*Question E7E09:
What occurs when the input signal levels to a mixer are too high?*  

*Correct Answer is  A: Spurious mixer products are generated*  

### AI Response: (may contain errors)  

When the input signal levels to a mixer are too high, the mixer can become nonlinear. This nonlinearity leads to the generation of unwanted signals known as spurious mixer products. These are additional frequencies that are not the desired output and can interfere with the intended signal processing.

### Explanation:

1. **Correct Answer: A: Spurious mixer products are generated**
   - **Why it's correct:**  
     - Mixers are designed to combine two signals and produce sum and difference frequencies. However, when the input levels are too high, the mixer operates outside its linear range, causing it to produce additional, unwanted frequencies. These are called spurious products and can degrade the performance of the system by introducing noise and interference.

2. **Why the other choices are incorrect:**
   - **B: Mixer blanking occurs**  
     - Mixer blanking is not a phenomenon associated with high input levels. Blanking typically refers to temporarily disabling a circuit to prevent unwanted signals, which is not related to the operation of a mixer under high input conditions.
   
   - **C: Automatic limiting occurs**  
     - Automatic limiting is a process where the amplitude of a signal is restricted to prevent distortion. While limiting can occur in some circuits, it is not a function of a mixer when input levels are too high.
   
   - **D: Excessive AGC voltage levels are generated**  
     - Automatic Gain Control (AGC) is used to maintain a consistent output level despite varying input levels. Excessive AGC voltage is not directly related to the operation of a mixer with high input levels, but rather to the AGC circuit's response to strong signals.

### Useful Rule of Thumb:

- **Linear Operation:**  
  Mixers should be operated within their linear range to avoid generating spurious products. This ensures that only the desired sum and difference frequencies are produced.

Understanding the behavior of mixers under different conditions is crucial for ensuring optimal performance in radio frequency systems.