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How to Build a Ham Antenna Tuner

For a modest cost, a ham antenna tuner can provide your radio with precision signal transmission and reception. The tuner transforms the antenna's impedance, or opposition to electrical flow, to a level that matches the radio's. This matching impedance allows the radio to maximize its transmission power and reception sensitivity, thereby tuning to weak and distant signals. Build this antenna tuner to connect with hams around the world.

Things You'll Need

  • Variable capacitor, 365 pf, air type
  • PVC tube, 1 inch wide by 3 inches long
  • Magnet wire, 24-gauge, 35 feet long
  • Electrical wire, 16-gauge, 1 1/2 feet long
  • Plywood board, 1/2-inch thick, 6 inches square,
  • Power drill, 1/4-inch and 1/8-inch bits
  • 2 machine screws, 1/4 inch by 1 inch
  • 4 machine screw nuts, 1/4 inch
  • Alligator clip, solderless
  • Sandpaper
  • Soldering iron and solder
  • Pliers
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Instructions

    • 1

      Drill two 1/4-inch holes in a corner of the board. Insert the screws through the bottom of the board, threads facing up. Fasten the screws in place with nuts.

    • 2

      Drill two 1/8-inch holes, 1/4 inch from one end of the PVC tube, and thread the magnet wire through the holes. Wrap the wire tightly around the tube 100 times, twisting the wire into a small loop every 10 turns. Drill two more 1/8-inch holes in the tube after the 100th turn, and thread the wire through these holes to lock it in place.

    • 3

      Remove the plastic coating on the wire loops with sandpaper to expose the wire. Clip one end of the magnet wire short, and leave 3 feet of excess wire on the other end. Place a dab of epoxy on each wire end where they thread through the holes to secure the wire tightly in place.

    • 4

      Epoxy the variable capacitor to a corner of the board adjacent to the screws. Make sure the capacitor knob faces out. Epoxy the PVC tube vertically, to the corner diagonal of the screws.

    • 5

      Cut the electrical wire into three 6-inch long pieces and strip 1/2 inch from each end. Crimp the alligator clip to the end of one wire using the pliers. Twist the free end of this alligator clip wire around one of the screws. This will be the antenna screw.

    • 6

      Solder the end of a wire to the rear metal frame of the capacitor. Twist the other end of the wire around the empty screw. This screw will be connected to the ground wire.

    • 7

      Solder one end of the remaining wire to a solder tab on the side of the capacitor. Twist the other end around the antenna screw.

    • 8

      Attach the antenna and ground wires to the corresponding screws. Tighten a second nut on each screw, securing the wires in place.

    • 9

      Attach the 3-foot end of the magnet wire to the external antenna jack of your ham radio. Connect the alligator clip to a loop on the PVC tube.

    • 10

      Tune the antenna by turning the capacitor knob and connecting the alligator clip to different wire loops.


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