Which of the following should be considered when selecting an accessory SWR meter?
The correct answer is A: The frequency and power level at which the measurements will be made. When selecting an accessory SWR meter, you should consider the frequency and power level at which you'll be making measurements. SWR meters are designed for specific frequency ranges and power levels, and using one outside its specifications can give inaccurate readings or damage the meter.
SWR meters must be rated for the frequency range you're using (VHF meters won't work well on HF, and vice versa) and must handle the power levels you'll be transmitting (a low-power meter can be damaged by high-power transmissions). The meter's specifications will indicate its frequency range and maximum power handling capability. Choosing a meter that matches your operating frequency and power level ensures accurate measurements and protects your equipment.
Exam Tip
SWR meter selection = Frequency and power. Remember: When selecting an SWR meter, consider the frequency range and power level you'll be using. The meter must be rated for both.
Memory Aid
"**S**WR **M**eter = **S**elect by **F**requency and **P**ower (think 'SM = SFP')"
Real-World Application
You're operating on 2 meters with 50 watts output. You need an SWR meter rated for VHF frequencies (covers 2 meters) and can handle at least 50 watts (preferably more for safety margin). You choose a meter rated for 1-200 MHz and 0-200 watts, which covers your 2-meter operation safely. Using an HF-only meter or a low-power meter could give inaccurate readings or be damaged.
FCC Part 97.3Key Concepts
Why Other Options Are Wrong
Option B: Incorrect. The distance from the antenna doesn't significantly affect SWR meter selection. SWR is measured in the feedline, and the meter location in the feedline is more important than distance from the antenna.
Option C: Incorrect. Modulation type doesn't affect SWR meter selection. SWR is a measure of impedance match, which is independent of modulation.
Option D: Incorrect. Not all options are correct. Only frequency and power level are the key considerations.
题目解析
The correct answer is A: The frequency and power level at which the measurements will be made. When selecting an accessory SWR meter, you should consider the frequency and power level at which you'll be making measurements. SWR meters are designed for specific frequency ranges and power levels, and using one outside its specifications can give inaccurate readings or damage the meter. SWR meters must be rated for the frequency range you're using (VHF meters won't work well on HF, and vice versa) and must handle the power levels you'll be transmitting (a low-power meter can be damaged by high-power transmissions). The meter's specifications will indicate its frequency range and maximum power handling capability. Choosing a meter that matches your operating frequency and power level ensures accurate measurements and protects your equipment.
考试技巧
SWR meter selection = Frequency and power. Remember: When selecting an SWR meter, consider the frequency range and power level you'll be using. The meter must be rated for both.
记忆口诀
**S**WR **M**eter = **S**elect by **F**requency and **P**ower (think 'SM = SFP')
实际应用示例
You're operating on 2 meters with 50 watts output. You need an SWR meter rated for VHF frequencies (covers 2 meters) and can handle at least 50 watts (preferably more for safety margin). You choose a meter rated for 1-200 MHz and 0-200 watts, which covers your 2-meter operation safely. Using an HF-only meter or a low-power meter could give inaccurate readings or be damaged.
错误选项分析
Option B: Incorrect. The distance from the antenna doesn't significantly affect SWR meter selection. SWR is measured in the feedline, and the meter location in the feedline is more important than distance from the antenna. Option C: Incorrect. Modulation type doesn't affect SWR meter selection. SWR is a measure of impedance match, which is independent of modulation. Option D: Incorrect. Not all options are correct. Only frequency and power level are the key considerations.
知识点
SWR meter, Frequency range, Power level, Equipment selection
Verified Content
Question from official FCC Technician Class question pool. Explanation reviewed by licensed amateur radio operators.