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177 Cards in this Set
- Front
- Back
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What is the resistor color-code form 0-9?
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Black, brown, red , orange, yellow, green, blue, violet, gray, and white.
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What are the resistor % tolerances that correspond to Gold, Silver, and "No Color" respectively?
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+- 5%, +-10%, +-20%
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What are 4 basic types of materials used in the construction of potentiometers?
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Carbon, Cermet, Conductive plastice, and Wire-wound
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What is the critical resistance of a resistor?
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the value of resistance where the maximum voltage and power rating occure simultaneously.
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What is the resolution of a potentiometer?
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the smallest change in resistance that can be realized as the wiper arm is rotated.
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What are the 4 basic types of materials used to manufacture fixed resistors?
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Carbon composition, Metal film, and Wire-wound
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What are the basic units of measurement for capacitance?
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the farad (F), microfarad (uF), and the picofarad (pF)
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When will 1 farad store 1 coulomb of charge (energy)?
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When a potential of 1 volt is applied across the capacitor plates.
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How is capacitance defined?
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The ability of a circuit to store electrical energy and oppose a change in voltage.
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What is a capacitor?
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A device used in an electrical circuit to store energy within an electrostatic field.
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What elements make up a capacitor?
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Two pieces of conducting material called plates (separated, with different polarities) and a dielectric (insulating material) that prevents current from flowing from plate to plate, through the capacitor.
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What happens when the dielectric of a capacitor breaks down?
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the capacitor becomes a conductor because current is allowed to flow from plate to plate.
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What is the dielectric strength of a capacitor?
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the ability of a capacitor's dielectric to hold a charge without breaking down.
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What is the dielectric constant of a capacitor?
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A measure of the ability of a capacitor's dielectric to store a charge.
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Why cant the charge in a capacitor be stored indefinitely?
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Because of the minute direct current that flows in a capacitor at a specific direct voltage due to the presence of a few carriers of charge in the dieletric know as DC Leakage.
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What are the 7 broad applications of capacitors?
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Blocking DC, coupling, bypassing, filtering, tuning, generation of non-sinusoidal waveforms
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List the following dielectric materials in order of their dielectric constant (low-high): mylar, tantalum, vacuum, ceramic, air, mica, and paper.
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1. vacuum 2. air 3. mylar 4. paper 5.Mica 6.tantalum 7.ceramic
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What characteristics of a capacitor determined the maximum voltage that can be impressed across a capacitor without causing irreparable damage?
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The dielectric used and the separation of the plates.
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How is capacitive reactance defined?
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the opposotion a capacitor offers to AC that decreases with an increase in frequency or an increase in capacitance.
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What are the 2 main classes of capacitors?
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Fixed and variable
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What is the difference between a fixed and a variable capacitor?
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A fixed capacitor is constructed to have a fixed or constant value of capacitance while a variable capacitor allows the capacitance to be varied or adjusted.
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What are the three factors that affect capacitance?
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Area of the plate surface, spacing between the plates, and the dielectric constant.
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How is the working voltage of a capacitor defined?
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The maximum voltage that can be steadly applied to the capacitor without the capacitor breaking down (shorting).
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What two factors affest the working voltage of a capacitor?
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the dielectric constant and the thickness of the dielectric.
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What two power losses are associated with capacitors?
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Dielectric leakage and dielectric hysteresis.
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What causes dielectric leakage in capacitors?
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the leakage current through the resistance in the dielectric. Although this resistance is extramely high, small amount of current does flow.
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How is dielectric hysteresis in a capacitor defined?
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An effect in dielectric material simular to the hysteresis found in magnetic material.
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How is inductance defined?
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The charateristics of an electrical circuit that opposes a change in current.
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How can the property of inductance be increased?
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by forming the conductor into a coil.
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What two materials can be used as the core of a coil?
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Soft iron or air
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What physical factors of a coil have the greatest effect on inductance?
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the number of turns, coild diameter, length, type of core, and number of coil winding layers.
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What are the units of measurement for insuctance?
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In Henrys (H), millihenerys (mH), and in microhenerys (UH)
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What are the three types of power loss in an inductor?
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Copper loss, hystersis loss, and eddy-current loss
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What causes hysteresis loss in an inductor?
