[Towertalk] Guy Wire Assistance

[Bill Ralston]

 Tom K4XG asks:
>
> >I am putting up 100 feet of Rohn 55 and have a guy wire question.  My
> >preference is to use Phyllistrand nonconductive guys and I have no
> experience
> >with this product having always used 3/16 inch steel.
> >
> >My question is which size of the Phyllistrand to use.
> [...]
> >Would the 2100 pound Phyllistrand work OK?   Any recommendations would be
> >appreciated. Thanks.

You might want to take a look at Kurt, K7NV's guyed tower study at
http://yagistress.freeyellow.com/towers1.html

The bottom line is that Phillystran stretches a lot more than steel. A tower
guyed with the same strength Philly as the EHS one would normally use (e.g.
replacing 1/4 EHS with HPTG6700) will wind up leaning a lot more and
developing more base stress (assuming the base is set in concrete).  Moving
to the smaller size could be a serious mistake.

For my 100' Rohn 55 tower, I opted to go with the HPTG11200. (The next size
up from 6700 carried by Texas Towers).  This is closer to the elastic
characteristics of 1/4 EHS (although still more elastic).  This also
provided larger safety margin (I'm still not entirely comfortable with the
Philly - it just doesn't seem as hefty as steel!).  A bonus of the Philly is
that it is much lighter than steel.

Based both on Kurt's study and the recommendations of the PE that looked at
my tower, I'd also suggest you upgrade the lower guys to 1/4 and use the
same sizes of EHS and Philly everywhere (rather than 3/16 shown in the Rohn
drawings).

One thing to keep in mind is that the big grips for the larger size of
Philly are quite long - 5' in the case of the 11200 size.  This is worth
keeping in mind when trying to keep your conductive guy lengths under
control.

-- Bill N7VM