The best approach is to use slewing bearings at the bottom of the tower.
This freestanding, 40m high, rotatable tower of a fellow ham
with stacked long boom quads works flawless for more the 20 years:
those bearings are obtainable pretty cheap at crane companies
[mailto:email@example.com] On Behalf Of Kelly Taylor
My big fear with a tower such as this is that instead of multiple weak links
(ring rotors), where perhaps one antenna bites it, you have one big weak
link that would make the whole assembly bite it. The other angle that is
perhaps not been explored either is the capacity of the tower to accept
additional loads along its length.
If I recall correctly, the Big Bertha tower worked because the entire tower
base was inserted into the bearings which were held down by lots of concrete
and because the design assumed from the start multiple antennas from top
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