[TowerTalk] Roof top towers

[Bob Turner]

FWIW,

I have a 9' Create Roof tower.  The roof has nailers between joists where
legs sit.  The tower is guyed on 4 points.  The guy anchors are 1/2 inch eye
bolts directly through the roof rafters.

There is about 14' of Chrome Moly 4130 mast in it.  About 8' sticks out of
the top, attached to this is about 7' of aluminum mast side clamped to the
Chrome Moly for a total of about 15' of mast sticking out the top.  On this
I have from bottom to top.

(5) El, 12', 6m yagi
(15) El, 21', 2m yagi.
(15) El, 19', 222 yagi
(22) El, 14', 432 yagi
(45) El, 12', 1296 looper - side mounted on horizontal crossmember attached
to mast
Create VHF Log Periodic - side mounted on horizontal crossmember attached to
mast
VHF tri band vertical.

I'm in the middle of my second winter with this up now.  Yesterday we had 50
mph winds.  I suspect its been exposed to slightly higher winds.  It is
still up without damage.  I've watched it in what I estimate to be 40 mph
gusts.  The tower does not budge.  The mast sways about 5" inches at the end
of its 15 foot length.

I used the MARC program available from Champion when calculating loads.
Everything appears within rated loads.


After reading other replies, I should add there are currently two ground
connections coming down from the roof to about 8 ground rods.  The grounds
come down off of different legs.  One is about #4 aluminum, and the other is
2" copper strap.  I intend to add more.


73
Bob
N2SCJ

-----Original Message-----
From: Dave D'Epagnier <DAVED@ctilidar.com>
To: 'Towertalk' <towertalk@contesting.com>
Date: Wednesday, January 12, 2000 10:59 AM
Subject: [TowerTalk] Roof top towers


>
>I just moved back to the city and unfortunately have a small lot where only
>a roof top tower will work. My roof is 25' high and I'm planning on putting
>a Glen Martin 17.5' roof top tower up so I can end up with about 45' or so
>at this installation.
>
>Does anyone have any experience with these towers? Are they really able to
>free stand under the wind loads that GM specifies? Does the '2x8x8 under
the
>rafter support' shown in the ARRL antenna books really work and hold up in
>the wind? Should this really be guyed etc? Am I making a mistake?
>By the way GM advertises that this tower has a ladder built into one side.
>The assembly instructions however state that GM does not recommend climbing
>this tower. How am I supposed to get my antenna up there? With a
helicopter?
>
>
>Any comments are appreciated.
>
>
>--Dave
>K0QE
>
>--
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>




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