005 - Transmitters, Modulation and Processing

Question 1

A-005-001-001
How is the positive feedback coupled to the input in a Hartley oscillator?

(a) Through a capacitive divider
(b) Through link coupling
(c) Through a tapped coil
(d) Through a neutralizing capacitor

Answer 1

A-005-001-001
How is the positive feedback coupled to the input in a Hartley oscillator?

(c) Through a tapped coil

Question 2

A-005-001-002
How is positive feedback coupled to the input in a Colpitts oscillator?

(a) Through a tapped coil
(b) Through a neutralizing capacitor
(c) Through a link coupling
(d) Through a capacitive divider

Answer 2

A-005-001-002
How is positive feedback coupled to the input in a Colpitts oscillator?

(d) Through a capacitive divider

Question 3

A-005-001-003
How is positive feedback coupled to the input in a Pierce oscillator?

(a) Through a neutralizing capacitor
(b) Through link coupling
(c) Through capacitive coupling
(d) Through a tapped coil

Answer 3

A-005-001-003
How is positive feedback coupled to the input in a Pierce oscillator?

(c) Through capacitive coupling

Question 4

A-005-001-004
Why is the Colpitts oscillator circuit commonly used in a VFO?

(a) It can be used with or without crystal lock-in
(b) The frequency is a linear function with load impedance
(c) It is stable
(d) It has high output power

Answer 4

A-005-001-004
Why is the Colpitts oscillator circuit commonly used in a VFO?

(c) It is stable

Question 5

A-005-001-005
Why must a very stable reference oscillator be used as part of a phase-locked loop (PLL) frequency synthesizer?

(a) Any phase variations in the reference oscillator signal will produce phase noise in the synthesizer output
(b) Any phase variations in the reference oscillator signal will produce harmonic distortion in the modulating signal
(c) Any amplitude variations in the reference oscillator signal will prevent the loop from changing frequency
(d) Any amplitude variations in the reference oscillator signal will prevent the loop from locking to the desired signal

Answer 5

A-005-001-005
Why must a very stable reference oscillator be used as part of a phase-locked loop (PLL) frequency synthesizer?

(a) Any phase variations in the reference oscillator signal will produce phase noise in the synthesizer output

Question 6

A-005-001-006
Positive feedback from a capacitive divider indicates the oscillator type is:

(a) Pierce
(b) Hartley
(c) Colpitts
(d) Miller

Answer 6

A-005-001-006
Positive feedback from a capacitive divider indicates the oscillator type is:

(c) Colpitts

Question 7

A-005-001-007
In an RF oscillator circuit designed for high stability, the positive feedback is drawn from two capacitors connected in series. These two capacitors would most likely be:

(a) silver mica
(b) ceramic
(c) electrolytics
(d) Mylar

Answer 7

A-005-001-007
In an RF oscillator circuit designed for high stability, the positive feedback is drawn from two capacitors connected in series. These two capacitors would most likely be:

(a) silver mica

Question 8

A-005-001-008
In an oscillator circuit where positive feedback is obtained through a single capacitor in series with the crystal, the type of oscillator is:

(a) Pierce
(b) Colpitts
(c) Hartley
(d) Miller

Answer 8

A-005-001-008
In an oscillator circuit where positive feedback is obtained through a single capacitor in series with the crystal, the type of oscillator is:

(a) Pierce

Question 9

A-005-001-009
A circuit depending on positive feedback for its operation would be a:

(a) mixer
(b) detector
(c) variable-frequency oscillator
(d) audio amplifier

Answer 9

A-005-001-009
A circuit depending on positive feedback for its operation would be a:

(c) variable-frequency oscillator

Question 10

A-005-001-010
An apparatus with an oscillator and a class C amplifier would be:

(a) a fixed-frequency single-sideband transmitter
(b) a two-stage frequency-modulated transmitter
(c) a two-stage CW transmitter
(d) a two-stage regenerative receiver

Answer 10

A-005-001-010
An apparatus with an oscillator and a class C amplifier would be:

(c) a two-stage CW transmitter

Question 11

A-005-001-011
In an oscillator where positive feedback is provided through a capacitor in series with a crystal, that type of oscillator is a:

(a) Colpitts
(b) Pierce
(c) Hartley
(d) Franklin

Answer 11

A-005-001-011
In an oscillator where positive feedback is provided through a capacitor in series with a crystal, that type of oscillator is a:

(b) Pierce

Question 12

A-005-002-001
The output tuning controls on a transmitter power amplifier with an adjustable PI network:

(a) allow switching to different antennas
(b) reduce the possibility of cross-modulation in adjunct receivers
(c) allow efficient transfer of power to the antenna
(d) are involved with frequency multiplication in the previous stage

Answer 12

A-005-002-001
The output tuning controls on a transmitter power amplifier with an adjustable PI network:

(c) allow efficient transfer of power to the antenna

Question 13

A-005-002-002
The purpose of using a centre-tap return connection on the secondary of transmitting tube’s filament transformer is to:

(a) reduce the possibility of harmonic emissions
(b) prevent modulation of the emitted wave by the alternating current filament supply
(c) keep the output voltage constant with a varying load
(d) obtain optimum power output

Answer 13

A-005-002-002
The purpose of using a centre-tap return connection on the secondary of transmitting tube’s filament transformer is to:

