Question
What is the purpose of delaying RF output after activating a transmitter’s keying line to an external amplifier?
Answer Options
- A) To prevent key clicks on CW
- B) To prevent transient overmodulation
- C) To allow time for the amplifier to switch the antenna between the transceiver and the amplifier output
- D) To allow time for the amplifier power supply to reach operating level
Correct Answer: C
Explanation
When an external RF power amplifier is used, the system must perform a sequence of events when the operator transitions from receive to transmit. The most crucial part of this sequence is safely switching the antenna from the receiver’s input to the amplifier’s high-power output port. This switching is performed by a relay or vacuum relay inside the amplifier.
To protect the sensitive receiver front end and the relay contacts, the RF output from the transceiver (driver) must be delayed. The purpose of this delay (often milliseconds) is to allow time for the amplifier to switch the antenna between the transceiver and the amplifier output, ensuring the relay contacts are fully seated before high-power RF is applied.
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