🔍 Key Concepts

• Amplifier classes and how the conduction angle (portion of the RF cycle the device conducts) affects efficiency • Difference between linearity (faithful reproduction of signal) and efficiency (how much DC power becomes RF output) • Typical use of different classes (A, B, C, D) in RF power output/final stages on transmitters

💭 Think About

• Which amplifier class conducts for the smallest portion of the input cycle while still being useful in RF service with a resonant output circuit? • Which class is typically used in final RF stages where the modulation/linearity is handled earlier, and the main goal is high plate efficiency? • Think about which class is known for very high efficiency but poor linearity, usually paired with tuned/filtered circuits to clean up the waveform.

✅ Before You Answer

• Review typical efficiencies: Class A (low), Class B (medium), Class C (high), Class D (switching/filtered, very high in some uses) • Confirm which class is commonly specified for vacuum tube RF final amplifier stages in marine/HF transmitters • Make sure you distinguish between audio power amplifiers (where linearity is key) and RF power output stages (where efficiency and use with tuned circuits matter).