Owen Duffy wrote:
Does the outer conductor 'shield' the vertical so that it will not
radiate?

No, the outside surface of the shield is the radiatior, it just has a
quarter wave o/c stub in series from the feedline to the radiating
element.

Owen, feedline radiation in this particular system might
increase the efficiency which would be a good thing.
--
73, Cecil http://www.w5dxp.com