Bill,
Here is a copy from an old e-mail by K2AV concerning hybrid
Philystran/steel guy configurations. I hope it helps. An
effective compromise for you would be 45' of Philystran for the
top guy, 33' for the second and 22' for the third. With your
concern for 80/160, I would suggest breaking up the remaining
steel sections on the top two levels in 22 foot (1/6 wave)
segments
> In the modeling for high band beams I have done with induced
> current on guy wires, the following combination methods seem
> to get the most bang for the buck, varying by what one has to
> pay for stuff, whether you have insider/free access. Note that
> it's the 1/2 wavelength plus metallic right under the antenna
> that does the most damage. Any metallic right at tower is
> insulated at the tower.
>
> 1) Philly for first 33 feet, then unbroken metallic.
> (45 feet is somewhat better for 40 meters.)
> 2) 21 ft fiberglass insulator, then 11 foot metallic,
> then regular insulator, then unbroken metallic.
> 3) three 11 foot metallic sections with insulators, then
> unbroken metallic.
> 4) 21 ft fiberglass insulator, then unbroken metallic.
> 5) two 11 foot metallic sections with insulators.
>
> First option is a lot of value out of 100' of Philly.
> Last two options are not much help on 40 meters.
>
> The ARRL published figures for non-resonant sections are
> ineffective on metallic guys directly under an antenna,
> because the current is unequally induced across it's length,
> and the current does not distribute according to the classic
> halfwave sinusoidal form. The 27 foot length directly under
> the antenna is PARTICULARLY ineffective on 10 and 15. The
> only metallic length worthwhile directly under a beam is 3/8
> wl, 1/3 wl or less at the highest frequency in use.
73,
... Joe, W4TV
> -----Original Message-----
> From: towertalk-bounces@contesting.com
> [mailto:towertalk-bounces@contesting.com] On Behalf Of bill rubin
> Sent: Saturday, August 04, 2007 5:52 AM
> To: towertalk@contesting.com
> Subject: [TowerTalk] phillystran length ?
>
>
> I am planning to put up a 100ft rohn 45g with 3 sets of guys
> 1 at 94 ft. 2 at 61ft, 3 at 31 ft.
> The antenna will be a steppir 3 ele. 6-20 meters and with 30-40
> meter dipole option. also at the 85 ft level I plan on feeding
> my 80/160 fan dipole (inverted)
>
> Using a hybrid Phillystran 1/4 to EHS 1/4 configuration for
> the guys to reduce / remove guy resonance what should be the
> MINIMAL lengths be using the Phillystran ?
>
> Yes I know more is better, but budget wise i would like to know.
>
> Do I only need it at the top level ? Two levels ?
>
> Alternative if i use 502 insulators how many and where ?
>
> Thanks 73 N1HWC Bill
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