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Power consumed in reversing the magnetic field of the core each time the current changes direction.
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What causes eddy-current loss in an inductor?
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Core heating caused by circulating currents induced in an iron core by the magnetic field of the core.
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When does mutual inductance take place between two inductors?
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When they are located so that the flux lines of force from one coil links with the flux lines of force from the other coil.
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What determines the amount of mutual inductance of two coils?
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The relative position of the axis of the two coils, the permeability of the cores, their physical dimentions, number of turns, and the distance between coils.
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What is the phase relationship between current and voltage in an ideal inductor?
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Voltage leads current by 90 degrees in an inductor.
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What is the phase realationship between current and voltage in an ideal capacitor?
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current leads voltage by 90 degrees in an capacitor.
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What are Eddy curents?
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Currents that are set up in magnetic core by induced voltages because of changing magnetic fieldds known as Eddy currents. They are currents in the core producing heat.
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What could result by operating a transformer at a frequency considerably lower than it rated frequency?
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It could cause the primary current to rise excessively, even to a value far in excess of the full-load primary current which would then burn out the winding.
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How could a transformer be safely operated at a considerably lower rated frequency with normal flux?
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By decreasing the applied voltage in direct proportion to the decrease in frequency.
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What are copper losses?
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The power lost in the primary and secondary windings of the transformer due to ohmic resistance of the windings.
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How is alternating current (AC) defined?
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Current that is constanly changing in amplitude and direction.
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What are the advantages of using AC over DC?
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AC can be generated at a high levels, transmitted over long distances, and stepped down by the use of transformers.
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What is an AC voltage waveform?
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A graphical picture of changes in voltage or current values over a period of time.
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What happens to a conductor in a magnetic field when either the field or the conductor moves?
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Electromagnetic induction takes place. A voltage is induced into the conductor.
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How is a sine wave produced?
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A loop of wire is rotated in a magnetic field producing a voltage which constantly changes in amplitute and direction.
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What two alternations make up a sine wave?
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Positive and Negative.
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What is a cycle of AC?
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A 360 degree revolution of a conductor through a magnetic field.
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How is the frequency of an AC waveform defined?
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the number of cycles of AC per second, measured in Hertz.
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What is 1 Hertz equal to?
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One cycle in one second.
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How is the period of an AC waveform defined?
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The time required to complete one cycle of a waveform.
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How is the wavelength of an AC waveform defined?
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The distance covered during the time it takes a waveform to complete one full cycle.
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How is the wavelength of an AC waveform measured?
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From a point on a given waveform to the corresponding point on the next waveform.
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What is peak value of a sine wave?
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the maximum value reached during on alteration.
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What is the peak-to peak value of a sine wave?
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The maximim voltage reached during the positive alteration to the maximum value reached during the negative alteration
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How is the instantaneous value of a sine wave defined?
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the value of voltage or current at one particulaar instant of time.
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What is the average value of a periodic waveform?
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it is equal to its net area one cycle divided by its period.
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What must take place for two sine waves to be in phase?
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They must gothroughtheir minimum and maximum points at the same time and in the same direction.
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What must take place for two sine waves to be out of phase?
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They must go through their minimum and minimum points at different times.
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When does a sine wave tag another sine wave?
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When it reaches its minimum and maximum values some time after the other.
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What causes the inductance in an AC circuit?
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The creation or destruction of a magnetic field.
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What effect does inductance have on an AC circuit when current increases?
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Inductance tries to hold current down.
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What effedt does inductance have on an AC circuit when current decreases?
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Inductance tries to hold current up.
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What is self-inductance?
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The process by which a circuit induces an emf int itself by its own moving magnetic field.
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What effect does capacitance have on an AC circuit when the voltage is increased?
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Capacitance tries to hold voltage down.
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What effect do capacitors in parallel have on a circuit?
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The effect of capacitors in parallel is the same as incresing the plate are of a single capacitor which increases the total capacitance of the circuit.
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How is inductive reactance defined?
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The opposition an inductor offers to AC that increases with an increase in frequency or an increase in inductance.
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What determines which formula to use for computing the reacance of an AC series circuit?
