Canadian (from VE2AAY) Basic Qualification pool, section L07

Subelement L07

Active Devices: Diodes, Transistors and Tubes.

Section L07

B-4-1-1

A circuit designed to increase the level of its input signal is called:

A.
a receiver
Correct Answer
B.
an amplifier
C.
a modulator
D.
an oscillator

B-4-1-1

key word: INCREASE. An amplifier reproduces its input signal into a larger output signal ( more voltage, more current, more power).

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-1-2

If an amplifier becomes non-linear, the output signal would:

A.
be saturated
B.
cause oscillations
C.
overload the power supply
Correct Answer
D.
become distorted

B-4-1-2

If an amplifier is 'linear', amplification, as a ratio of output versus input, will be constant regardless of frequency or amplitude of the input signal. Linearity is synonym with 'absence of distortion'. 'Non-linear' implies distortion.

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B-4-1-3

To increase the level of very weak radio signals from an antenna, you would use:

Correct Answer
A.
an RF amplifier
B.
an RF oscillator
C.
an audio oscillator
D.
an audio amplifier

B-4-1-3

key words: INCREASE WEAK RADIO signals. A radio frequency (RF) amplifier must be used.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-1-4

To increase the level of very weak signals from a microphone you would use:

A.
an RF amplifier
B.
an audio oscillator
Correct Answer
C.
an audio amplifier
D.
an RF oscillator

B-4-1-4

key words: INCREASE WEAK microphone signal. An 'audio amplifier'. Frequently called a 'speech amplifier' or 'microphone amplifier' for this particular application.

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B-4-1-5

The range of frequencies to be amplified by a speech amplifier is typically:

A.
300 to 1000 Hz
B.
40 to 40 000 Hz
Correct Answer
C.
300 to 3000 Hz
D.
3 to 300 Hz

B-4-1-5

Frequencies audible to humans range from 20 Hz to 20 000 Hz. Speech frequencies important for intelligibility in communications range from 300 Hz to 3000 Hz.

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B-4-1-6

Which of the following is not amplified by an amplifier?

A.
Current
B.
Power
C.
Voltage
Correct Answer
D.
Resistance

B-4-1-6

key word: NOT. Amplifiers work on voltage, current and power.

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B-4-1-7

The increase in signal level by an amplifier is called:

A.
modulation
Correct Answer
B.
gain
C.
attenuation
D.
amplitude

B-4-1-7

Gain (synonymous with amplification) is an increase in signal voltage/current/power. 'Attenuation' is a loss (opposite to gain). 'Amplitude' is the instantaneous value of a signal. 'Modulation' is the impression of a message onto another signal.

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B-4-1-8

A device with gain has the property of:

A.
oscillation
B.
modulation
Correct Answer
C.
amplification
D.
attenuation

B-4-1-8

Gain and Amplification are synonymous. 'Attenuation' is a loss (opposite to gain). 'Oscillation' is the production of an Alternating Current (AC) signal. 'Modulation' is the impression of a message onto another signal.

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B-4-1-9

A device labelled "Gain = 10 dB" is likely to be an:

A.
attenuator
B.
oscillator
C.
audio fader
Correct Answer
D.
amplifier

B-4-1-9

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-1-10

Amplifiers can amplify:

A.
voltage, current, or inductance
Correct Answer
B.
voltage, current, or power
C.
current, power, or inductance
D.
voltage, power, or inductance

B-4-1-10

Recall that Inductance, a property of coils, is influenced by "The core material, the core diameter, the length of the coil and the number of turns of wire used to wind the coil".

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B-4-1-11

Which of the following is not a property of an amplifier?

A.
Distortion
Correct Answer
B.
Loss
C.
Gain
D.
Linearity

B-4-1-11

key word: NOT. Gain and Amplification are synonymous. Linearity (or lack of distortion) is a specification of amplifiers. Loss has nothing to do with amplifiers.

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B-4-2-1

Zener diodes are used as:

A.
RF detectors
B.
AF detectors
Correct Answer
C.
voltage regulators
D.
current regulators

B-4-2-1

ZENER diodes maintain a constant voltage across their terminals. Hence, they are used for voltage regulation.

