*Question T7A10:
What device increases the transmitted output power from a transceiver?*  

*Correct Answer is  B: An RF power amplifier*  

### AI Response: (may contain errors)  

To understand the question about what device increases the transmitted output power from a transceiver, let's analyze each option:

### Correct Answer: B - An RF power amplifier

- **Explanation**: An RF power amplifier is specifically designed to increase the power level of the radio frequency (RF) signal generated by a transceiver. It takes the low-level output from the transceiver and amplifies it to a higher power level suitable for transmission. This is essential for ensuring that the signal can travel longer distances and overcome losses in the transmission medium.

### Why the Other Choices Are Incorrect:

- **A: A voltage divider**  
  - **Explanation**: A voltage divider is a circuit that reduces voltage levels, not increases them. It is used to obtain a lower voltage from a higher voltage source and is not suitable for amplifying RF signals.

- **C: An impedance network**  
  - **Explanation**: An impedance network (such as a matching network) is used to match the impedance of the transmitter to the antenna or load. While it can improve efficiency and maximize power transfer, it does not increase the output power itself. Its primary function is to ensure that the maximum amount of power is transferred without reflections.

- **D: All these choices are correct**  
  - **Explanation**: Since options A and C do not increase power, this choice is incorrect. Only the RF power amplifier is designed to increase transmitted output power.

### Useful Formulas or Rules of Thumb:

- **Power Gain**: The gain of an amplifier can be expressed in decibels (dB) using the formula:
  
  $$G_{dB} = 10 \log_{10} \left( \frac{P_{out}}{P_{in}} \right)$$

  where:
  - $G_{dB}$ = gain in decibels
  - $P_{out}$ = output power
  - $P_{in}$ = input power

This formula helps you understand how much the power is increased by the amplifier. 

In summary, the RF power amplifier is the only device among the options that increases the transmitted output power from a transceiver, while the other options serve different functions.