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The largest inductive or capacitive value. hte smallest reactance should be subtracted from the largest reactance.
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What is the phase angle of an AC circuit?
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The number of degrees that current leads or lags voltage.
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How is true power defined in an AC circuit?
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The power dissipated across the resistance of the circuit.
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How is reactive power defined in an AC circuit?
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The power returned to the source by the reactive elements of the circuit.
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What does the superposition theorem state as applied to linear circuits for finding the response of a circuit that is energized by more than one source?
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the response of a circuit energized by a number of independent sources is equal to the sum of the responses of each source with all remaining sources set to zero.
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How is direct current (DC) defined?
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Current that flows in one direction only.
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What does a basic DC circuit consist of?
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A load, source, and a switch.
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How is the load of a basic DC circuit defined?
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Any device from which an electrical current flows and changes electrical energy into a more useful form.
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How is the source of a basic DC circuit defined?
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Any device that furnishes the electrical energy used by the load.
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Why does a capacitor in a DC circuit not allow current to flow continuously in the circuit?
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In a DC circuit, current will flow only long enough for the capacitor to charge to the source voltage.
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How is the switch of a basic DC circuit defined?
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Any device that permits control of an electrical circuit by interrupting the current delivered to the load.
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What is a schematic diagram?
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A drawing of a circuit, which uses symbols to represent components.
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How is current defined?
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The movement of electrons past a refrence point within a conductor. Measured in amperes.
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In what direction, in relation to the source, does current flow in a circuit?
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From the negative side, through the circuit load, to the positive side of the source.
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How is voltage defined?
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the force or pressure that causes current to flow within a conductor.
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How is series aiding voltage defined?
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Voltage that cause current to flow in the same sirection. The equivalent voltage is the additive within the circuit.
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How is series opposing voltage defined.
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Voltage that causes current to flow in the opposite direction.
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How is resistance defined?
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The opposition a device or material offers to the flow of current.
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What happens to the current in a circuit when resistance is increased?
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the current decreases proportionately.
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What happens to the current in a circuit when voltage is increased?
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the current increases proportionately.
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How is Ohm's law defined?
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The current in an electrical circuit is directly proportional to the applied voltage and inversely proportional to the circuit resistance.
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How is power defined?
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The rate of soing work per unit of time.
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What does the power rating of a device indicate?
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the reate at which it converts electrical energy into another form of energy.
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What are watt hours?
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The measure of the amount of power used by an electrical device.
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What is the 1st rule for series DC circuits?
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The same current flows through each part of the series.
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What is the 2nd fule for series DC circuits?
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The total resistance of a series circuit is equal to the sum of the individual resistances.
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What is the 3rd rule for series DC circuits?
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The total voltage across a series circuit is equal to the sum of the individual voltage drops.
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What is the 4th rule for series DC circuits?
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The voltage drop across a resistor in a series DC circuit is proportional to the ohmic value of the resistor.
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What is the 5th rule for series DC circuits?
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The total power in a series circuit is equal to the sum of the individual power used by each circuit component.
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What does Kirchoff's Voltage Law state?
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That the algebraic sum of voltage in a closed-circuit path is always equal to zero.
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What is an electrical refrence point?
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A point chosen in a circuit to which all other points are compared.
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How is an open circuit defined?
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A circuit in which a break exists in the complete conducting pathway.
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How is a short circuit defined?
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a circuit that had an accidental path of low resistance which passes an abnormally high amount of current.
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How is the internal resistance of a source defined?
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A decreased in terminal voltage from the source caused by the voltage drop across the natural internal resistance of the source as current flows thorugh it.
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When is high efficiency achieved in a circuit?
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when the resistance of the load is high with respects to the resistance of the source.
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When is power transfer highest is a circuit?
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When the resistance of the load equals the resistance of the source.
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How is parallel DC circuit defined?
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A circuit having more than one current path connect to a common voltage source.
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What is a turned circuit?
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A combination of inductive and capacitive reactances arranged so that the impedance of the combination changes abruptly at some specific frequency, or narrow range of frequencies.
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What term is used to describe the frequency at which the tuned circuit exhibits its sharp change in impedence?
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The resonant frequency.
