How to Build a CB Linear Amplifier

Written by simon foden | 13/05/2017
How to Build a CB Linear Amplifier
Measure the cable jack so you know how big a hole to drill. (Dynamic Graphics Group/Dynamic Graphics Group/Getty Images)

Radio frequency amplifiers typically have linear circuits for broadcasting AM and FM signals. Linear amplifiers can produce a significantly higher output than the input voltage. Citizen's Band (CB) radio communication relies on linear amplification. While most amplifiers increase the volume of a signal, CB amplifiers increase the frequency or amplitude of a signal. Building your own CB amplifier requires moderate soldering skill and basic to intermediate knowledge of electrical circuits.

Source your parts. You can purchase them separately or in a kit. Using a kit is advantageous because all of the parts are made to measure and mutually compatible.

Clean your soldering iron. Wipe any solder residue away with a wet sponge. Dry the iron with a clean cotton cloth.

Read the schematic. This illustrates the layout of the amplifier circuit. Familiarise yourself with the nature of each connection and the location of each component. Refer to this document when populating the circuit board.

How to Build a CB Linear Amplifier
Expand the range of your CB radio with an amplifier. (Digital Vision./Digital Vision/Getty Images)

Prepare the amplifier housing. Measure the cable jacks that you normally use to connect your CB antenna to the transmitter. Use a standard electric drill to cut two holes large enough for the cable jacks. Calculate the surface area of IEC power supply socket. Sketch the outline on the back of the amplifier. Use a dremel tool to cut a square on the rear panel of the amplifier housing, large enough for the IEC power supply plug to fit.

Assemble the circuit. Push the diodes, transistors, fuses, capacitors and resistors into their turret on the blank circuit board. Push them in so that the connector pins poke out through the bottom of the circuit board.

How to Build a CB Linear Amplifier
Don't touch the tip once the iron is on. (Hemera Technologies/ Images)

Turn the soldering iron and let it heat up.

Consult the schematic to ensure that each part is located in the correct turret.

Connect the circuit. Place the circuit board face down. Push each connector pin so it lies flat against the metal strip on the base of the board. Dip the tip of the soldering iron in solder and then press it against the connector pin and metal strip to form a solder joint over the two.

Mount the circuit. Screw the board down into the base of the chassis enclosure.

Connect the power supply. Solder the red wire from the IEC power supply to the positive terminal on the circuit board. Solder the black wire to the negative terminal.

Enclose the amplifier housing. Screw the lid down with a Phillips screwdriver.


CB amplifiers must operate on the CB frequency, which is 27MHz.


Always obey national broadcasting laws when using CB radio.

Tips and warnings

  • CB amplifiers must operate on the CB frequency, which is 27MHz.
  • Always obey national broadcasting laws when using CB radio.

Things you need

  • Amplifier chassis
  • Blank circuit board
  • Diodes
  • Resistors
  • Capacitors
  • Relay coils
  • Soldering iron
  • Solder
  • Sponge
  • Cotton cloth
  • Power supply
  • Standard electric drill
  • Standard drill bit set
  • Dremel tool

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