I had an aluminum mast up for several years in a Rohn 25 "snorkle"
type top section. Upon removal, I found that the aluminum was heavily
scored where it rubbed against the steel. The use of an aluminum
mast would seem to dictate the use of a thrust bearing to prevent
eventual failure of the mast. I don't think that using a bushing in
the snorkle would be advisable because of the reduction in the mast
diameter that could be accomodated.
73, Roger
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