A radio frequency (RF) antenna is a structure used for transmitting and receiving radio frequency signal. A broadcaster uses an antenna to send AM and FM signals. These signals are picked up by the antenna on your radio. If you are picking up only weak signals, an RF antenna amplifier can be used to increase the strength of the signal. You can build your own amplifier circuit which can either be attached to your antenna or integrated into your radio device.
- Skill level:
- Moderately Challenging
Things you need
- Circuit chassis
- Circuit board
- Relay coils
- Soldering iron
- Standard electric drill
- 0.8-inch drill bit
Acquire the parts. You can do this two ways. Purchase the parts separately from an electronics store or purchase the parts as a complete package. The advantage of the latter is that all of the parts and the circuit board will be made to measure, so no extra drilling is required.
Study the schematic. This document illustrates the layout of and connections in the circuit. Use marker pens to colour-code the parts on the schematic with the physical components and their place on the circuit board.
Dismantle the radio. Use a Phillips screwdriver to remove the back of the radio chassis. Disconnect the antenna input from the circuit board. Melt the solder joint connecting the base of the antenna and the board by pressing a clean soldering iron over the connector pins. Disconnect the receiver input connection next to the antenna input in the same fashion. The amplifier circuit will be located between these two components.
Assemble the circuit board. Push each component into its turret with sufficient pressure that the connector pins poke through the base. Start with transistors, then capacitors, resistors and relay coils. Once complete, flip the board over and gently press the connector pins against the metal conductor strip.
Connect the circuit. Dip the soldering iron in solder, wait for the excess to drip off and then press the tip against the connector pin and metal strip.
Mount the board in a chassis. If there is no room to mount the board inside the radio, screw the circuit into the base of a separate chassis. Use a 0.8-inch drill bit to screw two holes to feed the wire through.
Connect the antenna. If there is room, screw the new circuit into the radio chassis before connecting and then solder the antenna base directly to the board. If there isn't room, connect the antenna to the board by soldering a wire between the antenna base and the input eyelet on the board.
Connect the radio. If the board is mounted inside the chassis, solder the radio receiver input directly to the output eyelet on the board. This places the amplifier circuit between the antenna and the receiver. It is positioned to strengthen the signal received by the antenna before passing it on to the receiver.
Tips and warnings
- If housed in a separate chassis, use electrical tape to secure the amplifier circuit to the radio. This prevents the wires being pulled.
- Never touch the tip of a soldering iron when it is turned on.
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