Lesson 14: Amplifiers and Devices Quizzez

1. Which of the following is used to determine if an antenna is resonant at the desired operating frequency?  Choose only ONE best answer.

• A. A VTVM

• B. An antenna analyzer

• C. A Q meter

• D. A frequency counter

Answer explanation

This answer is correct.

An antenna analyzer is an instrument that can be used to determine whether an antenna is resonant at the desired operating frequency. The antenna analyzer puts out a tiny signal just like your own transmitter, except the antenna analyzer can determine the reactance, impedance, standing wave ratio and resonant frequency of the antenna being evaluated, and in some cases it can detect a cable fault in your feed line.

Tags

NGSS.HS-PS4-1

2. Which of the following is used to convert a signal from one frequency to another?  Choose only ONE best answer.

• A. Phase splitter

• B. Mixer

• C. Inverter

• D. Amplifier

Answer explanation

This answer is correct.

The mixer circuit is used to convert a radio signal from one frequency to another. When two RF signals are mixed together you will get two additional frequencies. One will be the sum of the two frequencies and the other will be the difference of the two signals. So if you mix together a 5-MHz frequency and a 3-MHz frequency, you will get an 8-MHz frequency and a 2-MHz frequency. 5 MHz + 3 MHz = 8 MHz (sum) and 5 MHz - 3 MHz = 2 MHz (difference).

Tags

NGSS.HS-PS4-5

3. Which of the following can damage a multimeter? Choose only ONE best answer.

• A. Attempting to measure resistance using the voltage setting

• B. Failing to connect one of the probes to ground

• C. Attempting to measure voltage when using the resistance setting

• D. Not allowing it to warm up properly

Answer explanation

This answer is correct.

Inattention to detail or being in a hurry can easily and quickly damage sensitive test equipment. Please pay attention and be safe when making any measurements on an energized circuit.

4. Which term describes the ability of a receiver to discriminate between multiple signals? Choose only ONE best answer.

• A. Discrimination ratio

• B. Sensitivity

• C. Selectivity

• D. Harmonic distortion

Answer explanation

This answer is correct.

Selectivity is the ability of a receiver to discriminate between multiple signals. Selectivity is another important property of a receiver. The selectivity of a receiver measures its ability to allow you to receive your desired signals when other stronger stations are on adjacent frequencies. This is another important performance indicator to consider when purchasing amateur radio equipment.

Tags

NGSS.HS-PS4-5

5. What is the name of a circuit that generates a signal at a specific frequency? Choose only ONE best answer.

• A. Reactance modulator

• B. Product detector

• C. Low-pass filter

• D. Oscillator

Answer explanation

This answer is correct.

An oscillator circuit generates a signal at a specific frequency. There are many different types of oscillators that are used in radio circuits; the Pierce and crystal oscillator circuits are just two examples. Some modern amateur transmitters still offer high-stability crystal oscillators as an added accessory option.

6. Which of the following precautions should be taken when measuring in-circuit resistance with an ohmmeter? Choose only ONE best answer.

• A. Ensure that the applied voltages are correct

• B. Ensure that the circuit is not powered

• C. Ensure that the circuit is grounded

• D. Ensure that the circuit is operating at the correct frequency

Answer explanation

This answer is correct.

This is for both personal safety and the safety of your test equipment. When taking measurements using test equipment, always devote your full attention to what you are doing.

7. How is a voltmeter connected to a component to measure applied voltage? Choose only ONE best answer.

• A. In series

• B. In parallel

• C. In quadrature

• D. In phase

Answer explanation

This answer is correct.

The correct way to connect a voltmeter to a circuit is in parallel. This configuration will measure the voltage across the circuit. Always start on a higher scan and slowly work down. Remember: safety first when measuring values in energized circuits.

8. Which of the following measurements are made using a multimeter? Choose only ONE best answer.

• A. Signal strength and noise

• B. Impedance and reactance

• C. Voltage and resistance

• D. All these choices are correct

Answer explanation

This answer is correct.

Multimeters have a minimum of two modes, one that measures voltage and one that measures resistance. More advanced meters may measure other items, but this question is focused on the basics.

9. Which instrument is used to measure electric current? Choose only ONE best answer.

• A. An ohmmeter

• B. An electrometer

• C. A voltmeter

• D. An ammeter

Answer explanation

This answer is correct.

An ammeter is an instrument used to measure electric current. Remember: I (electric current) is measured in amperes.

10. What is the characteristic appearance of a cold tin-lead solder joint? Choose only ONE best answer.

• A. Dark black spots

• B. A bright or shiny surface

• C. A rough or lumpy surface

• D. Excessive solder

Answer explanation

This answer is correct.

There are many YouTube videos on proper soldering techniques. Each type of solder material has its own unique look and when using cold tin-lead, it has a rough finish when the soldering is complete.