Topband: 160 Shunt-Fed Tower Readings

Larry K4AB larry.k4ab at
Wed Dec 10 14:41:03 EST 2014

The antenna is a 94' Rohn 25, with a Force 12 24'boom Delta 6BA
on top. Note that the elements are insulated from the boom. The base
of the tower is grounded.

73 radials are attached to the base ranging in length from 130'-250'.
15,000 feet of radials, average length of ~200'.

It is fed through a  series 1000pF 10KV Jennings vacuum variable.
The shunt is a 4 wire cage about 3" in diameter and attached at ~45'
level.  It is spaced about 3' from the tower.

Here are the readings I get from a RigExpert AA-30 at the feedpoint:

1.830 kHz
Series model: lZI: 59.7 Ohms
R:59.5 Ohms
SWR: 1.23
X:5.6 Ohms
C: 15893 pF

What are these reading telling me,and how can I improve the antenna?

Thanks, in advance!

Larry K4AB

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