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SITOR-ARQ is a common mode of data communications in the maritime service. It is a system based on transmission bursts and acknowledgements. What is the baud, and interval between the burst transmissions:
Weather information is commonly sent by radio in map form by one-way facsimile transmission. Two common parameters which must be set by the receiving station are:
Lines-per-inch (LPI), and primary scan direction (PSD) (0% chose this)
Frequency shift (FS), and phase response pattern (PRP) (0% chose this)
Black-mode signal (BMS), and frequency jitter tolerance (FJT) (0% chose this)
Index of cooperation (IOC), and revolutions per minute (RPM) (0% chose this)
2182 kHz is the international radiotelephone distress frequency. It is also used for a calling channel. The authorized mode of emission is H3E (single-sideband full carrier). A3E (double-sideband full carrier) is only authorized for equipment:
Solely intended for distress and safety communications (0% chose this)
Built and sold after the GMDSS implementation date (0% chose this)
Built and sold before the GMDSS implementation date (0% chose this)
Solely intended for ship-to-shore public correspondence (0% chose this)
Ship's power is generated as 3-phase and is ungrounded. On a delta-wound transformer with 120 VAC line-to-line secondary, what is the voltmeter reading from line to ground:
Approx 67 volts for a normal balanced system with no faults (0% chose this)
0 VAC for a system with that phase faulted to ground (0% chose this)
120 VAC when another phase is faulted to ground (0% chose this)
When passing through areas of static charge, high voltages can accumulate on antennas which are insulated from ground. What protects a connected receiver from damage?
Lightning arresters and suppressors (0% chose this)
Protection diodes on receiver input (0% chose this)
Capacitive coupling and static dissipative circuits (0% chose this)
Vertical shipboard antennas for use in the MF band (410-525 kHz) are often fitted with top-hat loading sections. What is the purpose of these structures?
Provides aerodynamic compensation for stress during high winds (0% chose this)
Permits a physically short antenna to appear electrically longer (0% chose this)
Improves the near-field radiated pattern at the expense of the far-field pattern (0% chose this)
Prevents salt build-up on antennas from shunting RF energy to ground (0% chose this)
Modern reserve transmitters are solid-state designs and transmit using only A2 modulation. When measuring transmitter center frequency, what precaution must be taken:
Antenna must be grounded to suppress spurious side-lobes (0% chose this)
Modulation must be reduced to zero to eliminate sidebands (0% chose this)
Voltage to the PA must be kept at half-value (0% chose this)
Antenna current must be reduced to about 2.5 uA (0% chose this)
The property of a conductor or coil which causes a voltage to be developed across its terminals when the number of magnetic lines of force in the circuit or coil is changed is:
The current through two resistors in series is 3 A. Resistance #1 is 50 ohms, resistance #2 drops 50 V across its terminals. What is the total voltage?
An 18 ohm and a 15 ohm resistor are connected in parallel; a 36 ohm resistor is connected in series with this combination; a 22 ohm resistor is connected in parallel with this total combination. The total current is 5 A. What current is flowing in the 15 ohm resistor?
If L and C in a parallel resonant circuit resonants at 1000 kHz are so varied that their product remains constant, what will be the resulting resonant frequency?
If there is no resistance in either leg of a circuit with an inductance of 5 henrys in parallel with a capacitance of 1 microfarad, what is the equivalent impedance of the parallel network circuit?
Theoretical gain of a tube. The ratio of a small change in plate voltage to give a certain small change in plate current to a change in grid which would cause the same current:
The maximum negative anode voltage with respect to the cathode. It equals the DC voltage at the input to the plus the peak AC voltage applied during the nonconducting portion of the cycle of operation of the tube:
What is the primary purpose of the suppressor grid of a pentode?
