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Re: [TowerTalk] 30 foot Rohn 25G calculations

To: w4tv@subich.com, towertalk@contesting.com
Subject: Re: [TowerTalk] 30 foot Rohn 25G calculations
From: TexasRF--- via TowerTalk <towertalk@contesting.com>
Reply-to: TexasRF@aol.com
Date: Fri, 13 Feb 2015 10:11:01 -0500
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Joe, the over tightened leg bolts you saw were very likely someone's  
attempt to  
 
 
In a message dated 2/13/2015 6:21:23 A.M. Pacific Standard Time,  
w4tv@subich.com writes:


I  saw plenty of Heights and Universal towers that were egged out
during my  time on Ohio.  Many of them had the bolts/nuts tightened
to the point  that the legs were somewhat flattened but that did
not prevent "egging  out".  I know one old timer in the Columbus
area who replaced towers  twice within 10 years - both times because
they were so badly egged out  that nobody would climb them to repair
antennas.

Again after what I  saw of those towers, I would not trust one here
in the higher/constant  winds in Florida.  If I had to use a free-
standing tower here, it  would be the biggest sections available
from AN Wireless or a properly  engineered commercial - Rohn SSV,
Pirod (if they're still around), etc. -  tower with bolted flanges.

73,

... Joe,  W4TV


On 2015-02-12 5:09 PM, n8de@thepoint.net wrote:
>  Joe,
>
> The 'egging out' is usually caused by insufficient  tightness in the
> original erection.
> Have had many (over eight)  Universal towers since 1975, and only once
> did that factor into the  situation ... my error is not retightening the
> bolts/nuts AFTER  erection.
>
> Those 'light duty' towers are TV towers in my mind,  and would never use
> one.
>
> 73
> Don
>  N8DE
>
>
> Quoting "Joe Subich, W4TV"  <lists@subich.com>:
>
>>
>> On 2015-02-12 2:00  PM, n8de@thepoint.net wrote:
>>>
>>> A free-standing  Universal aluminum tower composed of 26" tapered,
>>> 22" tapered,  and 18" topper will support ANY common
>>> tribander/vertical/VHF  combo presently being used in ham radio.
>>
>> While that  may be true in Michigan where the wind requirements are not
>>  particularly high (70 MPH rev F, 90 MPH Rev G), that may not be true  in
>> Seminole County, Florida where the building requirements are  for 140
>> MPH (139) wind speed.
>>
>> Note the  force due to wind is *2.5 times higher* at 140 MPH than at
>> 90  MPH.  Directly comparing the allowable antenna in Rohn's  example
>> designs for 90 and 130 MPH indicates the same tower will  support
>> less than half as much antenna 1t 130 MPH as it will  support at 90
>> MPH.
>>
>> Universal Towers does  not even give windload data for 140 MPH on their
>> web site (they  provide spec's at 80, 100 and 110 MPH for the light duty
>> towers  but nothing for the heavy duty models) but given the nearly
>>  constant winds in Seminole County, FL, I would *never* trust one  of
>> their towers as I've seen how badly their bolted connections  "egg
>> out" after only a few years in the much more calm areas of  the Great
>> Lakes region.
>>
>>  73,
>>
>>    ... Joe,  W4TV
>>
>>
>> On 2015-02-12 2:00 PM,  n8de@thepoint.net wrote:
>>> Unless he is intending to put up a  stack of huge monobanders and/or
>>> SteppIR yagis, he doesn't  need the 30" sections.
>>>
>>> A free-standing  Universal aluminum tower composed of 26" tapered, 22"
>>> tapered,  and 18" topper will support ANY common tribander/vertical/VHF
>>>  combo presently being used in ham radio.
>>>
>>> Do  the research ... I have 3 Universal towers up now ... and plan to  
