Deep Dive: G4C04
The correct answer is A: On-and-off humming or clicking. The sound heard from an audio device experiencing RF interference from a CW transmitter is on-and-off humming or clicking. CW signals are keyed on and off, creating the characteristic on-and-off pattern. For amateur radio operators, this is a common RFI symptom. Understanding this helps identify CW interference.
Why Other Answers Are Wrong
Option B: Incorrect. CW interference doesn't produce a pure audio frequency tone - it produces on-and-off interference, not a continuous tone. The on-and-off pattern is the key. Option C: Incorrect. CW interference doesn't produce a chirpy signal - chirp is a transmitter problem, not an interference symptom. The on-and-off pattern is the key. Option D: Incorrect. CW interference doesn't produce severely distorted audio - that's more typical of SSB interference. CW produces on-and-off interference.
Exam Tip
CW interference sound = on-and-off humming or clicking. Think 'C'W 'I'nterference = 'C'licking 'W'hen keyed. CW signals are keyed on and off, creating on-and-off interference pattern. Not pure tone, not chirpy, not distorted audio - just on-and-off.
Memory Aid
CW interference sound = on-and-off humming or clicking. Think 'C'W 'I'nterference = 'C'licking 'W'hen keyed. CW signals are keyed on and off, creating on-and-off interference pattern. Characteristic CW interference symptom.
Real-World Example
A nearby CW transmitter is interfering with your audio system. You hear on-and-off humming or clicking that follows the CW keying pattern - when the transmitter is keyed, you hear interference; when it's not keyed, the interference stops. This is the characteristic sound of CW interference.
Source & Coverage
Question Pool: 2023-2027 Question Pool
Subelement: G4C
Reference: 2023-2027 Question Pool · G4 - Amateur Radio Practices
Key Concepts
Verified Content
Question from the official FCC General Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the G4C topic.