Is highly negative with respect to the plate and returns secondary emission to the plate, increasing the permissible gain and the tube efficiency (0% chose this)
Reduces interelectrode capacitance between control grid and plate making plate efficiency about 10% greater than a triode (0% chose this)
Characteristics of a vacuum tube operating as a class A amplifier:
Low plate circuit efficiency, about 25%; practically no grid driving power; plate current flowing for 360 degrees of each cycle; practically no distortion of the output waveshape (0% chose this)
Plate circuit efficiency, about 50-60%; plate current flows slightly more than 180 degrees of each cycle, medium power output (0% chose this)
High efficiency, up to 80%; plate current drawn in bursts; great distortion of output waveshape (0% chose this)
Characteristics of a vacuum tube operating as a class B amplifier:
Low plate circuit efficiency, about 25%; practically no grid driving power; plate current flowing for 360 degrees of each cycle; practically no distortion of the output waveshape (0% chose this)
Plate circuit efficiency, about 50-60%; plate current flows slightly more than 180 degrees of each cycle, medium power output (0% chose this)
High efficiency, up to 80%; plate current drawn in bursts; great distortion of output waveshape (0% chose this)
Characteristics of a vacuum tube operating as a Class C amplifier:
Low plate circuit efficiency, about 25%; practically no grid driving power; plate current flowing for 360 degrees of each cycle; practically no distortion of the output waveshape (0% chose this)
Plate circuit efficiency, about 50-60%; plate current flows slightly more than 180 degrees of each cycle; medium power output (0% chose this)
High plate circuit efficiency, up to 80%; plate current drawn in bursts; great distortion of output waveshape (0% chose this)
Depends on the ability of the grid leak and capacitor to follow the average grid current variations which are directly proportioned to the modulation envelope (0% chose this)
Depends on second harmonic distortion (0% chose this)
What is the maximum permissible RMS value of audio voltage which can be applied to the grid of a Class A audio amplifier which has a grid bias of 10 V?
What is the DC plate voltage of a resistance-coupled amplifier state with a plate-supply voltage of 260 V, a plate current of 1 mA, and a plate load resistance of 100,000 ohms?
A vacuum tube operated Class C audio amplifier is not feasible, either in single or push-pull:
Since the plate current only flows 120 degrees, even in push-pull, only 2/3 of the cycle is reproduced and the resultant distortion would be unacceptable for audio (0% chose this)
Tank circuits, which replace the missing portions of the cycle, can't be used in an audio amplifier because they only operate on one frequency (0% chose this)
A battery with a terminal voltage of 12.5 V is to be trickle-charged at a 0.5 A rate. What resistance should be connected in series with the battery to charge from a 110 V line?
A discharged storage battery of 3 cells has an open circuit voltage of 1.8 V per cell and an internal resistance of 0.1 ohm per cell. What voltage is needed to give an initial charging rate of 10 A?
What capacity in amperes of storage battery is required to operate a 50 W emergency transmitter for 6 hr.? Assume a continuous transmitter load of 70% of the key-locked demand of 40 A, and an emergency light load of 1.5 A.
A battery rated greater than 177 amperhours (0% chose this)
A battery rated at least 177 amperhours (0% chose this)
What is the maximum allowable secondary voltage of a transformer used as a center-tapped full-wave rectifier with tubes having a peak inverse voltage rating of 10,000 V?
The power transformer and rectifier of a radio receiver are designed to supply a plate voltage of 250 V when operating from a 110 V 60 Hz supply, if the transformer is connected to 110 VDC what will happen?
The secondary would burn out (0% chose this)
The primary would overheat and burn out (0% chose this)
The circuit breaker would open to protect the circuit (0% chose this)
When the first speech-amplifier of a transmitter were overexcited, but the modulation capabilities were not exceeded what would be the effect on the output?
The waveform would be sawtooth causing undermodulation (0% chose this)
The waveform would be square wave creating cross-modulation (0% chose this)
Given the following: (1) audio power for 100% modulation equals 50% of DC input power to RF modulated amplifier, (2) load presented to the modulated tube consists of the DC plate impedance of the modulated amplifier, (3) constant grid excitation voltage, very lot distortion, what type of modulation?
What value of sinusoidal audio power is required to insure 100% modulation when the DC plate input to a modulated Class C amplifier has an efficiency of 60 % , and is 200 W?
What would be the antenna current when a transmitter has an antenna current of 8 amp, under A -1, even if it is 100% modulated by sinusoidal modulation?
9.8 amp (0% chose this)
The antenna current will increase by 22.5% (0% chose this)
Given a vacuum tube of the following characteristics: plate voltage 1000 V, plate current 127 ma, filament current 5.4 amp, mutual conductance 8000 microvolts, and amplification factor of 25. What is the correct volume of negative grid bias for Class B amplifier?
A transmitter has a master-oscillator, intermediate amplifier, and final amplifier. In what order should the circuit be adjusted in putting the transmitter in operation?
