This really doesn't sound like a long mast vs another tower section.
It sounds to me like using a mast in place of the tapered portion of the
top section.
I use an accessory plate in the top section, even with the top cross
braces and mount a thrust bearing on it. Then a second plate farther
down to hold the rotator. This means the mast sticks up little more than
it would using the taper section.
Put grease zerks in place of the bolts at the top sleeve with a smooth
fitting shaft running through. Even for thrust bearings, I prefer to
not have them support any weight so the sleeve bearing is ideal. I
would however use steel over aluminum most any day. This is not a place
where saving weight over strength is important.
73
Roger (K8RI)
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