All 48 FCC GROL questions for 3L Installation, Maintenance & Repair with the correct answers marked, from the official current FCC question pool. Test yourself with the free practice exam.
3-74L1
What is a 1/2 digit on a DMM?
A. Smaller physical readout on the left side of the display.
B. Partial extended accuracy on lower part of the range. ✓
C. Smaller physical readout on the right side.
D. Does not apply to DMMs.
3-74L2
A 50 microampere meter movement has an internal resistance of 2,000 ohms. What applied voltage is required to indicate half-scale deflection?
A. 0.01 volts
B. 0.10 volts
C. 0.005 volts.
D. 0.05 volts. ✓
3-74L3
What is the purpose of a series multiplier resistor used with a voltmeter?
A. It is used to increase the voltage-indicating range of the voltmeter. ✓
B. A multiplier resistor is not used with a voltmeter.
C. It is used to decrease the voltage-indicating range of the voltmeter.
D. It is used to increase the current-indicating range of an ammeter, not a voltmeter.
3-74L4
What is the purpose of a shunt resistor used with an ammeter?
A. A shunt resistor is not used with an ammeter.
B. It is used to decrease the ampere indicating range of the ammeter.
C. It is used to increase the ampere indicating range of the ammeter. ✓
D. It is used to increase the voltage indicating range of the voltmeter, not the ammeter.
3-74L5
What instrument is used to indicate high and low digital voltage states?
A. Ohmmeter.
B. Logic probe. ✓
C. Megger.
D. Signal strength meter.
3-74L6
What instrument may be used to verify proper radio antenna functioning?
A. Digital ohm meter.
B. Hewlett-Packard frequency meter.
C. An SWR meter. ✓
D. Different radio.
3-75L1
How is a frequency counter used?
A. To provide reference points on an analog receiver dial thereby aiding in the alignment of the receiver.
B. To heterodyne the frequency being measured with a known variable frequency oscillator until zero beat is achieved, thereby indicating the unknown frequency.
C. To measure the deviation in an FM transmitter in order to determine the percentage of modulation.
D. To measure the time between events, or the frequency, which is the reciprocal of the time. ✓
3-75L2
What is a frequency standard?
A. A well-known (standard) frequency used for transmitting certain messages.
B. A device used to produce a highly accurate reference frequency. ✓
C. A device for accurately measuring frequency to within 1 Hz.
D. A device used to generate wide-band random frequencies.
3-75L3
What equipment may be useful to track down EMI aboard a ship or aircraft?
A. Fluke multimeter.
B. An oscilloscope.
C. Portable AM receiver. ✓
D. A logic probe.
3-75L4
On an analog wattmeter, what part of the scale is most accurate and how much does that accuracy extend to the rest of the reading scale?
A. The accuracy is only at full scale, and that absolute number reading is carried through to the rest of the range. The upper 1/3 of the meter is the only truly calibrated part. ✓
B. The accuracy is constant throughout the entire range of the meter.
C. The accuracy is only there at the upper 5% of the meter, and is not carried through at any other reading.
D. The accuracy cannot be determined at any reading.
3-75L5
Which of the following frequency standards is used as a time base standard by field technicians?
A. Quartz Crystal.
B. Rubidium Standard. ✓
C. Cesium Beam Standard.
D. LC Tank Oscillator.
3-75L6
Which of the following contains a multirange AF voltmeter calibrated in dB and a sharp, internal 1000 Hz bandstop filter, both used in conjunction with each other to perform quieting tests?
A. SINAD meter. ✓
B. Reflectometer.
C. Dip meter.
D. Vector-impedance meter.
3-76L1
What is used to decrease circuit loading when using an oscilloscope?
A. Dual input amplifiers.
B. 10:1 divider probe. ✓
C. Inductive probe.
D. Resistive probe.
3-76L2
How does a spectrum analyzer differ from a conventional oscilloscope?
A. The oscilloscope is used to display electrical signals while the spectrum analyzer is used to measure ionospheric reflection.
B. The oscilloscope is used to display electrical signals in the frequency domain while the spectrum analyzer is used to display electrical signals in the time domain.
C. The oscilloscope is used to display electrical signals in the time domain while the spectrum analyzer is used to display electrical signals in the frequency domain. ✓
D. The oscilloscope is used for displaying audio frequencies and the spectrum analyzer is used for displaying radio frequencies.
