Alex:
I have a very similar setup and can make a few recommendations:
*First of all, all Dick Weber at Rotating Tower Systems before
you buy anything. He is a very talented engineer and the
designer of the system. He will probably tell you the
following, too!
*Spend the extra $$ for Rohn 55G with what you're putting up.
Last time I checked it was about $50/section more than 45G,
so you'd be looking at another $750 for the tower. But 55G is
way better, especially with all you plan to put up. My 55G
with similar antennas (plus a KLM 80m dipole at the top
of an 18 foot mast coming out of the 14th section) has been
up since 1989. I have rings at 40, 80 and 120 feet, with
the rotor at the bottom.
*Rotors are the problem. I have a big Telrex unit that came
with the tower when I bought it (used). It can handle the
incredible torque that comes from 150 feet of tower and
all that aluminum trying to twist around in the wind. But
as Dick Weber will tell you, he recommends using a 2:1
gear ratio to keep the tower at 1/2 RPM, which is painfully
slow. In response to a complaint that this is too slow for
contesting, he is quoted as saying that's why contesters
don't use rotating towers; only DXers do!
*The only other rotor he recommends is the Hy Gain HDR300
and some people have used them successfully. Prop pitch
motors will also work. I was going to try the M-2 OR2800P
but the claims that M-2 folks made to me at Visalia turn out
to be bull...so I'm not going to waste my money or time.
*In terms of selecting a rotor, note that there is almost no
top load as the weight of the tower sits on the bearing. And
you can turn the tower by hand when the chain is off, so it
doesn't require tremendous power to rotate. The problems
are in turning it in the wind and in stopping it without
the rotor self destructing. When the Telrex stops, the bottom
section stops immediately. But if you look up the tower at
the big KLM 6 element 20 near the top, it goes another 1/8
turn. That's alot of steel tower twisting!! And that's one big
reason to go with Rohn 55G rather than the lighter tubing 45G.
Good Luck...73, Howard WZ6Z
If I plan to stack a 150' tower (Rohn 45G) with 80m,40,20,and 10/15 meter
yagis, can the Tower be turned (using the RTS) using a high windload
rotator? The yagis are going to be greater than 40ft in boom length each
and windload very high numbers? Was just wondering.. Thank You in advance.
-Alex
Best 73,
de KB4LBX/Alex
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