FREE HAM Radio Extra Class Test Practical Circuits and Components Questions and Answers

Question 1

In a simple Zener diode voltage regulator circuit, what is the primary purpose of the series resistor?

Accepted Answer

To limit the current through the Zener diode

Answer

To provide a path for the load current

Answer

To filter ripple from the unregulated DC input

Answer

To set the output voltage of the regulator

Question 2

Which of the following best describes the ideal input and output impedance characteristics of an operational amplifier (op-amp)?

Accepted Answer

High input impedance, low output impedance

Answer

Low input impedance, high output impedance

Answer

Low input impedance, low output impedance

Answer

High input impedance, high output impedance

Question 3

A technician is designing an RF oscillator for a VHF application and needs good frequency stability with low noise. Which oscillator design is generally preferred for this scenario due to its use of a tapped capacitive voltage divider for feedback?

Accepted Answer

Colpitts Oscillator

Answer

Hartley Oscillator

Answer

Armstrong Oscillator

Answer

Crystal Oscillator

Question 4

What is the primary function of a Class C amplifier in an RF transmitter?

Accepted Answer

To function as a highly efficient, non-linear RF power amplifier, often for CW or FM

Answer

To provide high-fidelity audio amplification

Answer

To act as a linear final amplifier for single-sideband (SSB) signals

Answer

To serve as a low-distortion intermediate frequency (IF) amplifier

Question 5

In a frequency synthesizer circuit, what is the core function of the Phase-Locked Loop (PLL)?

Accepted Answer

To compare the phase of a Voltage-Controlled Oscillator (VCO) with a reference signal and adjust the VCO's frequency until they are locked

Answer

To directly generate a wide range of frequencies through digital-to-analog conversion

Answer

To amplify the reference oscillator signal to the final output power

Answer

To filter out unwanted harmonics from the output of a multiplier stage

Question 6

A pi-network is frequently used in the output stage of a vacuum tube transmitter. What is the primary purpose of this circuit?

Accepted Answer

To transform the high output impedance of the tube to the low impedance of the antenna

Answer

To provide negative feedback to stabilize the amplifier's gain

Answer

To function as a high-pass filter to remove low-frequency hum

Answer

To invert the phase of the signal for push-pull operation