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How to Make an RF Choke for a Shortwave

If your shortwave radio tends to send and receive significant amounts of signal static, you may need to install an RF choke between your antenna and the radio's feed line. An RF choke improves your radio's performance by canceling feed line radiation caused by an electrical imbalance in the antenna system. The choke balances the impedance, or resistance to electrical current, between the antenna and radio, which maximizes the radio's transmitting potential.

Things You'll Need

  • Power drill and 1/8-inch bit
  • PVC pipe, 5-inch outer diameter, 1 1/2-feet long
  • Coaxial cable, RG-58 with connectors, 50-ohm, 25-feet long
  • Electrical tape
  • Zip ties
  • Scissors
  • 2 coaxial adapters, BNC female to BNC female
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Instructions

    • 1

      Drill two horizontal 1/8-inch holes, 1/4-inch apart, 1/2 inch from the end of the PVC tube. Drill a second pair of 1/8-inch holes, 1/4-inch apart, 1 inch from the first pair of holes. Drill a third pair of holes, similarly, 1 inch from the second pair.

    • 2

      Measure two feet from the end of the coaxial cable. With this length extending from the end of the PVC tube, wrap the remaining cable tightly around the tube, starting after the third pair of drill holes. Continue to wrap the cable around the tube until three feet of excess cable remain at the opposite end. Secure the turns temporarily with electrical tape.

    • 3

      Drill two 1/8-inch holes, 1/4-inch apart, after the last cable turn on the PVC tube. Drill two additional pairs of holes toward the end of the tube, each separated from the previous pair by 1 inch.

    • 4

      Run plastic zip ties through holes in the PVC tube, and across the length of the wrapped cabled. One zip tie each, should thread through a corresponding hole at either end of the wrapped cable. Pull the zip ties tight. You should have two parallel zip ties, tightened across the wrapped cable and securing it to the tube.

    • 5

      Position the excess coaxial cable between the remaining two pairs of drill holes, at either end of the PVC tube. Thread zip ties through each pair of holes to secure the cable at two points at each end of the tube. Remove the electrical tape, and trim the zip tie excess with scissors. The zip ties should secure the cable firmly to the PVC tube.

    • 6

      Connect one end of the RF choke coaxial cable to the feed line that runs to your ham radio input, using a coaxial adapter. Connect the other end of the coaxial cable to the antenna line, using a coaxial adapter.


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