Question
Why do most solid-state transmitters reduce output power as SWR increases beyond a certain level?
Answer Options
- A) To protect the output amplifier transistors
- B) To comply with FCC rules on spectral purity
- C) Because power supplies cannot supply enough current at high SWR
- D) To lower the SWR on the transmission line
Correct Answer: A
Explanation
When SWR (Standing Wave Ratio) is high, a significant portion of the transmitted power is reflected back toward the radio (T7C06). This reflected power creates a condition of high voltage and high current (a standing wave) on the output side of the transmitter’s final amplifier stage.
These extreme conditions can instantly damage or destroy the delicate and expensive solid-state output amplifier transistors. To prevent this, modern radios automatically engage a protection circuit that senses the high SWR and reduces the output power, thereby protecting the amplifier transistors from thermal and electrical failure.
This topic was automatically created to facilitate community discussion about this exam question. Feel free to share study tips, memory tricks, or additional explanations!