(b) prevent modulation of the emitted wave by the alternating current filament supply

Question 14

A-005-002-003
In a grounded grid amplifier using a triode vacuum tube, the input signal is applied to:

(a) the plate
(b) the cathode
(c) the control grid
(d) the filament leads

Answer 14

A-005-002-003
In a grounded grid amplifier using a triode vacuum tube, the input signal is applied to:

(b) the cathode

Question 15

A-005-002-004
In a grounded grid amplifier using a triode vacuum tube, the plate is connected to the pi-network through a:

(a) blocking capacitor
(b) by-pass capacitor
(c) tuning capacitor
(d) electrolytic capacitor

Answer 15

A-005-002-004
In a grounded grid amplifier using a triode vacuum tube, the plate is connected to the pi-network through a:

(a) blocking capacitor

Question 16

A-005-002-005
In a grounded grid amplifier using a triode vacuum tube, the plate is connected to a radio frequency choke. The other end of the radio frequency choke connects to the:

(a) filament voltage
(b) B+ (high voltage)
(c) ground
(d) B- (bias)

Answer 16

A-005-002-005
In a grounded grid amplifier using a triode vacuum tube, the plate is connected to a radio frequency choke. The other end of the radio frequency choke connects to the:

(b) B+ (high voltage)

Question 17

A-005-002-006
In a grounded grid amplifier using a triode vacuum tube, the cathode is connected to a radio frequency choke. The other end of the radio frequency choke connects to the:

(a) ground
(b) filament voltage
(c) B- (bias)
(d) B+ (high voltage)

Answer 17

A-005-002-006
In a grounded grid amplifier using a triode vacuum tube, the cathode is connected to a radio frequency choke. The other end of the radio frequency choke connects to the:

(c) B- (bias)

Question 18

A-005-002-007
In a grounded grid amplifier using a triode vacuum tube, the secondary winding of a transformer is connected directly to the vacuum tube. This transformer provides:

(a) B- (bias)
(b) B+ (high voltage)
(c) filament voltage
(d) Screen voltage

Answer 18

A-005-002-007
In a grounded grid amplifier using a triode vacuum tube, the secondary winding of a transformer is connected directly to the vacuum tube. This transformer provides:

(c) filament voltage

Question 19

A-005-002-008
In a grounded grid amplifier using a triode vacuum tube, what would be the approximate B+ voltage required for an output of 400 watts at 400 mA with approximately 50 percent efficiency?

(a) 500 volts
(b) 3000 volts
(c) 1000 volts
(d) 2000 volts

Answer 19

A-005-002-008
In a grounded grid amplifier using a triode vacuum tube, what would be the approximate B+ voltage required for an output of 400 watts at 400 mA with approximately 50 percent efficiency?

(d) 2000 volts

Question 20

A-005-002-009
In a grounded grid amplifier using a triode vacuum tube, each side of the filament is connected to a capacitor whose other end is connected to ground. These are:

(a) by-pass capacitors
(b) tuning capacitors
(c) electrolytic capacitors
(d) blocking capacitors

Answer 20

A-005-002-009
In a grounded grid amplifier using a triode vacuum tube, each side of the filament is connected to a capacitor whose other end is connected to ground. These are:

(a) by-pass capacitors

Question 21

A-005-002-010
After you have opened a VHF power amplifier to make internal tuning adjustments, what should you do before you turn the amplifier on?

(a) Make sure that the power interlock switch is bypassed so you can test the amplifier
(b) Be certain no antenna is attached so that you will not cause any interference
(c) Remove all amplifier shielding to ensure maximum cooling
(d) Be certain all amplifier shielding is fastened in place

Answer 21

A-005-002-010
After you have opened a VHF power amplifier to make internal tuning adjustments, what should you do before you turn the amplifier on?

(d) Be certain all amplifier shielding is fastened in place

Question 22

A-005-002-011
Harmonics produced in an early stage of a transmitter may be reduced in a later stage by:

(a) tuned circuit coupling between stages
(b) larger value coupling capacitors
(c) greater input to the final stage
(d) transistors instead of tubes

Answer 22

A-005-002-011
Harmonics produced in an early stage of a transmitter may be reduced in a later stage by:

(a) tuned circuit coupling between stages

Question 23

A-005-003-001
In a simple 2 stage CW transmitter circuit, the oscillator stage and the class C amplifier stage are inductively coupled by a RF transformer. Another role of the RF transformer is to:

(a) act as part of a pi filter
(b) provide the necessary feedback for oscillation
(c) act as part of a balanced mixer
(d) be part of a tuned circuit

Answer 23

A-005-003-001
In a simple 2 stage CW transmitter circuit, the oscillator stage and the class C amplifier stage are inductively coupled by a RF transformer. Another role of the RF transformer is to:

(d) be part of a tuned circuit

Question 24

A-005-003-002
In a simple 2 stage CW transmitter, current to the collector of the transistor in the class C amplifier stage flows through a radio frequency choke (RFC) and a tapped inductor. The RFC, on the tapped inductor side, is also connected to grounded capacitors. The purpose of the RFC and capacitors is to:

(a) provide negative feedback
(b) form a key-click filter
(c) form a RF-tuned circuit
(d) form a low-pass filter

