What is the function of a transceiver’s PTT input?
The correct answer is B: Switches transceiver from receive to transmit when grounded. The PTT (Push-To-Talk) input on a transceiver switches the unit from receive to transmit mode when grounded (connected to ground or pulled low). This is the standard control method for transceivers - when you press the PTT button on your microphone, it grounds the PTT line, which activates the transmitter and switches the antenna from the receiver to the transmitter. When you release PTT, the line goes high (ungrounded), switching back to receive mode. For amateur radio operators, understanding PTT function is essential for proper station operation and troubleshooting switching problems. The PTT line is separate from the audio input and is a control signal, not an audio signal.
Exam Tip
PTT = Push-To-Talk = switches RX to TX when grounded. Think 'P'TT = 'P'ress to 'T'ransmit. It's a control signal that switches modes, not an audio input or tuning function.
Memory Aid
"PTT = Push-To-Talk = switches RX/TX when grounded. Think 'P'TT = 'P'ress to 'T'ransmit. Grounding switches to transmit, releasing switches to receive."
Real-World Application
When you press the PTT button on your microphone, it grounds the PTT line on your transceiver. This immediately switches the radio from receive to transmit mode - the receiver turns off, the transmitter activates, and the antenna switches from RX to TX. When you release PTT, everything switches back to receive. This is how voice operation works - PTT controls the mode switching.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. PTT is for voice operation, not CW. CW (Morse code) uses a separate key input or is sent via audio. PTT switches modes, it doesn't send code.
Option C: Incorrect. PTT doesn't provide tuning tones - it simply switches between receive and transmit. Tuning functions are separate.
Option D: Incorrect. Preamplifier tuning is a separate function. PTT only controls transmit/receive switching, not preamplifier functions.
题目解析
The correct answer is B: Switches transceiver from receive to transmit when grounded. The PTT (Push-To-Talk) input on a transceiver switches the unit from receive to transmit mode when grounded (connected to ground or pulled low). This is the standard control method for transceivers - when you press the PTT button on your microphone, it grounds the PTT line, which activates the transmitter and switches the antenna from the receiver to the transmitter. When you release PTT, the line goes high (ungrounded), switching back to receive mode. For amateur radio operators, understanding PTT function is essential for proper station operation and troubleshooting switching problems. The PTT line is separate from the audio input and is a control signal, not an audio signal.
考试技巧
PTT = Push-To-Talk = switches RX to TX when grounded. Think 'P'TT = 'P'ress to 'T'ransmit. It's a control signal that switches modes, not an audio input or tuning function.
记忆口诀
PTT = Push-To-Talk = switches RX/TX when grounded. Think 'P'TT = 'P'ress to 'T'ransmit. Grounding switches to transmit, releasing switches to receive.
实际应用示例
When you press the PTT button on your microphone, it grounds the PTT line on your transceiver. This immediately switches the radio from receive to transmit mode - the receiver turns off, the transmitter activates, and the antenna switches from RX to TX. When you release PTT, everything switches back to receive. This is how voice operation works - PTT controls the mode switching.
错误选项分析
Option A: Incorrect. PTT is for voice operation, not CW. CW (Morse code) uses a separate key input or is sent via audio. PTT switches modes, it doesn't send code. Option C: Incorrect. PTT doesn't provide tuning tones - it simply switches between receive and transmit. Tuning functions are separate. Option D: Incorrect. Preamplifier tuning is a separate function. PTT only controls transmit/receive switching, not preamplifier functions.
知识点
PTT input, Transmit/receive switching, Transceiver control, TR switching
Verified Content
Question from official FCC Technician Class question pool. Explanation reviewed by licensed amateur radio operators.