Question E1F11:
[97.317] Which of the following best describes one of the standards that must be met by an external RF power amplifier if it is to qualify for a grant of FCC certification?  

Choices:  
A: It must produce full legal output when driven by not more than 5 watts of mean RF input power  
B: It must have received an Underwriters Laboratory certification for electrical safety as well as having met IEEE standard 14.101(B)  
C: It must exhibit a gain of less than 23 dB when driven by 10 watts or less  
D: It must satisfy the FCC’s spurious emission standards when operated at the lesser of 1500 watts or its full output power    

Correct Answer is  D: It must satisfy the FCC’s spurious emission standards when operated at the lesser of 1500 watts or its full output power  

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Why the correct answer is correct

- FCC Part 97.317 requires that an external RF power amplifier, to be FCC certified, must meet the spurious emission limits when operated at the lesser of its full rated output or 1500 W.  
- Those limits come from Part 97.307, which (for most HF/VHF cases) require spurious emissions to be suppressed by at least  
  $$A_{\text{spurious}} \ge 43 + 10\log_{10}\!\big(P_{\text{out}}\big)\ \text{dB}$$  
  where $P_{\text{out}}$ is in watts and attenuation is in dBc (relative to the carrier).
- Example: at $P_{\text{out}}=1500\ \text{W}$,  
  $$A_{\text{spurious}} \ge 43 + 10\log_{10}(1500) \approx 43 + 31.76 \approx 74.8\ \text{dB}.$$  
  This is exactly what is referenced by “satisfy the FCC’s spurious emission standards … at the lesser of 1500 W or its full output power.”

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Why the other choices are incorrect

- Choice A (must produce full legal output with ≤ 5 W drive): Incorrect. There is no such requirement; in fact, rules are designed to discourage high gain with very low drive (to prevent CB misuse), not mandate it.
- Choice B (UL certification and IEEE 14.101(B)): Incorrect. UL/IEEE certifications are not part of FCC Part 97’s amplifier certification criteria.
- Choice C (gain < 23 dB when driven by ≤ 10 W): Incorrect. The numbers and scope are wrong. Part 97.317 includes anti-CB provisions (e.g., limitations in the 24–35 MHz region and restrictions related to low drive levels), but not a general “<23 dB at ≤10 W” rule.

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Useful rules of thumb

- Spurious suppression requirement (typical for exam problems):  
  $$A_{\text{spurious}} \ge 43 + 10\log_{10}(P_{\text{out}})\ \text{dB}.$$
- “Lesser of 1500 W or full output” means: test at 1500 W if the amp can do ≥1500 W; otherwise test at its maximum rated output.