Lab 5: RF Amplifier

Purpose

There is only one objective for Lab 5:

• Breadboard the RF amplifier circuit

This lab does not take very long. The objective is to breadboard the RF amplifier circuit which shows how adding in a choke to the CS circuit gives a better amplification. After adding the RFC, the type of amplifier changes from a CS amplifier to the RF amplifier.

Summary

To understand the benefit of the choke/RF amplifier, we first build the CS amplifier and observe its results. Once the circuit is built the Q-point and gain for the 1MΩ, 10kΩ, and 1kΩ resistor are recorded. This can be compared to the Q-point and gains with the RF amplifier once it is built. A summary of this comparison is seen below in Table 1. After that the choke and making the RF amplifier, the RF amplifier is further analyzed. The analysis shows that the load resistance can change with out changing the gain. The data for this analysis is in Table 2. This lab shows how the RF amplifier will be chosen for the radio instead of the simple CS amplifier that has verifying gain by load resistance.

Suggestion

Like last time, I enjoyed this lab because it showed how all the circuits worked together to reach the end goal of building a radio.

Figure 1: CS amplifier with AM input

Table 1: Measurements of CS amplifier with and without the RF choke.

Figure 2: RF amplifier with AM signal input

Table 2: Gain of the RFC and CS amplifier (RF amplifier)