How to Build a DK3 Screwdriver Antennaby J.R. Hartig
CB enthusiast Don Johnson invented the DK3 screwdriver antenna in 1991. He designed a CB antenna using a modified electric screwdriver motor installed inside the lower section to create a multiband antenna. The tubing on the lower part of the antenna fully encases the screwdriver and also increases the antenna's radiation efficiency, which makes it work better. The DK3 screwdriver antenna maintains its superiority and most CB experts recommend buying the original DK3 antenna design for an already-assembled mast section of the antenna.
Assemble the mast section using its accompanying instructions. The mast section contains the screwdriver motor and the coiled inductance portion plus connection wires.
Combine two 1.5-liter water bottles base-to-base with the bottoms removed using aluminum foil duct tape or another heavy-duty tape to prevent dust or other debris from degrading the antenna's performance.
Cut the top off one of the two water bottles, and secure the bottles to the mast section with aluminum duct tape.
Assemble a grounding plane (a mat) for the antenna to stand on. Tape together several pieces of aluminum foil attic insulation using aluminum foil duct tape. Make the final area 48 inches by 60 inches in area. The ground plane lets you use the antenna in any non-vehicle area.
Build the base. Assemble four pieces of 2-by-4s, 24 inches long into an "X" pattern. Drill a 1-inch diameter hole in the center of the top 2-by-4. Nail this 2-foot length to a second 2-foot length after drilling a 3/8-inch hold in its center. Drill another 1-inch hole in the center of the third 2-by-4, and nail it perpendicular to the other two joined 2-by-4s. Cut the fourth 2-by-4 in half, and nail these two 12-inch pieces to the joined wood, with each piece touching the cross member 2-by-4.
Wrap the entire wood base with aluminum foil duct tape. This creates an inductance surface to attract RF current between the bottom of the DK3 antenna and the RF ground plane you put together.
Insert the DK3 antenna base, which comes equipped with a 1-inch stud, into the center hole of the base. Secure the antenna to the base with a 3/8-inch, No. 24 screw. Tighten the screw with a socket wrench inserted into the bottom hole of the base.
Attach the whip. Insert a 3-feet length of aluminum rod threaded at both ends through the plastic bottle opening and screw it into the threaded end of the mast section.
Drill a 3/8-inch hole in the center of a 12-inch diameter metal pizza pan. The pizza pan serves as a capacitance hat, making up for the shorter length of the antenna whip.
Screw a 3/8-inch hex nut onto the threaded end of the whip, and place a metal washer on top of it. Slide the pizza pan onto the the threaded end of the whip and secure it with a second metal washer and second 3/8-inch hex nut tightened as much as possible.
Connect two wires to the wire leads of the mast section, and attach those two wires to a two-position switch to control the coil movement of the antenna by remote.
Items you will need
- DK3 antenna mast kit
- 2 Empty water bottles, 1.5 liters
- Aluminum foil duct tape
- Aluminum foil attic insulation
- Antenna whip
- Antenna mount
- Pizza pan
- Power drill
- Drill bits
- Connecting wire
- 4 Pieces wood, 2-by-4
- No. 24 wood screw, 3/8-inch
- Socket wrench
- 2 Hex nuts, 3/8 inch
- Metal washers
- Two-position switch
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