Sure, there lots of ways to skin the cat - thicker wall, larger diameter,
plytubular - all with +'s and -'s. All can get you to higher bending moment
resistance. I did my own stree analysis, so did not try yagistress. I had
lots of bits and pieces of tubing that made plytubular most atttractive for
me.
Gene / W2LU.
----- Original Message -----
From: "Pete Smith" <n4zr@contesting.com>
To: "Tower and HF antenna construction topics." <towertalk@contesting.com>
Cc: <lists@subich.com>; <brahmangou@aol.com>
Sent: Saturday, January 23, 2010 3:37 PM
Subject: Re: [TowerTalk] LP v SteppIR
> I'm not sure, but can't such designs be modeled in Yagistress,and isn't
> there more than one way to skin a cat? This sounds very much like the
> Telrex approach - remember those elements with no visible sag? VE1JF
> and others can offer practical experience with extreme environments and
> a different approach - low wind area and flexibility to match.
>
> 73, Pete N4ZR
> Visit the Contesting Compendium at http://wiki.contesting.com
> The World Contest Station Database, updated daily at
> www.conteststations.com
> The Reverse Beacon Network at http://reversebeacon.net
>
>
> On 1/23/2010 3:10 PM, Gene Fuller wrote:
>> Hi Joe -
>> Mostly valid points. However, smaller diameter elements can be strong.
>> The
>> 45 foot linear loaded elements in my design are only 1 5/8 " O.D. . They
>> are
>> "plytubular" design with up to four internal layers of tubing. 45 feet
>> long,
>> opened 10 feet out with 1" O.D. extren rod to allow for the linear
>> loading.
>> Design is good for 100 mph with 1/4" of ice. So far, after about ten
>> years,
>> it has had up to 85 MPH gusty wind with no ice, and no failures.
>> Regardless of the antenns model considered, anyone's element design would
>> have to have sufficient bending moment resistance and therefore cost and
>> weight, plytubular design allows smaller O.D. and therefore smaller
>> projected wind surface area.
>> Gene / W2LU
>>
>> ----- Original Message -----
>> From: "Joe Subich, W4TV"<lists@subich.com>
>> To: "'Tower and HF antenna construction topics.'"
>> <towertalk@contesting.com>;<brahmangou@aol.com>
>> Sent: Saturday, January 23, 2010 2:12 PM
>> Subject: Re: [TowerTalk] LP v SteppIR
>>
>>
>>
>>>
>>>> All things considered from my perspective, The Log is cheap,
>>>> light , easy, broadbanded, sufficient gain, automatic band
>>>> switching, unlimited power and duty rating, light wind
>>>> loading, and directly fed without matching devices or a
>>>> balun.
>>>>
>>> Unfortunately, if one wants a log that will hold up to any
>>> kind of wind for more than a couple years, it is not going
>>> to be cheap or light. The logs with light weight (small
>>> diameter) elements are not going to handle either ice or
>>> the constant vibration of wind. By the time one builds
>>> enough strength into them, they become heavy and expensive
>>> like the old Hy-Gain, and Collins designs for the Department
>>> of State and/or Department of Defense.
>>>
>>> By the way, the better performing LP designs are 200 Ohm
>>> feed systems and require a 4:1 balun or other matching
>>> system.
>>>
>>> 73,
>>>
>>> ... Joe, W4TV
>>>
>>>
>>> _______________________________________________
>>>
>>>
>>>
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>>
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>>
>>
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