*Question E1A01:
[97.305, 97.307(b)] Why is it not legal to transmit a 3 kHz bandwidth USB signal with a carrier frequency of 14.348 MHz?*  

*Correct Answer is  D: The upper 1 kHz of the signal is outside the 20-meter band*  

### AI Response: (may contain errors)  

To understand why it is not legal to transmit a 3 kHz bandwidth USB signal with a carrier frequency of 14.348 MHz, we need to consider the frequency allocations for the 20-meter band.

### Correct Answer: D
**The upper 1 kHz of the signal is outside the 20-meter band.**

- The 20-meter band extends from 14.000 MHz to 14.350 MHz.
- A 3 kHz USB signal centered at 14.348 MHz would occupy the frequency range from 14.346 MHz to 14.351 MHz.
- The upper edge of this signal (14.351 MHz) exceeds the maximum frequency of the 20-meter band (14.350 MHz), making it illegal.

### Why the Other Choices are Incorrect:
- **A: USB is not used on 20-meter phone**
  - This is incorrect because USB (Upper Sideband) is indeed used on the 20-meter band for voice communications. The issue here is not the mode of transmission but the frequency range.

- **B: The lower 1 kHz of the signal is outside the 20-meter band**
  - This is incorrect because the lower edge of the signal (14.346 MHz) is still within the 20-meter band. The problem lies with the upper edge of the signal.

- **C: 14.348 MHz is outside the 20-meter band**
  - This is incorrect because 14.348 MHz is actually within the 20-meter band. The frequency itself is legal; it’s the bandwidth of the signal that causes the issue.

### Summary
- The key takeaway is to always check the frequency range of your signal against the band limits. For USB signals, remember that the bandwidth extends both above and below the carrier frequency. In this case, the upper edge of the 3 kHz bandwidth exceeds the 20-meter band limit, making it illegal to transmit.