*Question E2A08:
Why should effective radiated power (ERP) be limited to a satellite that uses a linear transponder?*  

*Correct Answer is  B: To avoid reducing the downlink power to all other users*  

### AI Response: (may contain errors)  

When using a satellite with a linear transponder, it's important to manage the effective radiated power (ERP) to ensure fair and efficient use of the satellite's resources.

### Correct Answer: B

- **To avoid reducing the downlink power to all other users**:  
  A linear transponder on a satellite has a fixed amount of power available for downlinking signals back to Earth. If one user transmits with excessive ERP, it can consume a disproportionate amount of the satellite's power budget. This reduces the available power for other users, leading to weaker signals and potential communication issues for them.

### Why Other Choices Are Incorrect:

- **A: To prevent creating errors in the satellite telemetry**:  
  Satellite telemetry is typically managed separately from user communications. Excessive ERP from users is unlikely to directly cause errors in telemetry data, which is designed to be robust against interference.

- **C: To prevent the satellite from emitting out-of-band signals**:  
  Out-of-band emissions are generally controlled by the design of the satellite's transponder and the user's equipment. Limiting ERP is not directly related to preventing out-of-band emissions.

- **D: To avoid interfering with terrestrial QSOs**:  
  Terrestrial QSOs (contacts) are usually on different frequencies and modes than satellite communications. The main concern with excessive ERP is the impact on other satellite users, not terrestrial interference.

### Useful Concepts:

- **Linear Transponder**:  
  A device on a satellite that receives signals on one frequency band and retransmits them on another. It can handle multiple signals simultaneously, but the total power is shared among all users.

- **Power Budget**:  
  The total power available for downlinking signals is limited. Users must share this power to ensure all can communicate effectively.

By understanding these concepts, you can see why managing ERP is crucial for maintaining fair access to satellite resources.