What is the primary purpose of a dummy load?
The correct answer is A: To prevent transmitting signals over the air when making tests. The primary purpose of a dummy load is to prevent transmitting signals over the air when making tests. A dummy load is a non-radiating load (typically a 50-ohm resistor) that absorbs transmitter power instead of radiating it. This allows you to test and tune your transmitter without transmitting signals that could cause interference or violate regulations. For amateur radio operators, dummy loads are essential for safe transmitter testing, power measurement, and tuning. They're required equipment for any serious station, allowing you to work on your equipment without affecting the band or causing interference.
Exam Tip
Dummy load = prevents transmitting during tests. Think 'D'ummy load = 'D'oesn't radiate (prevents signals over the air). It's a non-radiating load for safe testing. Not for modulation, efficiency, or receiver performance.
Memory Aid
"Dummy load = Doesn't radiate. Think 'D'ummy load = 'D'oesn't radiate signals. Prevents transmitting over the air during tests. Absorbs power as heat."
Real-World Application
You need to test your transmitter's output power and tune it, but you don't want to transmit signals that could interfere with other operators or violate regulations. You connect a dummy load (50-ohm resistor) instead of your antenna. Your transmitter puts out full power, but it's absorbed by the dummy load as heat instead of being radiated. This allows safe testing without affecting the band.
Key Concepts
Why Other Options Are Wrong
Option B: Incorrect. Dummy loads don't prevent over-modulation - that's controlled by audio input levels and transmitter circuits. Dummy loads just absorb power.
Option C: Incorrect. Dummy loads don't improve antenna efficiency - they replace the antenna. An antenna's efficiency is determined by its design, not by using a dummy load.
Option D: Incorrect. Dummy loads don't improve receiver signal-to-noise ratio - they're for transmitter testing, not receiver operation.
题目解析
The correct answer is A: To prevent transmitting signals over the air when making tests. The primary purpose of a dummy load is to prevent transmitting signals over the air when making tests. A dummy load is a non-radiating load (typically a 50-ohm resistor) that absorbs transmitter power instead of radiating it. This allows you to test and tune your transmitter without transmitting signals that could cause interference or violate regulations. For amateur radio operators, dummy loads are essential for safe transmitter testing, power measurement, and tuning. They're required equipment for any serious station, allowing you to work on your equipment without affecting the band or causing interference.
考试技巧
Dummy load = prevents transmitting during tests. Think 'D'ummy load = 'D'oesn't radiate (prevents signals over the air). It's a non-radiating load for safe testing. Not for modulation, efficiency, or receiver performance.
记忆口诀
Dummy load = Doesn't radiate. Think 'D'ummy load = 'D'oesn't radiate signals. Prevents transmitting over the air during tests. Absorbs power as heat.
实际应用示例
You need to test your transmitter's output power and tune it, but you don't want to transmit signals that could interfere with other operators or violate regulations. You connect a dummy load (50-ohm resistor) instead of your antenna. Your transmitter puts out full power, but it's absorbed by the dummy load as heat instead of being radiated. This allows safe testing without affecting the band.
错误选项分析
Option B: Incorrect. Dummy loads don't prevent over-modulation - that's controlled by audio input levels and transmitter circuits. Dummy loads just absorb power. Option C: Incorrect. Dummy loads don't improve antenna efficiency - they replace the antenna. An antenna's efficiency is determined by its design, not by using a dummy load. Option D: Incorrect. Dummy loads don't improve receiver signal-to-noise ratio - they're for transmitter testing, not receiver operation.
知识点
Dummy loads, Transmitter testing, Non-radiating loads, Safe operation
Verified Content
Question from official FCC Technician Class question pool. Explanation reviewed by licensed amateur radio operators.