*Question E8C12:
What factors affect the bandwidth of a transmitted CW signal?*  

*Correct Answer is  C: Keying speed and shape factor (rise and fall time)*  

### AI Response: (may contain errors)  

To understand the factors that affect the bandwidth of a transmitted CW (Continuous Wave) signal, let's analyze the correct answer and the other choices.

### Correct Answer: C - Keying speed and shape factor (rise and fall time)

1. **Keying Speed**: The speed at which the signal is turned on and off (keyed) directly affects the bandwidth. Faster keying speeds result in wider bandwidth because the signal transitions more rapidly, creating more frequency components.
  
2. **Shape Factor (Rise and Fall Time)**: The rise and fall times of the signal also influence bandwidth. A slower rise time means the signal takes longer to reach its peak, which can limit the frequency components present in the signal. Conversely, a faster rise time increases the bandwidth.

### Why the Other Choices Are Incorrect:

- **A: IF bandwidth and Q**: 
  - While the Intermediate Frequency (IF) bandwidth and Quality factor (Q) are important in receiver design, they do not directly affect the bandwidth of the transmitted CW signal itself. They pertain more to the filtering and selectivity of the receiver rather than the characteristics of the transmitted signal.

- **B: Modulation index and output power**: 
  - The modulation index is relevant for modulated signals (like SSB or FM), but CW is not modulated in this way. Output power does not affect bandwidth; it influences the range and strength of the signal but not its frequency characteristics.

- **D: All these choices are correct**: 
  - Since A and B are incorrect, this choice cannot be correct.

### Summary

The bandwidth of a transmitted CW signal is primarily influenced by:

- **Keying Speed**: Faster keying increases bandwidth.
- **Shape Factor (Rise and Fall Time)**: Faster rise and fall times also increase bandwidth.

Understanding these factors is crucial for optimizing CW transmission and ensuring effective communication.