All 36 FCC GROL questions for 3G Transmitters with the correct answers marked, from the official current FCC question pool. Test yourself with the free practice exam.
3-51G1
What class of amplifier is distinguished by the presence of output throughout the entire signal cycle and the input never goes into the cutoff region?
A. Class A. ✓
B. Class B.
C. Class C.
D. Class D.
3-51G2
What is the distinguishing feature of a Class A amplifier?
A. Output for less than 180 degrees of the signal cycle.
B. Output for the entire 360 degrees of the signal cycle. ✓
C. Output for more than 180 degrees and less than 360 degrees of the signal cycle.
D. Output for exactly 180 degrees of the input signal cycle.
3-51G3
Which class of amplifier has the highest linearity and least distortion?
A. Class A. ✓
B. Class B.
C. Class C.
D. Class AB.
3-51G4
Which class of amplifier provides the highest efficiency?
A. Class A.
B. Class B.
C. Class C. ✓
D. Class AB.
3-51G5
What class of amplifier is distinguished by the bias being set well beyond cutoff?
A. Class A.
B. Class C. ✓
C. Class B.
D. Class AB.
3-51G6
Which class of amplifier has an operating angle of more than 180 degrees but less than 360 degrees when driven by a sine wave signal?
A. Class A.
B. Class B.
C. Class C.
D. Class AB. ✓
3-52G1
The class B amplifier output is present for what portion of the input cycle?
A. 360 degrees.
B. Greater than 180 degrees and less than 360 degrees.
C. Less than 180 degrees.
D. 180 degrees. ✓
3-52G2
What input-amplitude parameter is most valuable in evaluating the signal-handling capability of a Class
A. amplifier? A. Average voltage.
B. RMS voltage.
C. Peak voltage. ✓
D. Resting voltage.
3-52G3
The class C amplifier output is present for what portion of the input cycle?
A. Less than 180 degrees. ✓
B. Exactly 180 degrees.
C. 360 degrees.
D. More than 180 but less than 360 degrees.
3-52G4
What is the approximate DC input power to a Class AB RF power amplifier stage in an unmodulated carrier transmitter when the PEP output power is 500 watts?
A. 250 watts.
B. 600 watts.
C. 800 watts.
D. 1000 watts. ✓
3-52G5
The class AB amplifier output is present for what portion of the input cycle?
A. Exactly 180 degrees.
B. 360 degrees
C. More than 180 but less than 360 degrees. ✓
D. Less than 180 degrees.
3-52G6
What class of amplifier is characterized by conduction for 180 degrees of the input wave?
A. Class A.
B. Class B. ✓
C. Class C.
D. Class D.
3-53G1
What is the modulation index in an FM phone signal having a maximum frequency deviation of 3,000 Hz on either side of the carrier frequency when the modulating frequency is 1,000 Hz?
A. 0.3
B. 3,000
C. 3 ✓
D. 1,000
3-53G2
What is the modulation index of a FM phone transmitter producing a maximum carrier deviation of 6 kHz when modulated with a 2 kHz modulating frequency?
A. 3 ✓
B. 6,000
C. 2,000
D. 1
3-53G3
What is the total bandwidth of a FM phone transmission having a 5 kHz deviation and a 3 kHz modulating frequency?
A. 3 kHz.
B. 8 kHz.
C. 5 kHz.
D. 16 kHz. ✓
3-53G4
How does the modulation index of a phase-modulated emission vary with RF carrier frequency?
A. It does not depend on the RF carrier frequency. ✓
B. Modulation index increases as the RF carrier frequency increases.
C. It varies with the square root of the RF carrier frequency.
D. It decreases as the RF carrier frequency increases.
3-53G5
How can a single-sideband phone signal be generated?
A. By driving a product detector with a DSB signal.
B. By using a reactance modulator followed by a mixer.
C. By using a loop modulator followed by a mixer.
D. By using a balanced modulator followed by a filter. ✓
3-53G6
What is a balanced modulator?
A. An FM modulator that produces a balanced deviation.
B. A modulator that produces a double sideband, suppressed carrier signal. ✓
C. A modulator that produces a single sideband, suppressed carrier signal.
D. A modulator that produces a full carrier signal.
3-54G1
What is an L-network?
