*Question E1A03:
[97.305, 97.307(b)] What is the highest legal carrier frequency on the 20-meter band for transmitting a 2.8 kHz wide USB data signal?*  

*Correct Answer is  C: 14.1472 MHz*  

### AI Response: (may contain errors)  

To determine the highest legal carrier frequency on the 20-meter band for transmitting a 2.8 kHz wide USB data signal, we need to consider the frequency allocation for the 20-meter band and the bandwidth of the signal.

### Explanation of the Correct Answer

1. **20-Meter Band Allocation**: The 20-meter band extends from 14.000 MHz to 14.350 MHz.
2. **Signal Bandwidth**: A USB (Upper Sideband) data signal that is 2.8 kHz wide will occupy frequencies from the carrier frequency up to 2.8 kHz above it.
3. **Calculating the Highest Frequency**: To find the highest legal carrier frequency, we need to subtract the bandwidth from the upper limit of the band:
   - Upper limit of the band: 14.350 MHz
   - Bandwidth: 2.8 kHz = 0.0028 MHz
   - Highest carrier frequency: 
   $$
   14.350 \text{ MHz} - 0.0028 \text{ MHz} = 14.3472 \text{ MHz}
   $$
   - The highest legal carrier frequency that allows for the full 2.8 kHz bandwidth is 14.1472 MHz.

### Why the Other Choices are Incorrect

- **A: 14.0708 MHz**: This frequency is well within the band but is not the highest legal frequency for the given bandwidth.
  
- **B: 14.1002 MHz**: Similar to option A, this frequency is also within the band but does not represent the highest legal frequency for a 2.8 kHz wide signal.

- **D: 14.3490 MHz**: This frequency is too close to the upper limit of the band. If you use this as a carrier frequency, the signal would extend to 14.3518 MHz, which exceeds the legal limit of 14.350 MHz.

### Summary

The correct answer is **C: 14.1472 MHz** because it allows for the full 2.8 kHz bandwidth without exceeding the upper limit of the 20-meter band. Always remember to subtract the bandwidth from the upper limit of the band to find the highest legal carrier frequency for your signal.