1D

Question 1

Modern wave generators produce outputs that are:

Answer 1

sinusoidal, square, rectangular, or sawtooth.

Question 1

___ ___ are used extensively in the field of electronics and especially in the RF career field.

Answer 1

Wave generators

Question 2

Wave generators are usually called ___.

Answer 2

oscillators

Question 3

Oscillators are classified in two categories:

Answer 3

Sinusoidal and Non-sinusoidal

Question 4

A ___ oscillator produces a sine wave output signal while ____ oscillators generate complex waveforms such as square waves, rectangular waves, trigger wave, and sawtooth waves.

Answer 4

sinusoidal
non-sinusoidal

Question 5

A non-sinusoidal oscillator is often referred to as a ____ oscillator.

Answer 5

relaxation

Question 6

An oscillator is a device that converts ___ from a power supply into an ___ signal.

Answer 6

DC
AC

Question 7

The primary purpose of an oscillator is to generate a ___ ___ at a constant amplitude (peak-to-peak) and at a specific frequency while maintaining this waveform within certain limits.

Answer 7

repetitive waveform

Question 8

Almost every piece of electronic equipment that uses an oscillator has two stability requirements:

Answer 8

amplitude (voltage) stability and frequency stability.

Question 9

Amplitude stability refers to an oscillator’s ability to maintain a constant amplitude output waveform under normal circumstances. The more ____ the amplitude output waveform, the better the oscillator. Oscillators must have good amplitude stability to prevent voltage or current spikes that could damage equipment.

Answer 9

constant

Question 10

Frequency stability refers to the oscillator’s ability to generate a signal at a ___ ___ with minimal frequency fluctuation.

Answer 10

constant frequency

Question 11

The basic requirements to sustain oscillation at a constant amplitude and at a predetermined frequency are a:

Answer 11

DC Power Supply
Frequency Determining Device (FDD)
Amplifier
Regenerative Feedback

Question 12

The following describes which of the four requirements for oscillation?

Oscillators operate at specific frequencies and require a ____ to create that frequency. ____ can be crystals, tank circuits (made up of inductors and capacitors), or RC (resistor and capacitor) networks. Another circuit, called a phase lock loop, is used in some modern oscillators to ensure frequency stability.

Answer 12

Frequency Determining Device (FDD)

Question 13

Another circuit, called a ___ ___ ___, is used in some modern oscillators to ensure frequency stability.

Answer 13

phase lock loop

Question 14

The following describes which of the four requirements for oscillation?

The ____ is necessary to provide voltage gain. The gain must be large enough to provide for the load device and supply a signal for regenerative feedback. The ____ uses a transistor, or other non-linear devices, to split the power requirement.

Answer 14

Amplifier

Question 15

The following describes which of the four requirements for oscillation?

Returns the signal from the FDD to its proper amplitude. It provides the oscillator with amplitude stability and compensates for damping effects. Damping is the steady decrease in oscillation amplitude caused by internal resistance.

Answer 15

Regenerative Feedback

Question 16

The following describes which of the four requirements for oscillation?

Provides the electrical power to the amplifier

Answer 16

DC Power Supply

Question 17

Tank circuits are created by placing a capacitor and an inductor in ____.

Answer 17

parallel

Question 18

A ___ ___, a type of crystal oscillator, is the most widely used oscillator.

Answer 18

quartz oscillator

Question 19

The quartz crystal in the oscillator is a ___ ___ and must be excited and measured for proper operation.

Answer 19

mechanical resonator

Question 20

Taking advantage of the ___ ___, which is the generation of a charge across the crystal or by mechanical compression, capitalizes on this phenomenon.

Answer 20

piezoelectric effect

Question 21

When dealing with any crystal, ____ and ____ are two factors that influence its performance.

Answer 21

temperature and aging

Question 22

Two solutions for the temperature issue are enclosing the crystal in an electronically regulated ___ or using a temperature-compensated crystal oscillator.

Answer 22

oven

Question 23

Aging is the second factor affecting all quartz oscillators. These effects provide a near linear (uniform) change in resonant frequency
with time. We can’t ____ the deterioration of the oscillator as it ages, but good manufacturing designs can limit the deterioration, and we can observe and account for it.

Answer 23

prevent

Question 24

As illustrated in Figure 1-147, crystals are mounted in holders which ____ support the crystals, ____ them from the elements, and provide the electrical ____. The holder must allow the crystal the freedom to vibrate.

Answer 24

physically protect connection

Question 25

The crystal oscillator, shown in Figure 1-148 has an obvious identifying feature, being ___, the crystal.

