[TowerTalk] Rohn RSL tower - slightly off topic
john at kk9a.com
john at kk9a.com
Thu Jun 6 19:18:52 EDT 2019
I missed the torque part however I wish someone could explain this in simple terms.
From: Byron Tatum [mailto:bjtatum1 at att.net]
Sent: Thursday, June 06, 2019 23:03
To: towertalk at contesting.com; john at kk9a.com
Subject: Re: [TowerTalk] Rohn RSL tower - slightly off topic
I believe that Steve K7LXC is referring to the torque load on the mast and not the wind load, per se.
On Thursday, June 6, 2019 05:45:55 PM CDT, john at kk9a.com <john at kk9a.com> wrote:
I wish that I understood how mounting antennas on opposite sides of the mast
cancels their wind load.
Also I am not sure how well a single tribander will work at 115 ft high
whenever the sunspots return and 10m opens.
> Hello-? ? I was at a friend's QTH recently viewing his new Rohn
RSL100L10, a 100' self supporter put together with 10' sections R-10H
through R-1. It is rated for 25 ft/2 wind load at 90 MPH, dropping back to
11 ft2 at 100 MPH. We were discussing his planned installation of a KT-36
and M2 3 ele 40 meter yagi. He wishes to have the KT-36 about 15' above the
tower top plate with the 40 meter yagi approx. 1' or 2' above tower top.
Both antennas are fairly close in weight (approx. 95#), boom length (36')
and wind load (10 ft2). ? I wanted to get opinions of folks experienced with
large antennas and self supporting towers if this planned installation is OK
for this tower.
Hiya, Byron --
The proposed configuration sounds good to me but I'm not offering an
answer to your question. What I am offering is a tower technique that I
Install the antennas on opposite sides of the mast. That way many of the
wind vectors cancel each other out. This was determined by Dick Weber, K5IU,
a PE and the article appeared in QEX years ago. Anything you can do to
reduce the wind induced torque on a mast is a good thing. Did I mention this
is highly recommended?
Cheers.Steve K7LXCTOWER TECH
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