Deep Dive: G4E04
The correct answer is B: The socket's wiring may be inadequate for the current drawn by the transceiver. Why DC power for a 100-watt HF transceiver should not be supplied by a vehicle's auxiliary power socket is that the socket's wiring may be inadequate for the current drawn by the transceiver. A 100-watt transceiver draws about 20 amps, which may exceed the socket's wiring capacity. For amateur radio operators, this is a safety and reliability concern. Understanding this helps when installing mobile equipment.
Why Other Answers Are Wrong
Option A: Incorrect. RF-shielded power cable isn't the issue - the issue is current capacity, not RF shielding. RF shielding isn't the concern. Option C: Incorrect. DC polarity reversal isn't the issue - modern sockets have correct polarity. Polarity isn't the concern. Option D: Incorrect. Engine overheating from power draw isn't the issue - the issue is wiring capacity, not engine cooling. Engine overheating isn't the concern.
Exam Tip
Don't use auxiliary socket for 100W = wiring may be inadequate for current. Think 'A'uxiliary 'S'ocket = 'A'dequate for 'S'mall loads only. Socket wiring may not handle 20+ amps needed for 100W transceiver. Not RF shielding, not polarity, not engine - just wiring capacity.
Memory Aid
Don't use auxiliary socket for 100W = wiring may be inadequate for current. Think 'A'uxiliary 'S'ocket = 'A'dequate for 'S'mall loads. Socket wiring may not handle 20+ amps needed for 100W transceiver. Safety and reliability concern.
Real-World Example
A 100-watt HF transceiver draws about 20 amps. A vehicle's auxiliary power socket is typically wired for 10-15 amps (for small devices). Using the socket for a 100-watt transceiver may overload the wiring, causing voltage drop, overheating, or fire hazard. Direct battery connection with heavy-gauge wire is safer.
Source & Coverage
Question Pool: 2023-2027 Question Pool
Subelement: G4E
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 G4E topic.