Taller Vertical Antenna – “North Mast”

The main 56 foot low band vertical has been extended to 65 feet.  It took a full day to do it because of it’s unwieldiness and a constant 16 mph wind.  Thanks to John, KC0RF for giving up a full day to help.  Here’s what it looks like with the additional height and a small top hat to resonate to 3.573 kHz  (the FT-8 freq). This is both a vertical antenna and the north mast which is planned to hold up two dipoles.  The south mast (below) is planned to have the other end of one of the dipoles attached.

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The 30″ top hat is very hard to see when it’s 65 feet up in air.  A better picture is coming soon.

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The antenna is designed as a full quarter wave on 80 meters.  Using a MFJ 259B  the impedance at 3.573 kHz reads 55 -j0.  SWR is 1.1.   Apparently we hit the resonance perfectly but the ground screen needs to be improved to bring the resistance down to 36 ohms.  The match was planned to be a direct match for a 50 ohm coax.  As an experiment we left the existing tuner installed and tried it on other bands.  It works on all bands, 160 through 10 meters even though the take off angles may be awful and the tuner losses may be especially high at the even harmonic frequencies.  We’ll leave the tuner in for a a few weeks to see where it works and where it doesn’t.

 

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