[TowerTalk] Fwd: How to get another 10' in height? Add a mast

[Jim Thomson]

Date: Wed, 11 Jan 2012 07:45:02 -0500 (EST)
From: HansLG at aol.com
Subject: [TowerTalk] Fwd: How to get another 10' in height? Add a mast
or add an...

You only have to climb a tower once to know that you want as little as  
possible "complications" once you are "up there". Also, it is not the top of 
the  tower that is exposed to stress, it's the bottom. The tower section 
"below" have  to take the mechanical stress from whatever is above. That's the 
reason you  design the tower from top-down.
 
Design the tower for the height you need and don't plan to add anything  
later.
 
Hans - N2JFS

//  a buddy installed  190 feet of rohn 55 g... with 4 x sets of KX0G  rings.   The entire
tower rotates.   I discovered that Rohn makes these super heavy duty versions of  45, 55, 65 G.
They are not only Z braced, they are also X braced.   He used 3 of the super heavy duty sections
for the top 3 x sections of the tower.   The very top guy ring was at 175 feet.  So he has 25`feet of
unsupported tower above the top ring.  A 2-el 80m yagi is at the very top of the tower.  4-el 40m yagi
below that..and a 5-el 20m yagi below that..all  in that  25 foot unsupported section .   Each of the 
heavy duty sections costs a bit more..and also weighs a bit more.  They are VERY strong sections. 
One helluva lot stronger than a stock 45,55,65 section.  We also looked at using 65G.  My problem with
65g was each step is 18 inchs...  vs  15 inchs on 45G, and 55G.   With horizontal steps  being 18 inchs
apart, that makes climbing tougher to say the least.   Once 55G  was decided on, the next step was to
figure out how much unsupported  tower can be above the top ring.  The 3 x new guy anchors are out aprx
175`feet.  The  re-enforced X + Z braced stuff for the top 3 x sections  fit the bill perfectly.   So far, so good.
The same tower  supports 1 x  80m yagi,   2 x 40m yagi`s.... 3 x 20m yagi`s.. and a single yagi for 17,15,12,10,6m. 
So  x 11 yagi`s in total. 

later.... Jim   VE7RF