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What occurs in a properly tuned inductance-capacitance circuit?
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The desired frequency is accepted with other frequencies rejected.
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What is the figure of merit, or "Q" of a coil?
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It is the reactance to resistance ration.
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In electrical wave filters, what is the effect of increasing the 'Q"?
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It provides sharper cut-off, higher attenuation ratios, and better defined resonance.
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What characteristics of an inductor affect the "Q"?
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The distributed capacitance of its winding.
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What are the effects of lowering the "Q" of a tuned circuit and how may it be accomplished?
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It broadens the frequency response. The "Q" may be decreased by putting a resistor in parallel with the coil.
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When does a parallel-tuned circuit have maximum impedance?
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At its resonant frequency.
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When does a seris-tuned circuit have minimum impedance?
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At its resonant frequency.
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How does a series-tuned circuit act above resonance?
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Inductively.
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How does a series-tuned act below resonance?
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Capacitely.
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How does a parallel-tuned circuit act below resonance?
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inductively
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How does a parallel-tuned circuit act above resonance?
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Capacitively
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What are 4 basis types of filters?
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low pass, high pass, bandpass, and band rejection.
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What type of components are used in passive filters?
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resistors, capacitors, and inductors.
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What is the difference between a passive filter and an active filter?
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Active filtrers require and external power source to operate active components such as high-gain Op amps.
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Where is the bandwidth of a filter measure at?
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Between the half-power points on the curve.
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Name 5 prominent communications modes of operation?
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Simplex, Half duplex, semi-duplex, full duplex, and broadcast.
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What are "point-to-point" communications system?
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Systems that are established to communicate over long distance trunks or links between fixed terminals.
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Of the 3 types of message traffice normally sent to the fleet which one allow the fleet to preserve radio silence?
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Broadcast and intercept.
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to use crystals in oscillators at high operating frequencies requires that they be ground so thin that they are susceptible to cracking easily: how can this problem be overcome?
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By raising the oscillator output frequencies using frequency multipliers.
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What is the term used to describe the process when two or more circuits are tuned using a single control, such as in a transceiver when a fixed difference is required in tuning multiple stages to maintain a constant IF frequency?
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Ganged tuning.
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What is used to increase the maximum number of intelligible transmission taking place in the radio spectrum per unit of time?
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Multiplexing
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What is involved in multiplexing?
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The simultaneous transmission of a number intelligible signals using only a single transmitting path.
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What are two common methods of multiplexing?
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Time-division-multiplexing and Frequency-division multiplexing.
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What is the use of the Low-frequency band?
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Long-range direction finding, medium and long-range communications, and aeronautical radio navigation.
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Why are only the upper and lower ends of the Medium-frequency band used by the Navy?
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because the 500-1700 khz range is allocated for commercial broadcasts.
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What is the primary use of the High-frequency band?
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Long-range voice and teletype communications by mobile and maritime units.
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What band is used by the Navy in amphibious and special operations?
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A significant portion of the lower end of the Very-high-frequency band?
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What band is used extensively by the Navy for short-range and aircraft communications?
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the upper portion of the VHF band and lower portion of the Ultra-high-frequency band.
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What is the use of the frequencies above 400 Mhz in the UHF band through the Extremely-high-frequency band?
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Radar and special equipment.
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What is the Very-high-frequency band used for?
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Aeronautical radio navigation and communications, rader, amateur radio, and mobile communications. The Navy uses this band for mobile communications, such as for boat crews and landing parties.
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What is the use of the Ultra-high-frequency band?
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Line-of-sight short-range or satellite communications.
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What is meant by the acronym LOS?
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LOS means that both antennas must be able to see each other for proper operation.
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What type of circuit is used in radio receivers, FM transmitters, and frequency synthesizers to maintain frequency stability.
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Automatic frequency control circuits.
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What are the 2 primary sections required in an AFC circuit?
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A frequency detector and a variable reactance.
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Name a widely used type of AFC circuit?
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Balanced-phase detector or Phase-discriminator.
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What is the long term accuracy required from many local ascillators used in mondern communications equipment?
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1 part in a million.
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What is frequency synthesis?
