Topband: Shunt Fed Tower Info

[k6se at juno.com]

Regarding floating elements be aware that the driven element, although
insulated from the boom, acts like it is grounded to the boom on 160m
because of the feedline's coupling to the tower on its way down to the
ground.  Therefore, the driven element already fully adds to the
top-loading and there is no reason to "ground" the driven element to the
boom when you shunt feed the tower on 160m.

As Tom, W8JI pointed out, it is wise to ground the parasitic elements to
the boom because of the high RF voltages present, especially at the ends
of the boom.  Several hams have had arcing problems from the 20-meter
reflector element to the boom on Force 12 beams when they used their
shunt-fed towers on 160m.  They solved the problem by grounding the
parasitic elements to the boom.

If you ground the parasitic elements your tower will have substantially
more top loading, therefore the shunt feed parameters will be quite
different than with insulated parasitic elements.

73, de Earl, K6SE