Master-oscillator, intermediate amplifier, final amplifier, antenna circuit (0% chose this)
Antenna circuit, master-oscillator, intermediate amplifier, final amplifier (0% chose this)
Final amplifier, antenna circuit, master-oscillator, intermediate amplifier (0% chose this)
Master-oscillator, intermediate amplifier, antenna circuit, final amplifier (0% chose this)
In a self-biased RF amplifier stage: plate voltage is 1250 V, plate current 150 ma, grid current 15 ma, grid-leak resistance of 4000 ohms, what is the operating grid bias?
The plate current of the final RF amplifier in a transmitter increases and radiation decreases, if the antenna circuit is in good order, what could be the cause?
Neutralization may have been upset (0% chose this)
The plate circuit may have been detuned, bias may have been lost (0% chose this)
Grid excitation may have decreased, there may be a faulty tube, or there may be parasitic oscillations (0% chose this)
A master-oscillator power-amplifier transmitter has been operating normally. The antenna ammeter suddenly reads zero. All filaments are burning and plate and grid meters read normal currents and voltages. What happened?
A shorted antenna ammeter (0% chose this)
An open connection in the remote reading meter (0% chose this)
In a radiotelegraph transmitter with a DC generator plate voltage source, an AC generator filament supply, and grid-bias keying, what could be wrong when the emission continues with the key contacts open?
Insufficient grid blocking bias is applied to the grid when the key is open (0% chose this)
A station has an assigned frequency of 8000 kHz and a frequency tolerance of plus or minus 0.04%. The oscillator operates at 1/8th of the input. What is the maximum permitted deviation of the oscillation frequency in Hz, which will not exceed the tolerance?
A transmitter operating on 5000 kHz uses a 1000 kHz crystal with a tempered coefficient of - 4 Hz/MHz/0 degrees centigrade. What is the change in the output frequency of the transmitter if the temperature increases 6 degrees centigrade?
Omni-directional pattern which is maximum in the directions of the plane of the loop, and minimum in the directions broadside to the loop (0% chose this)
Non-directional with regard to compass points (0% chose this)
Has minimum radiation or reception in the direction of the ends of the antenna (0% chose this)
Has a bi-directional pattern which is maximum in the direction of the plane of the loop, and minimum in the directions broadside to the loop (0% chose this)
Communication at frequencies in the order of 15 kHz are usually accomplished by ground waves, and require generation of ____ power outputs for reliable and continuous operation:
On an average yearly basis the received Trans-Atlantic signals increased in strength in proportion to the degree of ____. Made on the basis of the 11 year cycle:
A superheterodyne receiver may not successfully be used for reception of frequencies very near the IF frequency:
Because those near frequencies would pass directly through the IF amplifier and not be greatly affected by the tuning of the RF or oscillator stages (0% chose this)
Because those near frequencies would not pass directly through the IF amplifier (0% chose this)
Because those near frequencies would be greatly affected by the tuning of the RF or oscillator stages (0% chose this)
An incoming RF carrier is coupled into the tuned-grid circuit and applied to the grid (0% chose this)
It is then amplified in the usual manner. A controllable portion of the plate signal is coupled back into the grid circuit (0% chose this)
The coupled back signal is in phase with the original signal thus amplifying it and providing a greater output signal in the plate circuit (0% chose this)
If signals are heard with headphones in the detector plate circuit of a receiver, but none are heard with headphones in the first AF stage plate circuit, what might be the cause?
Open winding of the coupling transformer (0% chose this)
Feeding back into the control grids of the IF and RF amplifiers a negative DC bias which is proportioned to the average magnitude of the received carrier wave accomplished:
The center-tap connection in a filament supply transformer:
Prevents hum voltages from modulating the normal signal (0% chose this)
The voltage change on one side of the filament will be effectively cancelled out by an equal and opposite voltage change at the other side of the filament, yielding no hum (0% chose this)
Four consecutive dashes from C.5 to D.5 seconds, separated by spaces ranging from 0.1 to 0.5 seconds. The combination may not exceed 5 seconds (0% chose this)
Three consecutive dashes from D.5 to 5.5 seconds, separated by spaces ranging from 0.5 to A.0 seconds (0% chose this)
Five consecutive dashes from B.5-3.5 seconds, separated by spaces ranging from 0.01 to 0.25 seconds. The combination may not exceed 5 seconds (0% chose this)
What is the directional reception pattern of a loop antenna?
