Ham Radio General Class Practice Test

Which of the following might be useful in reducing RF interference to audio-frequency devices?

1. Bypass inductor

2. Bypass capacitor

3. Forward-biased diode

4. Reverse-biased diode

The correct answer is: Bypass capacitor

Using a bypass capacitor is effective in reducing RF interference to audio-frequency devices because it provides a low-impedance path for high-frequency signals. When RF energy is coupled into audio circuits, it can create noise that interferes with the intended audio signals. A bypass capacitor shunts these unwanted high-frequency signals to ground, preventing them from affecting the audio frequencies. Bypass capacitors are specifically designed to filter out noise and stabilize voltage supplies by bypassing high-frequency AC noise while allowing the DC voltage to pass through. This is especially important in audio applications where clarity and fidelity are paramount. By connecting a bypass capacitor across power supply lines, it helps ensure that the audio frequencies are preserved while reducing the influence of any RF interference. In contrast, while inductors and diodes have their own applications in circuit design, they do not specifically function to effectively shunt high-frequency noise like a bypass capacitor does. Inductors tend to impede high frequencies rather than safely redirect them, while the operation of diodes depends on their biasing conditions and is not specifically aimed at filtering audio or RF interference.