Answer 24

A-005-003-002
In a simple 2 stage CW transmitter, current to the collector of the transistor in the class C amplifier stage flows through a radio frequency choke (RFC) and a tapped inductor. The RFC, on the tapped inductor side, is also connected to grounded capacitors. The purpose of the RFC and capacitors is to:

(d) form a low-pass filter

Question 25

A-005-003-003
In a simple 2 stage CW transmitter, the transistor in the second stage would act as:

(a) a power amplifier
(b) a frequency multiplier
(c) the master oscillator
(d) an audio oscillator

Answer 25

A-005-003-003
In a simple 2 stage CW transmitter, the transistor in the second stage would act as:

(a) a power amplifier

Question 26

A-005-003-004
An advantage of keying the buffer stage in a transmitter is that:

(a) key clicks are eliminated
(b) changes in oscillator frequency are less likely
(c) the radiated bandwidth is restricted
(d) high RF voltages are not present

Answer 26

A-005-003-004
An advantage of keying the buffer stage in a transmitter is that:

(b) changes in oscillator frequency are less likely

Question 27

A-005-003-005
As a power amplifier is tuned, what reading on its grid current meter indicates the best neutralization?

(a) Minimum grid current
(b) Maximum grid current
(c) A minimum change in grid current as the output circuit is changed
(d) A maximum change in grid current as the output circuit is changed

Answer 27

A-005-003-005
As a power amplifier is tuned, what reading on its grid current meter indicates the best neutralization?

(c) A minimum change in grid current as the output circuit is changed

Question 28

A-005-003-006
What does a neutralizing circuit do in an RF amplifier?

(a) It eliminates AC hum from the power supply
(b) It reduces incidental grid modulation
(c) It cancels the effects of positive feedback
(d) It controls differential gain

Answer 28

A-005-003-006
What does a neutralizing circuit do in an RF amplifier?

(c) It cancels the effects of positive feedback

Question 29

A-005-003-007
What is the reason for neutralizing the final amplifier stage of a transmitter?

(a) To limit the modulation index
(b) To cut off the final amplifier during standby periods
(c) To eliminate parasitic oscillations
(d) To keep the carrier on frequency

Answer 29

A-005-003-007
What is the reason for neutralizing the final amplifier stage of a transmitter?

(c) To eliminate parasitic oscillations

Question 30

A-005-003-008
Parasitic oscillations are usually generated due to:

(a) harmonics from some earlier multiplier stage
(b) excessive drive or excitation to the power amplifier
(c) a mismatch between power amplifier and transmission line
(d) accidental resonant frequencies in the power amplifier

Answer 30

A-005-003-008
Parasitic oscillations are usually generated due to:

(d) accidental resonant frequencies in the power amplifier

Question 31

A-005-003-009
Parasitic oscillations would tend to occur mostly in:

(a) high gain audio output stages
(b) high voltage rectifiers
(c) mixer stages
(d) RF power output stages

Answer 31

A-005-003-009
Parasitic oscillations would tend to occur mostly in:

(d) RF power output stages

Question 32

A-005-003-010
Why is neutralization necessary for some vacuum-tube amplifiers?

(a) To reduce grid-to-cathode leakage
(b) To cancel AC hum from the filament transformer
(c) To cancel oscillation caused by the effects of interelectrode capacitance
(d) To reduce the limits of loaded Q

Answer 32

A-005-003-010
Why is neutralization necessary for some vacuum-tube amplifiers?

(c) To cancel oscillation caused by the effects of interelectrode capacitance

Question 33

A-005-003-011
Parasitic oscillations in an RF power amplifier may be caused by:

(a) overdriven stages
(b) poor voltage regulation
(c) excessive harmonic production
(d) lack of neutralization

Answer 33

A-005-003-011
Parasitic oscillations in an RF power amplifier may be caused by:

(d) lack of neutralization

Question 34

A-005-004-001
What type of signal does a balanced modulator produce?

(a) FM with balanced deviation
(b) Double sideband, suppressed carrier
(c) Full carrier
(d) Single sideband, suppressed carrier

Answer 34

A-005-004-001
What type of signal does a balanced modulator produce?

(b) Double sideband, suppressed carrier

Question 35

A-005-004-002
How can a single-sideband phone signal be produced?

(a) By driving a product detector with a DSB signal
(b) By using a loop modulator followed by a mixer
(c) By using a balanced modulator followed by a filter
(d) By using a reactance modulator followed by a mixer

Answer 35

A-005-004-002
How can a single-sideband phone signal be produced?

(c) By using a balanced modulator followed by a filter

Question 36

A-005-004-003
Carrier suppression in a single-sideband transmitter takes place in:

(a) the balanced modulator stage
(b) the carrier decouple stage
(c) the mechanical filter
(d) the frequency multiplier stage

Answer 36

A-005-004-003
Carrier suppression in a single-sideband transmitter takes place in:

(a) the balanced modulator stage

Question 37

A-005-004-004
Transmission with SSB, as compared to conventional AM transmission, results in:

(a) 6 dB gain in the receiver
(b) 6 dB gain in the transmitter and 3 dB gain in the receiver
(c) a greater bandpass requirement in the receiver
(d) 3 dB gain in the transmitter

Answer 37

A-005-004-004
Transmission with SSB, as compared to conventional AM transmission, results in:

(b) 6 dB gain in the transmitter and 3 dB gain in the receiver

Question 38

A-005-004-005
The peak power output of a single-sideband transmitter, when being tested by a two-tone generator is:

(a) equal to the RF peak output power of any of the tones
(b) one-half of the RF peak output power of any of the tones
(c) twice the RF power output of any of the tones
(d) one-quarter of the RF peak output power of any of the tones

Answer 38

A-005-004-005
The peak power output of a single-sideband transmitter, when being tested by a two-tone generator is:

(c) twice the RF power output of any of the tones

Question 39

A-005-004-006
What kind of input signal is used to test the amplitude linearity of a single-sideband phone transmitter while viewing the output on an oscilloscope?

