*Question G4A01:
What is the purpose of the notch filter found on many HF transceivers?*  

*Correct Answer is  B: To reduce interference from carriers in the receiver passband*  

### AI Response: (may contain errors)  

The correct answer to the question about the purpose of the notch filter found on many HF transceivers is:

**B: To reduce interference from carriers in the receiver passband.**

### Explanation of the Correct Answer:
- **Notch Filter Functionality**: A notch filter is designed to attenuate (reduce) a specific frequency while allowing other frequencies to pass through. In the context of HF transceivers, it is particularly useful for eliminating unwanted signals, such as carriers from other stations, that may interfere with the desired signal.
- **Application**: When a strong carrier signal is present in the receiver passband, it can mask weaker signals. The notch filter effectively removes this interference, allowing the operator to hear the desired signal more clearly.

### Why the Other Choices are Incorrect:
- **A: To restrict the transmitter voice bandwidth**  
  - This is incorrect because a notch filter is not used to limit the bandwidth of transmitted audio. Instead, it focuses on removing specific unwanted frequencies from the received signal.

- **C: To eliminate receiver interference from impulse noise sources**  
  - This is incorrect as impulse noise (like static or electrical interference) is typically broadband and not confined to a specific frequency. Notch filters are not effective for this type of noise.

- **D: To remove interfering splatter generated by signals on adjacent frequencies**  
  - This is incorrect because splatter refers to unwanted emissions that occur outside the intended frequency range of a signal, often due to overmodulation. A notch filter targets specific frequencies rather than addressing adjacent channel interference.

### Summary:
- The notch filter is a valuable tool in HF transceivers for improving reception by targeting and reducing specific unwanted signals, particularly strong carriers that can interfere with the desired communication. Understanding its purpose helps in effectively managing interference in amateur radio operations.