Which of the following is the best instrument to use for checking the keying waveform of a CW transmitter?
The correct answer is A: An oscilloscope. The best instrument to use for checking the keying waveform of a CW transmitter is an oscilloscope. Oscilloscopes display waveforms visually, allowing you to see the keying waveform shape, rise time, and other characteristics. For amateur radio operators, this is essential for checking proper keying. Understanding this helps when troubleshooting CW keying.
Exam Tip
Check keying waveform = oscilloscope. Think 'K'eying 'W'aveform = 'K'eep 'W'atching with oscilloscope. Oscilloscopes display waveforms visually, allowing you to see keying waveform shape. Not field strength meter, sidetone, or wavemeter - just oscilloscope.
Memory Aid
"Check keying waveform = oscilloscope. Think 'K'eying 'W'aveform = 'K'eep 'W'atching with oscilloscope. Oscilloscopes display waveforms visually, allowing you to see keying waveform shape. Best instrument for keying checks."
Real-World Application
You want to check if your CW transmitter has proper keying (no key clicks, proper rise/fall times). You connect an oscilloscope to monitor the keying waveform. The oscilloscope displays the waveform visually, showing you the keying shape, rise time, and any problems. This is the best way to check keying.
Key Concepts
Why Other Options Are Wrong
Option B (Field strength meter): Incorrect. Field strength meters measure RF field strength, they don't display waveforms. They can't show keying waveform shape.
Option C (Sidetone monitor): Incorrect. Sidetone monitors let you hear the keying, they don't display waveforms. They're audio devices, not waveform displays.
Option D (Wavemeter): Incorrect. Wavemeters measure frequency, they don't display waveforms. They can't show keying waveform shape.
题目解析
The correct answer is A: An oscilloscope. The best instrument to use for checking the keying waveform of a CW transmitter is an oscilloscope. Oscilloscopes display waveforms visually, allowing you to see the keying waveform shape, rise time, and other characteristics. For amateur radio operators, this is essential for checking proper keying. Understanding this helps when troubleshooting CW keying.
考试技巧
Check keying waveform = oscilloscope. Think 'K'eying 'W'aveform = 'K'eep 'W'atching with oscilloscope. Oscilloscopes display waveforms visually, allowing you to see keying waveform shape. Not field strength meter, sidetone, or wavemeter - just oscilloscope.
记忆口诀
Check keying waveform = oscilloscope. Think 'K'eying 'W'aveform = 'K'eep 'W'atching with oscilloscope. Oscilloscopes display waveforms visually, allowing you to see keying waveform shape. Best instrument for keying checks.
实际应用示例
You want to check if your CW transmitter has proper keying (no key clicks, proper rise/fall times). You connect an oscilloscope to monitor the keying waveform. The oscilloscope displays the waveform visually, showing you the keying shape, rise time, and any problems. This is the best way to check keying.
错误选项分析
Option B (Field strength meter): Incorrect. Field strength meters measure RF field strength, they don't display waveforms. They can't show keying waveform shape. Option C (Sidetone monitor): Incorrect. Sidetone monitors let you hear the keying, they don't display waveforms. They're audio devices, not waveform displays. Option D (Wavemeter): Incorrect. Wavemeters measure frequency, they don't display waveforms. They can't show keying waveform shape.
知识点
Oscilloscope, Keying waveform, CW transmitter, Waveform checking
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.