*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 the correct answer is "The upper 1 kHz of the signal is outside the 20-meter band," let's break down the problem:

1. **20-Meter Band Limits**:  
   The 20-meter amateur radio band ranges from 14.000 MHz to 14.350 MHz.

2. **USB Signal Bandwidth**:  
   An Upper Sideband (USB) signal with a 3 kHz bandwidth means that the signal extends 3 kHz above the carrier frequency.

3. **Carrier Frequency**:  
   If the carrier frequency is 14.348 MHz, the USB signal will extend from 14.348 MHz to 14.351 MHz (14.348 MHz + 3 kHz).

4. **Band Edge Violation**:  
   Since the 20-meter band ends at 14.350 MHz, the upper 1 kHz of the USB signal (from 14.350 MHz to 14.351 MHz) is outside the band.

### Explanation of Choices:

- **Choice A: USB is not used on 20-meter phone**  
  This is incorrect. USB is commonly used on the 20-meter band for phone operations.

- **Choice B: The lower 1 kHz of the signal is outside the 20-meter band**  
  This is incorrect. The lower edge of the signal starts at 14.348 MHz, which is within the band.

- **Choice C: 14.348 MHz is outside the 20-meter band**  
  This is incorrect. 14.348 MHz is within the 20-meter band.

- **Choice D: The upper 1 kHz of the signal is outside the 20-meter band**  
  This is correct. The signal extends to 14.351 MHz, which is outside the 20-meter band.

### Rule of Thumb:

- Always ensure that the entire bandwidth of your signal fits within the allocated band limits. For USB, this means the carrier frequency plus the bandwidth must not exceed the upper band limit.