[TowerTalk] 5/8 Wave Verticals

[Jim Reid]

A German company is selling a 26 meter (~83 foot) tall
vertical (the Titanex).  This height is about 5/8
wave on 40 meters.  The antenna is costly,  and an
additional cost remote tuner of some sort is also
offered to tune the antenna.  Not sure what the tuner is,
or if it is just the coil, couple of relays and variable
caps as described by the K7K guys that used this antenna
on 160 out on Kure Island last Fall.

I checked with AO,  and come up with a base feed point
impedance of 102 - j366 ohms at 7.005 mHz.  Seems to
me that this antenna and its' radials could be fed
with 450 ohm balanced transmission line,  and the
tuning taken care of in the shack using a balanced
tuner.  To 450 ohm line,  the above impedance is
a vswr of 7.4;  while to 50 ohm coax it is 28:1,
thus the need for the base tuning of the antenna/
line at the antenna.

On 160 (1.825mHz) the feed point Z is 10.5 - j237.  or a
vswr of 112:1 to a 50 ohm line without base loading/
tuning.  Still 55:1 to a 450 ohm balanced line.

Has anyone ever tried feeding a vertical with balanced line
and used a balanced tuner at the rig end of the line??

73,  Jim, KH7M


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