FCC Flashcards
FCC test
Where do you make an application for inspection of a ship GMDSS radio station?
To the Engineer-in-Charge of the FCC District nearest the proposed place of inspection.
When is it legal to transmit high power on Channel 13?
Failure of vessel being called to respond. In a blind situation such as rounding a bend in a river. During an emergency.
Under what circulstances may a coast guard station using telephony transmit a general call to a group of vessels?
When announcing or preceding the transmission of Distress, Urgency, Safety or other important messages.
Under what circumstances may a ship or aircraft station interfere with public coast station?
In cases of distress.
What is Distress traffic?
All messages relative to the immediate assistance required by a ship, aircraft or other vehicle threatened by grave or imminent danger, such as life and safety or persons on board, or man overboard.
What is the best way for a radio operator to minimize or prevent interference to other stations?
Determine that a frequency is not in use by monitoring the frequency before transmitting.
On what frequency should a ship station normally call a coast station when using a radio-telephony emission?
Calls should be initiated on the appropriate ship-to-shore working frequency of the coast station.
What are the highest priority communications from ships at sea?
Distress calls are highest and then communications preceded by Urgency and then Safety signals.
By international agreement, which ships must carry radio equipment for the safety of life at sea?
Cargo ships of more than 300 gross tons and vessels carrying more than 12 passengers.
The primary purpose of bridge-to-bridge communications is:
Navigational communications.
Who determines when a ship station may transmit routine traffic destined for a coast or government station in the maritime mobile service?
Ship stations must comply with instructions given by the coast or government station.
On what frequency should a ship station normally call a coast station when using a radio-telephony emission?
Calls shoul be initiated on the appropriate ship-to-shore working frequency of the coast station
What information must be included in a Distress message?
Name of vessel Location Types of distress and specifics of help requested
When may a bridge-to-bridge transmission be more than 1 watt?
When broadcasting distress messages and rounding a bend in a river or traveling in a blind spot.
Who determines when a ship station may transmit routine traffic destined for a coast or government station in the maritime mobile service?
Ship stations must comply with instructions given by the coast or government station.
What traffic management service is operated by the U.S. Coast Guard in certain designated water areas to prevent ship collisions, groundings and environmental harm?
Vessel Traffic Safety (VTS).
Ordinarily, how often would a station using a telephony emission identify?
At the beginning and end of each transmission and at 15 minute intervals
What are the highest priority communications from ships at sea?
Distress calls are highest and then communications preceded by Urgency and then Safety signals.
A ship station using VHF bridge-to-bridge Channel 13:
May be identified by the name of the ship in lieu of call sign.
The radio-telephone Distress call and message consists of:
MAYDAY spoken three times, followed by the name of the vessel and the call sign phonetics spoken three times. Particulars of its position, latitude and longitude, and other information which might facilitate rescue, such as length, color and type of vessel, and number of persons on board Nature of distress and kind of assistance required
What is required of a ship station which has established initial contact with another station on 2182 kHz or Ch-16?
The stations must change to an authorized working frequency for transmission of message.
In the International Phonetic Alphabet, the letters E, M, and S are represented by the words:
Echo, Mike, Sierra
How does a coast station notify a ship that it has a message for the ship?
The coast station may transmit, at intervals, lists of call signs in alphabetical order for which they have traffic.
What is a Distress communication?
An internationally recognized communication indicating that the sender is threatened by grave and imminent danger and requests immediate assistance.
Where must the principle radiotelephone operating position be installed in a ship station?
In the room or an adjoining room from which the ship is normally steered while at sea.
When may the operator of a ship radio station allow an unlicensed person to speak over the transmitter?
When under the supervision of the licensed operator.
What is the most actual transmitter frequency could differ from a reading of 462,100,000 hertz on a frequency counter with a time base accuracy of + or - 1.0 ppm?
462.1 Hz
At pi/3 radians,, what is the amplitude of a sine-wave having a peak value of 5 volts?
+4.3 volts.
If a resistance to which a constant voltage is applied is halved, what power dissipation will result?
Double
What is the meaning of the term “time constant of an RL circuit”? The time required for the:
Current in the circuit to build up to 63.2% of the maximum value
What is the time constant of a circuit having a 100-microfarad capacitor and a 470 kilohm resistor in series?
