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Re: [TowerTalk] LM-470 question

To: Rob Salsgiver <rob@quailsoftltd.net>, "towertalk@contesting.com" <towertalk@contesting.com>
Subject: Re: [TowerTalk] LM-470 question
From: Jim Hoge <knowkode@verizon.net>
Reply-to: Jim Hoge <knowkode@verizon.net>
Date: Mon, 15 Jul 2013 07:54:33 -0700 (PDT)
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
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 

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