(a) An audio-frequency sine wave
(b) Two audio-frequency sine waves
(c) An audio-frequency square wave
(d) Normal speech

Answer 39

A-005-004-006
What kind of input signal is used to test the amplitude linearity of a single-sideband phone transmitter while viewing the output on an oscilloscope?

(b) Two audio-frequency sine waves

Question 40

A-005-004-007
When testing the amplitude linearity of a single-sideband transmitter what audio tones are fed into the microphone input and on what kind of kind of instrument is the output observed?

(a) Two non-harmonically related tones are fed in, and the output is observed on an oscilloscope
(b) Two harmonically related tones are fed in, and the output is observed on an oscilloscope
(c) Two harmonically related tones are fed in, and the output is observed on a distortion analyzer
(d) Two non-harmonically related tones are fed in, and the output is observed on a distortion analyzer

Answer 40

A-005-004-007
When testing the amplitude linearity of a single-sideband transmitter what audio tones are fed into the microphone input and on what kind of kind of instrument is the output observed?

(a) Two non-harmonically related tones are fed in, and the output is observed on an oscilloscope

Question 41

A-005-004-008
What audio frequencies are used in a two-tone test of the linearity of a single-sideband phone transmitter?

(a) 20 Hz and 20 kHz tones must be used
(b) 1200 Hz and 2400 Hz tones must be used
(c) Any two audio tones may be used, but they must be within the transmitter audio passband, and must be harmonically related
(d) Any two audio tones may be used, but they must be within the transmitter audio passband, and should not be harmonically related

Answer 41

A-005-004-008
What audio frequencies are used in a two-tone test of the linearity of a single-sideband phone transmitter?

(d) Any two audio tones may be used, but they must be within the transmitter audio passband, and should not be harmonically related

Question 42

A-005-004-009
What measurement can be made of a single-sideband phone transmitter’s amplifier by performing a two-tone test using an oscilloscope?

(a) Its frequency deviation
(b) Its percent of carrier phase shift
(c) Its percent of frequency modulation
(d) Its linearity

Answer 42

A-005-004-009
What measurement can be made of a single-sideband phone transmitter’s amplifier by performing a two-tone test using an oscilloscope?

(d) Its linearity

Question 43

A-005-004-010
How much is the carrier suppressed below peak output power in a single-sideband phone transmission?

(a) At least 40 dB
(b) No more than 20 dB
(c) No more than 30 dB
(d) At least 60 dB

Answer 43

A-005-004-010
How much is the carrier suppressed below peak output power in a single-sideband phone transmission?

(a) At least 40 dB

Question 44

A-005-004-011
What is meant by “flat topping” in a single-sideband phone transmission?

(a) Signal distortion caused by insufficient collector current
(b) The transmitter’s automatic level control is properly adjusted
(c) The transmitter’s carrier is properly suppressed
(d) Signal distortion caused by excessive drive

Answer 44

A-005-004-011
What is meant by “flat topping” in a single-sideband phone transmission?

(d) Signal distortion caused by excessive drive

Question 45

A-005-005-001
In an FM phone signal having a maximum frequency deviation of 3000 Hz either side of the carrier frequency, what is the modulation index, when the modulating frequency is 1000 Hz?

(a) 0.3
(b) 3
(c) 3000
(d) 1000

Answer 45

A-005-005-001
In an FM phone signal having a maximum frequency deviation of 3000 Hz either side of the carrier frequency, what is the modulation index, when the modulating frequency is 1000 Hz?

(b) 3

Question 46

A-005-005-002
What is the modulation index of an FM phone transmitter producing an instantaneous carrier deviation of 6 kHz when modulated with a 2 kHz modulating frequency?

(a) 3
(b) 0.333
(c) 2000
(d) 6000

Answer 46

A-005-005-002
What is the modulation index of an FM phone transmitter producing an instantaneous carrier deviation of 6 kHz when modulated with a 2 kHz modulating frequency?

(a) 3

Question 47

A-005-005-003
What is the deviation ratio of an FM phone transmitter having a maximum frequency swing of plus or minus 5 kHz and accepting a maximum modulation rate of 3 kHz?

(a) 1.66
(b) 60
(c) 0.16
(d) 0.6

Answer 47

A-005-005-003
What is the deviation ratio of an FM phone transmitter having a maximum frequency swing of plus or minus 5 kHz and accepting a maximum modulation rate of 3 kHz?

(a) 1.66

Question 48

A-005-005-004
What is the deviation ratio of an FM phone transmitter having a maximum frequency swing of plus or minus 7.5 kHz and accepting a maximum modulation rate of 3.5 kHz?

