Where should an RF power meter be installed?
The correct answer is A: In the feed line, between the transmitter and antenna. An RF power meter (and SWR meter) should be installed in the feedline, between the transmitter and antenna. This position allows the meter to measure both forward power (power going to the antenna) and reflected power (power reflected back from the antenna).
Placing the meter between the transmitter and antenna is the standard location because it can measure the power flow in both directions. The meter samples a small portion of the RF energy in the feedline and displays the power levels. This position also allows the meter to calculate SWR (Standing Wave Ratio) by comparing forward and reflected power. Installing it elsewhere (like at the power supply) wouldn't allow it to measure RF power.
Exam Tip
RF power meter = In feedline between TX and antenna. Remember: Install RF power meters in the feedline between the transmitter and antenna. This allows measurement of forward and reflected power.
Memory Aid
"**R**F **P**ower **M**eter = **R**F **P**ath **M**iddle (think 'RPM = RPM' = RF Path Middle, between TX and antenna)"
Real-World Application
You're installing an SWR/power meter in your station. You disconnect the feedline from your transceiver, connect the transceiver to the meter's input, and connect the meter's output to the feedline going to your antenna. Now the meter is in the feedline between the transmitter and antenna, where it can measure the RF power flowing in both directions and calculate SWR.
FCC Part 97.3Key Concepts
Why Other Options Are Wrong
Option B: Incorrect. The power supply output measures DC power, not RF power. RF power meters need to be in the RF feedline.
Option C: Incorrect. Parallel connections don't work for RF power measurement. The meter needs to be in series with the feedline.
Option D: Incorrect. The power supply cable carries DC, not RF. RF power meters must be in the RF feedline.
题目解析
The correct answer is A: In the feed line, between the transmitter and antenna. An RF power meter (and SWR meter) should be installed in the feedline, between the transmitter and antenna. This position allows the meter to measure both forward power (power going to the antenna) and reflected power (power reflected back from the antenna). Placing the meter between the transmitter and antenna is the standard location because it can measure the power flow in both directions. The meter samples a small portion of the RF energy in the feedline and displays the power levels. This position also allows the meter to calculate SWR (Standing Wave Ratio) by comparing forward and reflected power. Installing it elsewhere (like at the power supply) wouldn't allow it to measure RF power.
考试技巧
RF power meter = In feedline between TX and antenna. Remember: Install RF power meters in the feedline between the transmitter and antenna. This allows measurement of forward and reflected power.
记忆口诀
**R**F **P**ower **M**eter = **R**F **P**ath **M**iddle (think 'RPM = RPM' = RF Path Middle, between TX and antenna)
实际应用示例
You're installing an SWR/power meter in your station. You disconnect the feedline from your transceiver, connect the transceiver to the meter's input, and connect the meter's output to the feedline going to your antenna. Now the meter is in the feedline between the transmitter and antenna, where it can measure the RF power flowing in both directions and calculate SWR.
错误选项分析
Option B: Incorrect. The power supply output measures DC power, not RF power. RF power meters need to be in the RF feedline. Option C: Incorrect. Parallel connections don't work for RF power measurement. The meter needs to be in series with the feedline. Option D: Incorrect. The power supply cable carries DC, not RF. RF power meters must be in the RF feedline.
知识点
RF power meter, Feedline, Installation location, Power measurement
Verified Content
Question from official FCC Technician Class question pool. Explanation reviewed by licensed amateur radio operators.