On 12/9/2015 2:34 PM, Cqtestk4xs--- via Topband wrote:
On 160 I'm leaning toward a wire vertical suspended from a rope coming
from the tower which would make the antenna about 65 or 70 feet tall and to
compensate for that I would make it a T-top.
Normally, a T-top is great, but in your case it will royally screw up
the patterns of the higher frequency Yagi's. What were you thinking??
I think this will work, but you need to model it:
Build a cage around the tower suspended from the non rotating
part of the guy rings. The cage should be electrically insulated
from the lower guy ring. For the top ring, there are two
possibilities: Case 1: if the ring is inherently
electrically conductive between rotor and stator,
use it to electrically connect the cage to the tower
at the upper guy ring. Case 2: If the ring is
inherently electrically insulating, just let the top of
the cage float.
In either case the bottom of the cage is insulated from ground
and is what you drive against your radials. Case 1 is the
classic skirt method of shunt feeding a grounded tower.
Case 2 uses the cage as the vertical and I think it will
work in spite of the tower and antennas above it, but you
need to model.
In case 2, there may be a way to get an electrical connection
across the guy ring by hanging some wires loosely from a
few feet above it on the tower, such that the wires have
enough slack to allow the tower to rotate. Alternately,
there may be a way to let the wires hang down in a U shape.
Comments?
Rick N6RK
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