47 seconds
At 150 degrees, what is the amplitude of a sine-wave having a peak value of 5 volts?
+2.5 volts.
In a circuit where AC voltage and current are out of phase, how can the true power be determined?
By multiplying the apparent power times the power factor.
After two time constants, the capacitor in an RC circuit is charged to what percentage of the supply voltage?
86.5%
What does the power factor equal in an R-L circuit having a 30 degree phase angle between the voltage and the current?
0.866
The second harmonic of a 380 kHz frequency is:
760 kHz
What is the time constant of a circuit having a 220-microfarad capacitor and a 1-megaohm resistor in parallel?
220 seconds
What is the second harmonic pf SSB frequency 4146 kHz?
8292 kHz
At pi/3 radians, what is the amplitude of a sine-wave having a peak value of 5 volts?
+4.3 volts
What is the term for the time required for the current in an RL circuit to build up to 63.2% of the maximum value?
One time constant.
The second harmonic of a 380 kHz frequency is:
760 kHz
What is the equivalent to the root-mean-square value of an AC voltage?
The DC voltage causing the same heating in a given resistor as the RMS AC voltage of the same value.
What does the power factor equal in an R-L circuit having a 60 degree phase angle between the voltage and the current?
0.5
Determine the phase relationship between the two signals shown in Figure 3B3.
B is lagging A by 90 degrees
What is the most actual transmit frequency could differ from a reading of 462,100,000 Hertz on a frequency counter with a time base accuracy of + or - 01 ppm?
46.32 Hz
What does the power factor equal in an R-L circuit having a 60 degree phase angle between the voltage and the current?
0.5
Which class of amplifier has the highest linearity and least distortion?
Class A
The Class B amplifier output is present for what portion of the input cycle?
180 degrees.
How can a single-sideband phone signal be generated?
By using a balanced modulator followed by a filter.
What is a pi-network?
A network consisting of one inductor and two capacitors or two inductors and one capacitor.
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?
100 watts
What class of amplifier is distinguished by the bias being set well beyond cutoff?
Class C
What is a balanced modulator?
A modulator that produces a double sideband, suppressed carrier signal.
What is a pi-L network?
A network consisting of two inductors and two capacitors.
What class of amplifier is distinguished b the presence of output throughout the entire signal cycle and the input never goes into the cutoff region?
Class A
What input-amplitude parameter is most valuable in evaluating the signal=handling capability of a Class A amplifier?
Peak voltage
How can a single-sideband phone signal be generated?
By using a balanced modulator followed by a filter.
What is an L-network?
A network consisting of an inductor and a capacitor.
What will occur when a non-linear amplifier is used with a single-sideband phone transmitter?
Distortion.
What class of amplifier is characterized by conduction for 180 degrees of the input wave?
Class B
What is the total bandwidth of an FM phone transmission having a 5 kHz deviation and a 3 kHz modulating frequency?
16 kHz.
Which class of amplifier provides the highest efficiency?
Class C
The class C amplifier output is present for what portion of the input cycle?
Less than 180 degrees.
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?
3
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?
100 watts.
What class of amplifier is distinguished by the presence of output throughput the entire signal cycle and the input never goes into the cutoff region?
Class A
What class of amplifier is characterized by conduction for 180 degrees of the input wave?
Class B
What is the modulation index of a FM phone transmitter producing a maximum carrier dviation of 6 kHz when modulated with a 2 kHz modulating frequency?
3
Which three network types are commonly used to match an amplifying device to a transmission line?
L network, pi network and pi-L network.
To produce a single-sideband suppressed carrier transmission it is necessary to ______the carrier and to ______the unwanted sideband.
Cancel, filter.
What is a balanced modulator?
A modulator that produces a double sideband, suppressed carrier signal.
What is the distinguishing feature of a Class A amplifier?
Output for the entire 360 degrees of the signal cycle.
What is the distinguishing feature of a Class A amplfier?
Output for the entire 360 degrees of the signal cycle.
What is the modulation index of an FMphone transmitter producing a maximum carrier deviation of 6 kHz when modulated with a 2 kHz modulating frequency?
3
What is a pi-L network?
A network consisting of two inductors and two capacitors.
