Chris R. Burger, ZS6EZ, wrote:
> Because of the absence of any lateral play in the mast, alignment is
> pretty critical. However, it's a small price to pay. I have the
> ability to remove rotators without moving the mast, as there's a
> short piece of stub mast between the rotator and the main mast. The
> joint can be removed, after which the rotator comes out without any
> hassle. The mast remains supported by the bearings.
Here's another tip that I've discussed with Dick, K5IU: If you make
the stub mast you refer to out of aluminum tube at least 10 ft. long it will
act as a torsional shock absorber. Since you are using dual thrust bearings
there is no chance of it bending, as you've pointed out.
> A new idea that's being incorporated in my new station's design is
> to use two concentric masts. The inner mast has a concentric
> rotator, while the outer mast has a motorcycle drive sprocket to an
> offset rotator. This way, you can have an independently rotatable
> top antenna without much additional cost. The rest of the stack is
> turned through the motorcycle chain.
What a fabulous idea.