My dipole is fed with really old twin lead. I think it is one inch
spaced, it was made by Saxton Products, and I got it from an OT who was
selling most of his old gear and stuff. The wires are solid copper,
maybe about 18 AWG and the spacers are white polyethylene, maybe 1/4"
diameter, with the wires pressed into them when they were hot. I think
it is supposed to be 450 ohm line. It is much lighter than an equal
length of RG-8, maybe around the same weight as RG-58 would be, but
probably lighter and certainly lighter than a ferrite core balun at the
center of the dipole would be. Since the feedline is so light weight I
can use really thin copper wire, I think it may be 22 AWG varnished
wire. The three old glass antenna insulators that I am using for the
center and ends of the dipole probably weigh more than the wire that
makes up the antenna. I don't know how long the antenna is exactly. I
just made it the right length to fit between to two palm trees that hold
it up. I know it is less than a half wave on 80 meters and more than a
half wave on 40 meters. I can put the full output of my Ten-Tec Titan
425 into my Johnson kW Matchbox and I never have to worry about arc
over, heating or losses in the feedline on any band. If I used coax, I
would have to use at least RG-8 or RG-213 or similarly sized and heavy
coax to handle full power, even if I had gone to the trouble of trimming
the antenna to resonance on one band. The antenna wire would have to be
much bigger to support the coax, the tension would have to be much
higher, the wind loading would be higher and it would only be usable on
one or two bands (perhaps 40 and 15 meters) without a tuner. Even with a
tuner I doubt I could give it full power on more than just one or two
bands without some fireworks in the coax. Using the old ladder line and
the Matchbox I can put full power into it on several bands, and by
adding lengths of modern "window line" twin lead in the shack I can tune
it to the other bands, and run full power there too. I think it is a
pretty efficient setup, and I like the looks of the ladder line outside
my shack window. I guess there is more than one definition for
efficiency. This antenna works for me.
Hope to work you on 40 CW, or most any band.
73 ES ALOHA DE KH6/N6KB
|