What is the approximate ratio of peak envelope power to average power during normal voice modulation peak in a single-sideband phone signal?
2.5 to 1.
What would be the voltage across a 50-ohm dummy load dissipating 1,200 watts?
245 volts (sq rt of 1200x 50)
The class AB amplifier output is present for what portion of the input cycle?
More than 180 but less than 360 degrees.
How can a single sideband phone signal be generated?
By using a balanced modulator followed by a filter.
Which network provides the greatest harmonic suppression?
Pi-L network
In a single-sideband phone signal, what determines the PEP-to-average power ratio?
The speech characteristics.
What class of amplifier is distinguished by the bias being set well beyond cutoff?
Class C
What class of amplifier is characterized by conduction for 180 degrees of the input wave?
Class B
What is a balanced modulator?
A modulator that produces a double sideband, suppressed carrier signal.
What is the resonant frequency in an electrical circuit?
The frequency at which capacitive reactance equals inductive reactance.
What is the approximate DC input power to a Class AB RF power amplifier stage in an unmodulated carrier transmitter when PEP output power is 500 watts?
1000 watts
How does the modulation index of a phase-modulated emission vary with RF carrier frequency?
It does not depend on the RF carrier frequency.
A transformer primary of 2250 turns connected to 120 VAC will develop what voltage across a 500-turn secondary?
26.7 volts (500/2250 times 120)
A switching electronic voltage regulator:
Switches the control device on or off, with the duty cycle proportional to the line or load conditions
What are the three terminals of a TRIAC?
Gate, anode 1, and anode 2.
What is the principal characteristic of a tunnel diode?
Negative resistance region
What is the meaning of the term “alpha” with regard to bipolar transistors? The change of:
Collector current with respect to emitter current.
A capacitor is sometimes placed in series with the primary of a power transformer to:
Improve the power factor.
A three-terminal regulator:
Contains a voltage reference, error amplifier, sensing resistors and transistors, and a pass element.
How might two similar SCRs be connectors to safely distribute the power load of a circuit?
In parallel, reverse polarity
What is one common use for PIN diodes?
RF switch
What does it mean for a transistor to be fully saturated?
The collector current is at its maximum value.
In a linear electronic voltage reguator
The conduction of a control element is varied in direct proportion to the line voltage or load current.
What special type of diode is capable of both amplification and oscillation?
Tunnel diodes.
What are the three terminals of a bipolar transistor?
Base, collector and emitter.
What is the range of voltage ratings available in Zener diodes?
2.4 volts to 200 volts and above.
What is the transistor called that is fabricated as two complementary SCRs in parallel with a common gate terminal?
TRIAC.
A capacitor is sometimes placed in series with the primary of a power transformer to:
Improve the power factor.
In a linear electronic voltage regulator
The conduction of a control element is varied in direct proportion to the line voltage or load current.
A capacitor is sometimes placed in series with the primary of a power transformer to:
Improve the power factor.
In a linear voltage regulator
The conduction of a control element is varied in direct proportion to the line volage or load current.
In a regulated power supply, what type of component will most likely be used to establish a reference voltage?
Zener diode
Which of the following devices acts as two SCRs connected back to back, bu facing in opposite directions and sharing a common gate?
TRIAC
Structurally, what are the two main categories of semiconductor diodes?
Junction and point contact,
A tree-terminal regulator
Contains a voltage reference, error amplifier, sensing resistors and transistors, and a pass element.
What is the term “beta”with regard to bipolar transistors? The change of:
Collector current with respect to base current.
A power transformer has a primary winding of 200 turns of #24 wire and a secondary winding consisting of 500 turns of the same wire. When 20 volts are applied to the primary winding, the expected secondary voltage will be:
50 volts
What are the three terminals of an SCR?
Anode, cathode, and gate.
A transformer used to step up its input voltage must have:
More turns of wire on its secondary than on its primary.
What is the range of voltage ratings available in Zener diodes?
2.4 volts to 200 volts and above.
What circuit might contain an SCR?
A light-dimming circuit.
The beta cutoff frequency of a bipolar transistor is the frequency at which:
Emitter current gain has decreased to 0.707 of maximum.
In rectangular coordinates, what is the impedance of a network composed of a 10-microhenry inductor in series with a 40-ohm resistor, at 500 MHz?