A. A low power Wi-Fi RF network connection.
B. A network consisting of an inductor and a capacitor. ✓
C. A “lossy” network.
D. A network formed by joining two low pass filters.
3-54G2
What is a pi-network?
A. A network consisting of a capacitor, resistor and inductor.
B. The Phase inversion stage.
C. An enhanced token ring network.
D. A network consisting of one inductor and two capacitors or two inductors and one capacitor. ✓
3-54G3
What is the resonant frequency in an electrical circuit?
A. The frequency at which capacitive reactance equals inductive reactance. ✓
B. The highest frequency that will pass current.
C. The lowest frequency that will pass current.
D. The frequency at which power factor is at a minimum.
3-54G4
Which three network types are commonly used to match an amplifying device to a transmission line?
A. Pi-C network, pi network and T network.
B. T network, M network and Z network.
C. L network, pi network and pi-L network. ✓
D. L network, pi network and C network.
3-54G5
What is a pi-L network?
A. A Phase Inverter Load network.
B. A network consisting of two inductors and two capacitors. ✓
C. A network with only three discrete parts.
D. A matching network in which all components are isolated from ground.
3-54G6
Which network provides the greatest harmonic suppression?
A. L network.
B. Pi network.
C. Pi-L network. ✓
D. Inverse L network.
3-55G1
What will occur when a non-linear amplifier is used with a single-sideband phone transmitter?
A. Reduced amplifier efficiency.
B. Increased intelligibility.
C. Sideband inversion.
D. Distortion. ✓
3-55G2
To produce a single-sideband suppressed carrier transmission it is necessary to ____ the carrier and to ____ the unwanted sideband.
A. Filter, filter.
B. Cancel, filter. ✓
C. Filter, cancel.
D. Cancel, cancel.
3-55G3
In a single-sideband phone signal, what determines the PEP-to-average power ratio?
A. The frequency of the modulating signal.
B. The degree of carrier suppression.
C. The speech characteristics. ✓
D. The amplifier power.
3-55G4
What is the approximate ratio of peak envelope power to average power during normal voice modulation peak in a single-sideband phone signal?
A. 2.5 to 1. ✓
B. 1 to 1.
C. 25 to 1.
D. 100 to 1.
3-55G5
What is the output peak envelope power from a transmitter as measured on an oscilloscope showing 200 volts peak-to-peak across a 50-ohm load resistor?
A. 1,000 watts.
B. 100 watts. ✓
C. 200 watts.
D. 400 watts.
3-55G6
What would be the voltage across a 50-ohm dummy load dissipating 1,200 watts?
A. 245 volts. ✓
B. 692 volts.
C. 346 volts.
D. 173 volts.
3-56G1
How can intermodulation interference between two transmitters in close proximity often be reduced or eliminated?
A. By using a Class C final amplifier with high driving power.
B. By installing a terminated circulator or ferrite isolator in the feed line to the transmitter and duplexer. ✓
C. By installing a band-pass filter in the antenna feed line.
D. By installing a low-pass filter in the antenna feed line.
3-56G2
How can parasitic oscillations be eliminated in a power amplifier?
A. By tuning for maximum SWR.
B. By tuning for maximum power output.
C. By neutralization. ✓
D. By tuning the output.
3-56G3
What is the name of the condition that occurs when the signals of two transmitters in close proximity mix together in one or both of their final amplifiers, and unwanted signals at the sum and difference frequencies of the original transmissions are generated?
A. Amplifier desensitization.
B. Neutralization.
C. Adjacent channel interference.
D. Intermodulation interference. ✓
3-56G4
What term describes a wide-bandwidth communications system in which the RF carrier varies according to some pre-determined sequence?
A. Spread-spectrum communication. ✓
B. AMTOR.
C. SITOR.
D. Time-domain frequency modulation.
3-56G5
How can even-order harmonics be reduced or prevented in transmitter amplifier design?
A. By using a push-push amplifier.
B. By operating class C.
C. By using a push-pull amplifier. ✓
D. By operating class AB.
3-56G6
What is the modulation type that can be a frequency hopping of one carrier or multiple simultaneous carriers?
A. SSB.
B. FM.
C. OFSK.
D. Spread spectrum. ✓