(a) 0.47
(b) 47
(c) 0.214
(d) 2.14

Answer 48

A-005-005-004
What is the deviation ratio of an FM phone transmitter having a maximum frequency swing of plus or minus 7.5 kHz and accepting a maximum modulation rate of 3.5 kHz?

(d) 2.14

Question 49

A-005-005-005
When the transmitter is not modulated, or the amplitude of the modulating signal is zero, the frequency of the carrier is called its:

(a) frequency deviation
(b) centre frequency
(c) frequency shift
(d) modulating frequency

Answer 49

A-005-005-005
When the transmitter is not modulated, or the amplitude of the modulating signal is zero, the frequency of the carrier is called its:

(b) centre frequency

Question 50

A-005-005-006
In an FM transmitter system, the amount of deviation from the centre frequency is determined solely by the:

(a) amplitude of the modulating frequency
(b) frequency of the modulating frequency
(c) amplitude and the frequency of the modulating frequency
(d) modulating frequency and the amplitude of the centre frequency

Answer 50

A-005-005-006
In an FM transmitter system, the amount of deviation from the centre frequency is determined solely by the:

(a) amplitude of the modulating frequency

Question 51

A-005-005-007
Any FM wave with single-tone modulation has:

(a) two sideband frequencies
(b) four sideband frequencies
(c) an infinite number of sideband frequencies
(d) one sideband frequency

Answer 51

A-005-005-007
Any FM wave with single-tone modulation has:

(c) an infinite number of sideband frequencies

Question 52

A-005-005-008
Some types of deviation meters work on the principle of:

(a) detecting the frequencies in the sidebands
(b) the amplitude of power in the sidebands
(c) a carrier null and multiplying the modulation frequency by the modulation index
(d) a carrier peak and dividing by the modulation index

Answer 52

A-005-005-008
Some types of deviation meters work on the principle of:

(c) a carrier null and multiplying the modulation frequency by the modulation index

Question 53

A-005-005-009
When using some deviation meters, it is important to know:

(a) modulation index
(b) modulating frequency and the modulation index
(c) modulating frequency
(d) pass-band of the IF filter

Answer 53

A-005-005-009
When using some deviation meters, it is important to know:

(b) modulating frequency and the modulation index

Question 54

A-005-005-010
What is the significant bandwidth of an FM-phone transmission having a +/- 5-kHz deviation and a 3-kHz modulating frequency?

(a) 8 kHz
(b) 16 kHz
(c) 5 kHz
(d) 3 kHz

Answer 54

A-005-005-010
What is the significant bandwidth of an FM-phone transmission having a +/- 5-kHz deviation and a 3-kHz modulating frequency?

(b) 16 kHz

Question 55

A-005-005-011
What is the frequency deviation for a 12.21-MHz reactance-modulated oscillator in a +/- 5-kHz deviation, 146.52-MHz FM-phone transmitter?

(a) +/- 12 kHz
(b) +/- 5 kHz
(c) +/- 416.7 Hz
(d) +/- 41.67 Hz

Answer 55

A-005-005-011
What is the frequency deviation for a 12.21-MHz reactance-modulated oscillator in a +/- 5-kHz deviation, 146.52-MHz FM-phone transmitter?

(c) +/- 416.7 Hz

Question 56

A-005-006-001
If the signals of two repeater transmitters mix together in one or both of their final amplifiers and unwanted signals at the sum and difference frequencies of the original signals are generated and radiated, what is this called?

(a) Neutralization
(b) Adjacent channel interference
(c) Intermodulation interference
(d) Amplifier desensitization

Answer 56

A-005-006-001
If the signals of two repeater transmitters mix together in one or both of their final amplifiers and unwanted signals at the sum and difference frequencies of the original signals are generated and radiated, what is this called?

(c) Intermodulation interference

Question 57

A-005-006-002
How does intermodulation interference between two repeater transmitters usually occur?

(a) When the signals are reflected in phase by aircraft passing overhead
(b) When they are in close proximity and the signals cause feedback in one or both of their final amplifiers
(c) When the signals are reflected out of phase by aircraft passing overhead
(d) When they are in close proximity and the signals mix in one or both of their final amplifiers

Answer 57

A-005-006-002
How does intermodulation interference between two repeater transmitters usually occur?

(d) When they are in close proximity and the signals mix in one or both of their final amplifiers

Question 58

A-005-006-003
How can intermodulation interference between two repeater transmitters in close proximity often be reduced or eliminated?

(a) By installing a low-pass filter in the antenna transmission line
(b) By installing a terminated circulator or ferrite isolator in the transmission line to the transmitter and duplexer
(c) By installing a high-pass filter in the antenna transmission line
(d) By using a Class C final amplifier with high driving power

Answer 58

A-005-006-003
How can intermodulation interference between two repeater transmitters in close proximity often be reduced or eliminated?

(b) By installing a terminated circulator or ferrite isolator in the transmission line to the transmitter and duplexer

Question 59

A-005-006-004
If a receiver tuned to 146.70 MHz receives an intermodulation product signal whenever a nearby transmitter transmits on 146.52, what are the two most likely frequencies for the other interfering signal?

