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Things You'll Need
Instructions
Calculate the total length of the dipole wire that will be required for 27.185 MHz. To calculate this length, use the mathematical formula Length (in feet) = 468 / frequency (megahertz). Divide 468 by 27.185 to arrive at a total dipole length of 17.22 feet. Since this guide will be detailing an "Inverted V" style of dipole antenna, an additional calculation is necessary where 5 percent is taken away from the total length to compensate for the wire slopes. This will result in a total length of 16.35 feet, or 8.175 feet for each dipole wire leg from center.
Roll out the full length of wire, and round up to the nearest foot of length to allow for antenna adjustment when matching it to the radio transmitter. Rather than 16.35 feet, simply roll out a full 17 feet of wire. Measure to the center with a tape measure and cut with wire cutters to form two halves. This will result in two pieces, each being 8 feet 6 inches in length.
Lay the balun in between the two wire halves. Note that the balun has two metal terminals, one on each side, with a threaded antenna connector on one end. Connect the left wire to the left terminal, and the right wire to the right terminal. Use a soldering iron and solder to connect the wires to these terminals. Use a liberal amount of solder for the best connection possible.
Tightly screw down one end of the coaxial cable to the PL-258 threaded connector on the bottom of the balun. Tie one end of the rope to the top of the balun securely, then carefully throw the spool over a tree limb of a nearby tree, allowing the spool of rope to return to the ground. If a tree isn't available, use a ladder to climb and secure the balun to the top of a structure such as the building in which the radio is located. If using a tree, pull the rope to lift the balun to about 15 feet high and tie off the rope at the base of the tree to hold the balun up in the air.
Connect the two wire ends to ceramic wire insulators. Do not solder the wires yet so adjustments can be made. Twist the wires near the insulators so they don't pull out.
Cut two pieces of rope from the spool, each length being about 6 feet long. Tie one end of each rope to each of the insulators securely, then use them to pull each of the wire legs outward until the entire antenna looks like an upside-down V with equal angles at the balun.
Hammer tent pegs into the ground and tie the rope to the pegs to maintain the inverted V shape of the antenna and the equal angles at the balun. This will secure the final antenna into position.
Connect an SWR meter between the radio and the antenna, then power up the radio and transmit for two or three seconds. Observe the SWR reading. If the SWR reading is above 2.0, don't transmit any further. Return to the antenna and use wire cutters to remove 1 inch of wire from each end of the wire legs, at the ceramic insulators, and test again. Continue removing 1 inch from each leg until the SWR reading is between 1.2 and 1.5. The lower the SWR, the more efficient the antenna.
Solder the wires near each of the ceramic insulators to finalize the antenna installation, making it as secure as possible.