Answer 25

Y1

Question 26

The crystal (Y1) determines the oscillator’s output frequency, so it is the ___ of the oscillator.

Answer 26

FDD

Question 27

___ ___ are used along with a crystal. The transistor, Q1, helps to guide the regenerative feedback back to the FDD in order to help maintain steady oscillation, while transistor Q2 is where the output waveform is generated.

Answer 27

Two transistors

Question 28

Three of the four requirements of an oscillator are clearly seen in Figure1-148. ____, located at the top of the figure, is the power source, the ____ is the FDD, and the amplifier ___ provides the output (a common base amplifier is used). The regenerative feedback, not clearly shown in Figure 1-148, consists of the output from Q2, from the tie point going left to the base of Q1. Q1 is a common collector amplifier that creates a lot of current through R1, which in turn creates a substantial voltage feeding back to crystal Y1 to keep Y1 energized and prevent the damping effect.

Answer 28

VCC crystal Q2

Question 29

A good timing source is an oscillator that provides an ___ ___ when synchronizing a two- way communications network.

Answer 29

accurate clock

Question 30

Accuracy is affected by several factors. One factor is the oscillator’s ____. A 10MHz oscillator is more accurate than a 5KHz oscillator because it breaks down each second of time into 10 million equal parts or cycles. The 5KHz oscillator breaks down each second into only 5,000 cycles. Another factor that can limit clock accuracy is an increase in the amount of ____ in the output frequency.

Answer 30

frequency drift

Question 31

A timing oscillator is classified as either a ____ frequency standard or a ____ frequency standard.

Answer 31

primary secondary

Question 32

Any frequency source, regardless of its accuracy or stability, can be a primary frequency standard if it is used as the ___ ___ reference for other frequency sources.

Answer 32

sole calibration

Question 33

A secondary frequency standard is a device that is calibrated ___ a primary frequency standard, and then used to calibrate other frequency sources.

Answer 33

against

Question 34

For example, if you calibrate your watch to the clock in your work center, the work center clock becomes a ____ frequency standard, and your watch is a ____ frequency standard.

Answer 34

primary secondary

Question 35

Two kinds of oscillators commonly used as frequency sources are ____ oscillators and ____ oscillators.

Answer 35

quartz atomic

Question 36

___ ___ is considered the most accurate timing source because it generates more highly stable clocks than Mean Solar Time does.

Answer 36

Atomic Time

Question 37

An atomic oscillator is used to create accurate seconds through the oscillations or vibrations of highly stable ___.

Answer 37

atoms

Question 38

Two of the most common types of atomic oscillators are the ___ ___ ___ oscillator and the ___ ___ oscillator.

Answer 38

rubidium gas cell cesium beam

Question 39

Rubidium Gas only drifts approximately __ ___ in 24 hours.

Answer 39

1 microsecond

Question 40

Cesium Beam drifts only ___ ___ in 24 hours.

Answer 40

200 nanoseconds

Question 41

The ___ ___ ___ is an oscillator whose frequency can be varied using a variable control voltage.

Answer 41

Voltage Control Oscillator (VCO)

Question 42

As seen in Figure 1-149, ___ can produce several types of waveforms. This is a piece of test equipment used in the Air Force to test radio functions.

Answer 42

VCOs

Question 43

The following schematic is a symbol for what?

Answer 43

Varactor

Question 44

Figure 1-150 shows a VCO using a variable DC voltage. When the input voltage is increased, the output frequency is higher. Decreasing the input voltage will cause the opposite to happen. A tank circuit is used to store and transfer energy alternately between an inductor and a capacitor to produce a sinusoidal wave. The operation of this movement is called the ___ ___ since the signal rocks back and forth.

Answer 44

flywheel effect

Question 45

In the VCO tank circuit, there is an additional component called a ___. A ___ (a variable diode) can be used as a voltage-variable capacitor to change the output frequency of the oscillator and allows it a greater frequency range for the output as well.

Answer 45

varactor

Question 46

Voltage Controlled Oscillator uses components called ___ ___ and a ____.

Answer 46

tank circuits varactor

Question 47

As mentioned in the introduction, a VCO sometimes uses a circuit called a ___ ___ ___ (PLL) to create a more stable signal output.

Answer 47

Phase Lock Loop

Question 48

In the previous section, we studied circuits that generated a sinusoidal wave. Now, we’ll discuss circuits that generate non-sinusoidal waves. These circuits, called ____, produce either a specific non-sinusoidal wave repeatedly, or they produce one non-sinusoidal wave when pulsed (triggered) while remaining inactive until another pulse is applied.

