GROL Licensing Flashcards
What is the term for the out of phase power associated with inductors and capacitors?
Reactive Power
The opposition to the creation of magnetic lines of force in a magnetic circuit is known as:
Reluctance
What is the relative dielectric constant for air?
1
How would you calculate the total capacitance of three capacitors in parallel?
Ct = C1 + C2 + C3
How does the input impedance of a field-effect transistor compare with that of a bipolar transistor?
An FET has high input impedance; a bipolar transistor has low input impedance.
By what factor must the voltage measured in an AC circuit, as indicated on the scale of an AC voltmeter, be multiplied to obtain the average voltage value?
0.9
What is a sine wave?
A wave whose amplitude at any given instant can be represented by the projection of a point on a wheel rotating at a uniform speed.
Halving the cross-sectional area of a conductor will:
Double the resistance.
Which of the following Ohms Law formulas is incorrect?
I = R/E
What is the maximum DC or RMS voltage that may be connected across a 20-watt, 2000-ohm resistor?
200 volts
Wat is the most the actual transmitter frequency could differ from a reading of 156,520,000 hertz on a frequency counter with a time base accuracy of +- 1.0 ppm?
156.52 Hz
What is the RMS value of a 340-volt peak-to-peak pure sine wave?
120 volts AC
746 watts, corresponding to the lifting of 550 pounds at the rate of one-foot-per-second, is the equivalent of how much horsepower?
One Horsepower
What is the meaning of the term “time constant of an RC circuit”? The time required to charge the capacitor in the circuit to:
23.7% of the supply voltage.
What is the time constant of a circuit having two 220-microfarad capacitors and two 1-megohm resistors all in series?
220 seconds
In rectangular coordinates, what is the impedance of a network composed of a 1.0-millihenry inductor in series with a 200-ohm resistor, at 30 kHz?
200 + j188
What is the impedance of a network composed of a 100-picofarad capacitor in parallel with a 4000-ohm resistor, at 500 KHz? Specify your answer in polar coordinates
2490 ohms, / -51.5 degrees
Given a power supply with a full load voltage of 200 volts and a regulation of 25%, what is the no load voltage?
250 volts
What is the photoconductive effect?
The increased conductivity of an illuminated semiconductor junction
In figure 3C5 , what capacitor (labeled 1 through 4) is being used as a bypass capacitor?
3
What is the ratio of he output frequency to the input frequency of a single-phase full-wave rectifier?
2:1
A switching electronic voltage regulator:
Switches the control device on or off, with the duty cycle proportional to the line or load conditions
What is the transistor called that is fabricated as two complementary SCRs in parallel with a common gate terminal?
TRIAC
What type of semiconductor diode varies its internal capacitance as the voltage applied to its terminals varies?
Varactor diode
What are the three terminals of a bipolar transistor?
Base, collector, and emitter
An emitter-follower amplifier has:
More current gain than common emitter or common base.
What circuit component must be connected in series to protect an LED?
Series resistor
What is the piezoelectric effect?
Mechanical vibration of a crystal by the application of a voltage.
What is the approximate magnitude of the impedance of a series R-L-C circuit at resonance?
Approximately equal to the circuit resistance.
What are the characteristics of an inverting operational amplifier (op-amp) circuit?
It has input and output signals 180 degrees out of phase.
What spectral impurity components might be generated by a phase-locked-loop synthesizer?
Broadband noise.
In figure 3D10 witha square wave input what would be the output?
3
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
What is a characteristic of a NAND gate?
Produces a logic “0” at its output only when all inputs are logic “1”
In a positive-logic circuit, what level is used to represent a logic 1?
High level
How many flip-flops are required to divide a signal frequency by 4?
2
What is a biostable multivibrator circuit commonly named?
flip-flop
What is the name of the random-accessed semiconductor memory IC that must be refreshed periodically to maintain reliable data storage in its memory matrix?
DRAM - Dynamic Random-Access Memory
In a microprocessor-controlled two-way radio, a “watchdog” timer:
Verifies that the microprocessor is executing the program.
What integrated circuit device converts digital signals to analog signals?
DAC
What is meant by the term noise figure of a communications receiver?
The level of noise generated in the front end and succeeding stages of a receiver.
What is the advantage of a GaAsFET preamplifier in a modern VHF radio receiver?
High gain and low noise floor
What is the oscillator stage called in a frequency synthesizer?
VCO
What are the principal frequencies that appear at the output of a mixer circuit?
The original frequencies and the sum and difference frequencies.
How should the filter bandwidth of a receiver IF section compare with the bandwidth of a received signal?
Slightly greater than the received-signal bandwidth
What is the primary purpose of the final IF amplifier stage in a receiver?
Gain.
What is an m-derived filter?
A filter that uses a trap to attenuate undesired frequencies too near cutoff for a constant-k filter.
In a CTCSS controlled FM receiver, the CTCSS tone is filtered out after the:
Discriminator but before the audio section.
What makes a Digital Coded Squelch work?
Digital Codes.
Pulse type interference to automobile radio receivers that appears to the speed of the engine can often be reduced by:
Installing resistances in series with spark plug wires.
What class of amplifier is distinguished by the bias being set well beyond cutoff?
Class C
The class B amplifier output is present for what portion of the input cycle?
180 degrees.
What is the modulation index in an FM phone signal having a maximum frequency deviation of 3000 Hz on either side of the carrier frequency when the modulating frequency is 1000 Hz?
