Topband: Gamma matching crank-up tower
George & Marijke Guerin
Fri, 25 Oct 2002 06:19:31 -0400
Dear Jim et al,
As many have commented, the cables that hang down on stand-offs make
shuntfeeding a tower difficult at best.
Rather than sweat the details or argue about cable dressing along tower
legs please consider an inverted-L hung off the top of the tower when it is
cranked up. A wire 80+ feet up and 80- feet out makes a nice 160 ft
inverted-L that is easily matched with a series vacuum variable capacitor of
about 450 pfd.
One can set the feed point a few feet from the base of the crank-up
tower and use about 10 ft of rope with a sliding insulator to support the
center of the wire. That way, no work is needed on the tower and isolating
or reworking a dipole or inverted-V antenna can be avoided.
Good luck, 73, George K8GG