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

Question 1

What is the primary function of a mixer in a superheterodyne receiver?

Accepted Answer

To shift the incoming signal to an intermediate frequency

Answer

A mixer combines the incoming RF signal with a signal from a local oscillator. This process, called heterodyning, creates sum and difference frequencies. The difference frequency, known as the Intermediate Frequency (IF), is selected and amplified. This allows the majority of the receiver's amplifier and filter stages to operate at a fixed, lower frequency, which is more efficient and provides better selectivity.

Question 2

In a high-voltage power supply, what is the main safety purpose of a bleeder resistor?

Accepted Answer

To discharge the filter capacitors when the power is turned off

Answer

High-voltage power supplies use large filter capacitors that can store a lethal charge long after the unit is turned off. A bleeder resistor is connected in parallel with the capacitors to provide a safe discharge path, reducing the voltage to a safe level and preventing accidental electric shock.

Question 3

An operator is designing a circuit to provide a stable reference voltage for a digital logic circuit, despite variations in the main power supply voltage. Which of the following components is best suited for this voltage regulation task?

Accepted Answer

A Zener diode

Answer

A Zener diode is specifically designed to operate in reverse-bias breakdown. When the voltage across it reaches its 'Zener voltage,' it conducts and maintains a nearly constant voltage across its terminals, making it ideal for use as a voltage regulator or stable voltage reference.

Question 4

What are the key characteristics of a common-emitter amplifier?

Accepted Answer

High voltage gain, high current gain, and an inverted output

Answer

The common-emitter amplifier configuration is widely used because it provides both significant voltage gain and significant current gain, resulting in high power gain. A characteristic feature is that the output signal is 180 degrees out of phase with the input signal, meaning it is inverted.

Question 5

Which of the following best describes the operation of a Class C amplifier?

Accepted Answer

The amplifying device is biased to conduct for less than 180 degrees of the input cycle, resulting in high efficiency but poor fidelity.

Answer

A Class C amplifier is biased so the active device (transistor) conducts for significantly less than half (less than 180 degrees) of the input signal cycle. This results in brief pulses of current. While this creates high distortion, it also leads to very high efficiency (often over 80%). They are typically used in RF applications where a resonant tank circuit at the output restores the full sine wave.

Ham Radio General Class Test Practice Test

Ham Radio General Class Test Practice Test

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