sweep (or loft? ) on spiral with section which is reduced

[Gisnio]

Bye to all,
I was trying to make a conical spiral solid that had an initial section of ø100 mm and a ø20 mm finish.
to give two data:
ø initial 500 (to string)
3 revolutions
step 150
Is there a way to do it?

 

[Gisnio]

I found the solution in the loft extrusion.
just use the center line to drive the extrusion. I was trying to use the driving curve first.