[TowerTalk] LM354HDSP Rotor Mounting Location

[Tommy]

Hi Mike,

I keep waiting for some input on your question about your mast, but haven't
seen anything. Did you get direct email replies?

Since this is going to be my first tower/yagi, here is what I am going to
do, but please understand I really have no experience with this. Instead of
chrome moly, I am going to use 22, long 1026 DOM with 1/4" wall thickness.
At the top of the mast I am going to mount a 2sel 40m yagi that weighs 66
pounds and an 80 mph wind load of 6.8 sq ft. 10 below that yagi I am going
to mount a 16-element tri-bander that weighs 99 pounds and has a 80 mph wind
load of 12.6 sq ft. and this yagi will be mounted 2' above the top of the
tower. Then the mast will protrude 10 feet down into the tower and rest on
an Orion 2800 rotor. At this time I plan to use one thrust bearing tightened
enough to hold the mast from lateral movement, but no to support any of the
yagi/mast weight. The combined mast/yagi's is well within the weight bearing
capability of the Orion 2800 rotor.

This design is based only on my reading material and a quick consultation
with Jay of Array Solutions. I trust that Jay knows this subject a heck of a
lot better than I do.

73,

Tom - W4BQF


-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Michael Hofe, AI3H
Sent: Wednesday, October 14, 2009 5:56 PM
To: towertalk at contesting.com
Subject: [TowerTalk] LM354HDSP Rotor Mounting Location

All,

I have an LM354HDSP that was manufactured by Tri-Ex (prior to Tash Towers).
I am installing a Prosistal PST-51 rotor in the tower (yes it fits) and was
wondering what depth the rotor should be nested inside the tower?  I will
have a thrust bearing on the top of the tower and have a 20' Chrome Moly
mast.  Although I can't confirm it, I have seen references to 4' or 5' down
from the thrust bearing, but I wanted to get everyone's opinion based on
actual use or personal knowlege.  I bought the LM354HDSP new about 8 years
ago and am ready to install the rotor, mast and antenna load.  The antennas
will consist of 18 ft2 of antennas with 9.5 ft2 of the load on the thrust
bearing and 8.5 ft2 located about 12' above the thrust bearing. 

Any thoughts would be appreciated.

Mike Hofe, AI3H
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