Pete Smith wrote:
> At 04:27 PM 6/11/2008, Roger (K8RI) wrote:
>
>> My preference is the Phillystran. Although it has a tiny bit of stretch
>> the catenary with EHS will allow a lot of movement. ROHN recommends
>> 3/16" EHS . 1/4" would add a lot of weight. Tensioned properly
>> resonance is not normally a problem with EHS. Catenary is very shallow
>> using Phillystran.
>>
>
>
> If you haven't checked it out, take a look at http://www.k7nv.com/notebook/
> . He has done several very relevant engineering analyses of guyed tower
> mechanics and guying materials.
>
>
After reading it I made the choice to go with Phillystran. OTOH he
forgot to include units when talking about elongation.
Having used both 1/4" and 5/16" and tensioning it to 10% of the working
strength the elongation is no more than a couple inches with either.
With EHS I can throw my weight on the tower and get it to move enough to
feel due to the catenary. When tensioning EHS as it pulls the catenary
up there is a great deal of "take up" with the turnbuckles. With
Phyllistran the tower is rock solid. Admittedly the Phyllistran is more
fragile than EHS, but I gave up trying to cut it with box cutters and
used cable cutters. Also you don't have to worry about grass fires with
EHS so always use at least 10' of the stuff between the anchor and the
end of the Phyllistran.
Roger (K8RI - ARRL Life Member)
www.rogerhalstead.com
N833R (World's oldest Debonair)
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