Topband: Re: WWV/WWVH Antennas

[Phil Clements]

Hi Jim, and fellow Topbanders!

My 160 meter vertical is somewhat similar to the WWVH
verticals. The insulators are mounted at the 60 foot level
on a Rohn 25 tower. Above the insulators there is another
125 feet of tower. The three guy wires at the 60 foot level
are used as elevated radials. They slope down from 60 feet
at the tower to about 10 feet above ground at the far ends.
They are not "resonant." They are cut to about 120 electrical
degrees on 1.830 mhz. The entire system resonates on 1520
khz. A single vacuum variable set at 750 pf resonates the
antenna on 1.830. No other matching is required, as the base
impedance came out to 47 ohms. There are 120 half-wave
radials on the ground under the tower that serve as a screen,
and are not connected to the tower. The measured current in
in each of the three elevated radials is exactly the same from
1.8 to 2.0 mhz. This tower also supports a K8UR 4-Square for
80 meters. The Comtec box is mounted just below the insulators
at the 59 foot level on the tower.

(((73)))
Phil, K5PC







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