Why should DC power for a 100-watt HF transceiver not be supplied by a vehicle’s auxiliary power socket?
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.
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 Application
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.
Key Concepts
Why Other Options 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.
题目解析
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.
考试技巧
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.
记忆口诀
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.
实际应用示例
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.
错误选项分析
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.
知识点
Auxiliary power socket, Inadequate wiring, Current capacity, Mobile power
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.