Rob,
I had a motorized LM470E tower. It had no mechanical stop for tower extension
to 70', only a limit switch. The tower will not extend completely out of the
top (there is a mechanical limit) but it can become overextended, leading to
instability. If your tower is motorized, never blindly rely on a limit switch
but rather always watch the raising and lowering of the tower with your hand on
the switch. Many have painted a dayglow orange mark on the outer most tower
section to indicate where the bottom of the next smaller section should stop
when the tower is fully extended.
My tower when fully extended was a noisy beast in the wind. I had a Tennadyne
T-12 log periodic about 18" above the thrust bearing. The antenna would swing
from side to side and with that motion, the tower section would torque, causing
the clanking noises. BTW, the rotor was a Tailtwister. The clanking was greatly
reduced if the tower was lowered. I'm not sure if lowering the tower really got
the antenna out of the wind but it limited the tower's profile.
I never noticed the top of the tower "lean" but without the positive pulldown
cable on the winch, lowering the tower with a windload on it could have been
next to impossible. Lowering a tower without a pulldown cable requires one to
ensure no slack is allowed in the hoisting cable. Under windload, this can
easily occur. Perhaps this will give you some idea as to the tower section's
loose fits.
73,
Jim W5QM
________________________________
From: Rob Salsgiver <rob@quailsoftltd.net>
To: towertalk@contesting.com
Sent: Monday, July 15, 2013 9:08 AM
Subject: [TowerTalk] LM-470 question
Greetings all,
I have an LM-470 from an SK estate that I've put back up. Last night I did the
first up/down test after transport and was surprised to see the top section
"wiggle" a bit when it got to full extension. Is this normal? I expect some
amount of play in it, but when you see the top of your tower move a few inches
sideways when it's 70' up, it's a little disconcerting when you're planning to
put a 40' beam up there... <g>.
Anybody have experience with these beasts that suggests whether this is normal
or not?
Cheers,
Rob Salsgiver - NR3O
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|