Assemble the Can and Antenna

Printable instructions (PDF)

The printable horn and can guide covers can assembly on page 5. The steps below add detailed demonstrations.

The can forms the back end of the horn antenna. A copper probe inside it connects to the receiver through an SMA feedthrough.

Use a new, empty 1-gallon F-style metal can. Do not cut, drill, or heat a container that held flammable liquid.

You will also need:

• A 5.25 cm copper probe and a four-hole, panel-mount male SMA feedthrough connector.
• Solder, a soldering iron or hot air gun, and helping-hand clips.
• A smooth-edge can opener, a drill with a 1/4-inch bit, and a wooden support block.
• Aluminum foil tape and tweezers or needle-nose pliers.

On this page: Make the probe, prepare the can, and attach the antenna.

Making the Feedthrough Antenna

The demonstration uses 4-gauge copper wire. The printable 2021 guide allows 4- or 6-gauge wire, cut to 5.25 cm.

1. Place the copper wire and SMA connector horizontally in the helping-hand clips.
2. Melt a small solder drop onto the connector’s pin and the copper wire’s end.
3. Bring the soldered ends together. Keep the connector and wire aligned while soldering the joint.
4. Let both parts cool before handling. Use tweezers or needle-nose pliers to move hot parts.

Watch the soldering demonstration:

Preparing the Can

Prepare the can in four steps:

1. Remove the bottom.
2. Drill the hole for the antenna.
3. Cover the spout with foil tape.
4. Attach the antenna.

Removing the Bottom of the Paint Thinner Can

Use a smooth-edge can opener with a top turning knob. The original instructions specify the OXO Smooth Edge Can Opener, model 2128100. It cuts along the outside edge and leaves a smooth rim.

A side turning knob can hit the can wall. A regular opener may not reach the inner edge or follow the rounded corners. Remove the bottom as shown in the demonstration:

Drilling the Feedthrough Hole

1. Mark the centerline on the can’s broad side. On the demonstrated can, this is 3.25 inches from the side edge.
2. Mark the drilling point 5.25 cm from the uncut, capped end.
3. Place a snug wooden support block inside the can beneath the mark.
4. Drill a 1/4-inch hole through the can wall. The block supports the wall during drilling.
5. Remove the support block.

Watch the drilling demonstration:

Taping the Spout

Cover the spout before attaching the antenna. Cut two 2-inch lengths of 1.5-inch-wide aluminum tape. Cover the inside and outside of the spout opening. Keep the tape smooth and flush with its edges.

Watch the taping demonstration:

Attaching the Feedthrough Antenna

1. Melt solder around the 1/4-inch hole using the soldering iron or hot air gun.
2. Make the solder pool as wide as the connector’s base, then let it cool.
3. Insert the antenna with the copper probe pointing into the can.
4. Center the probe in the hole. Keep the probe and its solder joint clear of the metal wall.
5. Heat the connector base, solder ring, and can until the solder melts and the base sits level.
6. Let the assembly cool. Check that the connector base is firmly attached and the probe remains clear of the wall.

Watch the attachment demonstration:

Next, attach the can to the horn.