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B-4-2-2

One important application for diodes is recovering information from transmitted signals. This is referred to as:

A.
biasing
Correct Answer
B.
demodulation
C.
regeneration
D.
ionization

B-4-2-2

Detection = DEmodulation = Recovery of the message carried on a radio signal.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-2-3

The primary purpose of a Zener diode is to:

A.
to boost the power supply voltage
B.
provide a path through which current can flow
Correct Answer
C.
regulate or maintain a constant voltage
D.
provide a voltage phase shift

B-4-2-3

ZENER diodes maintain a constant voltage across their terminals. Hence, they are used for voltage regulation.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-2-4

The action of changing alternating current to direct current is called:

A.
amplification
B.
transformation
C.
modulation
Correct Answer
D.
rectification

B-4-2-4

Changing AC to DC is called 'Rectification'. AC is turned into 'pulsating DC' (it flows in one direction only) after going through a diode. In Power Supply circuits, diodes are called 'Rectifiers'. Diodes have two electrodes: Cathode and Anode. Electrons flow from Cathode to Anode in a forward-biased (i.e., a diode subjected to a voltage polarity which permits conduction) diode.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-2-5

The electrodes of a semiconductor diode are known as:

A.
cathode and drain
Correct Answer
B.
anode and cathode
C.
gate and source
D.
collector and base

B-4-2-5

A DIODE, vacuum tube or semiconductor, has two electrodes: Anode and Cathode. Electrons flow from Cathode to Anode in a forward-biased (i.e., a diode subjected to a voltage polarity which permits conduction) diode. Cathode/Grid/Anode(plate) are electrodes in a vacuum triode. Source/Gate/Drain are electrodes in a Field Effect Transistor (FET, N-Channel or P-Channel). Emitter/Base/Collector are electrodes in a Bipolar Transistor ( type PNP or NPN ).

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B-4-2-6

If alternating current is applied to the anode of a diode, what would you expect to see at the cathode?

A.
No signal
B.
Steady direct current
C.
Pulsating alternating current
Correct Answer
D.
Pulsating direct current

B-4-2-6

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-2-7

In a semiconductor diode, electrons flow from:

A.
grid to anode
Correct Answer
B.
cathode to anode
C.
anode to cathode
D.
cathode to grid

B-4-2-7

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-2-8

What semiconductor device glows different colours, depending upon its chemical composition?

A.
A vacuum diode
Correct Answer
B.
A light-emitting diode
C.
A fluorescent bulb
D.
A neon bulb

B-4-2-8

key word: SEMI-CONDUCTOR. "LED", a Light-Emitting Diode.

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B-4-2-9

Voltage regulation is the principal application of the:

Correct Answer
A.
Zener diode
B.
junction diode
C.
light-emitting diode
D.
vacuum diode

B-4-2-9

ZENER diodes maintain a constant voltage across their terminals. Hence, they are used for voltage regulation.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-2-10

In order for a diode to conduct, it must be:

A.
enhanced
B.
reverse-biased
Correct Answer
C.
forward-biased
D.
close coupled

B-4-2-10

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-3-1

Which component can amplify a small signal using low voltages?

A.
A multiple-cell battery
Correct Answer
B.
A PNP transistor
C.
A variable resistor
D.
An electrolytic capacitor

B-4-3-1

key words: AMPLIFY, LOW VOLTAGE. A transistor amplifies signals and can work at a low voltage. Bipolar Transistors ( type PNP or NPN ) as well as Field Effect Transistor (FET, N-Channel or P-Channel) can amplify signals.

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B-4-3-2

The basic semiconductor amplifying device is the:

Correct Answer
A.
transistor
B.
tube
C.
P-N junction
D.
diode

B-4-3-2

key words: SEMICONDUCTOR, AMPLIFY. A transistor amplifies signals. Bipolar Transistors ( type PNP or NPN ) as well as Field Effect Transistor (FET, N-Channel or P-Channel) can amplify signals. A 'single P-N junction' is a diode. Diodes have two main uses: 'Rectification' and 'Detection'.

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B-4-3-3

The three leads from a PNP transistor are named:

A.
drain, base and source
B.
collector, source and drain
C.
gate, source and drain
Correct Answer
D.
collector, emitter and base

B-4-3-3

Emitter/Base/Collector are electrodes in a Bipolar Transistor ( type PNP or NPN ). Source/Gate/Drain are electrodes in a Field Effect Transistor (FET, N-Channel or P-Channel). Cathode/Grid/Anode(plate) are electrodes in a vacuum triode.

