TW TW4040, Instruction Manual

Page: 18 / 22

TM
TransWorld Antennas
TW4040
TM
14 TW4040 Instruction Manual
Final tuning notes
If lower bands exhibit very low VSWR, but higher bands suffer VSWR problems
(or vice-versa), the spread of the center coil can be adjusted to effect which
bands tune best. By spreading the center coil slightly, the low-frequency bands
will tune better, and by compressing the center coil, the higher-frequency bands
will tune better. But note that if the center coil is changed, the tuned center
frequencies may change and the tuning process above will have to be repeated.
If tuning proves difficult, follow this checklist to eliminate common tuning
problems:
Is your antenna placed at least 30 feet away from other objects (buildings,
people, trees, etc.)? The ends of the antenna
’s arms are very sensitive to
coupling with external objects.
Is your antenna installed such that the arms are at least
24” off the ground?
The spacing between the antenna
’s arms and the ground should be between 24”
and 36
”.
Is your coax cable a high-quality RG-8 or RG-8X cable?
Is your coax cable long enough? At least 65 feet of coax should be used for
best results.
Is your coax installed at a 45-degree angle with respect to the antenna as in
the figure on page 11?
Are you checking the VSWR using less than five watts? Once at least five
watts is applied to the antenna, VSWR readings may improve significantly.