3-76L3
What stage determines the maximum frequency response of an oscilloscope?
A. Time base.
B. Horizontal sweep.
C. Power supply.
D. Vertical amplifier. ✓
3-76L4
What factors limit the accuracy, frequency response, and stability of an oscilloscope?
A. Sweep oscillator quality and deflection amplifier bandwidth. ✓
B. Tube face voltage increments and deflection amplifier voltage.
C. Sweep oscillator quality and tube face voltage increments.
D. Deflection amplifier output impedance and tube face frequency increments.
3-76L5
An oscilloscope can be used to accomplish all of the following except:
A. Measure electron flow with the aid of a resistor.
B. Measure phase difference between two signals.
C. Measure velocity of light with the aid of a light emitting diode. ✓
D. Measure electrical voltage.
3-76L6
What instrument is used to check the signal quality of a single-sideband radio transmission?
A. Field strength meter.
B. Signal level meter.
C. Sidetone monitor.
D. Oscilloscope. ✓
3-77L1
A(n) ____ and ____ can be combined to measure the characteristics of transmission lines. Such an arrangement is known as a time-domain reflectometer (TDR).
A. Frequency spectrum analyzer, RF generator.
B. Oscilloscope, pulse generator. ✓
C. AC millivolt meter, AF generator.
D. Frequency counter, linear detector.
3-77L2
What does the horizontal axis of a spectrum analyzer display?
A. Amplitude.
B. Voltage.
C. Resonance.
D. Frequency. ✓
3-77L3
What does the vertical axis of a spectrum analyzer display?
A. Amplitude. ✓
B. Duration.
C. Frequency.
D. Time.
3-77L4
What instrument is most accurate when checking antennas and transmission lines at the operating frequency of the antenna?
A. Time domain reflectometer.
B. Wattmeter.
C. DMM.
D. Frequency domain reflectometer. ✓
3-77L5
What test instrument can be used to display spurious signals in the output of a radio transmitter?
A. A spectrum analyzer. ✓
B. A wattmeter.
C. A logic analyzer.
D. A time domain reflectometer.
3-77L6
What instrument is commonly used by radio service technicians to monitor frequency, modulation, check receiver sensitivity, distortion, and to generate audio tones?
A. Oscilloscope.
B. Spectrum analyzer.
C. Service monitor. ✓
D. DMM.
3-78L1
Can a P25 radio system be monitored with a scanner?
A. Yes , regardless if it has P25 decoding or not.
B. No.
C. Yes, if the scanner has P25 decoding. ✓
D. Yes, but it must also have P26 decoding.
3-78L2
Which of the following answers is true?
A. The RF Power reading on a CDMA (code division multiple access) radio will be very accurate on an analog power meter.
B. The RF Power reading on a CDMA radio is not accurate on an analog power meter. ✓
C. Power cannot be measured using CDMA modulation.
D. None of the above.
3-78L3
What is a common method used to program radios without using a “wired” connection?
A. Banding.
B. Using the ultraviolet from a programmed radio to repeat the programming in another.
C. Infra-red communication. ✓
D. Having the radio maker send down a programming signal via satellite.
3-78L4
What is the common method for determining the exact sensitivity specification of a receiver?
A. Measure the recovered audio for 12 dB of SINAD. ✓
B. Measure the recovered audio for 10 dB of quieting.
C. Measure the recovered audio for 10 dB of SINAD.
D. Measure the recovered audio for 25 dB of quieting.
3-78L5
A communications technician would perform a modulation-acceptance bandwidth test in order to:
A. Ascertain the audio frequency response of the receiver.
B. Determine whether the CTCSS in the receiver is operating correctly.
C. Verify the results from a 12 dB SINAD test.
D. Determine the effective bandwidth of a communications receiver. ✓
3-78L6
What is the maximum FM deviation for voice operation of a normal wideband channel on VHF and UHF?
A. 2.5 kHz
B. 5.0 kHz ✓
C. 7.5 kHz
D. 10 kHz
3-79L1
When soldering or working with CMOS electronics products or equipment, a wrist strap:
A. Must have less than 100,000 ohms of resistance to prevent static electricity. ✓
B. Cannot be used when repairing TTL devices.
C. Must be grounded to a water pipe.
D. Does not work well in conjunction with anti-static floor mats.
3-79L2
Which of the following is the preferred method of cleaning solder from plated-through circuit-board holes?
