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DIY RDF

The Federal Communications Commission considers the amateur radio community to be self-policing. Among other things, that means you are expected to do your own detective work to locate sources of radio interference within your band allocations. This responsibility has spawned a ham radio sport known as RDF -- or radio direction finding -- "foxhunts." The designated "fox" hides a small low-powered transmitter, and then the other participants hone their skills in locating the transmitter. Typically, foxhunters attach a DIY directional loop antenna to an existing portable receiver, to create an RDF receiver.

Things You'll Need

PVC pipe, 1/2-inch diameter by 2 feet long
1/2-inch PVC cross
Measuring tape
Hacksaw
20 feet of insulated electrical wire
Electrical tape
Wire stripper
Variable capacitor

Instructions

- 1
  Cut the PVC pipe into four equal-length pieces. Insert the pieces into the cross.
- 2
  Use the hacksaw to notch the exposed ends of the pipes, to hold the wire. Wrap the wire around the perimeter of the cross for five turns. Leave 2 feet of free wire on each end. Tape the wire to the cross.
- 3
  Bring the free ends of the wire along one of the legs to the center of the cross. Strip a half-inch of insulation from each wire at the center of the cross.
- 4
  Connect the variable capacitor across the two wires where you stripped the insulation. Tape the capacitor to the cross.
- 5
  Connect one of the wire ends to the receiver's antenna input. Then connect the other wire to the receiver's ground connection.

Ham Radio