Thank you Jack,
It is similar to where I was heading, but I am planing to use one set of guy
wires and a slightly smaller base. If you have guy wires the size of the base
is not that critical.
I have someone working with me now on the engineering and drawings based on
information from the Rohn 25G catalog and the TI 222 document.
Best regards - Brian Carling
AF4K
117 Sterling Pine St.
Sanford, FL 32773
Tel: +USA 321-262-5471
> On Jan 30, 2015, at 1:56 AM, Jack Brindle <jackbrindle@me.com> wrote:
>
> Rohn has a section in their catalog for unguided towers which includes Rohn
> 25. They call for something like 2.5’ x 2.5’ x 4’ of concrete for the base.
> I’m not sure I really want to be up 35 feet on that, but it has been in their
> literature for as long as I can remember. I am sure many folks have built one
> of these, and would love to hear opinions on ways to make it safe. I suspect
> this is what the original poster was referring to. Not all of us can have
> tall towers - sometimes 35 feet will have to do, and extensive guy systems
> can be problematic on small city lots. So, the question really is how do we
> put this stuff up and make it safe? Is this where you were heading, bcarling?
>
> 73,
>
> Jack B, W6FB
>
>
>> On Jan 29, 2015, at 8:19 PM, Roger (K8RI) on TT <K8RI-on-TowerTalk@tm.net>
>> wrote:
>>
>> On 1/29/2015 6:57 PM, Grant Saviers wrote:
>>> My 140' Rohn 65 base is 4x4x2 ft. PE engineered. So 3' of concrete is a
>>> bit much, check the Rohn catalog. The most important thing with a base in
>>> concrete is the legs go through it and into some gravel for drainage. I've
>>> seen many legs split by water freezing in them.
>>
>> Or use a pier pin base with solid lefs. Easy to make and not expensive.
>>
>> 73
>>
>> Roger (K8RI)
>>
>>>
>>> I wouldn't go as far as "3/4 ply and broomsticks" but the loads from 30'
>>> won't need much of a base for 2000psi soils. It's all in the catalog.
>>>
>>> Grant KZ1W
>>>
>>>
>>>> On 1/29/2015 10:10 AM, Wilson wrote:
>>>> I think you are being led around by the short hairs.
>>>> How did you decide a 27’ tower needed to be in 3’ of concrete?
>>>> For practical purposes there is no bending and no horizontal load at the
>>>> base of this tower, assuming it is guyed, of course, which –25 must be.
>>>> You could stand 30’ of 25 on a piece of 3/4” plywood and three broomsticks
>>>> and have a fine installation!
>>>> The guywire and anchors are your real design hotspots, so a reasonable
>>>> estimate of overturning moment is necessary.
>>>> With it, you figure the worst guyline load and that gives you an anchor
>>>> capacity requirement.
>>>> You may have the perfect place for some screw in anchors, or an ideal
>>>> place to display some heavy yard art!
>>>> Yes, you’ll have a little horizontal load due to drag on the tower itself,
>>>> if it’s in the clear, so maybe use rebar or pipe instead of the
>>>> broomsticks.
>>>> I have a 2’ square pad and a tilt plate for mine (40’) and it’s overkill.
>>>> The tilt plate is great for antenna maintenance.
>>>>
>>>> And are you required to tell them all about the antennae to be installed?
>>>> The less you tell them, the better, since you’ll be changing eventually
>>>> anyway.
>>>>
>>>> WL
>>>> _______________________________________________
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>>
>> --
>>
>> 73
>>
>> Roger (K8RI)
>>
>>
>> ---
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