put
>>> up 4 more soon.
>>>
>>>  73
>>> Don
>>>  N8DE
>>>
>>>
>>> Quoting Gedas  <w8bya@mchsi.com>:
>>>
>>>> Brian, I would  not rule out a free standing tower esp since you need 
to
>>>>  stay under 30'.
>>>>
>>>> I have several  self-supporting Universal towers here, each of which
>>>> uses  as their first 3 sections, their 30" HD series sections.   When
>>>> assembling the towers and after getting those first 3  sections up in
>>>> the air, you realize how strong that  structure is.
>>>>
>>>> In your case, since you  mentioned 24', I would use two 30" HD 
sections.
>>>> See if you  can get the top section modified either by Universal or by
>>>>  a local welding/fab place to make it a topper with a collar where  you
>>>> can then use a 2" or 2.5" mast.  My gut tells me  that two 30" HD
>>>> sections with a 4'-5' mast will still be  standing long after your home
>>>> is leveled from some severe  wind storm.
>>>>
>>>> Gedas,  W8BYA
>>>>
>>>> Gallery at  http://w8bya.com
>>>> Light travels faster than  sound....
>>>> This is why some people appear bright until you  hear them speak.
>>>>
>>>> On 2/12/2015 1:03 PM,  Brian Carling wrote:
>>>>> Many thanks  Bud.
>>>>>
>>>>> I will need to review  which version they are using. Yes I had
>>>>> someone  pointing me in the direction of a freestanding tower but  I
>>>>> think I may go to using  guys.
>>>>>
>>>>> It's either that or  trade my tower sections in on a stronger better
>>>>> built  freestanding tower designed for that purpose. I only  need
>>>>> about 24 to 28 feet in height.  Maximum.
>>>>>
>>>>> Best regards - Brian  Carling
>>>>> AF4K Crystals Co.
>>>>> 117  Sterling Pine St.
>>>>> Sanford, FL  32773
>>>>>
>>>>> Tel: +USA  321-262-5471
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>  On Feb 12, 2015, at 12:27 PM, W2RU - Bud Hippisley
>>>>>>  <W2RU@frontiernet.net>  wrote:
>>>>>>
>>>>>>
>>>>>>>  On Feb 12, 2015, at 9:58 10AM, bcarling@cfl.rr.com  wrote:
>>>>>>> I am putting together a permit  application with my city which
>>>>>>> requires  certfication for 139 mph
>>>>>>> for three second  gusts as in TI-222 spec. Also steady 100 or  110
>>>>>>> mph I  think.
>>>>>>> We are making a 30 foot Rohn 25G tower  according to the Rohn
>>>>>>> specification with   4 foot
>>>>>>> cube base of concrete with no  guys.
>>>>>> I?m not sure I understand what you?re hoping  to find.
>>>>>>
>>>>>> My 4-year old  Rohn catalog makes it VERY clear that 30 feet of   
Rohn
>>>>>> 25 can hold only 1.7 sq. ft. of added antenna  when the  environment
>>>>>> is 90 mph (ANSI/EIA-222  Rev. E) and NO ICE.  (For  areas that
>>>>>>  experience icing, Rohn 25 is specified by the  manufacturer at  ZERO
>>>>>> sq. ft. of additional antenna load!)   From  your e-mail address and
>>>>>> the wind speeds  you mention, I?m going to  guess you?re in  Central
>>>>>> Florida, and I daresay a 90-mph Rohn   EIA-222 Rev. E specification
>>>>>> is not going to be  adequate for your   city.
>>>>>>
>>>>>> Nowhere in your  posting do you mention what total antenna,   
rotator,
>>>>>> feedline, etc. wind surface area or wind  load you  anticipate
>>>>>> putting on this  tower.  But my guess is that NO  freestanding  30?
>>>>>> Rohn 25 tower is going to make the  grade.
>>>>>>
>>>>>> Also, you fail  to mention which version of TIA/EIA-222 your city   
is
>>>>>> using.  The latest I?m aware of is Rev. G  ? a substantial  revision
>>>>>> from previous  methods of specifying wind  loading.
>>>>>>
>>>>>> Bud,  W2RU
>>>>>>
>>>>>>
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