Question E1A07:
[97.313(k)] What is the maximum power permitted on the 2200-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  C: 1 watt EIRP (equivalent isotropic radiated power)  

On 2200 meters (135.7–137.8 kHz), FCC §97.313(k) limits amateur stations to a maximum of 1 watt EIRP. That’s the total radiated power referenced to an isotropic radiator, not the transmitter’s output power.

Why C is correct (1 watt EIRP)
- The 2200 m band is power-limited by EIRP, and the cap is 1 W. You may run higher transmitter output if your antenna system is very inefficient, but the radiated EIRP must not exceed 1 W.

Why the others are incorrect
- A (50 W PEP) and B (100 W PEP): On LF/MF bands, the limit is not PEP at the transmitter; it’s EIRP. These values don’t apply here and would likely exceed 1 W EIRP.
- D (5 W EIRP): That is the general EIRP limit for the 630 m band, not 2200 m. For 2200 m the limit is lower: 1 W EIRP.

Useful formulas and rules of thumb
- EIRP calculation (linear):
  $$\mathrm{EIRP} = P_\text{out} \times G_\text{ant,linear}$$
- EIRP including losses (dB):
  $$\mathrm{EIRP\,(dBW)} = P_\text{out\,(dBW)} + G_\text{ant\,(dBi)} - L_\text{feed\,(dB)}$$
- Relation between EIRP and ERP:
  $$\mathrm{EIRP} = 1.64 \times \mathrm{ERP} \quad\text{or}\quad \mathrm{ERP} = \frac{\mathrm{EIRP}}{1.64}$$

Exam tip: Remember the pair—2200 m is 1 W EIRP; 630 m is 5 W EIRP (with special regional exceptions not needed for this question).