Home >> Hobbies >> Ham Radio

How to Wire a K40 Speech Processor

The K40 Voice Processor is a microphone that compensates for either the loudness or softness in speech to provide a flat volume response. Popular with CB and ham radio operators, this microphone often requires special installation and wiring depending on the type of transceiver you employ. Many users of the K40 seek out the original microphone that was sold with a 40-channel radio. As second-hand items rarely include documentation, the installation and wiring are often difficult for the hobby CB user.

Things You'll Need

25-watt soldering iron
Rosin-core solder

Instructions

- 1
  Consult included documentation and circuit diagrams to determine the switching system that your CB transceiver employs: electronic, direct relay, transistor relay or power switching. This documentation also indicates the receive line, transmit line, relay coil, +12 volts line, and audio line of your CB transceiver.
- 2
  Solder the color-coded wires to your electronic switching receiver array using your 25-watt soldering iron and rosin-core solder in the following manner: shield to ground, black to ground, blue to receiving line, red to transmit line, and white to audio line. Disregard the yellow lead. Leave the internal white jumper located in your K40 microphone in position 1.
- 3
  Solder the color-coded wires to your direct relay receiver array in the following manner: shield to ground, black to ground, red to relay coil, and white to audio line. Disregard the blue and yellow leads. Leave the internal white jumper located in your K40 microphone in position 1.
- 4
  Solder the color-coded wires to your transistor-driven relay receiver array in the following manner: shield to ground, black to relay coil, red to +12 Volts, and white to audio line. Disregard the blue and yellow leads. Leave the internal white jumper located in your K40 microphone in position 1.
- 5
  If your transceiver employs power switching, then solder the color-coded wires to your receiver array in the following manner: shield to ground, black to +12 Volts, blue to transmit line, red to receive line, and white to audio line. Disregard the yellow lead. Leave the internal white jumper located in your K40 microphone in position 2.

Ham Radio