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Alternate Feedline Connection
Another way to make a reliable feedline connection using customer supplied coaxial cable is using
the
DXE-RADP-3
Radial Plate with the
DXE-112-KIT
SO-239 Chassis Mount Connector as
shown in
Figure 13
. Use a customer supplied insulated wire soldered on the center pin of the
chassis mounted SO-239 (14 gage insulated wire is adequate) to a ring terminal which is connected
to the antenna feedpoint hardware. Make the wire long enough so it will not bind when raising or
lowering the antenna. When connected in this manner, the customer supplied coaxial cable will feed
the antenna and the shield will have a positive and reliable connection to the radial field.
Figure 13 - Feedline connection using a DXE-112-KIT SO-239 Chassis Mount
on a DXE-RADP-3 Radial Plate
Tuning the Vertical
It’s best to use an antenna analyzer such as the MFJ-259B for determining antenna resonance. Use
the X=0 an +/- j0 readings to determine the resonant frequency. The SWR will be adjusted by the
impedance matching assembly mounted at the feed point once the vertical is resonant at the desired
frequency.
The
DXE-7580FS-VA-1
should resonate at approximately 3.6 MHz with the recommended ground
radial system installed and the vertical dimensions as shown in
Figure 10
. Resonance is adjusted
by the length of the vertical element sections.
If you are having trouble achieving resonance, make sure the element section lengths are correct.
Make sure you have at least 16 radials (32 are better), 65 feet long, symmetrically placed around the
vertical. Our test vertical employed 32 radials, 65 feet long. The difference in resonance from 16 to
32 radials is about 30 kHz.
The antenna resonant frequency may be centered at any point by merely adjusting the overall
length. To raise the base resonant frequency, shorten the element tubing stack. Adjusting the
vertical base measurement in
Figure 10
will move the resonant frequency 20 to 30 kHz.
Measurements are taken from the bottom of the base element tube to the first vertical element
section. To ensure sufficient nesting of the base tube, do not go less than 4" of separation. The more
of the base element tube that is nested, the stronger the bottom section will be. For maximum
strength, the base section can be nested until it is slightly above the top clamp on the tilt-base. If a