A vertical loop antenna has a bidirectional pattern which is maximum in the directions in the plane of the loop, and minimum in the directions broadside to the loop (0% chose this)
A horizontal loop antenna is nondirectional along the plane of the loop. It has minimum radiation or reception vertically (0% chose this)
A horizontal loop antenna is directional along the plane of the loop antenna (0% chose this)
During daytime hours, approximately what is the maximum distance in nautical miles from LORAN transmitting stations from which LORAN lines of position can be determined?
About 700 miles (0% chose this)
During nighttime hours, the maximum distance is increased to about 1800 miles by the use of sky waves (0% chose this)
In all cases other than those in which the transmitter output must be maintained at a fixed value, what amount of power should be employed for routine communications?
The maximum amount of power to maintain communications (0% chose this)
The transmitter must be maintained at a fixed value (0% chose this)
The minimum amount of power necessary to ensure reliable communications (0% chose this)
Upon compulsorily equipped vessels which are required to have an accurate clock in the radio room, how frequently must this clock be adjusted and be compared with standard time?
The distress call should be made three times (0% chose this)
SOS should be called twice (0% chose this)
The distress call shall include the distress signal transmitted three times, the word DE, and the call signal of the mobile station in distress transmitted three times (0% chose this)
How frequently must the quantity of fuel in the supply tank for use with an oil or gas driven emergency generator be checked while the vessel is in the open sea?
For how long a period of continuous operation should the emergency power supply of a compulsorily equipped ship station be capable of energizing the emergency radiotelegraph installation?
Under what condition may an eligible person hold a radiotelegraph operator's license and a Marine Radio Operator permit?
When the planned telegraphy operation will occur aboard ship in international waters and another vessel is licensed for operation on the inland waterways (0% chose this)
When the commercial radio operator is legally eligible for both foreign and domestic employment (0% chose this)
No person may hold any class of radiotelegraph operator's certificate and a Marine Radio Operator Permit (0% chose this)
Commercial radiotelegraphers are required to also hold a Marine Radio Operator Permit when the operation occurs on vessels of less than 1600 gross tons (0% chose this)
How does a First Class Radiotelegraph Operator renew an unexpired license?
Renewal document indicating license serial number must be forwarded to the FCC during the last 90 days of the license term (0% chose this)
Application is made to the nearest Commercial Operator Licensing Examination Manager (COLEM) during the final six months of the license term (0% chose this)
By submitting Form 756, current license copy, and appropriate fee to the FCC during the last year of the five year license term (0% chose this)
A current Radio telegraphy Proficiency Testimonial (RPT) obtained from the ship's master must be attached to the renewal application Form 739 (0% chose this)
What examination requirements are necessary to obtain a Second Class Radiotelegraph Operator's Certificate?
Written Element 1 (radio law), Element 3 (electronic fundamentals), Element 5 (radiotelegraph operations) and sending/receiving 16/20 words per minute (0% chose this)
Telegraphy Element 1 (sending/receiving 16 code groups per minute) and Telegraphy Element 2 (16 code groups and 20 words per minute text.) (0% chose this)
Successful completion of written test Elements 1, 5 and 6 on basic radio law and operating practices plus telegraphy Elements 1 and 2 (0% chose this)
Successful completion of written test Elements 1, 3, 5 and 6 on basic radio law and operating practices plus telegraphy Elements 1 and B (0% chose this)
How does an applicant qualify for a Third Class Radiotelegraph Operator's Certificate?
By passing the appropriate written examinations and receiving by ear code groups and plain text for a period of one minute without error at the appropriate speed (0% chose this)
Applicant must send and receive radiotelegraphy at the prescribed speed and be at least 21 years old (0% chose this)
By the successful completion of radiotelegraphy Elements 1 and 2 plus written examinations on radio law, telegraphy practices and transmitter maintenance (0% chose this)
By passing a written examination on radio law, electronic fundamentals and radiotelegraph practices plus a telegraphy receiving examination (0% chose this)
When may a public coast station authorized to use high frequency narrow-band direct-printing (NB-DP) establish contact with a ship station using telegraphy?
Never. Contact may only be established using NB-DP circuits (0% chose this)
When the ship is in excess of 300 gross tons (0% chose this)
When the radio station license reflects authority for this type of operation and harmful interference is avoided (0% chose this)
When it is known that the vessel does not have a selective ringing or calling device (0% chose this)