Deep Dive: G4D10
The correct answer is A: At least 3 kHz above the edge of the segment. How close to the lower edge of a band's phone segment your displayed carrier frequency should be when using 3 kHz wide LSB is at least 3 kHz above the edge of the segment. LSB extends below the carrier, so you need 3 kHz clearance above the edge to prevent out-of-band operation. For amateur radio operators, this ensures legal operation. Understanding this helps when operating near band edges.
Why Other Answers Are Wrong
Option B: Incorrect. 3 kHz below the edge would put you out of band - LSB extends below the carrier, so you need clearance above the edge, not below. Option C: Incorrect. 1 kHz below the edge would put you out of band - you need 3 kHz clearance above the edge for 3 kHz LSB. Option D: Incorrect. 1 kHz above the edge isn't enough - you need 3 kHz clearance for 3 kHz LSB bandwidth.
Exam Tip
LSB near lower edge = at least 3 kHz above edge. Think 'L'SB = 'L'ower sideband extends 'L'ower, so need clearance 'A'bove edge. LSB extends below carrier, so need 3 kHz clearance above lower edge. Not below edge, not 1 kHz - just 3 kHz above.
Memory Aid
LSB near lower edge = at least 3 kHz above edge. Think 'L'SB = 'L'ower sideband extends 'L'ower, so need clearance 'A'bove. LSB extends below carrier, so need 3 kHz clearance above lower edge. Ensures legal operation.
Real-World Example
The lower edge of the phone segment is 7.200 MHz. You operate 3 kHz LSB. Your carrier must be at least 7.203 MHz (3 kHz above the edge) so your signal (which extends 3 kHz below the carrier) doesn't go below 7.200 MHz. This ensures legal operation.
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.