Answer 48

multivibrators

Question 49

Circuits of this type are also referred to as relaxation oscillators.

Answer 49

Multivibrators

Question 50

The output frequency of a multivibrator is a ____ wave or ____ wave.

Answer 50

square rectangular

Question 51

Multivibrators use the principle of an on-off switch. Multivibrators are basically two amplifier circuits, transistors, arranged with ___ ___. When an input voltage is large enough it will cause one transistor to act like an open switch and the other to act like a closed switch, producing a square or rectangular wave.

Answer 51

regenerative feedback

Question 52

A square wave or rectangular wave can be produced by opening and closing the switch S1. This is essentially turning on and turning off the power, generating the highs (1) and lows (0) that create our wave form. If the switch is opened and closed for equal lengths of time, the output voltage will be a ____ wave (Figure 1-154). If the lengths of time are unequal, the output will be a ____ wave (Figure 1-155).

Answer 52

square rectanglular

Question 53

There are three basic types of multivibrators:

Answer 53

astable, bistable, and monostable

Question 54

The following describes what type of waveform? Two alternation equal in time Voltage (amplitude) are also equal

Answer 54

Square Wave

Question 55

The following describes what type of waveform? Two alternation unequal in time Voltage (amplitude) may not be equal

Answer 55

Rectangular Waveform

Question 56

An ____ multivibrator has no stable states, causing its output to continuously oscillate between its two unstable states.

Answer 56

astable

Question 57

The following describes which type of multivibrator? No stable state Free running (constantly switches) relaxation oscillator Two outputs 180°

Answer 57

Astable

Question 58

It is classified as a free-running multivibrator.

Answer 58

Astable

Question 59

As the name ____ implies, this device has one stable state.

Answer 59

Monostable Multivibrator

Question 60

It is a widely used multivibrator circuit that must always be triggered to generate each output pulse.

Answer 60

Monostable

Question 61

The following describes which type of multivibrator? Also referred to as start-stop or one-shot One stable condition Requires one trigger for each positive pulse Output can be square wave or rectangular wave

Answer 61

Monostable

Question 62

The following describes which type of multivibrator? Also known as a Flip-Flop Two stable states Stays in last state until triggered to change Requires 2 input triggers for each positive pulse

Answer 62

Bistable

Question 63

Radar sets, oscilloscopes, and computer circuits all use ___ (voltage or current) waveforms. ___ waveshapes must have linear rise characteristics.

Answer 63

sawtooth

Question 64

The sawtooth waveform is often used to produce a uniform, progressive movement of an electron beam across the face of the oscilloscope screen. The movement of the electron beam is called a ____.

Answer 64

sweep

Question 65

The circuit which provides the sawtooth waveform is called...?

Answer 65

sweep generator, time base generator, or ramp generator

Question 66

Sawtooth waves can be generated by use of an ___ network in which the transistor operates as a switch.

Answer 66

RC

Question 67

Output is used as external trigger sources for other circuits

Answer 67

Sawtooth generator

Question 68

The linearity of the sawtooth is dependent on two variables: the time constant (TC) of the RC circuit and the length of the negative gate applied to the circuit. For the circuit to produce a linear sawtooth, the components selected should be such that no more than one-tenth of one TC is used. Referring to the Universal Time Constant Chart in Figure 1-160, the most linear part of the curve is the first __% of the first time constant.

Answer 68

10%

Question 69

Oscillators require a ___, ___, ___ and ___ to sustain oscillations.

Answer 69

DC power source amplifier frequency-determining device (FDD) regenerative feedback

Question 70

Crystal Oscillators make use of a ____ as the frequency-determining device for good frequency stability.

Answer 70

crystal

Question 71

A Voltage Control Oscillator varies frequency using a ____.

Answer 71

varactor

Question 72

The lesson also covered multivibrators, which produce ___ ___.

Answer 72

non-sinusoidal waveforms

Question 73

The astable multivibrator is a free-running device that can produce two square or rectangular waveform outputs ___° out of phase.

Answer 73

180 degrees

Question 74

The monostable multivibrator has one steady state. It is also called a __-__ or __-__ multivibrator. It requires a trigger for each output pulse.

Answer 74

start-stop one-shot

Question 75

The bistable multivibrator (__-__) has two stable states and must be triggered to change states.

Answer 75

flip-flop

Question 76

Sweep generators create a ___ waveform and are used for testing frequency response.

Answer 76

sawtooth