[TowerTalk] Torque bars for Create CR-45 Tower-----REVISITED

Michael Lamb n7ml@imt.net
Fri, 14 Aug 1998 19:34:52 -0600




----------
From: 	WBH3@chrysler.com[SMTP:WBH3@chrysler.com]
Sent: 	Friday, August 14, 1998 12:07 PM
To: 	towertalk@contesting.com
Subject: 	[TowerTalk] Torque bars for Create CR-45 Tower-----REVISITED

Bill:  I think your tower is the same one I used about 10 years ago in the Seattle area.  I simply laid two 2X4's parallel to the pitch of the roof one on each side of the peak.  I had the two 2X4's bolted into I think 3 rafters each using about 4 inch lag bolts.  The tower base was anchored with 3 inch lag bolts that went through the 2X4's and the plywood sheets below.  

The tower supported an M2 50 foot six meter yagi . You could really see the tower twist in a wind.  I did not feel it was going to last a long time so I eventually took it down and replaced it with the self-supporting 89 foot  
US Tower crank up.  That tower was so strong I wound up putting an EME array for six and two meters on a BIG H frame, but that's another story.

By the way, when I took the tower down after perhaps two years, some of the lag bolts had started rusting even though I had caulked over their heads.  The water got in between the 2X4 and the roof shingles.  To do it over again, I would probably try to use bolts that went through the roof like the handbook shows with 2X4's mounted UNDER the rafters inside the attic.  Better safe than sorry!

I think your tower will handle a KT-34A, but I would sure be afraid of a full sized KT-34XA, especially if you are in any kind of high wind area.  Sorry, it's only a gut feeling, no engineering analysis to support it.

73/Mike, N7ML





I really needed some help on this and was ....well.....very disappointed
that I got only 2 comments back on my questions.  Both comments basically
said ....FORGET  IT!

I have reconsidered and am now going to put my KT34XA about 1 foot above
the tower.  I STILL NEED SOME ADVICE on the feasibility of this project
and any construction hints relating to the  home-brewing of torque bars for
this square tower.  Are my ideas unsound?  Is the KT34XA just plain TOO big
to put on this kind of  a tower?  Does anyone have experience or knowledge
of someone who has attempted this scenario?   Please ignore the  comments
about putting the antenna 5 feet above tower.................My initial
posting follows:


---------------------- Forwarded by William B Haselmire/SCI/Chrysler on
08/14/98 12:29 PM ---------------------------


William B Haselmire
08/06/98 09:54 AM

To:   towertalk@contesting.com
cc:   bg@tir.com
Subject:  Torque bars for Create CR-45 Tower

Greetings all:
Actually, I have a whole bunch of questions related to the Create tower
installation I am doing on the 2nd. story of my house.  This particular
tower is almost 15 feet tall  with a base section one meter on a side.  The
tower necks down to about  7 inches square at the top.  I have no problems
getting the thing mounted securely on my roof, but I am worried about a
couple of things:

     1.I plan to put up my KLM KT34-XA.  I'm buying a 15 foot mast ,  0.12
" wall and  87000 psi., from Texas Towers.  Now the rotator mounting plate
is at the 10 foot level of the tower, so I will have 9  feet sticking out
of the top of the tower.  I plan to put the KT34 5 feet above the tower
(and thrust bearing) and the boom support bracket will be about 3 feet
above that.  So, question 1, am I being a little bit over optimistsic
putting the  beam that far above the tower?  I really don't want to put it
just a foot above the tower,.  I do plan to put a piece of reinforcing
metal on the very top of the tower for structural support.  I also plan to
put some bracing between the sides of the the tower at 2 different levels
also.

2.Since the KT34 -XA has a 30 foot boom, I want to provide some torque bars
to help things along.  The tower is square  and will be guyed 5 feet up and
15 feet upl  The guys will obviously be at 45 degrees to the sides of the
tower.  I had thought about  putting steel angle iron along each edge of
the tower and about 18 inches out and then guying to that.

Another idea is to put a plate on top of the tower,  bend the corners down
about 60 degrees and secure a strong hasp to the corners and the other end
of the hasp to an aluminum bar about 18 inches long and guy to that.  (this
seems to be a better idea in my mind).  Any other ideas or comments??
I'll be using Phillystran at 1200 lbs strength.

I'm putting 8 - inch long feet on each leg, each made out of 2 inch angle
aluminum  a quarter inch thick.  The legs will be anchored through the roof
with two lengths of 1/2 inch threaded rod to a 2 by 6 attached to the roof
joists.  The guying points will be half inch threaded rod with a welded 1
inch eye also going through the roof  into a 2 by 6 nailed between the roof
joists (which are on 2 foot centers).  The roof is only one half inch chip
board and seems to be the weakest link here.

I realize the KT34-XA is a pretty big antenna but it has been a super
performer for me and I sure hate to downsize!  On the other hand, with the
expertise on this reflector,  I am sure I'll find out if I am being too
aggressive.

Thanks and 73,

Bill  WX8S



























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