(a) 146.34 MHz and 146.61 MHz
(b) 146.88 MHz and 146.34 MHz
(c) 146.01 MHz and 147.30 MHz
(d) 73.35 MHz and 239.40 MHz

Answer 59

A-005-006-004
If a receiver tuned to 146.70 MHz receives an intermodulation product signal whenever a nearby transmitter transmits on 146.52, what are the two most likely frequencies for the other interfering signal?

(a) 146.34 MHz and 146.61 MHz

Question 60

A-005-006-005
What type of circuit varies the tuning of an amplifier tank circuit to produce FM signals?

(a) A balanced modulator
(b) A phase modulator
(c) A double balanced mixer
(d) An audio modulator

Answer 60

A-005-006-005
What type of circuit varies the tuning of an amplifier tank circuit to produce FM signals?

(b) A phase modulator

Question 61

A-005-006-006
What audio shaping network is added at an FM transmitter to attenuate the lower audio frequencies?

(a) An audio prescaler
(b) A heterodyne suppressor
(c) A pre-emphasis network
(d) A de-emphasis network

Answer 61

A-005-006-006
What audio shaping network is added at an FM transmitter to attenuate the lower audio frequencies?

(c) A pre-emphasis network

Question 62

A-005-006-007
Which type of filter would be best to use in a 2-metre repeater duplexer?

(a) A DSP filter
(b) A cavity filter
(c) An L-C filter
(d) A crystal filter

Answer 62

A-005-006-007
Which type of filter would be best to use in a 2-metre repeater duplexer?

(b) A cavity filter

Question 63

A-005-006-008
The characteristic difference between a phase modulator and a frequency modulator is:

(a) the centre frequency
(b) de-emphasis
(c) pre-emphasis
(d) frequency inversion

Answer 63

A-005-006-008
The characteristic difference between a phase modulator and a frequency modulator is:

(c) pre-emphasis

Question 64

A-005-006-009
In most modern FM transmitters, to produce a better sound, a compressor and a clipper are placed:

(a) between the multiplier and the PA
(b) between the modulator and the oscillator
(c) in the microphone circuit, before the audio amplifier
(d) between the audio amplifier and the modulator

Answer 64

A-005-006-009
In most modern FM transmitters, to produce a better sound, a compressor and a clipper are placed:

(d) between the audio amplifier and the modulator

Question 65

A-005-006-010
Three important parameters to be verified in an FM transmitter are:

(a) power, frequency deviation and frequency stability
(b) distortion, bandwidth and sideband power
(c) modulation, pre-emphasis and carrier suppression
(d) frequency stability, de-emphasis and linearity

Answer 65

A-005-006-010
Three important parameters to be verified in an FM transmitter are:

(a) power, frequency deviation and frequency stability

Question 66

A-005-006-011
Intermodulation interference products are not typically associated with which of the following:

(a) final amplifier stage
(b) receiver frontend
(c) intermediate frequency stage
(d) passive intermodulation

Answer 66

A-005-006-011
Intermodulation interference products are not typically associated with which of the following:

(c) intermediate frequency stage

Question 67

A-005-007-001
Maintaining the peak RF output of a SSB transmitter at a relatively constant level requires a circuit called the:

(a) automatic gain control (AGC)
(b) automatic level control (ALC)
(c) automatic output control (AOC)
(d) automatic volume control (AVC)

Answer 67

A-005-007-001
Maintaining the peak RF output of a SSB transmitter at a relatively constant level requires a circuit called the:

(b) automatic level control (ALC)

Question 68

A-005-007-002
Speech compression associated with SSB transmission implies:

(a) full amplification of high level signals and reducing or eliminating signals amplification of low level
(b) full amplification of low level signals and reducing or eliminating amplification of high level signals
(c) a lower signal-to-noise ratio
(d) circuit level instability

Answer 68

A-005-007-002
Speech compression associated with SSB transmission implies:

(b) full amplification of low level signals and reducing or eliminating amplification of high level signals

Question 69

A-005-007-003
Which of the following functions is not included in a typical digital signal processor?

(a) Analog to digital converter
(b) Digital to analog converter
(c) Aliasing amplifier
(d) Mathematical transform

Answer 69

A-005-007-003
Which of the following functions is not included in a typical digital signal processor?

(c) Aliasing amplifier

Question 70

A-005-007-004
How many bits are required to provide 256 discrete levels, or a ratio of 256:1?

(a) 6 bits
(b) 8 bits
(c) 16 bits
(d) 4 bits

Answer 70

A-005-007-004
How many bits are required to provide 256 discrete levels, or a ratio of 256:1?

(b) 8 bits

Question 71

A-005-007-005
Adding one bit to the word length, is equivalent to adding ____ dB to the dynamic range of the digitizer:

(a) 1 dB
(b) 4 dB
(c) 3 dB
(d) 6 dB

Answer 71

A-005-007-005
Adding one bit to the word length, is equivalent to adding ____ dB to the dynamic range of the digitizer:

(d) 6 dB

Question 72

A-005-007-006
What do you call the circuit which employs an analog to digital converter, a mathematical transform, a digital to analog converter and a low pass filter?

(a) Digital formatter
(b) Mathematical transformer
(c) Digital signal processor
(d) Digital transformer

Answer 72

A-005-007-006
What do you call the circuit which employs an analog to digital converter, a mathematical transform, a digital to analog converter and a low pass filter?

