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Things You'll Need
Instructions
Coil and Mast Assembly
File or sand a 1/2 inch to 3/4 inch flat strip along the length of each of the two 1-1/2-inch PVC pipe sections to create an effective coil tap point location. Drill a 3/8 inch hole into the center of each end cap.
Place a reducer and an end cap on each end of each of the 6-inch length of PVC section for the loading coil. Do not cement into place at this time. Drill a 1/10 inch hole into the tube, on the side opposite the flat strip created in Step 1, just at the edge of the end cap. Drill a second hole into the tube at the edge of the reducer, on the same side as and aligned with the first hole. Remove the end cap and reducer.
Insert three inches of one end of a 12-foot section of the 12-gauge wire into the hole closest to the end cap of the 6-inch tube, and solder a wire lug to that end of the wire. Insert the ferrule onto the end cap, first placing a washer and then securing the lug firmly onto the ferrule bolt inside the end cap with the nut. Use thread-locking compound to secure the nut into place. Pulling excess wire back through the hole as needed, cement the end cap with the ferrule and wire assembly firmly back onto the 6-inch PVC tube.
Wind the wire around the 6-inch PVC tube, between the end cap and reducer, for 22 turns. The turns will be about 1/8 inch apart. Secure with electrical tape as needed while completing the winding. Trim the wire so about one inch can be inserted into the second hole above the reducer to help anchor the coil. Cement the reducer onto the tube. Secure the coil with the putty or high-voltage lacquer. Press a bead of putty through the wire onto the tube in three or four strips. Do not cover the flat section of the tube. If using lacquer, mask the area of the flat strip first, then apply several coats to the entire coil, letting it dry sufficiently between coats.
Insert the end of the 36-inch long 1/2-inch PVC tube into the reducer end of the loading coil just completed and cement into place.
Place the remaining end cap and reducer onto the 4-inch tube, for the matching coil. Do not cement at this time. On the opposite side of the flat strip created in Step 1, drill two 1/10-inch holes into the 4-inch tube at the edge of the end cap, spacing them about one inch apart. Drill two holes into the tube at the edge of the reducer, one inch apart, aligning them with the first two holes.
Solder one end of a 6-inch length of the 12-gauge insulated wire to a wire lug. Remove the end cap and insert the 3/8-inch mounting bolt through the end cap, the head of the bolt inside the cap. Place a washer and the lug with the 6-inch wire lead on the bolt on the outside of the end cap. Secure snugly with the nut. Use a few drops of locking compound to keep the nut in place.
Insert an end of the remaining 18-foot length of bare wire through both holes nearest the end cap in the 4-inch PVC tube so that only about 1/2-inch of the wire protrudes through for a pigtail to attach the ground. Bend the end of the wire down to help anchor the coil. Wind the wire around the tube for 10 turns, each turn about 1/8 inch apart, between the end cap and the reducer. Secure turns with plastic electrical tape as needed. Insert the free end of the wire through both holes near the reducer, pulling completely through to secure the coil windings. Do not cut wire at this time. Secure the coil with putty or high-voltage lacquer as in Step 4. Cement the reducer to the loading coil tube.
Align the flat strip of both coils, facing them the same direction, and cement the end of the 36-inch PVC tube and loading coil assembly to the reducer on the matching coil. Continue winding the wire along the 36-inch shaft, from the reducer of the matching coil to the reducer of the loading coil, for approximately 28 turns. Space turns 1 1/4 inch apart. Leave a 2-inch pigtail to attach the wire lead and trim off any excess wire. Wrap the entire 36-inch shaft with plastic electrical tape.
Solder the remaining 12-inch length of 12-gauge insulated wire to the pigtail at the top of the shaft. Solder an alligator clip to the end of each of the insulated wire leads at both the mounting bolt and the top of the center shaft. Solder the 1/2-inch copper braid onto the pigtail at the bottom of the matching coil.
Mask the coil-tap areas above the flat strips on both coils and spray paint the coils with flat enamel for protection. Insert the wire whip into the ferrule at the top of the loading coil and secure with the locking screw.
Mounting and Tuning
Mount the antenna on a standard bumper mount or other frame-supported point such as trailer hitch mount or through the frame of a pick-up truck bed. Support the antenna with a brace attached to a vehicle roof-rack or other similar type device.
Attach securely the copper braid ground the the vehicle's frame. A wire lug can be soldered to the copper braid to ensure a good ground connection. Most antenna problems can be attributed to mounting or grounding insufficiency.
Tune the center of each band using an SWR meter between your rig and the antenna's attachment point on the mounting bolt. Locate the tap point on the loading coil that results in the best SWR reading, closest to 1:1, and fine-tune it by finding the best tap point on the matching coil. Note and mark the tap points for each band. At 6, 15,17 and 20 meters, these points should be easily found. At 12 meters the whip needs to be retracted about one foot. At 10 meters, retract the whip down about 2 feet.