[TowerTalk] LM-470 question

[Jim Hoge]

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 at quailsoftltd.net>
To: towertalk at 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 at contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk