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Re: [TowerTalk] Request for Advice - Rohn 25 vs TRI-EX HZN 471

Subject: Re: [TowerTalk] Request for Advice - Rohn 25 vs TRI-EX HZN 471
From: Bruce Ward <>
Date: Sun, 19 Feb 2012 11:56:17 -0600
List-post: <">>
I have another friend who is a tower climber.  He is has installed 60' 
freestanding Rohn 25Gs and is comfortable climbing them.  I am not 
comfortable with him doing so.

If I go with the Rohn 25G I will use boom truck to install the steel 
structure (I beam, tubing, pipe, etc approved by engineer).  Then the 
tower can be installed by the climber as a normal bracketed tower.  The 
tower would not extend more than 40' above the top bracket point.

With the TRI-EX he the boom truck would be used to install the tower.

If the tower were to fall over in a storm it would fall into a wooded 
area without damaging any structures.  I really want to avoid this 
scenario so I am investing in the bracketing.

I am in a county, outside the city, that does not have zoning or code 
issues.  Although I do not want to build anything that would not pass 
code inspection.

I am fairly sure my boom truck operator would not allow any riding of 
the ball.  He was very careful while installing the trusses for my house.

On 02/18/2012 09:53 PM, K8RI wrote:
> On 2/18/2012 8:58 PM, Gary K9GS wrote:
>> Seems like an awful lot of trouble when you can just buy an extra
>> section or two of used Rohn 25.
> Remember he can't guy it.
> Another problem is standing up this much tower, let along it being
> unguyed, and having to service it.
> No way would I consider climbing that much free standing 25G. So it'd
> have to go up with the coax and antennas in place.
> In "the old days" we would have had a crane lift it in place and either
> ride the tower up or climb it while the crane still held onto it. Either
> way meant "riding the ball" down, or rigging a release we could pull
> from the ground which with only 60 to 80 feet is not much of a problem.
> You can use heavy I-Beam with bracing at the bottom welded in place.  I
> believe they come in 24' lengths like most structural steel.   One 12
> incher might cost as much or more than your 60 foot 25 G.
> Another question is what happens if the tower goes over in a storm?  Are
> there any zoning restrictions? How will you prevent people from climbing it?
> Twas 30 plus years ago we had a problem at work that was one of those
> "how do we get some one up there and back down".  I suggested the crane.
> To say that was unacceptable would be a vast exaggeration.  Even the
> suggestion was considered unacceptable.<:-))
> I always thought "riding the ball" was fun.  Once in a while though
> you'd find a lot of grease on that sucker just to make things
> interesting.<:-))
> Amazing as many of us made "old age" as did.
> 73
> Roger (K8RI)
>> Just saying......
>> On 2/18/2012 6:33 PM, Bruce Ward wrote:
>>> Mark,
>>> You make a very sane suggestion.
>>> My reason for putting the tower on top of the building, if I do, is to
>>> get an extra 8' to 10' of height.  The building will be sufficient to
>>> handle the 1100 pound weight plus the horizontal wind loads.
>>> The tower site is covered in 60' plus trees and there is a similar
>>> height hill with similar height trees between my tower and the far end.
>>> I need to get above the trees plus above the fresnel zone so I want to
>>> go as high as I can.
>>> If I use the Rohn 25G we will add sections until we are high enough.
>>> This method could mean that I have to build sufficient structure to
>>> bracket even higher than 35'.  I would place the bottom section Rohn 25G
>>> on the ground (a concrete base) and bracket it to a pole embedded into
>>> the building.
>>> If I use the the TRI-EX I am stuck with its 70' height plus a 10' mast.
>>> Since it is a one shot deal I would like to start as high as I can.
>>> Thank you.
>>> On 02/18/2012 06:19 PM, Mark Robinson wrote:
>>>> I am not a mechanical engineer but why don't you put the tower in the 
>>>> ground
>>>> and the building next to the tower.
>>>> Mark N1UK
>>>> ----- Original Message -----
>>>> From: "Bruce Ward"<>
>>>> To:<>
>>>> Sent: Saturday, 18 February, 2012 6:53 PM
>>>> Subject: [TowerTalk] Request for Advice - Rohn 25 vs TRI-EX HZN 471
>>>>> I am setting up a tower (my first) to get internet service.  The
>>>>> antennas will be less than 2 square feet of wind loading combined and
>>>>> could be even less using 2 11x14" grid antennas.
>>>>> My plan is to build a 10'x10' 9' to 10' tall block building on a slab
>>>>> that is larger in all directions.  This building will will have a
>>>>> concrete roof with rebar and wire in all concrete.  The blocks will have
>>>>> rebar and concrete in every cell.  The structure will use 12  to 15
>>>>> yards of concrete plus 400 concrete blocks providing an over 45,000
>>>>> pound base for the tower.  I have a civil engineer friend who will be
>>>>> involved in the final design of the building.  The building is dual
>>>>> purpose, it will provide a secure home for my servers and a stable base
>>>>> for the tower.
>>>>> Now for the difficult part, I do not have room for guy wires.
>>>>> I am trying to decide between two options
>>>>> 1. I have 9 full and a top section of Rohn 25G in my yard waiting to be
>>>>> be installed.  Currently Rohn rates the 25G for freestanding use up to
>>>>> 40' with 1.4 square feet of wind loading.  From reading online it sounds
>>>>> like Rohn 25s have been used for decades even higher without guy wires.
>>>>> I do not want to risk stretching beyond Rohns specifications.  I have
>>>>> access to 40' lengths of 8" pipe. If I go with the Rohn 25G my intention
>>>>> would be to embed a  40' section of the 8" pipe into the building and
>>>>> bracket to that pipe up to 35' or so then have the tower extend another
>>>>> 35' to 40' above the pipe.  All the metal would be isolated from the
>>>>> ground and properly guided with a ground rod to avoid corrosion issues.
>>>>> 2. There is a TRI-EX HZN 471 available locally.  I would have jumped on
>>>>> this one earlier but it is worth more the the current owner than it is
>>>>> to me.  This is a 70' (71'?)  crank up tower with a motorized winch. The
>>>>> motor is broken and would need to be replaced.  The tower is free
>>>>> standing with the exception of three diagonal pipe braces that connect
>>>>> from the top of the bottom of the 4 sections to the ground around 10'
>>>>> out.  I like that this tower is freestanding and I believe I could do
>>>>> away with the braces if I bracketed the tower at the same location to a
>>>>> sufficiently strong structure.  If I used this tower I would likely
>>>>> build a 3'x3' column of solid concrete into my building and place the
>>>>> tower on top.
>>>>> I would very much appreciate any suggestions and advice.
>>>>> Thank you.


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