| 1 |
What is one way that RF energy can affect human body tissue?
|
|---|---|
| A | It heats body tissue |
| B | It causes radiation poisoning |
| C | It causes the blood count to reach a dangerously low level |
| D | It cools body tissue |
| 2 |
What does "time averaging" mean about RF radiation exposure?
|
|---|---|
| A | The average amount of power developed by the transmitter over a specific 24 hour period |
| B | The average time it takes RF radiation to have any long-term effect on the body |
| C | The total time of the exposure |
| D | The total RF exposure averaged over a certain time |
| 3 |
What effect does transmitter duty cycle have when evaluating RF exposure?
|
|---|---|
| A | A lower transmitter duty cycle permits greater short-term exposure levels |
| B | A higher transmitter duty cycle permits greater short-term exposure levels |
| C | Low duty cycle transmitters are exempt from RF exposure evaluation requirements |
| D | High duty cycle transmitters are exempt from RF exposure requirements |
| 4 |
What type of instrument can be used to measure an RF field accurately?
|
|---|---|
| A | A receiver with an S meter |
| B | A calibrated field strength meter with a calibrated antenna |
| C | An SWR meter with a peak-reading function |
| D | An oscilloscope with a high-stability crystal marker generator |
| 5 |
What precaution should operator take whenever adjustments or repairing to an antenna?
|
|---|---|
| A | Ensure that you and the antenna structure are grounded |
| B | Turn off the transmitter and disconnect the feed line |
| C | Wear a radiation badge |
| D | All of these choices are correct |
| 6 |
Which of the following is a primary reason for not placing a gasoline-fueled generator inside an occupied area?
|
|---|---|
| A | Danger of carbon monoxide poisoning |
| B | Danger of engine over torque |
| C | Lack of oxygen for adequate combustion |
| D | Lack of nitrogen for adequate combustion |
| 7 |
Why must the metal enclosure of every item of station equipment be grounded?
|
|---|---|
| A | It prevents a blown fuse in the event of an internal short circuit |
| B | It prevents signal overload |
| C | It ensures that the neutral wire is grounded |
| D | It ensures that hazardous voltages cannot appear on the chassis |
| 8 |
Which of the following causes opposition to the flow of alternating current in an inductor?
|
|---|---|
| A | Conductance |
| B | Reluctance |
| C | Admittance |
| D | Reactance |
| 9 |
What is one reason to use an impedance matching transformer?
|
|---|---|
| A | To minimise transmitter power output |
| B | To maximise the transfer of power |
| C | To reduce power supply ripple |
| D | To minimise radiation resistance |
| 10 |
Which of the following devices can be used for impedance matching at radio frequencies?
|
|---|---|
| A | A transformer |
| B | A Pi-network |
| C | A length of transmission line |
| D | All of these choices are correct |
| 11 |
What dB change represents a two-times increase or decrease in power?
|
|---|---|
| A | Approximately 2 dB |
| B | Approximately 3 dB |
| C | Approximately 6 dB |
| D | Approximately 12 dB |
| 12 |
How does the total current relate to the individual currents in each branch of a purely resistive parallel circuit?
|
|---|---|
| A | It equals the average of each branch current |
| B | It decreases as more parallel branches are added to the circuit |
| C | It equals the sum of the currents through each branch |
| D | It is the sum of the reciprocal of each individual voltage drop |
| 13 |
How many watts of electrical power are used if 400 VDC is supplied to an 800-ohm load?
|
|---|---|
| A | 0.5 watts |
| B | 200 watts |
| C | 400 watts |
| D | 3200 watts |
| 14 |
How many watts of electrical power are used by a 12 VDC light bulb that draws 0.2 amperes?
|
|---|---|
| A | 2.4 watts |
| B | 24 watts |
| C | 6 watts |
| D | 60 watts |
| 15 |
How many watts are dissipated when a current of 7.0 milliamperes flows through 1.25 kilohms resistance?
|
|---|---|
| A | Approximately 61 milliwatts |
| B | Approximately 61 watts |
| C | Approximately 11 milliwatts |
| D | Approximately 11 watts |
| 16 |
What is the RMS voltage of a sine wave with a value of 17 volts peak?
|
|---|---|
| A | 8.5 volts |
| B | 12 volts |
| C | 24 volts |
| D | 34 volts |
| 17 |
What is the output PEP from a transmitter if an oscilloscope measures 500 volts peak-to-peak across a 50-ohm resistive load connected to the transmitter output?
|
|---|---|
| A | 8.75 watts |
| B | 625 watts |
| C | 2500 watts |
| D | 5000 watts |
| 18 |
What causes a voltage to appear across the secondary winding of a transformer when an AC voltage source is connected across its primary winding?
|
|---|---|
| A | Capacitive coupling |
| B | Displacement current coupling |
| C | Mutual inductance |
| D | Mutual capacitance |
| 19 |
If three equal value resistors in series produce 450 ohms, what is the value of each resistor?
|
|---|---|
| A | 1500 ohms |
| B | 90 ohms |
| C | 150 ohms |
| D | 175 ohms |
| 20 |
What is the RMS voltage across a 500-turn secondary winding in a transformer if the 2250-turn primary is connected to 120 VAC?
|
|---|---|
| A | 2370 volts |
| B | 540 volts |
| C | 26.7 volts |
| D | 5.9 volts |
| 21 |
What is the turns ratio of a transformer used to match an audio amplifier having 600-ohm output impedance to a speaker having 4-ohm impedance?
|
|---|---|
| A | 12.2 to 1 |
| B | 24.4 to 1 |
| C | 150 to 1 |
| D | 300 to 1 |
| 22 |
What is the equivalent capacitance of two 5.0 nano farad capacitors and one 750 picofarad capacitor connected in parallel?
|
|---|---|
| A | 576.9 nanofarads |
| B | 1733 picofarads |
| C | 3583 picofarads |
| D | 10.750 nanofarads |
| 23 |
What is the inductance of three 10 millihenry inductors connected in parallel?
|
|---|---|
| A | 0.30 henrys |
| B | 3.3 henrys |
| C | 3.3 millihenrys |
| D | 30 millihenrys |
| 24 |
What is the inductance of a 20 millihenry inductor connected in series with a 50 millihenry inductor?
|
|---|---|
| A | 0.07 millihenrys |
| B | 14.3 millihenrys |
| C | 70 millihenrys |
| D | 1000 millihenrys |
| 25 |
What is the capacitance of a 20 microfarad capacitor connected in series with a 50 microfarad capacitor?
|
|---|---|
| A | 0.07 microfarads |
| B | 14.3 microfarads |
| C | 70 microfarads |
| D | 1000 microfarads |