Bruce, you may want to look into a clever device called a Hazer. It is like a
little cart that will attach to the Rohn 25 used to haul the antennas up and
down the tower --- your antenna would mount to the Hazer. If you use the Hazer
no one will need to climb the tower if you have antenna and/or feedline issues.
For your small antenna you could make a homebrew Hazer.
Regards, John NA6L
-----Original Message-----
From: Bruce Ward <Bruce@IPIntel.com>
To: towertalk <towertalk@contesting.com>
Sent: Sun, Feb 19, 2012 9:56 am
Subject: Re: [TowerTalk] Request for Advice - Rohn 25 vs TRI-EX HZN 471
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"<Bruce@IPIntel.com>
>>>> To:<towertalk@contesting.com>
>>>> 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.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|