What is the purpose of delaying RF output after activating a transmitter’s keying line to an external amplifier?
The correct answer is C: To allow time for the amplifier to switch the antenna between the transceiver and the amplifier output. The purpose of delaying RF output after activating a transmitter's keying line to an external amplifier is to allow time for the amplifier to switch the antenna between the transceiver and the amplifier output. Amplifiers need time to switch the antenna relay before RF is applied. For amateur radio operators, this prevents damage and ensures proper operation. Understanding this helps when using external amplifiers.
Exam Tip
RF output delay = allow time for antenna switching. Think 'D'elay = 'D'elay for 'A'ntenna 'S'witching. Allows amplifier time to switch antenna between transceiver and amplifier output before RF is applied. Not for key clicks, overmodulation, or power supply - just antenna switching.
Memory Aid
"RF output delay = allow time for antenna switching. Think 'D'elay = 'D'elay for 'A'ntenna 'S'witching. Allows amplifier time to switch antenna between transceiver and amplifier output. Prevents damage and ensures proper operation."
Real-World Application
You key your transmitter, which triggers an external amplifier. The amplifier needs time to switch the antenna relay from the transceiver to the amplifier output before RF is applied. The delay ensures the antenna is properly connected to the amplifier before RF appears. This prevents damage and ensures proper operation.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Delay doesn't prevent key clicks - key clicks are prevented by proper keying waveform shaping, not by delay. Delay is for antenna switching.
Option B: Incorrect. Delay doesn't prevent transient overmodulation - that's prevented by ALC and proper audio levels, not by delay. Delay is for antenna switching.
Option D: Incorrect. Delay isn't for power supply to reach operating level - power supplies should be ready before keying. Delay is for antenna switching.
题目解析
The correct answer is C: To allow time for the amplifier to switch the antenna between the transceiver and the amplifier output. The purpose of delaying RF output after activating a transmitter's keying line to an external amplifier is to allow time for the amplifier to switch the antenna between the transceiver and the amplifier output. Amplifiers need time to switch the antenna relay before RF is applied. For amateur radio operators, this prevents damage and ensures proper operation. Understanding this helps when using external amplifiers.
考试技巧
RF output delay = allow time for antenna switching. Think 'D'elay = 'D'elay for 'A'ntenna 'S'witching. Allows amplifier time to switch antenna between transceiver and amplifier output before RF is applied. Not for key clicks, overmodulation, or power supply - just antenna switching.
记忆口诀
RF output delay = allow time for antenna switching. Think 'D'elay = 'D'elay for 'A'ntenna 'S'witching. Allows amplifier time to switch antenna between transceiver and amplifier output. Prevents damage and ensures proper operation.
实际应用示例
You key your transmitter, which triggers an external amplifier. The amplifier needs time to switch the antenna relay from the transceiver to the amplifier output before RF is applied. The delay ensures the antenna is properly connected to the amplifier before RF appears. This prevents damage and ensures proper operation.
错误选项分析
Option A: Incorrect. Delay doesn't prevent key clicks - key clicks are prevented by proper keying waveform shaping, not by delay. Delay is for antenna switching. Option B: Incorrect. Delay doesn't prevent transient overmodulation - that's prevented by ALC and proper audio levels, not by delay. Delay is for antenna switching. Option D: Incorrect. Delay isn't for power supply to reach operating level - power supplies should be ready before keying. Delay is for antenna switching.
知识点
RF output delay, Keying line, Antenna switching, External amplifier
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.