40+j31400
Using the polar coordinate system, what visual representation would you get of a voltage in a sine wave circuit?
The plot shows the magnitude and phase angle.
A 1-watt, 10-volt Zener diode with the following characteristics: Imin.=5mA; Imax = 95 mA; and Z= 8 ohms, is to be used as part of a voltage regulator in a 20-V power supply. Approximately what size current-limiting resistor would be used to set its bias to the midpoint of its operating range?
200 ohms
What happens to the conductivity of photoconductive material when light shines on it?
It increases
In figure 3C5, the 1 microfarad capacitor is connected to a potentiometer that is used to:
Adjust tone.
What is the impedance of a network composed of a 0.1-microhenry inductor in series with a 20-ohm resistor, at 30 MHz? Specify your answer in rectangular coordinates.
20+j19
In polar coordinates, what is the impedance of a network composed of a 300-ohm-reactance capacitor, a 600-ohm-reactance inductor, and a 400-ohm resistor, all connected in series?
500 ohms, /37 degrees
What does the photoconductive effect in crystalline solids produce a noticeable change in?
The resistance of the solid.
In rectangular coordinates, what is the impedance of a network composed of a 0.01-microfarad capacitor in parallel with a 300-ohm resistor, at 50 kHz?
159-j150
What is the description of an optocoupler?
An LED and a photosensitive device.
In Figure 3C5, which capacitor (labeled 1 through 4) is being used as a bypass capacitor?
3
In rectangular coordinates, what is the impedance of a network composed of a 0.1-microhenry inductor in series with a 30-ohm resistor, at 5 MHz?
30+j3
In polar coordinates, what is the impedance of a network comprised of a 400-ohm-reactance inductor in parallel with a 300-ohm resistor?
240 ohms, /-36.9 degrees
What is the conductance (G) of a circuit if 6 amperes of current flows when 12 volts DC is applied?
.50 Siemens (mhos).
What is the photoconductive effect?
The increased conductivity of an illuminated semiconductor junction
In Figure 3C4, if a small variable capacitor were installed in place of the dashed line, it would?
Decrease parasitic oscillations.
In polar coordinates, what is the impedance of a network composed of a 100-ohm-reactance inductor in series with a 100-ohm resistor?
141 ohms,/45 degrees
What turns ratio does a transformer need in order to match a source impedance of 500 ohms to a load of 10 ohms?
7.1 to 1.
What is the purpose of a coupling capacitor?
It blocks direct current and passes alternating current.
Given a power supply with a no load voltage of 12 volts and a full load voltage of 10 volts, what is the percentage of voltage regulation?
20%
What happens to the conductivity of a photosensitive semiconductor junction when it is illuminated/
The junction resistance decreases.
What is the magnitude of the impedance of a series AC circuit having a resistance of 6 ohms, an inductive reactance of 17 ohms, and zero capacitive reactance?
18 ohms
What does the photoconductive effect in crystalline solids produce a noticeable change in?
The resistance of the solid.
What conditions exist when a transistor is operating in saturation?
The base-emitter junction and collector-base junction are both forward biased.
What determines the visible color radiated by an LED junction?
The materials used to construct the device.
What describes a diode junction that is forward biased?
It is a low impedance.
What is the approximate magnitude f a series R-L-C circuit at resonance?
Approximately equal to the circuit resistance.
Which of the following op-amp circuits is operated open-loop?
Comparator.
A common based amplifier has:
More voltage gain than common emitter or common collector.
An electrical relay is a:
Remotely controlled switching device.
How could voltage be greater across reactances in series than the applied voltage?
Resonance.
Where is the external feedback network connected to control the gain of a closed-loop op-amp circuit?
From output to the inverting input.
When an NPN transistor is operating as a Class A amplifier, the base-emitter junction:
Is forward biased and the collector-base junction is reverse biased.
What would be the maximum current to safely illuminate a LED?
20 mA
Why are special precautions necessary in handling FET and CMOS devices?
They are susceptible to damage from static charges
What is the characteristic of the current flow within the parallel elements in a parallel R-L-C circuit at resonance?
Maximum
What is the main advantage of using an op-am audio filter over a passive LC audio filter?
Op-amps exhibit gain rather than insertion loss.
