Jeff: Thru the years I have owned 8 or 10 different yagis. Some were
commercial jobs and some were homebuilt. I have used rope in some of the
elements, weights in the ends of some and nothing in others. The worst
vibration occured in a 4 el 15 which used elements with thin walls and a
single diameter change. It was born to oscillate and rope or end weights
would not stop it. Ultimately the elements developed fatigue cracks and
the tips fell to the ground.
I think F12 is on the right track using elements with many diameter
changes. Usually they are made up of 3 and 4 ft sections, sometimes with
sleeving. I do not like the many electrical contacts at the joints but
they seem to work well. I have a EF240/420 which shows little or no
oscillation tendencies and a 4BA which sways around in the wind but
doesn't seem to oscillate. 73, Dan, N5AR
Jeffrey Okamitsu wrote:
>
> Ok...now for another contentious issue with several of you.
>
> I'm putting up a F12 620/340, a 415/410, and a WARC7D. Some of you say
> that one should lay rope inside the elements of these antennas to
> preventy sympathetic (wind-driven) oscillation of the elements.
>
> F12 claims that, assuming you follow their construction (tapering) plans
> that rope is unnecessary.
>
> So, give your views including your personal experience along with a
> (brief) explaination as to why you believe what you do.
>
> Thanks and 73,
>
> Jeff, KN2R
>
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