John,
A house bracketed 25G or 45G tower is the way many of us got our first towers
up on smaller lots. It is a great way to go. Rohn specs are available for many
configurations. 40 feet is very reasonable. Normally, you will see two brackets
called out in the specs. Many installations are done with just a good base and
a single bracket. The biggest safety factors are:
- Quality of the base
- Strength of the attachment of the bracket to the house ** very important **
- Limiting the amount of tower extending above the highest bracket [not more
than one full section plus a top section is fairly conservative]
- Limiting the windload of the antennas you install [much more important than
the weight of the antennas]
One more thing that you should be aware of with any house-bracketed
installation - noise. Mechanical tower noises are transmitted through the
bracket to the house - and you will definitely hear them. There are several
sources of noise to be aware of:
- Antenna "play" in the rotor. When the antenna is blown back and forth by the
wind, there is sometimes a little noise generated, particularly with rotors
that have a "brake" - like Ham IV and TailTwister
- Tower twisting and bending in the wind can cause squeaky sounds to flow
through the house
- Any loose hardware will bang the side of the tower and you'll hear those
noises inside. Be particularly careful to secure the feedlines to the tower
legs
A couple of years ago, I upgraded my main tower to 45G from 25G. If I could
influence everyone to choose 45G or larger for ANY ham installation, I would.
The climbability and stability of 45G is just way beyond 25G. With only four
sections in your plan, you'll be a lot happier if you choose 45G, and it won't
cost that much.
"Just do it" and you will be very happy!
73,
Jim K1IR
[TowerTalk] Guying a Rohn Tower
from [John Geiger] [Permanent Link][Original]
To: <towertalk@contesting.com>,
<vhf@w6yx.stanford.edu>,<vhfcontesting@contesting.com>,
<wsvhf@mailman.qth.net>,<cq-contest@contesting.com>
Subject: [TowerTalk] Guying a Rohn Tower
From: "John Geiger" <ne0p@lcisp.com>
Date: Sun, 3 Jul 2005 03:20:49 -0000
List-post: <mailto:towertalk@contesting.com>
I am in the planning stages for getting a tower up in the next couple of years
(hopefully) and am hoping to get some feedback from the group concerning this.
Here is my situation: I don't have much room for guy wires in my yard, nor a
desire to have guys running all over my yard. I wonder if I could go with Rohn
25 or 45 unguyed, as I could use house brackets on 2 sides to help support it.
I would like to have 40 feet or so of tower, with a 2 element tribander (16
pounds), a cushcraft 13B2 (5 pounds), and a Cushcraft 719B (3 pounds) mounted
on the mast-whatever that weights. Is this a reasonable setup, or would Rohn
25 or 45 have to be guyed, even with the house brackets?
Or any other suggests for an unguyed tower or mast? Trying to keep the cost
down a little also.
73s John NE0P
Jim Idelson K1IR
email k1ir at designet.com
web http://www.designet.com/k1ir
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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