3
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 term describes a wide-bandwidth communications system in which the RF carrier varies according to some pre-determined sequence?
Spread-spectrum communication
What is the deviation ratio for an FM phone signal having a maximum frequency deviation of plus or minus 5 kHz and accepting a maximum modulation rate of 3 kHz?
1.66
What type of signals are used to conduct an SSB two-tone test?
Two non-harmonically related audio signals that are within the modulation band pass of the transmitter.
What is an important factor in pulse-code modulation using time-division multiplex?
Synchronization of transmit and receive clock pulse rates.
What capacity in amperes does a storage battery need to be in order to operate a 50-watt transmitter for 6 hours? Assume a continuous transmitter load of 70% of the key-locked demand of 40 A, and an emergency light load of 1.5 A.
177 ampere-hours
What current will flow in a 6-volt storage battery with an internal resistance of 0.01 ohms, when a 3-watt, 6-volt lamp is connected?
0.4995 amps
What is the line current of a 7-horsepower motor operating on 120 volts at full load, a power factor of 0.8, and 95% efficient?
57.2 amps
What is meant by the term antenna bandwidth?
The frequency range over which an antenna can be expected to perform well.
An antenna radiates a primary signal of 500 watts output. If there is a 2nd harmonic output of 0.5-watt, what attenuation of the 2nd harmonic has occurred?
30 db
A vertical 1/4 wave antenna receives signals:
Equally from all horizontal directions.
Nitrogen is placed in transmission lines to:
Prevent moisture from entering the line.
What is the effective radiated power of repeater with 100 watts transmitter power output, 5 dB feedline loss, 4 dB duplexer and circulator loss, and 10 dB antenna gain.
126 watts.
The Distance Measuring Equipment (DME) measures from the aircraft to the DME ground station. This is referred to as:
The slant ranges.
Lines drawn from the VOR station in a particular magnetic direction are:
Radials
What is the frequency range of the localizer beam system used by aircraft to find the centerline of a runway during an Instrument Landing System (ILS) approach to an airport?
108.10 MHz to 111.95 MHz.
What type of encoding is used in an aircrafts mode C transponder transmission to a ground station of the Air Traffic Control RADAR Beacon System (ATCRBS)?
Pulse position modulation.
What type of antenna is attached to an aircrafts Mode C transponder installation and used to receive 1030 MHz interrogation signals from the Air Traffic Control Radar Beacon System (ATCRBS)?
An L-band monopole blade-type omnidirectional antenna.
What is the function of a commercial aircrafts SELCAL installation? SELCAL is a type of aircraft communications ______.
System where a ground-based transmitter can call a selected aircraft or group of aircraft without the flight crew monitoring the ground-station frequency.
What is the purpose of a shunt resistor with an ammeter?
It is used to increase the ampere indicating range of the ammeter.
Which of the following frequency standards is used as a time base standard by field technicians?
Rubidium Standard
How does a spectrum analyzer differ from conventional oscilloscope?
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.
What does the horizontal axis of a spectrum analyzer display?
Frequency
What is the maximum FM deviation for voice operation of a normal wideband channel on VHF and UHF?
5.0 kHz
Which of the following is preferred method of cleaning solder from a plated-through circuit-board holes?
Use a vacuum device.
What tolerance off of plumb should a single base station radio rack be installed?
Just inside the bubble on a level.
The tachometer of a buildings elevator circuit experiences interference caused by the radio system nearby. What is a common potential “fix” for the problems?
Add a .01 uF capacitor across the motor/tachometer leads.
A TDMA radio uses what to carry the multiple conversations sequentially?
Separate time slots.
The International Organization for Standardization has developed a seven-level reference model for a packet-radio communications structure. The ______ level arranges the bits into frames and controls data flow.
Link Layer
What is a SDR?
Software Defined Radio.
Maximum allowable frequency deviation for VHF marine radios is:
+/- 5 kHz
What type of wire connects an SSB automatic tuner to an insulated backstay?
GTO - 15 high-voltage cable.
Which of the following statements concerning satellite EPIRBs is true?
Once activated, these EPIRBs transmit a signal for use in identifying the vessel and for determining the position of the beacon.
What determines whether a NAVTEX receiver does not print a particular type of message content?
The subject indicator matches that programmed for rejection by the operator.
How should shielding be grounded on an NMEA data line?
Terminated to ground at the talker and unterminated at the listener.
What is the normal range of pulse repetition rates?
500 - 2000 pops.
What is the purpose of a synchro transmitter and receiver?
Transmits the angular position of the antenna to the indicator unit.
When a RADAR is being operated on the 6-mile range setting what is the most appropriate pulse width and pulse repetition rate?
0.25 PW and 1000 pops
To couple energy into and out of a waveguide use:
A thin piece of wire as an antenna.
Prior to testing an y RADAR system, the operator should first:
Assure no personnel are in front of the antenna.
What services are provided by the Iridium system?
Digital voice and Data at 2.4 kbps.
Which of the following describes the INMARSAT Satellite System?
AOR-E at 15.5 W, AOR-W at 54 W, POR at 178 E, and IOR at 64.5 E.
What is the best description for the INMARSAT-C system?
It is a store-and-forward system that provides routine and distress communications.
How many satellites must be received to provide complete position and time?
4
Sites having multiple transmitting antennas must include antennas with more than ____% of the maximum permissible power density exposure limit when evaluating RF site exposure.
5
What is the purpose of not putting sharp corners on the ground leads within a building?
Lighting will jump off of the ground lead because it is not able to make sharp bends.
