Deep Dive: G4D11
The correct answer is B: At least 3 kHz below the edge of the band. How close to the upper edge of a band's phone segment your displayed carrier frequency should be when using 3 kHz wide USB is at least 3 kHz below the edge of the segment. USB extends above the carrier, so you need 3 kHz clearance below 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 A: Incorrect. 3 kHz above the edge would put you out of band - USB extends above the carrier, so you need clearance below the edge, not above. Option C: Incorrect. 1 kHz above the edge would put you out of band - you need 3 kHz clearance below the edge for 3 kHz USB. Option D: Incorrect. 1 kHz below the edge isn't enough - you need 3 kHz clearance for 3 kHz USB bandwidth.
Exam Tip
USB near upper edge = at least 3 kHz below edge. Think 'U'SB = 'U'pper sideband extends 'U'pper, so need clearance 'B'elow edge. USB extends above carrier, so need 3 kHz clearance below upper edge. Not above edge, not 1 kHz - just 3 kHz below.
Memory Aid
USB near upper edge = at least 3 kHz below edge. Think 'U'SB = 'U'pper sideband extends 'U'pper, so need clearance 'B'elow. USB extends above carrier, so need 3 kHz clearance below upper edge. Ensures legal operation.
Real-World Example
The upper edge of the phone segment is 14.350 MHz. You operate 3 kHz USB. Your carrier must be at least 14.347 MHz (3 kHz below the edge) so your signal (which extends 3 kHz above the carrier) doesn't go above 14.350 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.