[TowerTalk] New Tower Installation

[ersmar at comcast.net]

Dave:

     I stick-built my Trylon T-500-64 five years ago.  It took me about two hours per section to erect it by myself.  My comments are embedded below.  Good luck with the project.

73 de
Gene Smar  AD3F


 -------------- Original message ----------------------
From: Dave <dave.n7drk at yahoo.com>
> A Northeast Washington Howdy to all.
> 
> I am new to this list and towers. At long last I have
> the room to put up a Titan 72 foot self-supporting
> tower. Not sure at this point what antenna I will use
> but a SteppIR is high on the list.
> 
> I am a bit overwhelmed at the volume of information
> here so please bear with me while I ask and learn.
> 
> I plan on doing most of the installation: digging the
> hole per mfg specs, fabrication of the rebar cage,
> erection of the first section, and "stick" building
> the rest. I know there are some on this list who have
> done this and I am a good listener and could use all
> the help/pointers I can get. Some initial questions I
> have:
> 
> 1 - Do I somehow bond the rebar cage together and
> bring a wire out of the concrete block?

No.  Simply connect the crosspoints of the rebar cage together with steel wire that you can purchase wherever you buy the rebar.  Don't let any wire exit the concrete block;  otherwise, when thw wire corrodes, water could infilitrate the concrete and begin to crack it.

Make sure you don't let the rebar rest on the dirt in the bottom of the hole.  Use a stack of two bricks under two rebar rods along each side of the rebar cage to elevate the cage inside the hole.  When you pour the concrete, the rebar ends will be supported by these masonry pieces, not setting on bare earth.  Otherwise you could allow the rebar to rust and expand inside the concrete, cracking it.


> 
> 2 - Do I likewise bond the three embedded tower legs
> together?

The tower legs will be connected together through the remainder of the tower structure.  In fact, you can't really install the legs without first constructing the bottom section of the tower on the legs.  That's how you get the proper position for the legs in the concrete - by using the first section as a template of sorts.  (See my final comment for more on this subject.)

> 
> 3 - Should I install a ground rod into the soil at the
> bottom of the base before pouring the concrete?

No need.  Your plans should include the installation of a minimum of two ground rods located within two feet of the tower (per NEC).  Hammering another rod into the dirt at the bottom of the excavation and running a wire from inside the concrete out to the rod will enable water to infiltrate the concrete (see #1 above.)  

My ground system consists of four rods in the dirt around the concrete, connected to the three legs with #2 solid tinned copper wire.  The three leg wires continue from those first ground rods away from the tower to an additional eight rods and about 125 feet of #2 wire conductor.  

Trylon towers have pre-drilled holes in the bottom sections that I used to connect the ground wires to the tower with Harger 222T clamps ( http://www.harger.com/lightningprotection.htm , then click on 2.6.1 Bonding Lugs .)  I also bought the #2 solid wire from Harger.

Use these pre-drilled holes for the ground wire, not a you-drilled hole at the bottom of each leg.  The pre-drilled holes are high enough on each leg that the ground wire will make a nice sweeping arc as it leaves the tower and heads into the dirt.  You will avoid right-angle connections from the leg to the wire by attaching it above the concrete base in this way.  And run thses ground wires through a piece of garden hose to protect them from the lawn mower.  (Plug up the top end of the hose with electrician's putty.)


> 
> 4 - Any other suggestions do's/don'ts at this point?

The trick to this type of assembly is to get the bottom section straight (no twists) and plumb (truly vertical.)  I did this by building the bottom section on a plywood platform that I made sure was level.  You can also use your garage floor if it's level.  I stood the first section up on this level platform after all the bolts were initially tightened.  Then I built a T out of wooden scraps and set it on top of the three legs.  (Thanks, K7LXC.)  I suspended a plumb line and weight from the center of this T and sighted through the tower along this string and each tower leg.  I loosened the bolts and tweaked the steel angles as required to ensure that each leg was in line with the string.  Once the bolts are tightened at this point, the bottom section will be a solid foundation for the remainder of the tower sections.  Now you can attach the legs to this bottom section and drag it over to the hole.

> 
> Cheers, Dave - N7DRK
> 
> 
> 
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