Why should you not set your transmit frequency to be exactly at the edge of an amateur band or sub-band?
The correct answer is D: All these choices are correct. You should not set your transmit frequency exactly at the edge of an amateur band or sub-band for all three reasons mentioned: to allow for calibration error, to prevent modulation sidebands from extending beyond the band edge, and to allow for transmitter frequency drift.
Transmitters are not always perfectly calibrated, and their frequency displays may have some error. Additionally, when you modulate a signal (especially with phone modes), sidebands are created that extend beyond your carrier frequency. If you're right at the band edge, these sidebands could extend outside the authorized band. Finally, transmitters can drift in frequency due to temperature changes or component aging. By staying away from band edges, you ensure that even with these factors, your signal and its sidebands remain within the authorized band.
Exam Tip
Band edges = Stay away. Remember: All three reasons are valid - calibration error, sidebands, and drift. When you see 'all these choices are correct' and all options are reasonable technical concerns, that's usually the answer.
Memory Aid
"**B**and **E**dge = **B**ad **E**verything (think 'BE = Bad Everything' - stay away from edges)"
Real-World Application
You're operating on 28.500 MHz, which is at the upper edge of the Technician phone segment (28.300-28.500 MHz). Your transmitter has a slight calibration error showing 28.500 MHz when you're actually on 28.501 MHz. When you modulate with voice, sidebands extend to 28.502 MHz, which is outside your authorized segment. By operating at 28.480 MHz instead, you have a safety margin that accounts for calibration error, sidebands, and any frequency drift.
FCC Part 97.101Key Concepts
Why Other Options Are Wrong
This question has no incorrect options since all choices are correct. However, it's important to understand that all three factors (calibration error, sidebands, and drift) are valid reasons to avoid band edges.
题目解析
The correct answer is D: All these choices are correct. You should not set your transmit frequency exactly at the edge of an amateur band or sub-band for all three reasons mentioned: to allow for calibration error, to prevent modulation sidebands from extending beyond the band edge, and to allow for transmitter frequency drift. Transmitters are not always perfectly calibrated, and their frequency displays may have some error. Additionally, when you modulate a signal (especially with phone modes), sidebands are created that extend beyond your carrier frequency. If you're right at the band edge, these sidebands could extend outside the authorized band. Finally, transmitters can drift in frequency due to temperature changes or component aging. By staying away from band edges, you ensure that even with these factors, your signal and its sidebands remain within the authorized band.
考试技巧
Band edges = Stay away. Remember: All three reasons are valid - calibration error, sidebands, and drift. When you see 'all these choices are correct' and all options are reasonable technical concerns, that's usually the answer.
记忆口诀
**B**and **E**dge = **B**ad **E**verything (think 'BE = Bad Everything' - stay away from edges)
实际应用示例
You're operating on 28.500 MHz, which is at the upper edge of the Technician phone segment (28.300-28.500 MHz). Your transmitter has a slight calibration error showing 28.500 MHz when you're actually on 28.501 MHz. When you modulate with voice, sidebands extend to 28.502 MHz, which is outside your authorized segment. By operating at 28.480 MHz instead, you have a safety margin that accounts for calibration error, sidebands, and any frequency drift.
错误选项分析
This question has no incorrect options since all choices are correct. However, it's important to understand that all three factors (calibration error, sidebands, and drift) are valid reasons to avoid band edges.
知识点
Band edges, Modulation sidebands, Frequency calibration, Transmitter drift
Verified Content
Question from official FCC Technician Class question pool. Explanation reviewed by licensed amateur radio operators.