Question E1A04:
[97.301, 97.305] May an Extra class operator answer the CQ of a station on 3.601 MHz LSB phone?  

Choices:  
A: Yes, the entire signal will be inside the SSB allocation for Extra class operators  
B: Yes, the displayed frequency is within the 75-meter phone band segment  
C: No, the sideband components will extend beyond the edge of the phone band segment  
D: No, US stations are not permitted to use phone emissions below 3.610 MHz    

Correct Answer is  C: No, the sideband components will extend beyond the edge of the phone band segment  

To operate phone on 80 meters, Extras may use 3.600–4.000 MHz [97.301, 97.305]. With SSB, your entire transmitted energy must stay inside the authorized segment [97.307].

Why C is correct (No, the sideband components will extend beyond the edge of the phone band segment):
- On LSB, your transmitted spectrum extends from the dial (suppressed carrier) frequency downward by the SSB audio bandwidth (about 2.4–3.0 kHz).
- Here, $f_{dial} = 3.601$ MHz and a typical $B_{SSB} \approx 2.8$–3.0 kHz.
- For LSB: 
  $$f_{lowest} \approx f_{dial} - B_{SSB}$$
  Using 3 kHz: $3.601 - 0.003 = 3.598$ MHz, which is below the 3.600 MHz phone segment edge. That places part of your phone emission outside the authorized phone sub-band.

Why the other choices are incorrect:
- A: “Entire signal will be inside…” Incorrect. As shown, the lower skirt falls below 3.600 MHz.
- B: “Displayed frequency is within the 75 m phone segment.” True but irrelevant. Compliance is about the occupied spectrum, not just the dial readout.
- D: “Not permitted below 3.610 MHz.” Incorrect. Extras may use phone starting at 3.600 MHz. There’s no rule at 3.610 MHz; that’s just a common on-air “safety margin” practice.

Useful formulas and rules of thumb:
- For LSB near a lower band edge:
  $$f_{dial} \ge f_{edge} + B_{SSB}$$
- For USB near an upper band edge:
  $$f_{dial} \le f_{edge} - B_{SSB}$$
- Typical SSB voice bandwidth: $B_{SSB} \approx 2.4$–3.0 kHz. A common exam-safe rule is 3 kHz.
- Practical tip: On 80 m LSB at the lower edge (3.600 MHz), keep your dial at or above about 3.603 MHz to keep all energy inside the segment.