[TowerTalk] Twinlead- Zepp
barry at mxg.com
Thu Nov 3 13:45:01 EST 2005
I don't think there is any such thing as a center-fed Zepp.
My 1926 ARRL Handbook shows the "Zeppelin" System of Voltage Feed,
using a two-wire feed line, with one wire "Dead Ended" at the
End Feed point, and is described:
"As two-wire R.F. lines operate so nicely without high losses
without trying to radiate and become part of the antenna when
they begin to get long, you had best stick to the two-wire
line even if you prefer voltage-feed to current-feed. The
"Zeppelin" voltage-feed system is most simple to erect and adjust.
It is flexible, too, and can be worked on any harmonic we wish
without difficulty just by tuning the primary circuit of the
oscillator to the desired wavelength. The "Zeppelin" arrangement
has one of the line wires dead-ended, the other one connecting
to the very end of the antenna which is always a voltage node,
no matter what harmonic you are working on with a Hertz Antenna.
The system is very flexible and has the great advantage that the wire
acting as the antenna can be entirely in the open, getting rid of
troublesome absorption losses that often keep an otherwise good
station from reaching out."
Long ago I removed the coax feedline and shorted across the center
insulator of what was a tower-mounted 80 meter inverted V, and
instead end fed it with 65 feet of 450 ohm ladder wire, one wire
"dead-ended" at the end insulator (isn't that magic??), and used
it that way on 80-10 on all bands with excellent results, thru a
MatchBox. On 160, I tie the ladder wire together and feed it as
a long wire thru a separate Dentron tuner.
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