Deep Dive: G4D08
The correct answer is C: 7.175 MHz to 7.178 MHz. The frequency range occupied by a 3 kHz LSB signal when the displayed carrier frequency is set to 7.178 MHz is 7.175 MHz to 7.178 MHz. LSB uses the lower sideband, so the signal extends from (carrier - 3 kHz) to carrier. For amateur radio operators, this helps understand SSB frequency ranges. Understanding this helps when operating SSB.
Why Other Answers Are Wrong
Option A: Incorrect. 7.178-7.181 MHz would be USB (upper sideband) - LSB extends below the carrier, not above. Option B: Incorrect. 7.178-7.184 MHz would be USB with wider bandwidth - LSB extends below the carrier, not above. Option D: Incorrect. 7.1765-7.1795 MHz is centered differently - LSB extends from (carrier - 3 kHz) to carrier, which is 7.175-7.178 MHz.
Exam Tip
3 kHz LSB at 7.178 MHz = 7.175-7.178 MHz. Think 'L'SB = 'L'ower sideband = 'L'ower frequencies (carrier - 3 kHz to carrier). LSB extends from (7.178 - 0.003) to 7.178 = 7.175-7.178 MHz. Not above carrier - below carrier.
Memory Aid
3 kHz LSB at 7.178 MHz = 7.175-7.178 MHz. Think 'L'SB = 'L'ower sideband = 'L'ower frequencies. LSB extends from (carrier - 3 kHz) to carrier. Lower sideband uses frequencies below the carrier.
Real-World Example
You operate LSB on 40 meters with carrier at 7.178 MHz. Your 3 kHz LSB signal occupies 7.175-7.178 MHz (from carrier - 3 kHz to carrier). LSB uses the lower sideband, so the signal extends below the carrier frequency. This is the LSB frequency range.
Source & Coverage
Question Pool: 2023-2027 Question Pool
Subelement: G4D
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 G4D topic.