When an NPN transistor is operating as a Class A amplifier, the base-emitter junction:
Is forward biased and the collector-base junction is reverse biased.
In which oscillator circuit would you find a quartz crystal?
Pierce
What is the characteristic of the current flow in a series R-L-C circuit at resonance?
Maximum.
What are the characteristics of an inverting operational amplifier (op-amp) circuit?
It has input and output signals 180 degrees out of phase.
What conditions exists when a transistor is operating in saturation?
The base-emitter junction and collector-base junction are both forward biased.
What describes a diode junction that is forward biased?
It is a low impedance.
What is the approximate magnitude of the impedance of a series R-L-C circuit at resonance?
Approximately equal to the circuit resistance
In an op-amp oscillator circuit shown in Figure 3D6, what would be the most noticeable effect if the capacitance of C were suddenly doubled?
Frequency would be lower.
A common base amplifier has:
More voltage gain than common emitter or common collector.
An LED facing a photodiode in a light-tight enclosure is commonly known as a/an:
Optoisolator.
Where is the external feedback network connected to control the gain of a closed-loop op-amp circuit?
From output to the inverting input.
For current to flow in an NPN silicon transistor’s emitter-collector junction, the base must be:
At least 0.7 volts positive with respect to the emitter.
What circuit component must be connected in series to protect an LED?
Series resistor.
An emitter-follower amplifier has:
More current gain than common emitter or common base.
What type of bias is required by the application of a voltage. for an LED to produce luminescence?
Forward bias.
What is the piezoelectric effect?
Mechanical vibration of a crystal
What is the main advantage of using an op-amp audio filter over a passive LC audio filter?
Op-amps exhibit gain rather than insertion loss.
What do the initials CMOS stand for?
Complementary metal-oxide semiconductor.
An emitter-follower amplifier has:
More current gain than common emitter or common base.
What is the definition of a phase-locked loop (PLL) circuit?
A servo loop consisting of a phase detector, a low-pass filter and voltage-controlled oscillator.
With a pure AC signal input to the circuit shown in Figure 3D11, what output wave form would you expect to see on an oscilloscope display?
2
What is the common power supply voltage for TTL series integrated circuits?
5 volts.
What is characteristic of a NAND gate?
Produces a logic “0” at its output only when all inputs are logic “1”.
Given the input levels shown in Figure 3E14 and assuming positive logic devices, what would the output be?
A is low, B is high and C is high.
A circuit that compares the output of a voltage-controlled oscillator (VCO) to a frequency standard and produces an error voltage that is then used to adjust the capacitance of a varactor diode used to control frequency in that same VCO is called what?
Phase-locked loop.
Given the combined DC input voltages, what would the output voltage be in the circuit shown in Figure 3D7?
-5.5 V
What is the voltage range considered to be valid logic low input in a TTL device operating at 5 volts?
Zero to 0.8 volts.
For the logic input levels given in Figure 3E13, what are the logic levels of test points A, B and C in this circuit? (Assume positive logic.)
A is high, B is high and C is high.
What spectral impurity components might be generated by a phase-locked-loop synthesizer?
Broadband noise.
Which of the following logic gates will provide an active high out when both inputs are active high?
AND
RF input to a mixer is 200 MHz and the local oscillator frequency is 150 MHz. What output would you expect to see at the IF output prior to any filtering?
50, 150, 200 and 300 MHz.
In Figure 3D9, determine if there is a problem with this regulated power supply and identify the problem.
There is no problem with the circuit.
TTL inputs left open develop what logic state?
A high-logic state.
What is characteristic of an OR gate?
Produces a logic “1” at its output if any input is logic “1”.
What is a truth table?
A list of input combinations and their corresponding outputs that characterizes a digital device’s function.
In Figure 3D10 with a square wave input what would be the output?
3
What do the initials TTL stand for?
Transistor-transistor logic.
What is the characteristic of a NOT gate?
Produces a logic “0” at its output when the input is logic “1” and vice versa.
What frequency synthesizer circuit uses a phase comparator, look-up table, digital-to-analog converter, and a low-pass antialias filter?
A direct digital synthesizer.
What characteristic of an AND gate?
Produces a logic “1” at its output only if all inputs are logic “1”.
In a negative-logic circuit, what level is used to represent a logic 0?
High level.
