snip
PS I built the tower its going on, 8.5 metres, teaching myself to weld
as I went. Welding gets better as you go up.......so, the next logical
step is to build the antenna that goes on top of that.........

Andrew VK3BFA.

So... the weakest portion of the tower is the bottom-most structure.
Sounds like you need to build another antenna tower from the "top,
down"....Or just flip the existing tower upside-down so the strongest
part is at the bottom.... G
Ken.