Greetings,
Been watching the comments on motorizing crank-up towers. I have a Tri-ex
LM470D with electric motor and remote control. While I have installed a CCTV
camera to which the antenna's and top 30' of tower, I have NEVER raised or
lowered the tower without standing near the base and carefully watching the
operation. I have had friends who always used the remote control and have
snagged coax, rotor cables and even pulled the tower down and damaged it! The
power of the electric motor coupled with all the pulleys is tremendous... It
can bend your tower like a pretzel in a few moments. The forces on the pull
down cables are very high.
If you do install a motor to raise & lower your tower, Always watch the
operation from a safe distance and be able to stop the operation at a moments
notice.
My LM-470D has been up for over 25 years. The secret is to limit the amount
of raising & lowering. It puts tremendous force on the cables. I usually keep
mine at around 65' which keeps about 5' overlapping in the top of the next
section. I was told by a PE that for every foot you lower the tower into the
next section, the load in SQ feet increases by 2 SQ feet. So if your tower is
rated 15 SQ feet @ 70 Mph, keeping it at 65' will increase that to 25 SQ feet
@ 70 Mph. The 5 feet will most likely not make any difference.
When I leave on vacation or for any extended period, I usually drop the tower
to 50' With about 9' in the top of each lower section, I'm very secure the
tower will stand up the strongest winds we will get.
Good Luck but be very careful.....
73 Steve/K2WE
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