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?  

Choices:  
A: USB is not used on 20-meter phone  
B: The lower 1 kHz of the signal is outside the 20-meter band  
C: 14.348 MHz is outside the 20-meter band  
D: The upper 1 kHz of the signal is outside the 20-meter band    

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

Why the correct answer is correct:
- A 3 kHz-wide USB signal occupies frequencies from the suppressed carrier up to 3 kHz above it:
  $$\text{USB span} = [f_c,\ f_c + B]$$
- With $f_c = 14.348\ \text{MHz}$ and $B = 3\ \text{kHz}$:
  $$f_{\text{top}} = 14.348\ \text{MHz} + 0.003\ \text{MHz} = 14.351\ \text{MHz}$$
- The 20 m band upper edge is 14.350 MHz. Since 14.351 MHz exceeds the band edge, the upper 1 kHz of the emission is outside the band. This violates 97.307(b), which requires emissions to stay within authorized band edges.
- Therefore, D is correct.

Why the other choices are incorrect:
- A: USB is not used on 20-meter phone  
  Incorrect. USB is both authorized (97.305) and customary on 20 m for SSB phone.

- B: The lower 1 kHz of the signal is outside the 20-meter band  
  Incorrect. For USB, the occupied spectrum is above the carrier. The lower edge is at $f_c = 14.348\ \text{MHz}$, which is within the band/phone segment.

- C: 14.348 MHz is outside the 20-meter band  
  Incorrect. The 20 m band is 14.000–14.350 MHz; 14.348 MHz is inside.

Useful formulas and rules of thumb:
- USB occupied range: $$[f_c,\ f_c + B]$$
- LSB occupied range: $$[f_c - B,\ f_c]$$
- To stay legal at an upper band edge $f_{\text{edge}}$ with USB:
  $$f_c \le f_{\text{edge}} - B$$
  Example for 20 m: with $B=3\ \text{kHz}$, the highest legal USB dial is $$14.350 - 0.003 = 14.347\ \text{MHz}$$
- To stay legal at a lower band edge $f_{\text{edge}}$ with LSB:
  $$f_c \ge f_{\text{edge}} + B$$

Remember: Your rig’s SSB dial shows the suppressed carrier frequency; make sure the entire sideband fits inside the band.