Well, it´s a matter how to express things I guess, if you
want to call it poor or not.
I know from personal experiense that it´s possible to
construct Yagi elements that doesn´t vibrate and fall
off due to mechanical resonance.
I have right now on the HF bands 57 elements in the air,
none vibrates and pieces doesn´t come down all of a
sudden.
In the past I have constructed elements that vibrates and
cracks, I would call that a poor design, however that poor
design could be fixed by adding ropes inside elements.
In the case of Force12, good or bad I honestly can´t say
since I have no personal experiense. If a lot of Force12
antennas do fail it´s poor, however failures could also be
due to other reasons.
Talking about Force12, there are one fellow in town that has
some Force12 stuff. A 40 mtr thing and a 3 bander I think
it is. As far as I know he hasn´t had any failures, guess it´s
good then.
Or it could be put this way, if ropes do fix the element problem
you could say that with the aid of ropes the design becomes
good, but ofcourse without since there is a problem one really
cant call it good.
73, Jim SM2EKM
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Från: w8ji@contesting.com [SMTP:w8ji@contesting.com]
Skickat: den 28 mars 2001 16:27
Till: towertalk@contesting.com; Jan.E.Holm@telia.se
Ämne: Re: [TowerTalk] rope in elements
Hi Jim,
> An antenna that needs ropes in elements are poorly
> constructed.
I disagree with that. My Rohn 25G with open ends at the top (I use
it as a vertical antenna and for supporting ropes, no yagi's) vibrates.
I'm not worried about the vibration because it is steel. I did know of
a fellow with an aluminum tower who lost the whole top 30 feet or
so of the tower in a mild breeze, because it vibrated and cracked.
As I look back, most of my tubing antennas vibrated. Some of
them had end caps and vibrated, but rope always fixed it. I had that
problem with Wilson yagis, and everything else.
I don't think that means the antenna is a poor design...not when it
is a problem so easily cured.
73, Tom W8JI
W8JI@contesting.com
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