T6: Electronic and Electrical Components – Ham Radio Technician License Study Guide

Every piece of amateur radio equipment — your transceiver, your antenna tuner, your power supply — is built from a small set of fundamental components. T6 teaches you what those components are, how they work, and how engineers represent them in circuit diagrams. Understanding components is the foundation for troubleshooting your station, modifying equipment, and reading technical documentation.

Four exam questions are drawn from this subelement, one from each group. T6A covers the basic passive and switching components: resistors, potentiometers, capacitors, inductors, switches, fuses, and batteries. T6B introduces semiconductors — diodes and transistors — the active devices that made modern electronics possible. T6C covers schematic diagrams: what they are, why they matter, and how to identify standard component symbols using the exam figures. T6D covers the functional roles of common components and circuits: rectifiers, relays, regulators, transformers, meters, LEDs, integrated circuits, and resonant circuits.

T6A: Basic Components

T6A covers the passive components and switching devices found in nearly every circuit. A resistor opposes the flow of current; it is the component that resists. A potentiometer is a variable resistor — the kind used as a volume control — and it controls resistance. A capacitor stores energy in an electric field and is constructed from conductive surfaces separated by an insulating material. An inductor stores energy in a magnetic field and is typically constructed as a coil of wire. An SPDT (single-pole double-throw) switch connects a single circuit to one of two other circuits. A fuse protects a circuit by breaking the connection when current exceeds a safe level. Battery chemistry determines rechargeability: nickel-metal hydride, lithium-ion, and lead-acid are all rechargeable; carbon-zinc is not. Figure T-2 is referenced for identifying switch types by their schematic symbols.

T6B: Semiconductors

T6B introduces the two most fundamental semiconductor devices: the diode and the transistor. A diode allows current to flow in only one direction — from anode to cathode. The cathode lead is identified on the physical package by a stripe. Some diode types have a lower forward voltage drop than others. A light-emitting diode (LED) produces light when forward current flows through it. The electrodes of a diode are called the anode and the cathode. A transistor consists of three regions of semiconductor material and can function as an electronic switch or amplifier. Transistors provide power gain — the ability to amplify a signal. A bipolar junction transistor (BJT) has three electrodes: emitter, base, and collector. A field-effect transistor (FET) has three electrodes: gate, drain, and source. FET stands for Field Effect Transistor. The term for a device's ability to amplify is gain.

T6C: Circuit Diagrams

T6C covers schematic diagrams and the standard symbols used to represent components. A schematic is an electrical wiring diagram that uses standard component symbols — it shows component connections accurately but does not represent wire lengths or the physical appearance of parts. The exam includes three schematic figures (T-1, T-2, T-3) with numbered components. You must identify each numbered component from its symbol. In Figure T-1: component 1 is a resistor, component 2 is a transistor, component 3 is a lamp, and component 4 is a battery. In Figure T-2: component 3 is an SPST switch, component 4 is a transformer, component 6 is a capacitor, component 8 is an LED, and component 9 is a variable resistor. In Figure T-3: component 3 is a variable inductor and component 4 is an antenna.

T6D: Component Functions

T6D covers what specific components and circuits do in practice. A rectifier converts alternating current into a varying direct current signal. A relay is an electrically-controlled switch — it allows a low-power signal to control a higher-power circuit. Shielded wire is used to prevent unwanted signal coupling to or from the wire. A meter displays an electrical quantity as a numeric value. A voltage regulator controls the output voltage from a power supply. A transformer converts 120 V AC power to a lower AC voltage for other uses. An LED serves as a visual indicator. A resonant (or tuned) circuit is formed by combining an inductor and a capacitor in series or parallel. An integrated circuit packages several semiconductors and other components into a single package. Figure T-1 component 2 (the transistor) controls the flow of current.

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