In a message dated 4/18/03 9:46:04 AM Eastern Daylight Time, k1ttt@arrl.net
writes:
>
> Un-possible. You have stated a problem where no one could win. By
> requiring a 'properly designed' tower and 'properly placed' guy wires
> you could take any example sent and say it simply wasn't 'properly'
> designed or the wires weren't 'properly' placed.
>
The 'properly' was put in to avoid smart alec situation by someone putting
guy wires on 100ft tower at 10ft off the ground and trying to snatch the
purse. Implies reasonable situations like lets say having 80ft
self-supporting tower, with tribander and 40m beam on 10 ft mast, designed
for 80 mph. I am saying that if you put set of guy wires attached to the top
or within top 1/3 of the tower, you will increase the survivability rather
than decrease, as it is was implied (tower not designed for extra down force
from guy wires). As Bill O'Reilly would say: Am I wrong?
> The original point of this discussion was about taking an off the shelf
> amateur tower that the manufacturer had not specified guy wires for and
> then adding them yourself.
>
And I state that tower with added guy wires will take more beating than
without and survive. Or as K3BZ wondered, getting older tower and making it
more secure, or adding extra bit of antennas.
One caution with aluminum towers, they can develop fatigue cracks around
welds, sometimes microscopic, hard to see. Careful inspection, even some
testing by flexing is in order before putting it up. Extra guy wires can only
help to sleep well when things get creaky out there.
The main reason for self-supporting towers, especially in commercial
installations is the lack of, or cost of, real estate needed for the guy wire
anchors spread. Self supporting tower structural members HAVE to be stronger,
you put money in the base and stronger structure. When you design tower, you
go for self-supporting or guyed for the purpose, but if your existing
situation and have a need for more beef, it is more sane to add guy wires
than go for brand new installation. Even in situation where lets say one guy
wire broke, self-supporting tower will be standing long enough for one to
unhook another guy wire and place it where the wind is blowing from
(providing anchor is still there). VE3KZ had the tower to pull the anchor out
after heavy rains and following strong winds.
Yuri, K3BU
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