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The process of selecting and/or heterodyning frequencies to produce a unique signal frequency that is not harmonically related to the crystal frequency or other signals used in the heterodyning process.
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How many seprate data transmission links are used by NTDS/CDS to maintain tactical communications?
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Four (Link 11,14,16, and 4-A)
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Which NTDS link provides a means of transmitting track information, identity, and other tactical data to those units not capable of participating in the link 11 net?
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Link 14
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What is passive satellite?
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A satellite that reflects radio signals back to the earth.
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What is the purpose of the "X" position on a Receiver or Transmitter transfer switchboard?
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To allow the transfer of circuits to additional switchboards to expand the flexibility and redundancy of remote control station and desired transmitter or receiver patching.
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What is the basic description of the Single audio system?
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It is a single red audio interface between variuos remote red phone lines and various plain or secrure baseband subsystems used with the ship's external communications systems.
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Name the 2 types of DC operations used to represent a mark and space in teletype circuits?
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Neutral and Polar
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Describe the basic difference between neutral and polar teletype circuits.
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Current is always flowing in a polar system and the polarity indicates whether it is a mark or a space: whereas current in a neutra system only flowa during a mark, and no current represents a space.
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What is the standard speed for defense communication system teletypewriter operation?
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100 words per minute or 75 baud.
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What happens to a teletype using neutral keying when it receives a steday space?
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It runs open.
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what is meant by the gain of a radio receiver?
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The amplification between the input of the receiver and its output.
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What are the 4 most important characteristics of a basic receiver?
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Sensitivity, noise, selectivity, and fidelity.
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When does reception occur?
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When a transmitted electromagnetic wave passes through trhe receiver antenna and induces a voltage in it.
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What is detection?
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The extraction of the modulation from an RF signal.
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What term describes the ability of a receiver to distinquish between a signal at the desired frequency and signals at adjacent fequencies?
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Receiver selectivity.
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What erm describes a receiver's ability to accuratly reproduce the input signal?
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Fidelity
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What term describes a receiver's ability to reproduce very weak signals?
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Receiver sensitivity.
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What is the undesirable limiting factor for the minimum usable signal a receiver can process and still produce a usable output?
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Noise
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HWat is the ideal noise figure in decibels for a receiver?
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0 dB
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Name a type of control circuit that limits unwanted variations in the output of a receiver caused by variations in strength of the received signal input?
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Automatic gain Control
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Which NTDS/CDS link enables the operational program to take control of the autopilot in a suitably equipped aircraft?
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Link-4A
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What subsystems make up a typical Link-4A system?
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The CDS computer, Data Terminal Set, communication switchboard, and a UHF radio.
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Which UHF radio is typically used for Link-4A and what mode of modulation does it employ?
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The AN/URC-93 which uses frequency shift keying for Link-4A operation.
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Up to how many controlled aircraft may a Link-4A control station communicate with?
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up to 100
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Name the 4 distinct modes of operation for Link-4A.
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Intercept vectoring, air traffic control, automatic carrier landing system, and percicion course direction.
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How does Link-4A control multiple aircraft independently on the same frequency?
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By using serial time-division multiplexing principles with a command-and-response protocol.
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What is the most common Data terminal set used in Link-4A shipboard installations?
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The AN/SSW-1
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What is the 2nd channel of dual channel AN/SSW-1 used for besides Link-4A?
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for transmitting CAINS data.
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What is the AN/SSW-1?
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A digital data communications control set. It is a 2 channel Link-4A NTDS control terminal and digital converter which interfaces the TDS computer via a Digital data switchboard such as the MK-70 to the I/O audio channels of the UHF transceiver via the SB-4176
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What are the 3 main functions performed by the Link-4A DTS?
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Overall Link-4A system timing, converts parallel data from CDS to serial data for transmission to controlled aircraft, and it converts serial data received from the controlled aircraft into parallel data for input to the CDS computer.
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List the 3 types of messages employed by Link-4A/
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Control, reply, and test
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What kind of information is contained in the sircraft control messages transmitted by the controlling station?
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Vectoring information, commands, and data pertaining to the target or destination of the controlled aircraft.
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How long are standard Link-4A control and reply messages?
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control messages are 14 msec and reply messages are 18 msec
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