Step-13: Connect feedline to antenna base.
2 100449 Solder lug
Prepare coax, as shown in FIG-13. Attach center conductor to main radiator and shield to ground radial ring
using solder lugs. For best weather protection, flood braid with a weather-resistant liquid sealant such as
Liquid Tape™. This will prevent water from entering the coax and wicking along the shield. Coil several turns
of coax next to the antenna base or install a choke-style current balun at the feed point (see Appendix-1 for
instructions). Feedline leading to station may be buried between radials.
Center Conductor
Shield
Coax Connection
1-3/4"
Cable Pigtail
FIG-13: Feedline Connection
Step-14: Install ground radials
Basic System: This set-up works especially well for installing the MA160V within the confines of a typical
residential house lot (FIG-14A). You’ll begin by installing 3 primary radials, then continue to add more—as
needed—until achieving a feed resistance of approximately 50 Ohms (or minimum SWR). Radials need not
be of equal length and may be arranged to fit the shape of your yard. The total number of wires needed
depends on local soil conductivity and the cut lengths used. Where possible, bury each wire 2-4 inches
below the surface to prevent breakage and to avoid creating a trip hazard for others. A turf cutter or edger
may be used to open a narrow slit in the ground. Radials may be routed around trees, buildings and other
landscaping features as needed. A symmetrical layout is best, but not essential. For best results, follow the
installation procedure below:
[ ] Cut a set of three primary radials to fit available space (20-50 feet long).
[ ] Scrape off enamel and install a #8 lug on one end of each wire. Solder in place.
[ ] Install the primary radial wires approximately 120-degrees apart and connect each to the radial ring.
[ ] Connect a SWR analyzer to the coax feed and tune the frequency control to find minimum SWR.
[ ] Prepare and add more radials (15-40 feet long), one at a time, while continuing to monitor SWR.
[ ] Stop adding radials when SWR approximates 1:1.
[ ] Retune the antenna’s stinger section for best SWR on your frequency of choice.
Notes: Remember to retune the frequency control of the analyzer after adding each radial—the SWR dip
should migrate down slightly in frequency as each new radial is added. Once the lowest SWR reading
possible has been obtained, continuing to install radials will cause SWR to rise again as the feed resistance
decreases below 50 Ohms. It may be possible to trim or add one or more short radial, as needed, to obtain
flat 1:1 SWR. The lower the minimum SWR reading, the wider the usable bandwidth will be. Once the radial
field is set in place, note that SWR may fluctuate slightly over time with changes in soil moisture, but you
should be able to achieve low SWR in all parts of the band by changing only the resonator stinger setting.
The MA-160V should also perform well over the radial system prescribed for the MA8040V.
added
radials as
needed
for lowest
SWR
Install
Primary Radials
Added Radials
FIG-14A: Example of Basic Residential Radial Installation
(16 pages)
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