(c) Digital signal processor

Question 73

A-005-007-007
Which principle is not associated with analog signal processing?

(a) Frequency division
(b) Compression
(c) Bandwidth limiting
(d) Clipping

Answer 73

A-005-007-007
Which principle is not associated with analog signal processing?

(a) Frequency division

Question 74

A-005-007-008
Which of the following is not a method used for peak limiting, in a signal processor?

(a) Frequency clipping
(b) RF clipping
(c) Compression
(d) AF clipping

Answer 74

A-005-007-008
Which of the following is not a method used for peak limiting, in a signal processor?

(a) Frequency clipping

Question 75

A-005-007-009
What is the undesirable result of AF clipping in a speech processor?

(a) Reduced average power
(b) Increased average power
(c) Increased harmonic distortion
(d) Reduction in peak amplitude

Answer 75

A-005-007-009
What is the undesirable result of AF clipping in a speech processor?

(c) Increased harmonic distortion

Question 76

A-005-007-010
Which description is not correct? You are planning to build a speech processor for your transceiver. Compared to AF clipping, RF clipping:

(a) has less distortion
(b) is easier to implement
(c) is more expensive to implement
(d) is more difficult to implement

Answer 76

A-005-007-010
Which description is not correct? You are planning to build a speech processor for your transceiver. Compared to AF clipping, RF clipping:

(b) is easier to implement

Question 77

A-005-007-011
Automatic Level Control (ALC) is another name for:

(a) AF compression
(b) RF compression
(c) RF clipping
(d) AF clipping

Answer 77

A-005-007-011
Automatic Level Control (ALC) is another name for:

(b) RF compression

Question 78

A-005-008-001
What digital code consists of elements having unequal length?

(a) Varicode
(b) AX.25
(c) Baudot
(d) ASCII

Answer 78

A-005-008-001
What digital code consists of elements having unequal length?

(a) Varicode

Question 79

A-005-008-002
Open Systems Interconnection (OSI) model standardizes communications functions as layers within a data communications system. Amateur digital radio systems often follow the OSI model in structure. What is the base layer of the OSI model involving the interconnection of a packet radio TNC to a computer terminal?

(a) The link layer
(b) The network layer
(c) The transport layer
(d) The physical layer

Answer 79

A-005-008-002
Open Systems Interconnection (OSI) model standardizes communications functions as layers within a data communications system. Amateur digital radio systems often follow the OSI model in structure. What is the base layer of the OSI model involving the interconnection of a packet radio TNC to a computer terminal?

(d) The physical layer

Question 80

A-005-008-003
What is the purpose of a Cyclic Redundancy Check (CRC)?

(a) Lossy compression
(b) Error correction
(c) Lossless compression
(d) Error detection

Answer 80

A-005-008-003
What is the purpose of a Cyclic Redundancy Check (CRC)?

(d) Error detection

Question 81

A-005-008-004
What is one advantage of using ASCII rather than Baudot code?

(a) ASCII includes built-in error correction
(b) ASCII characters contain fewer information bits
(c) The larger character set allows store-and-forward
(d) It includes both upper and lower case text characters in the code

Answer 81

A-005-008-004
What is one advantage of using ASCII rather than Baudot code?

(d) It includes both upper and lower case text characters in the code

Question 82

A-005-008-005
What type of error control system is used in AMTOR ARQ (Mode A)?

(a) The receiving station checks the frame check sequence (FCS) against the transmitted FCS
(b) The receiving station automatically requests repeats when needed
(c) Each character is sent twice
(d) Mode A AMTOR does not include an error control system

Answer 82

A-005-008-005
What type of error control system is used in AMTOR ARQ (Mode A)?

(b) The receiving station automatically requests repeats when needed

Question 83

A-005-008-006
What error-correction system is used in AMTOR FEC (Mode B)?

(a) Mode B AMTOR does not include an error-correction system
(b) The receiving station automatically requests repeats when needed
(c) Each character is sent twice
(d) The receiving station checks the frame check sequence (FCS) against the transmitted FCS

Answer 83

A-005-008-006
What error-correction system is used in AMTOR FEC (Mode B)?

(c) Each character is sent twice

Question 84

A-005-008-007
APRS (Automatic Packet Reporting System) does NOT support which one of these functions?

(a) Two-way messaging
(b) Telemetry
(c) Automatic link establishment
(d) Amateur-specific local information broadcast

Answer 84

A-005-008-007
APRS (Automatic Packet Reporting System) does NOT support which one of these functions?

(c) Automatic link establishment

Question 85

A-005-008-008
Which algorithm may be used to create a Cyclic Redundancy Check (CRC)?

(a) Dynamic Huffman code
(b) Convolution code
(c) Hash function
(d) Lempel-Ziv routine

Answer 85

A-005-008-008
Which algorithm may be used to create a Cyclic Redundancy Check (CRC)?

(c) Hash function

Question 86

A-005-008-009
The designator AX.25 is associated with which amateur radio mode?

(a) RTTY
(b) ASCII
(c) packet
(d) spread spectrum speech

Answer 86

A-005-008-009
The designator AX.25 is associated with which amateur radio mode?

(c) packet

Question 87

A-005-008-010
How many information bits are included in the Baudot code?

