Question E1A09:
[97.313(l)] Except in some parts of Alaska, what is the maximum power permitted on the 630-meter band?  

Choices:  
A: 50 watts PEP (peak envelope power)  
B: 100 watts PEP (peak envelope power)  
C: 1 watt EIRP (equivalent isotropic radiated power)  
D: 5 watts EIRP (equivalent isotropic radiated power)    

Correct Answer is  D: 5 watts EIRP (equivalent isotropic radiated power)  

To the point:

Correct answer: D — 5 watts EIRP

Why it’s correct:
- FCC Part 97.313(l) limits 630 m (472–479 kHz) amateur operation to a maximum of 5 W EIRP for most of the U.S.
- An exception applies to certain parts of Alaska, where the limit is 1 W EIRP due to shared-use constraints. The question asks “Except in some parts of Alaska,” so the general limit is 5 W EIRP.

Why the others are incorrect:
- A: 50 W PEP — The limit on 630 m is specified in EIRP, not transmitter PEP. 50 W PEP could easily exceed 5 W EIRP depending on antenna/line characteristics.
- B: 100 W PEP — Same issue: the rule is in EIRP, not PEP; 100 W PEP is not the governing metric.
- C: 1 W EIRP — That is the general limit for the 2200 m band and for some Alaska areas on 630 m, but not for the rest of the U.S. on 630 m.

Useful formulas and rules of thumb:
- EIRP (linear): 
  $$EIRP = P_{out} \times G_{iso} \times \eta$$
  where $P_{out}$ is transmitter output power (W), $G_{iso}$ is antenna gain relative to isotropic (linear), and $\eta$ accounts for line/other losses.
- In dB:
  $$EIRP_{dBm} = P_{out,dBm} + G_{dBi} - L_{dB}$$
- ERP to EIRP conversion:
  $$EIRP \approx 1.64 \times ERP \quad\text{or}\quad EIRP_{dB} = ERP_{dB} + 2.15\ \text{dB}$$
- Quick numbers: 
  $$1\ \text{W EIRP} = 30\ \text{dBm},\quad 5\ \text{W EIRP} \approx 37\ \text{dBm}$$

Exam tip: Remember the pair — 2200 m is 1 W EIRP; 630 m is 5 W EIRP (except some Alaska areas limited to 1 W EIRP).