FCC Commercial Element 3 pool, section 43

Subelement F

Receivers

Section 43

Oscillators

343F1

Why is the Colpitts oscillator circuit commonly used in a VFO (variable frequency oscillator)?

A.
It can be phase locked.
B.
It can be remotely tuned.
Correct Answer
C.
It is stable.
D.
It has little or no effect on the crystal’s stability.

343F1

Why is the Colpitts oscillator circuit commonly used in a VFO (variable frequency oscillator)?

It is stable.

See the Electronics Notes site for the articles on:

For an overview, please see the Tutorials Point site, for the article Sinusoidal Oscillators - Quick Guide

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343F2

What is the oscillator stage called in a frequency synthesizer?

Correct Answer
A.
VCO.
B.
Divider.
C.
Phase detector.
D.
Reference standard.

343F2

What is the oscillator stage called in a frequency synthesizer?

VCO.

From wp2ahg:

A voltage-controlled oscillator or VCO is an electronic oscillator whose oscillation frequency is controlled by a voltage input.

See the Electronics Notes site for the articles on:

For an overview, please see the Tutorials Point site, for the article Sinusoidal Oscillators - Quick Guide

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343F3

What are three major oscillator circuits found in radio equipment?

A.
Taft, Pierce, and negative feedback.
B.
Colpitts, Hartley, and Taft.
C.
Taft, Hartley, and Pierce.
Correct Answer
D.
Colpitts, Hartley, and Pierce.

343F3

What are three major oscillator circuits found in radio equipment?

Colpitts, Hartley, and Pierce.

Memory tip: Remember CHiPs!

A good to-the-point explanation on the kb6nu site called Oscillators and signal sources: types of oscillators; synthesizers and phase-locked loops; direct digital synthesizers; stabilizing thermal drift; microphonics; high-accuracy oscillators. The explanations are shorted than the title here.

Also, see the Electronics Notes site for the articles on:

For an overview, please see the Tutorials Point site, for the article Sinusoidal Oscillators - Quick Guide

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343F4

Which type of oscillator circuit is commonly used in a VFO (variable frequency oscillator)?

Correct Answer
A.
Colpitts.
B.
Pierce.
C.
Hartley.
D.
Negative feedback.

343F4

Which type of oscillator circuit is commonly used in a VFO (variable frequency oscillator)?

Colpitts.

See the Electronics Notes site for the articles on:

For an overview, please see the Tutorials Point site, for the article Sinusoidal Oscillators - Quick Guide

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343F5

What condition must exist for a circuit to oscillate? It must:

A.
Have a gain of less than 1.
B.
Be neutralized.
C.
Have sufficient negative feedback.
Correct Answer
D.
Have sufficient positive feedback.

343F5

What condition must exist for a circuit to oscillate? It must:

Have sufficient positive feedback.

See the Electronics Notes site for the articles on:

For an overview, please see the Tutorials Point site, for the article Sinusoidal Oscillators - Quick Guide

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343F6

In Figure 3F15, which block diagram symbol (labeled 1 through 4) is used to represent a local oscillator?

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

343F6

In Figure 3F15, which block diagram symbol (labeled 1 through 4) is used to represent a local oscillator?

First, there is the RF Amplifier and tuning of the received signal from the antenna. Then, (1) is the mixer, and (2) is the local oscillator.

See the Electronics Notes site for the articles on:

Superheterodyne Receiver Block Diagram

For an overview, please see the Tutorials Point site, for the article Sinusoidal Oscillators - Quick Guide

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