How to Build an AM Radio Signal Amplifier

Written by simon foden Google
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How to Build an AM Radio Signal Amplifier
The AM amplifier intensifies the strength of the signal received by the antenna. ( Images)

For a radio signal to be processed by the receiver, it must be modulated. The two common types of modulation are amplitude modulation (AM) and frequency modulation (FM). Amplitude modulation causes the strength of the radio signal to vary in intensity. These variations form an analogous image of the sound wave as the radio wave travels, which the radio receiver interprets and reproduces as sound. If your favourite radio station has a weak AM signal, using an AMP radio-signal amplifier is an efficient means of strengthening that signal before it reaches your radio.

Skill level:

Things you need

  • 30-by-35mm AM amplifier circuit board
  • Ampliifier circuit enclosure
  • Power source
  • Soldering iron
  • Solder
  • Standard electric drill
  • Standard 1/8-inch drill bit

Show MoreHide


  1. 1

    Source your parts. You can get your parts individually or collectively, as part of a kit. Using a kit ensures that all of the parts are made to measure and compatible.

  2. 2

    Study the schematic.This illustrates the layout and values of each board-mounted component. AM amplifier circuits can be very simple, with few board-mounted circuits. Or they can be complex, with a range of diodes, cathodes, resistors and capacitors.

  3. 3

    Unplug the antenna and remove the connection between it and the radio. Your AM amplifier circuit will be located between the antenna and radio receiver. It will receive the signal picked up by the transmitter, boost it and send it to the radio device.

  4. 4

    Dip the tip of a hot soldering iron in solder. Let the solder partially fuse to the tip of the iron. Solder the antenna cable to the start of the circuit, between the power supply and the output. Press it over the end of the antenna connector and the point on the board where you wish to connect it. This fuses the antenna connector and board point together.

  5. 5

    Solder the radio input cable to the end of the circuit, between the antenna cable solder joint and the output. Solder at arm's length. Do not hunch over the soldering iron. The smoke rising from the tip of the iron contains solder flux which is a potential irritant if inhaled.

  6. 6

    Connect the battery snap or IEC power supply. AM radio signal amplifiers do not require a large amount of power to operate. This affords you a choice of power supply methods. Batteries allow your amplifier to be portable, and electrical power gives you a constant and reliable source from the wall socket. Solder the power wire from the battery snap or power-supply socket to the positive eyelet on the board. Solder the ground wire to the negative eyelet on the board. Fit a 9-volt battery to the battery snap.

  7. 7

    Mount the completed circuit inside the housing. If necessary, use a standard electric drill and 1/8-inch standard drill bit to create holes to fit the cables and connectors through.

    How to Build an AM Radio Signal Amplifier
    A weak AM signal can ruin your listening enjoyment. (Jupiterimages/BananaStock/Getty Images)
  8. 8

    Turn on the antenna and radio receiver.

Tips and warnings

  • Always solder in a well-ventilated environment.
  • Minimise the volume on your radio device before turning it on.

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