Canadian Basic Qualification pool, section B-003-005

Subelement B-003

B-003

Section B-003-005

B-003-005-001

In an SSB/CW receiver, what is the purpose of the antenna?

A.
Separate signals from atmospheric noise
Correct Answer
B.
Convert electromagnetic waves into electrical currents
C.
Polarize signals received via sky-wave propagation
D.
Protect the receiver from overload

B-003-005-001

Regardless of the emission mode, the receiving antenna produces tiny electrical signals with the same frequency as the electromagnetic waves that propagate past it.

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-003-005-002

In an SSB/CW receiver, what is the purpose of the radio frequency (RF) amplifier?

Correct Answer
A.
Increase the sensitivity of the receiver
B.
Provide sufficient gain to activate the limiter circuit
C.
Provide sufficient drive for the automatic gain control circuit (AGC)
D.
Increase the local oscillator signal to drive the mixer

B-003-005-002

In a receiver, an RF amplifier is generally used to amplify the tiny signal (i.e., microvolts) arriving from the antenna. As those signals are really weak, the first amplifier stage must introduce as little supplementary noise as possible. Once amplified, the incoming signal is fed to the mixer.

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-003-005-003

In an SSB/CW receiver, what is the purpose of the mixer?

A.
Provide USB and LSB signals for sideband selection
Correct Answer
B.
Convert the received signal into the intermediate frequency
C.
Remove the carrier from the received signal
D.
Convert the beat frequency oscillator signal to audio

B-003-005-003

The mixer accepts two inputs: the incoming signal and the local oscillator. Mixing returns two new products: the sum of the two inputs and the difference of the two inputs. The IF filter seeks to let only one of the products into the intermediate frequency chain for amplification through the IF Amplifier.

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-003-005-004

In an SSB/CW receiver, what is the purpose of the signal generated by the local oscillator?

A.
It is fed to the receiver input to provide band edge markers
Correct Answer
B.
It is mixed with the incoming signal to produce the intermediate frequency
C.
It is mixed with the intermediate frequency signal to produce a CW sidetone
D.
It is mixed with the beat frequency oscillator signal to produce audio

B-003-005-004

The mixer in a receiver takes in the incoming signal and mixes it with a local oscillator to transpose (usually down) the incoming signal to a fixed intermediate frequency (the Superheterodyne concept). Using a fixed and lower intermediate frequency regardless of operating frequency facilitates the achievement of high gain and selectivity. Changing the operating frequency is a simple matter of changing the frequency of the local oscillator.

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-003-005-005

In an SSB/CW receiver, what is the purpose of the intermediate frequency (IF) filter?

A.
For SSB reception, select the desired sideband
Correct Answer
B.
Provide most of the selectivity of the receiver
C.
Reject RF from the product detector, passing only audio
D.
Suppress spurious signals from the IF amplifier

B-003-005-005

As opposed to the front-end that can be relatively wide, the IF chain in a superheterodyne receiver sets the final bandwidth so only one channel is received at a time.

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

Tags: none

B-003-005-006

In an SSB/CW receiver, what is the purpose of the intermediate frequency (IF) amplifier?

Correct Answer
A.
Provide most of the receiver gain
B.
Increase the level of the recovered modulation
C.
Provide sufficient gain to activate the limiter circuit
D.
Boost the signal as required for the mixer

B-003-005-006

In a superheterodyne receiver, the intermediate frequency chain supplies most of the gain and detection is performed on the amplified intermediate frequency signal.

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

Tags: none

B-003-005-007

In an SSB/CW receiver, what is the purpose of the product detector?

A.
Detect frequency drift to control the local oscillator
B.
For SSB reception, reject the unwanted sideband
Correct Answer
C.
Recover the transmitted modulation
D.
Convert audio frequency electrical signals into sound

B-003-005-007

In an SSB/CW receiver, detection (recovery of the message) is performed by a 'product detector'. The 'product detector' mixes the intermediate frequency with a signal from the beat frequency oscillator (BFO) to transpose the IF signal down to the audible range. The demodulated signal is applied to an audio amplifier to provide sufficient drive for the loudspeaker.

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

Tags: none

B-003-005-008

In an SSB/CW receiver, what is the purpose of the signal produced by the beat frequency oscillator (BFO)?

A.
It is fed to the receiver input to provide band edge markers
B.
It drives the automatic gain control circuit to maintain a constant audio level
Correct Answer
C.
It is mixed with the IF to recover the transmitted modulation
D.
It is mixed with the incoming signal to produce the intermediate frequency

B-003-005-008

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-003-005-009

In an SSB/CW receiver, what is the purpose of the audio frequency (AF) amplifier?

A.
Convert audio frequency electrical signals into sound
Correct Answer
B.
Increase the level of the recovered modulation
C.
Increase the BFO signal for driving the product detector
D.
Provide audible warning of receiver overload

B-003-005-009

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

Tags: none

B-003-005-010

In an SSB/CW receiver, which stage could include an audio band-pass filter?

Correct Answer
A.
AF amplifier
B.
IF amplifier
C.
IF filter
D.
Limiter

B-003-005-010

If an even sharper bandwidth is desired, it is possible to add selectivity in the audio chain.

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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