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B-4-3-4

If a low level signal is placed at the input to a transistor, a higher level of signal is produced at the output lead. This effect is known as:

A.
detection
B.
modulation
C.
rectification
Correct Answer
D.
amplification

B-4-3-4

Detection = DEmodulation = Recovery of the message carried on a radio signal. 'Modulation' is the impression of a message onto another signal. 'Rectification' turns AC into 'pulsating DC' (it flows in one direction only) after going through a diode.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-3-5

Bipolar transistors usually have:

A.
2 leads
B.
4 leads
Correct Answer
C.
3 leads
D.
1 lead

B-4-3-5

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-3-6

A semiconductor is described as a "general purpose audio NPN device". This would be:

A.
a triode
B.
an audio detector
Correct Answer
C.
a bipolar transistor
D.
a silicon diode

B-4-3-6

key word: NPN. The only choice in the group comprising a sandwich of N-semiconductor and P-semiconductor is the 'Bipolar Transistor'.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-3-7

The two basic types of bipolar transistors are:

A.
diode and triode types
B.
varicap and Zener types
C.
P and N channel types
Correct Answer
D.
NPN and PNP types

B-4-3-7

key word: BIPOLAR TRANSISTOR. It is constructed with a sandwich of N-semiconductor and P-semiconductor: NPN or PNP type.

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B-4-3-8

A transistor can be destroyed in a circuit by:

A.
saturation
B.
cut-off
Correct Answer
C.
excessive heat
D.
excessive light

B-4-3-8

Extreme operating temperatures can rapidly destroy transistors.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-3-9

In a bipolar transistor, the _____________ compares closest to the control grid of a triode vacuum tube.

Correct Answer
A.
base
B.
emitter
C.
source
D.
collector

B-4-3-9

Comparing Triode/Bipolar Transistor/FET in terms of their RESPECTIVE electrodes: Origin of charge carriers = Cathode/Emitter/Source. Control electrode = Grid/Base/Gate. Destination of charge carriers = Anode(plate)/Collector/Drain.

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B-4-3-10

In a bipolar transistor, the _____________ compares closest to the plate of a triode vacuum tube.

A.
gate
B.
emitter
C.
base
Correct Answer
D.
collector

B-4-3-10

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-3-11

In a bipolar transistor, the _____________ compares closest to the cathode of a triode vacuum tube.

A.
collector
B.
base
C.
drain
Correct Answer
D.
emitter

B-4-3-11

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-4-1

The two basic types of field effect transistors (FET) are:

A.
NPN and PNP
B.
germanium and silicon
C.
inductive and capacitive
Correct Answer
D.
N and P channel

B-4-4-1

In a field effect transistor, Source and Drain are the two extremities of a 'channel' made of a single semi-conductor type. NPN and PNP are the two types of BIPOLAR Transistors.

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B-4-4-2

A semiconductor having its leads labelled gate, drain, and source is best described as a:

Correct Answer
A.
field-effect transistor
B.
gated transistor
C.
bipolar transistor
D.
silicon diode

B-4-4-2

Source/Gate/Drain are electrodes in a Field Effect Transistor (FET, N-Channel or P-Channel). Emitter/Base/Collector are electrodes in a Bipolar Transistor ( type PNP or NPN ). Cathode/Grid/Anode(plate) are electrodes in a vacuum triode.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-4-3

In a field effect transistor, the ___________ is the terminal that controls the conductance of the channel.

A.
collector
Correct Answer
B.
gate
C.
drain
D.
source

B-4-4-3

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-4-4

In a field effect transistor, the ___________ is the terminal where the charge carriers enter the channel.

Correct Answer
A.
source
B.
gate
C.
drain
D.
emitter

B-4-4-4

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-4-5

In a field effect transistor, the ___________ is the terminal where the charge carriers leave the channel.

A.
source
B.
gate
Correct Answer
C.
drain
D.
collector

B-4-4-5

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-4-6

Which semiconductor device has characteristics most similar to a triode vacuum tube?

A.
Zener diode
B.
Bipolar transistor
Correct Answer
C.
Field effect transistor
D.
Junction diode

B-4-4-6

The triode and the FET both rely on a reverse voltage on their control electrodes to affect the current through the device.

