*Question G4C08:
Which of the following would reduce RF interference caused by common-mode current on an audio cable?*  

*Correct Answer is  A: Place a ferrite choke on the cable*  

### AI Response: (may contain errors)  

To reduce RF interference caused by common-mode current on an audio cable, the correct answer is:

**A: Place a ferrite choke on the cable.**

### Explanation of the Correct Answer:
- **Ferrite Choke**: A ferrite choke is a passive device that suppresses high-frequency noise and RF interference. It works by providing a high impedance to common-mode currents while allowing differential signals (the audio signal) to pass through with minimal loss. This helps to prevent unwanted RF signals from affecting the audio quality.

### Why the Other Choices are Incorrect:
- **B: Connect the center conductor to the shield of all cables to short circuit the RFI signal**: 
  - This approach can create a ground loop, which may actually increase interference rather than reduce it. It can also short-circuit the audio signal, leading to loss of sound.

- **C: Ground the center conductor of the audio cable causing the interference**: 
  - Grounding the center conductor can lead to potential differences and ground loops, which can introduce more noise into the system rather than eliminate it.

- **D: Add an additional insulating jacket to the cable**: 
  - While insulation can protect against physical damage and some environmental factors, it does not address the issue of common-mode currents. Insulation alone does not reduce RF interference.

### Summary:
Using a ferrite choke is the most effective method to mitigate RF interference on audio cables by targeting common-mode currents specifically. Other methods may inadvertently introduce more problems or fail to address the root cause of the interference.