Why do DX stations often transmit and receive on different frequencies?
The correct answer is D: All these choices are correct. Why DX stations often transmit and receive on different frequencies includes: because the DX station may be transmitting on a frequency that is prohibited to some responding stations, to separate the calling stations from the DX station, and to improve operating efficiency by reducing interference. All three are reasons for split-frequency operation. For amateur radio operators, this is important for DX operation. Understanding this helps when working DX.
Exam Tip
All three are reasons for DX split-frequency: frequency restrictions, separate calling stations, improve efficiency. When all listed reasons apply to DX split-frequency operation, 'all of the above' is usually the answer. All are valid reasons for split-frequency operation.
Memory Aid
"All three are reasons for DX split-frequency: Frequency restrictions, Separate calling stations, Improve efficiency. Think 'A'll 'D'X 'S'plit reasons. All three are valid reasons for split-frequency operation. Important for DX operation."
Real-World Application
DX stations often use split-frequency operation (transmit on one frequency, receive on another): (1) The DX station may be transmitting on a frequency prohibited to some responding stations, (2) It separates the calling stations from the DX station, (3) It improves operating efficiency by reducing interference. All three are reasons for split-frequency operation. This is why DX stations use split frequencies.
Key Concepts
Why Other Options Are Wrong
Option A: While correct, this is incomplete. Separating calling stations and improving efficiency are also reasons.
Option B: While correct, this is incomplete. Frequency restrictions and improving efficiency are also reasons.
Option C: While correct, this is incomplete. Frequency restrictions and separating calling stations are also reasons.
题目解析
The correct answer is D: All these choices are correct. Why DX stations often transmit and receive on different frequencies includes: because the DX station may be transmitting on a frequency that is prohibited to some responding stations, to separate the calling stations from the DX station, and to improve operating efficiency by reducing interference. All three are reasons for split-frequency operation. For amateur radio operators, this is important for DX operation. Understanding this helps when working DX.
考试技巧
All three are reasons for DX split-frequency: frequency restrictions, separate calling stations, improve efficiency. When all listed reasons apply to DX split-frequency operation, 'all of the above' is usually the answer. All are valid reasons for split-frequency operation.
记忆口诀
All three are reasons for DX split-frequency: Frequency restrictions, Separate calling stations, Improve efficiency. Think 'A'll 'D'X 'S'plit reasons. All three are valid reasons for split-frequency operation. Important for DX operation.
实际应用示例
DX stations often use split-frequency operation (transmit on one frequency, receive on another): (1) The DX station may be transmitting on a frequency prohibited to some responding stations, (2) It separates the calling stations from the DX station, (3) It improves operating efficiency by reducing interference. All three are reasons for split-frequency operation. This is why DX stations use split frequencies.
错误选项分析
Option A: While correct, this is incomplete. Separating calling stations and improving efficiency are also reasons. Option B: While correct, this is incomplete. Frequency restrictions and improving efficiency are also reasons. Option C: While correct, this is incomplete. Frequency restrictions and separating calling stations are also reasons.
知识点
DX stations, Transmit and receive on different frequencies, Split-frequency operation, DX operation
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.