Learning to read a citizens' band radio schematic is much like learning to read a road map. CB radio schematic navigation guides such as circuit symbols, abbreviations, and lines are like the symbols for reading a road map. With a key that identifies circuitry symbols and some knowledge of basic electronics, your CB radio schematic will no longer be a mystery.
While there is a large variety of electronic components and each has its own symbol and rating, the number needed to read a CB radio schematic is comparatively limited. Common symbols you will encounter include those for resistor, capacitor, antenna, microphone, diode, switch, transistor, rheostat, and ground. There are more in most amateur radios, of course, and they will vary with the make and model of your CB radio equipment.
Most citizens' band radios are sold with an owner’s manual including a CB radio schematic. The manual should contain a reference key for your schematic. For example, your schematic might include a symbol for a diode with the letter D, for diode, followed by the number 35. Referencing your manual, you can find the function and specifications for that particular diode.
Other electronic circuit components are identified with letters and numbers to include as much information as possible in a limited space. Most schematic components are logical in their labeling, such as “R5 10K Ω”. In the language of schematics, this indicates a specific resistor — R5 — in your circuit with a resistance value of 10,000 ohms — 10K Ω.
Similar logical labeling will identify most other CB schematic elements. The symbol for a power supply with “12V DC” indicates a 12-volt direct current power supply. If the power supply is alternating current (AC), a wavy line representing a sine wave preceded by a voltage rating will be on the drawing.
Lines on a CB radio schematic indicate conductors through which current flows. In your CB radio, these conductors might be color-coded wires or embedded metal pathways on a circuit board. When two solid lines on your schematic meet at a dot, it means that the two conductor pathways have a physical connection. If one line has an arc over another, it means that there is no physical connection between the conductors.
Citizens' band radios generally have more than one available channel accessible through different positions on a switch or tuner. Schematic symbols will vary depending on the type of switch or tuning component. The switch directs current through selected circuit components to permit reception and transmission on a specified channel. On some schematics, different pathways are indicated by color coding for ease of reading, while other pathways may be identified alphanumerically.
Symbols for reading a CB radio schematic are available in owner’s manuals, books on electronic circuitry, and online, as is information on the basics of electronics. Schematics are available online for many models of amateur radio. With a key for circuitry symbols and a basic knowledge of electronics, you should be successful in navigating the road map of CB radio schematics.