[TowerTalk] Guy Breakers

[Pete Smith]

At 02:34 AM 2/4/00 +0000, VE6YC wrote:
>
>Hi All:
>Could some one please send me the recommended lengths
>of guy wires to break up resonance.
>I know this has been discussed here before, but I just get lost 
>in the archives.
>
>Finally the 100 foot guyed tower is going to go up!

There are tables in the ARRL Handbook and Antenna Book.  They say that
grounded guys will exhibit resonances at odd multiples of a quarter
wavelength, while ungrounded guys exhibit complicated behavior.  They say
no  segment length over about 14 feet is free from resonances on all bands
through 28 mhz.

I have a 100-foot tower with grounded guys.  The lower 2 sets are insulated
from the tower near the tower end, while the top set have 21-foot Joslyn
fiberglass insulators at the tower end.  This arrangement appears to work
fine with yagis above the top guys, but modeling shows significant pattern
distortion when I stack a second tribander inside the guys, and significant
currents in the grounded guys from my 80-meter wire array.

Rather than spend the money on insulators and big grips, if I were starting
out from scratch I would use nonconductive guy material (Phillystran or
pultruded fiberglass) and avoid all guy-wire problems from the start.

73, Pete Smith N4ZR
n4zr@contesting.com 

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