(a) 7
(b) 5
(c) 8
(d) 6

Answer 87

A-005-008-010
How many information bits are included in the Baudot code?

(b) 5

Question 88

A-005-008-011
How many information bits are included in the ISO-8859 extension to the ASCII code?

(a) 8
(b) 7
(c) 6
(d) 5

Answer 88

A-005-008-011
How many information bits are included in the ISO-8859 extension to the ASCII code?

(a) 8

Question 89

A-005-009-001
What term describes a wide-band communications system in which the RF carrier varies according to some predetermined sequence?

(a) Amplitude-companded single sideband
(b) AMTOR
(c) Spread spectrum communication
(d) Time domain frequency modulation

Answer 89

A-005-009-001
What term describes a wide-band communications system in which the RF carrier varies according to some predetermined sequence?

(c) Spread spectrum communication

Question 90

A-005-009-002
What is the term used to describe a spread spectrum communications system where the centre frequency of a conventional carrier is changed many times per second in accordance with a pseudorandom list of channels?

(a) Direct sequence
(b) Time-domain frequency modulation
(c) Frequency companded spread spectrum
(d) Frequency hopping

Answer 90

A-005-009-002
What is the term used to describe a spread spectrum communications system where the centre frequency of a conventional carrier is changed many times per second in accordance with a pseudorandom list of channels?

(d) Frequency hopping

Question 91

A-005-009-003
What term is used to describe a spread spectrum communications system in which a very fast binary bit stream is used to shift the phase of an RF carrier?

(a) Direct sequence
(b) Frequency hopping
(c) Phase companded spread spectrum
(d) Binary phase-shift keying

Answer 91

A-005-009-003
What term is used to describe a spread spectrum communications system in which a very fast binary bit stream is used to shift the phase of an RF carrier?

(a) Direct sequence

Question 92

A-005-009-004
Frequency hopping is used with which type of transmission?

(a) Spread spectrum
(b) AMTOR
(c) Packet
(d) RTTY

Answer 92

A-005-009-004
Frequency hopping is used with which type of transmission?

(a) Spread spectrum

Question 93

A-005-009-005
Direct sequence is used with which type of transmission?

(a) AMTOR
(b) Packet
(c) RTTY
(d) Spread spectrum

Answer 93

A-005-009-005
Direct sequence is used with which type of transmission?

(d) Spread spectrum

Question 94

A-005-009-006
Which type of signal is used to produce a predetermined alteration in the carrier for spread spectrum communication?

(a) Pseudo-random sequence
(b) Frequency-companded sequence
(c) Quantizing noise
(d) Random noise sequence

Answer 94

A-005-009-006
Which type of signal is used to produce a predetermined alteration in the carrier for spread spectrum communication?

(a) Pseudo-random sequence

Question 95

A-005-009-007
Why is it difficult to monitor a spread spectrum transmission?

(a) It requires narrower bandwidth than most receivers have
(b) Your receiver must be frequency-synchronized to the transmitter
(c) It varies too quickly in amplitude
(d) The signal is too distorted for comfortable listening

Answer 95

A-005-009-007
Why is it difficult to monitor a spread spectrum transmission?

(b) Your receiver must be frequency-synchronized to the transmitter

Question 96

A-005-009-008
What is frequency hopping spread spectrum?

(a) The carrier is amplitude-modulated over a wide range called the spread
(b) The carrier frequency is changed in accordance with a pseudo-random list of channels
(c) The carrier is frequency-companded
(d) The carrier is phase-shifted by a fast binary bit stream

Answer 96

A-005-009-008
What is frequency hopping spread spectrum?

(b) The carrier frequency is changed in accordance with a pseudo-random list of channels

Question 97

A-005-009-009
What is direct-sequence spread spectrum?

(a) The carrier is amplitude modulated over a range called the spread
(b) The carrier is frequency-companded
(c) The carrier is altered in accordance with a pseudo-random list of channels
(d) The carrier is phase-shifted by a fast binary bit stream

Answer 97

A-005-009-009
What is direct-sequence spread spectrum?

(d) The carrier is phase-shifted by a fast binary bit stream

Question 98

A-005-009-010
Why are received spread-spectrum signals so resistant to interference?

(a) The receiver is always equipped with a special digital signal processor (DSP) interference filter
(b) Signals not using the spectrum-spreading algorithm are suppressed in the receiver
(c) If interference is detected by the receiver, it will signal the transmitter to change frequencies
(d) The high power used by a spread-spectrum transmitter keeps its signal from being easily overpowered

Answer 98

A-005-009-010
Why are received spread-spectrum signals so resistant to interference?

(b) Signals not using the spectrum-spreading algorithm are suppressed in the receiver

Question 99

A-005-009-011
How does the spread-spectrum technique of frequency hopping work?

(a) If interference is detected by the receiver, it will signal the transmitter to change frequency
(b) If interference is detected by the receiver, it will signal the transmitter to wait until the frequency is clear
(c) A pseudo-random bit stream is used to shift the phase of an RF carrier very rapidly in a particular sequence
(d) The frequency of an RF carrier is changed very rapidly according to a particular pseudo-random sequence

Answer 99

A-005-009-011
How does the spread-spectrum technique of frequency hopping work?

(d) The frequency of an RF carrier is changed very rapidly according to a particular pseudo-random sequence