HI Wayne
I just want to make a few clarifications
the 9H50 mast will go up at a maximum of 34 ft , is the only UPS shippable
mast of the line
for that reason shorter than the others.
You never mention what Tribander or rotor you will install , the variations
are
significant from model to model
in the 3 element tribander brand to brand.
The Mast brochure have this text :
Specifications:
All installations must be guyed or bracketed. Installation
of masts should be done by experienced professionals.
Telescoping Masts are not recommended for commercial,
CB or beam antenna installations.
I made several temporary installations of those mast with light tribanders
like
the A3S and the Th3JR and those works fine UP to 30-35ft with very light winds
I will never risk to leave it permanently in your area rated at 100mph, those
are not the mast needed from my point of view.
I use those mast during the past years a lot for Wi Fi and Ham things ,
recently the last one installed fail in the past year Micro storm with winds
of around 60+ miles, not a single guy where broken the tubing just can not
handle the wind and bend at the center with just a vertical dual bander on top
and a Dipole.
J.Hector Garcia XE2K / AD6D
Mexicali B.C DM22fp
P.O.Box 73
El Centro CA 92244-0073
http://xe2k.net
________________________________
From: Wayne Willenberg <wewill747@gmail.com>
To: towertalk@contesting.com
Sent: Wed, August 24, 2011 7:19:29 AM
Subject: [TowerTalk] Basic Help Needed
I have just returned to ham radio now that I am retired.
My first project is to get a tribander (10, 15, and 20m) up and on the air
as quickly as possible. I have selected a ROHN 9H50 telescoping mast that
extends to 50’ and has guy mounts at 4 locations up the mast. ROHN
recommends each set of guy wires start at 30’ from the base of the mast. I
have bought a pair of Chicago Grips for tensioning the guys and a LOOS
tension meter for setting the guy wire tension to 10% of its maximum
strength.
I thought this would be an easy project (even though I don’t have any
experience in erecting towers). But, it hasn’t turned out to be so easy
when I realized the projected area of the tribander I have chosen is about 4
sq ft of projected area (EPA), but the footnotes for the mast say the
antenna load should not exceed 2 EPA! When I add 1 sq ft for the rotator
and mast to support the antenna, my EPA is over 5 sq ft!
So, my question is: should I abandon this project or can I make changes in
the support of the mast so my tribander can stay up even in the 100mph area
max wind speed estimated for my county?
What I have thought of changing is: 1. Not using the ROHN recommended 18GA
wire as the guy wire but going to ROHN 3/16 EHS, 2. Using the software
called MARC (Antenna & Rotator Calculator) to calculate the required steel
alloy and thickness of the antenna mast, 3. Limiting the antenna mast and
rotator to only 2 ft above the top of the telescoping tower mast, and using
4 guys instead of 3 (for a total of 16 guy wires).
Can I make this mast stand up? What are the weak areas and how can I make
them stronger? Would you direct me to books that discuss tower supports?
Thank you for your help… I really need it.
Wayne KK6BT
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