Class C – AM Transmitter
Class C AM transmitters rule the amateur radio world. These solid-state transmitters deliver high efficiency at affordable prices. Amateur radio enthusiasts choose them for their simplicity and reliable performance.
Class C amplifiers work differently than switching amplifiers. The transistor conducts for less than 180 degrees of the input cycle. It stays off for the remaining time. This on-off operation creates impressive efficiency rates of 70-80%.
Circuit Design and Power Output
This transmitter uses three key components. Transistor Q1 creates the carrier oscillator. Q2 acts as a buffer stage. MOSFET U1 serves as the power amplifier. The mosfet U1 is easily available IRF510.
The MOSFET U1 delivers around five watts of RF output power. This power level works well for amateur radio applications. The high efficiency means less wasted energy and better performance.
Heat Management and Component Specifications
Class C amplifiers generate significant heat during operation. U1 requires proper heat sinking for reliable performance. Good heat management prevents component failure and maintains efficiency.
Coil Specifications:
- L1: 14 close-wound turns on 0.5-inch air core (16/18 wire)
- T1: 230/6v power transformer (modulation transformer)
- L2: 9 turns on T50-2 core (30 wire) OR 13 turns on 0.25-inch air core (30 wire)
- U2: 16t/16t air core transformer, 0.5-inch diameter (6/18 wire)
These specifications ensure proper circuit operation and maximum efficiency from your Class C transmitter.
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