Deep Dive: E1C10
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.
Why Other Answers 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.
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 Example
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.
Source & Coverage
Question Pool: 2024-2028 Question Pool
Subelement: E1C
Reference: FCC Part 97.307
Key Concepts
Official Pool Source
Question text and answer key are synchronized with the current NCVEC Extra Class pool and mapped to the E1C topic.