot tubular tower
that has a house bracket at about 10 feet. Been there for 24 years. I used
some minimum amount of concrete, like about 5 - 6 bags, mixed in a garbage
can. The Wilson is a crank up/tiltower; so, I needed enough concrete that
the thing did not take off while tilting, with the house bracket removed.

You want to be sure the bracket is fastened to some main horizontal beam,
not plywood, or 2x4s that are held in place with a couple of nails.

Tam/WB2TT
"W5GT" wrote in message
...
Can a Rohn 25G be safely self-supporting at ~ 40' with a house bracket at
15', or must it be guyed? The beam will be a 10 lb. Mosley 3el mini-beam
with only 2.5 sq ft of wind surface area.

Is a concrete base essential under these circumstances? I'm planning on
erecting one in the spring and want to plan properly, but don't have much
room for guy wires unless it's unsafe not to use them.

Thanks & 73s

Dave - W5GT

In the 60's I had 40 ft of 25G on a brake over base (5 -6 bags concrete
under it) and bracketed at 10 -12 ft to the house. Hang on to your hat, it
was topped off with a 4 element CB Hornet (24 ft boom). It stayed up until I
got tired of the nonsense, maybe 4 - 5 years. I'm in the middle of tornado
alley (NE Okla) and I'm sure it saw some good hard 80 - 90 mph wind. RM~

WARNING, any deviation you choose to make from Rohn specs is at your own
risk.

HAVING SAID THAT.

My Rohn 25 is 30 feet, with a 10 foot mast that sticks out of the top by 5
feet. The rotator is inside the tower at the lower end of the mast. A 2
element 5 band Quad (13 foot arms) is at the 34 foot level, and a 2meter
discone is at the 36 foot level. I used to have a TA33JR at the 35 foot
level, before I switched to the Quad.

I can find no place where Rohn authorizes these kind of loads more than 10
feet above the top guys.

I have NO base under my tower. There is about 3 inches of air between my
tower legs and the ground, with the only connection being a set of heavy
ground wires going to a driven ground rod.

I have an "owner designed and constructed" bracket which is bolted through
the garage foundation wall. It took me about an hour to drill
the two 1/2 inch holes through the foundation wall using a 1/2 inch
"consumer" hammer drill. A commercial hammer drill would have done the job
in much less time. Making the (welded) brackets from scrap steel took me
about 30 minutes. (Digging a hole is much more work.)

At the 13 foot level I have a house bracket, which is tied back to the ridge
pole as well as 2 other points of the garage roof, on the INSIDE of the
garage.

If my tower falls it will strike a nieghbors garage, NOT his living
quarters. There are NO above ground Power lines in my Nieghborhood.

I climb the tower to install antennas as it does not tilt over.

This arrangement has survived more than one storm with 70 mph winds that
have taken out trees in the area.

The most serious problem I have is that I have to keep cutting the trees to
keep them out of the quad.

John
KA9CAR



"W5GT" wrote in message
...
Can a Rohn 25G be safely self-supporting at ~ 40' with a house bracket at
15', or must it be guyed? The beam will be a 10 lb. Mosley 3el mini-beam
with only 2.5 sq ft of wind surface area.

Is a concrete base essential under these circumstances? I'm planning on
erecting one in the spring and want to plan properly, but don't have much
room for guy wires unless it's unsafe not to use them.

Thanks & 73s

Dave - W5GT