A. Use a dental pick.
B. Use a vacuum device. ✓
C. Use a soldering iron tip that has a temperature above 900 degrees F.
D. Use an air jet device.
3-79L3
What is the proper way to cut plastic wire ties?
A. With scissors.
B. With a knife.
C. With semi-flush diagonal pliers.
D. With flush-cut diagonal pliers and cut flush. ✓
3-79L4
The ideal method of removing insulation from wire is:
A. The thermal stripper. ✓
B. The pocket knife.
C. A mechanical wire stripper.
D. The scissor action stripping tool.
3-79L5
A “hot gas bonder” is used:
A. To apply solder to the iron tip while it is heating the component.
B. For non-contact melting of solder. ✓
C. To allow soldering both sides of the PC board simultaneously.
D. To cure LCA adhesives.
3-79L6
When repairing circuit board assemblies it is most important to:
A. Use a dental pick to clear plated-through holes.
B. Bridge broken copper traces with solder.
C. Wear safety glasses. ✓
D. Use a holding fixture.
3-80L1
What color is the binder for pairs 51-75 in a 100-pair cable?
A. Red
B. Blue
C. Black
D. Green ✓
3-80L2
What is most important when routing cables in a mobile unit?
A. That cables be cut to the exact length.
B. Assuring accessibility of the radio for servicing from outside the vehicle.
C. Assuring radio or electronics cables do not interfere with the normal operation of the vehicle. ✓
D. Assuring cables are concealed under floor mats or carpeting.
3-80L3
Why should you not use white or translucent plastic tie wraps on a radio tower?
A. White tie wraps are not FAA approved.
B. UV radiation from the Sun deteriorates the plastic very quickly. ✓
C. The white color attracts wasps
D. The black tie wraps may cause electrolysis.
3-80L4
What is the 6th pair color code in a 25 pair switchboard cable as is found in building telecommunications interconnections?
A. Blue/Green, Green/Blue.
B. Red/Blue, White/Violet.
C. Red/Blue, Blue/Red. ✓
D. White/Slate, Slate/White.
3-80L5
What tolerance off of plumb should a single base station radio rack be installed?
A. No tolerance allowed.
B. Just outside the bubble on a level.
C. All the way to one end.
D. Just inside the bubble on a level. ✓
3-80L6
What type of wire would connect an SSB automatic tuner to an insulated backstay?
A. GTO-15 high-voltage cable. ✓
B. RG8U.
C. RG213.
D. 16-gauge two-conductor.
3-81L1
On a 150 watt marine SSB HF transceiver, what would be indicated by a steady output of 75 watts when keying the transmitter on?
A. There is probably a defect in the system causing the carrier to be transmitted. ✓
B. One of the sidebands is missing.
C. Both sidebands are being transmitting.
D. The operation is normal.
3-81L2
The tachometer of a building’s elevator circuit experiences interference caused by the radio system nearby. What is a common potential “fix” for the problem?
A. Replace the tachometer of the elevator.
B. Add a .01 µF capacitor across the motor/tachometer leads. ✓
C. Add a 200 µF capacity across the motor/tachometer leads.
D. Add an isolating resistor in series with the motor leads.
3-81L3
A common method of programming portable or mobile radios is to use a:
A. A laptop computer. ✓
B. Dummy load.
C. A wattmeter.
D. A signal generator.
3-81L4
In a software-defined transceiver, what would be the best way for a technician to make a quick overall evaluation of the radio’s operational condition?
A. Set up a spectrum analyzer and service monitor and manually verify the manufacturer’s specifications.
B. Use another radio on the same frequency to check the transmitter.
C. Use the built-in self-test feature. ✓
D. Using on-board self-test routines are strictly prohibited by the FCC in commercial transmitters. Amateur Radio is the only service currently authorized to use them.
3-81L5
How might an installer verify correct GPS sentence to marine DSC VHF radio?
A. Press and hold the red distress button.
B. Look for latitude and longitude on the display. ✓
C. Look for GPS confirmation readout.
D. Ask for VHF radio check position report.
3-81L6
What steps must be taken to activate the DSC emergency signaling function on a marine VHF?
A. Separate 12 volts to the switch.
B. Secondary DSC transmit antenna.
C. GPS position input.
D. Input of registered 9-digit MMSI. ✓