*Question T7C01:
What is the primary purpose of a dummy load?*  

*Correct Answer is  A: To prevent transmitting signals over the air when making tests*  

### AI Response: (may contain errors)  

The primary purpose of a dummy load is to prevent transmitting signals over the air when making tests. 

### Explanation of the Correct Answer:
- **Correct Answer (A)**: A dummy load is a device that simulates an antenna by providing a resistive load to the transmitter. This allows you to test the transmitter's performance without radiating signals into the air, which is important for compliance with regulations and to avoid interference with other communications.

### Explanation of Incorrect Answers:
- **B: To prevent over-modulation of a transmitter**: Over-modulation refers to the condition where the modulation level exceeds the maximum capacity of the transmitter, leading to distortion. A dummy load does not prevent over-modulation; it simply provides a safe way to test the transmitter's output.

- **C: To improve the efficiency of an antenna**: A dummy load does not improve antenna efficiency. Instead, it is used when an antenna is not needed, such as during testing. Antenna efficiency is determined by the design and construction of the antenna itself.

- **D: To improve the signal-to-noise ratio of a receiver**: A dummy load does not affect the signal-to-noise ratio of a receiver. The signal-to-noise ratio is influenced by the quality of the received signal and the receiver's design, not by the use of a dummy load.

### Summary:
- A dummy load is essential for safely testing transmitters without causing interference.
- It does not prevent over-modulation, improve antenna efficiency, or enhance signal-to-noise ratios. 

Understanding the role of a dummy load is crucial for responsible amateur radio operation and testing.