Thanks to everyone for all the feedback. Like most questions, the
experiences vary. It sounds like there are some with maybe tighter
tolerances that don't wiggle as much, but the prevailing experience seems to
suggest that it's not horribly abnormal with this (or other) crank-up
towers.
I will check the tabs at the bottom of the sections to see how much "play"
there is.. are there any recommendations one way or the other on possibly
adjusting these things? I can do it, but I'm a little leery about pressing
them out if they're not designed to have that done to them.
As far as raising it to full extension - that is one thing that I did
notice. When raising it I kept my hand on the switch and had to stop it
manually, as the upper limit switch didn't appear to work. I'm going up the
ladder tomorrow with the wife on the switch to see whether it's mechanical
or electrical, and replace if needed. I like the day-glo orange mark idea
though - thanks!
Great to have the list as a resource!
For those of you with an LM-470, I ended up replacing the motor. The
original Baldor motors on both towers were kaput. Replacements cost about
$408, but an equivalent Leeson cost just under $250. Works like a champ.
Cheers,
Rob Salsgiver - NR3O
From: Jim Hoge [mailto:knowkode@verizon.net]
Sent: Monday, July 15, 2013 7:55 AM
To: Rob Salsgiver; towertalk@contesting.com
Subject: Re: [TowerTalk] LM-470 question
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
|