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Tower Loading

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Subject: Tower Loading
From: (Howard Brainen)
Date: Wed, 5 Feb 1997 18:51:16 -0800 (PST)
>>Reader poll:
>>Those of you with towers larger than 70':  What tower are you using?
>>How much windloading do you have at the top?  How much additional side
14 sections of Rohn 55G, sitting on base section 3 ft above ground
with rotating bearing (RTS systems).  Rotating guy rings at 40, 80
and 120 feet.  2 sections above top ring.  15 feet of mast coming out
top.  Phillystran guys on hillside.

Top of mast is KLM 80M rotating dipole (160ft approx)
Two big beams above top guy:  3 ele 40 (beefed up KLM) at 140ft
  and 6 ele 20 KLM/57' boom at 125 ft.
Side mounted:  4 ele 15 DXE at 90ft; 4 ele 10 Msquared at 80ft
On TIC ringrotor at 45ft:  KT34XA

I've varied this alot, with 6 ele monos on 10 and 15, 4 over 4 on 10 and
15, etc.
Curent plan is to replace the 4 ele 10 and 15 with another XA, but may move this
to second tower.

This tower has been up for 10 years.  Was preparing to put up first antenna
when Loma Prieta earthquake hit.  I was at the top of the tower and 3 guys were
setting a back stay rope in the forest.  It was one helluva ride.  Never
forget it!
But it survived the quake and its survived lots of 50 - 75 mph winds each year.
Even the KLM 40 has stayed up and perfect, but that's because of massive mods.

>>Who here has actually calculated the wind loading of their antenans on
>>guyed towers and determined if they are within the Rohn specified limit?

Each installation is different.  Since mine is a rotating system, Rohn doesn't
have a clue.  Dick Weber, president of Rotating Tower Systems does, and he
guided me through this.

I'm also interested in info on side mounting to non-rotating towers
as I intend to put up a second tower, probably 120 ft of 45g or 55g
with about 12-15 short monobanders for 10 and 15 meters
fixed on the sides.  I'll also rotate a tribander and 2 ele 40 on
a mast at the top.

>>I would like to know this so I can determine if this can be overcome by
>>larger anchors, larger (diameter) guys, strategic guy placement, increased
>>guying radius, etc.

My take on this is there is one correct way to guy; that's the way to do it.
Don't think you can overdo things on the tower by guying.  Guy it correctly,
don't skimp and it will work.

73, Howard WZ6Z

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