Ham Radio General Class Test Electronic Principles and Circuits Questions and Answers

Question 1

In a power supply circuit, what is the primary purpose of a filter capacitor?

Accepted Answer

To smooth the rectified DC voltage by reducing ripple.

Answer

A filter capacitor is used after the rectifier in a power supply to smooth out the pulsating DC. It stores energy when the voltage is rising and releases it when the voltage is falling, which significantly reduces the AC ripple and provides a more stable DC voltage.

Question 2

For a bipolar junction transistor (BJT) to operate as an amplifier, in which region must it be biased?

Accepted Answer

Active region

Answer

A BJT operates as an amplifier when it is in the active region. In this state, the emitter-base junction is forward-biased and the collector-base junction is reverse-biased, allowing a small base current to control a much larger collector current.

Question 3

What is the relationship between capacitive reactance and frequency?

Accepted Answer

Capacitive reactance is inversely proportional to frequency.

Answer

Capacitive reactance (Xc) is calculated by the formula Xc = 1 / (2πfC), where 'f' is the frequency and 'C' is the capacitance. This formula shows that as the frequency increases, the capacitive reactance decreases. Therefore, they are inversely proportional.

Question 4

A technician is building a band-pass filter for a receiver's intermediate frequency (IF) stage. Which of the following circuit configurations is commonly used for this purpose?

Accepted Answer

A parallel LC (tank) circuit

Answer

A parallel LC circuit, often called a tank circuit, exhibits maximum impedance at its resonant frequency and lower impedance at other frequencies. This characteristic allows it to selectively pass a narrow band of frequencies, making it ideal for use as a band-pass filter in applications like receiver IF stages.

Question 5

What is the primary purpose of impedance matching between a transmitter's output and an antenna system?

Accepted Answer

To maximize the transfer of power from the transmitter to the antenna.

Answer

The maximum power transfer theorem states that for maximum power to be transferred from a source (transmitter) to a load (antenna), the load impedance must be the complex conjugate of the source impedance. In RF systems, this is simplified to matching the impedances (e.g., 50 ohms) to minimize signal reflection and maximize power transfer.

Ham Radio General Class Test Practice Test

Ham Radio General Class Test Practice Test

Ham Radio General Class Test Electronic Principles and Circuits Questions and Answers