In a message dated 98-08-04 07:13:36 EDT, k3an@qsl.net writes:
> 2. If I go with the MAB mount, and put the rotator atop the tower, what's
> the maximum safe length of mast I can use and not overstress the rotator's
> bearings and other parts when I crank the tower over for antenna
> maintenance. I'm planning on a Force 12 C3SS beam. What would be your
> recommendation for the minimum rotator for this installation? Would I be
> better off going to the next one up the capacity chain?
The C3SS beam is relatively small so you don't need much rotator to turn
it. You need a rotator that can be mast-mounted. The Hy-Gains and Yaesus have
mast-mounting brackets available but you'll have to de-rate the rotator by 50%
in that configuration. A Ham IV/V or G800 will handle your C3SS.
As far as the mast, I wouldn't go more than a couple of feet. Any
additional height doesn't buy you much while placing more stress on the tower
and mast-mounted rotator.
BTW, the T2X TailTwister rotator will take a lateral force of 3,000
ft.lbs. before breaking. Lowering the tower with the C3SS won't over-stress
anything. A reprint of my 3-part series on rotators from my CQ Contest column
"Up The Tower" is available for a buck from Tower Tech, Box 572, Woodinville,
WA, 98072.
>
> 3. How do you go about ensuring that the base will be level, and the tower
> plumb, as you are pouring the concrete and letting it set? Can you shim
> the base in some manner after the concrete has cured? Will these questions
> be answered in the U.S. Tower planning information packet?
>
What sticks out of the concrete base are the threaded base bolts. The
tower sits on a nut and big washer and there is a nut on the top of the tower
base flange. You level it by adjusting the bottom nuts. You don't have to
worry about it being level at all since you level it when the concrete has set
(usually 2 weeks or more). The base bolts can be askew but you can still get
the tower level with the base nuts.
The thing to do is to get the base poured and cured before the tower
arrives. That way you can have a boom truck meet the truck with the tower when
it arrives. It can lift the tower off the truck and swing it over into place
on the anchor bolts. That way you only have to handle the tower once and in an
hour you're all done!
Cheers and GL, Steve K7LXC
Champion Radio Products
http://www.championradio.com
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