How to model this helix in Blender Given this simple openscad helix:
linear_extrude(height=300, twist=-360, $fn=160) 
union() {
    translate([0, 50, 0]) 
        circle(r=10); 
}

How can I model in Blender an identical helix?
I tried (in Blender 2.80 with Curves add-on):

Add Curve - Curve Profiles - Helix (3d)
Select curve in Object mode + &quot;Object Properies&quot; - Geometry - Set Bevel: Depth= 0.2

But the result is different (see images of top and front views.)
Even if I convert the curve to a mesh, add a cube and substract it from the helix at some height, to make the bottom and top caps parallel to the xy plane,
the resulting profile is not a round circle as required.
If you assign a Screw modifier in Z to a circle in the XY plane, you should get an object in the form of your openscad reference.

The circle is at helix-radius from the world origin.. by moving it there in Edit mode, you ensure its Object Origin (and therefore the center of rotation of the helix,) is left at World 0.
Any XY slice through the helix will show a circular profile.