*Question G4C10:
What could be a symptom caused by a ground loop in your station’s audio connections?*  

*Correct Answer is  A: You receive reports of “hum” on your station’s transmitted signal*  

### AI Response: (may contain errors)  

A ground loop occurs when there are multiple paths to ground in an electrical system, which can cause unwanted current to flow through the audio connections. This can introduce a low-frequency "hum" into the audio signal, which is often heard as a 60 Hz or 50 Hz hum, depending on the local power grid frequency.

### Explanation:

1. **Correct Answer (A):**  
   - **"You receive reports of 'hum' on your station’s transmitted signal"**  
     - Ground loops can introduce unwanted noise into audio systems, often manifesting as a hum. This is because the loop can pick up interference from the AC power lines, which is then superimposed onto the audio signal.

2. **Incorrect Answers:**
   - **(B) "The SWR reading for one or more antennas is suddenly very high"**  
     - SWR (Standing Wave Ratio) issues are typically related to mismatches in the antenna system, not ground loops in audio connections.
   
   - **(C) "An item of station equipment starts to draw excessive amounts of current"**  
     - Excessive current draw is usually due to a fault in the equipment or power supply issues, not ground loops in audio connections.
   
   - **(D) "You receive reports of harmonic interference from your station"**  
     - Harmonic interference is generally caused by non-linearities in the transmitter or amplifier, not by ground loops in audio connections.

### Key Points:
- Ground loops are a common cause of hum in audio systems.
- They occur when there are multiple grounding paths, leading to interference.
- The hum is typically at the frequency of the AC power supply (60 Hz or 50 Hz).