Question
What is the maximum mean power level for a spurious emission below 30 MHz with respect to the fundamental emission?
Answer Options
- A) - 43 dB
- B) - 53 dB
- C) - 63 dB
- D) - 73 dB
Correct Answer: A
Explanation
Spurious emissions (unwanted signals outside the necessary bandwidth, such as harmonics) must be strictly controlled to prevent interference. The FCC specifies a minimum suppression level relative to the power of the desired (fundamental) signal. This measure ensures that amateur equipment is well-designed and operated responsibly.
For signals below 30 MHz, the maximum mean power level for a spurious emission must be at least 43 dB below the mean power of the fundamental emission. For example, if the fundamental signal has a mean power of 100 Watts, the spurious emissions must be suppressed to a level no greater than 100 \text{ W} \times 10^{-43/10} \approx 50 \mu W. This is a stringent requirement often achieved through the use of low-pass filters at the transmitter output.
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