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Re: [TowerTalk] HDX-555 Tower Modification Feasibility

Subject: Re: [TowerTalk] HDX-555 Tower Modification Feasibility
Date: Mon, 11 Apr 2011 16:05:19 EDT
List-post: <">>
In a message dated 4/9/2011 12:01:09 P.M. Pacific Daylight Time, writes:

>  New to is Mike,  W7PIM and I would  very much 
appreciate any and all constructive input into my feasibility  research. 
I have read over much of the archives regarding the things I  want to 
accomplish and now I need all of you tower/antenna guys out there  to rip
into this challenge.   Overall objective:  Modify my  current HDX-555 
(555), to hold and rotate
2 or 3 large yagis.   (ie:  2 el. on 40, 2 X 6 el on 20, homebrew 
antennas)    I  have not listed any loading or weight numbers here yet 
because I am  dealing in concepts at the moment.  Those details will come
in the  detailed math analysis and design to follow.    
Howdy --
    Okay. Concept - the HDX-555 will not take any of  the modifications 
you're talking about reliably. Wasatch County is a 70 MPH  windspeed zone which 
the tower will handle with small to medium antennas - not  2-3 large yagis. 
>  Objective #1: 
Design and construct a bottom section that  would raise the tower an 
additional 20 ft.  Plan would be to use the  current winch and lift cable
to raise the current 555 to it's normal height  and then use a separate 
winch and lift cable to then lift the entire 555  the additional 20 feet 
inside the new tower section.  
>  Objective #2:  Design and 
construct a tower  rotating system that will mount on top of a very heavy
duty pedestal tower  or large post section about 3 ft. tall and then 
secure the entire assembly  from objective #1 to the top of the 3 ft. 
    I've seen this done but it'll take some clever  engineering and 
>  This brings me to Objective #3:   Design and  construct 
guy rings for the 555 that are custom fitted for each section  and would 
allow the entire tower to be rotated.  Now, before I stir  up all the 
naysayers out there, let me tell you why I want to do  this.  
    Too late. You cannot guy the 555. Guy rings are  generally pretty brute 
(see lots of poundage). Between the additional weight  of the guy rings and 
the added tension on the guys (lots more compression  on the tower lifting 
cables), all of a sudden the capacity of the 555 will be  negative numbers. 
>  Getting to 
old to climb tall towers,  and want to  homebrew antennas.  Need to move 
them on and off and up and down  tower.  This would give me the best of 
all worlds for what I  need.  Resources:  Very supportive wife, 10
acres of land, son  with MS ME, another son with MS EE, a son-in-law 
with ME, 2  brother-in-laws that are certified ASME+++++ welders and a 
machinist in  the family.  Have access to extensive Finite Element 
Analysis  support, a can do attitude and lots of experience at doing 
things that  most people won't tackle.  Have also reviewed K7NV's 
outstanding  paper on "Guyed Tower Behavior". 
    Glad to see you have the engineering resources  and have done some of 
your homework. 
    Just off the top of my head, I figure it'll cost  $10-20K to do what 
you're proposing. Why not put up a real tower that will  accommodate what you 
want to do and then pay a professional climber  when you need him? $10-20K 
will go a long way in that direction. 
    I'm not a big fan of homebrewing towers. I've  seen some real nifty 
ones but they had major bucks tied up in them - not  counting the construction 
or engineering. 
    The guy that mentioned the Hazer has the best  idea if done properly, 
even though I don't like the idea of loosening guy  wires to raise and lower 
the Hazer. 
Steve     K7LXC
Professional tower services for hams



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