What is the maximum mean power level for a spurious emission below 30 MHz with respect to the fundamental emission?
The correct answer is A: -43 dB. The maximum mean power level for a spurious emission below 30 MHz with respect to the fundamental emission is -43 dB. Spurious emissions below 30 MHz must be at least 43 dB below the fundamental. For amateur radio operators, this is important for transmitter compliance. Understanding this helps ensure legal operation.
Exam Tip
Spurious emission below 30 MHz = maximum -43 dB relative to fundamental. Think 'S'purious 'B'elow '3'0 MHz = '-4'3 dB. Spurious emissions below 30 MHz must be at least 43 dB below the fundamental. Not -53 dB, not -63 dB, not -73 dB - just -43 dB.
Memory Aid
"Spurious emission below 30 MHz = maximum -43 dB relative to fundamental. Think 'S'purious 'B'elow '3'0 MHz = '-4'3 dB. Spurious emissions below 30 MHz must be at least 43 dB below the fundamental. Important for transmitter compliance."
Real-World Application
A transmitter with fundamental at 14.200 MHz: Spurious emissions below 30 MHz must be at least 43 dB below the fundamental power. For example, if fundamental is 100 watts, spurious emissions must be less than 100/10^(43/10) = 0.005 watts (5 milliwatts). -43 dB is the maximum mean power level for spurious emissions below 30 MHz.
FCC Part 97.307Key Concepts
Why Other Options Are Wrong
Option B (-53 dB): Incorrect. -53 dB is too restrictive - the limit is -43 dB, not -53 dB. -53 dB is too strict.
Option C (-63 dB): Incorrect. -63 dB is too restrictive - the limit is -43 dB, not -63 dB. -63 dB is too strict.
Option D (-73 dB): Incorrect. -73 dB is way too restrictive - the limit is -43 dB, not -73 dB. -73 dB is too strict.
题目解析
The correct answer is A: -43 dB. The maximum mean power level for a spurious emission below 30 MHz with respect to the fundamental emission is -43 dB. Spurious emissions below 30 MHz must be at least 43 dB below the fundamental. For amateur radio operators, this is important for transmitter compliance. Understanding this helps ensure legal operation.
考试技巧
Spurious emission below 30 MHz = maximum -43 dB relative to fundamental. Think 'S'purious 'B'elow '3'0 MHz = '-4'3 dB. Spurious emissions below 30 MHz must be at least 43 dB below the fundamental. Not -53 dB, not -63 dB, not -73 dB - just -43 dB.
记忆口诀
Spurious emission below 30 MHz = maximum -43 dB relative to fundamental. Think 'S'purious 'B'elow '3'0 MHz = '-4'3 dB. Spurious emissions below 30 MHz must be at least 43 dB below the fundamental. Important for transmitter compliance.
实际应用示例
A transmitter with fundamental at 14.200 MHz: Spurious emissions below 30 MHz must be at least 43 dB below the fundamental power. For example, if fundamental is 100 watts, spurious emissions must be less than 100/10^(43/10) = 0.005 watts (5 milliwatts). -43 dB is the maximum mean power level for spurious emissions below 30 MHz.
错误选项分析
Option B (-53 dB): Incorrect. -53 dB is too restrictive - the limit is -43 dB, not -53 dB. -53 dB is too strict. Option C (-63 dB): Incorrect. -63 dB is too restrictive - the limit is -43 dB, not -63 dB. -63 dB is too strict. Option D (-73 dB): Incorrect. -73 dB is way too restrictive - the limit is -43 dB, not -73 dB. -73 dB is too strict.
知识点
Spurious emission, Below 30 MHz, Maximum mean power level, -43 dB
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.