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B-4-4-7

The control element in the field effect transistor is the:

A.
source
B.
drain
C.
base
Correct Answer
D.
gate

B-4-4-7

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-4-8

If you wish to reduce the current flowing in a field effect transistor, you could:

A.
increase the forward bias voltage
B.
increase the forward bias gain
Correct Answer
C.
increase the reverse bias voltage
D.
decrease the reverse bias voltage

B-4-4-8

The triode and the FET both rely on a reverse voltage on their control electrodes to affect the current through the device.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-4-9

The source of a field effect transistor corresponds to the _______ of a bipolar transistor.

A.
collector
Correct Answer
B.
emitter
C.
base
D.
drain

B-4-4-9

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-4-10

The drain of a field effect transistor corresponds to the _______ of a bipolar transistor.

A.
emitter
Correct Answer
B.
collector
C.
base
D.
source

B-4-4-10

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-4-11

Which two elements in a field effect transistor exhibit fairly similar characteristics?

A.
Source and gate
B.
Gate and drain
C.
Source and base
Correct Answer
D.
Source and drain

B-4-4-11

Source and Drain are the two ends of the same block of semiconductor material, the 'Channel'. Only the control electrode, the Gate, is made of the opposite type of material.

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B-4-5-1

What is one reason a triode vacuum tube might be used instead of a transistor in a circuit?

Correct Answer
A.
It may be able to handle higher power
B.
It uses less current
C.
It is much smaller
D.
It uses lower voltages

B-4-5-1

Vacuum triodes are larger, use current just to heat the filament and require higher voltages than transistors BUT they remain simpler to use in HIGH-POWER amplifiers.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-5-2

Which component can amplify a small signal but must use high voltages?

A.
An electrolytic capacitor
B.
A multiple-cell battery
Correct Answer
C.
A vacuum tube
D.
A transistor

B-4-5-2

key words: AMPLIFY, HIGH VOLTAGE. Vacuum tubes amplify signals but work at higher voltages than transistors (generally low-voltage devices).

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-5-3

A feature common to triode tubes and transistors is that both:

A.
convert electrical energy to radio waves
B.
use heat to cause electron movement
Correct Answer
C.
can amplify signals
D.
have electrons drifting through a vacuum

B-4-5-3

Only vacuum tubes use heat to facilitate electron movement within an envelope free of air.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-5-4

In a vacuum tube, the electrode that is operated with the highest positive potential is the _________.

A.
filament (heater)
B.
cathode
C.
grid
Correct Answer
D.
plate

B-4-5-4

The 'Plate' (or Anode) attracts electrons with a high positive voltage. The Cathode emits electrons. The Grid encircles the Cathode and controls the flow of electrons.

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B-4-5-5

In a vacuum tube, the electrode that is usually a cylinder of wire mesh is the _______.

Correct Answer
A.
grid
B.
filament (heater)
C.
cathode
D.
plate

B-4-5-5

The 'Grid' is a wire mesh (looking like a fence, so to speak) around the Cathode. The 'Plate' (or Anode) attracts electrons with a high positive voltage. The Cathode emits electrons. The Grid encircles the Cathode and controls the flow of electrons.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-5-6

In a vacuum tube, the element that is furthest away from the plate is the __________.

Correct Answer
A.
filament (heater)
B.
grid
C.
emitter
D.
cathode

B-4-5-6

key words: ELEMENT, FURTHEST. A "directly-heated triode" comprises a filament (serving as a cathode, emitting electrons), a grid and a plate (or anode). An "indirectly-heated triode" comprises a heater (heating the cathode), a cathode (emitting electrons), a grid and a plate (or anode).

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-5-7

In a vacuum tube, the electrode that emits electrons is the __________.

A.
grid
B.
collector
C.
plate
Correct Answer
D.
cathode

B-4-5-7

The 'Plate' (or Anode) attracts electrons with a high positive voltage. The Cathode emits electrons. The Grid encircles the Cathode and controls the flow of electrons.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-5-8

What is inside the envelope of a triode tube?

A.
Argon
B.
Air
C.
Neon
Correct Answer
D.
A vacuum

B-4-5-8

A 'vacuum' is the absence of air. Air is pumped out of vacuum tubes (like light bulbs) to prevent the filament from burning up.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-4-5-9

How many grids are there in a triode vacuum tube?

A.
Three plus a filament
Correct Answer
B.
One
C.
Two
D.
Three

B-4-5-9

key words: GRID, TRIODE. A triode is a 3-electrode device: a cathode, a single GRID and a plate (or anode).

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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