Key Topic 43: Oscillators

Question 1

3-43F1: 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.
C. It is stable.
D. It has little or no effect on the crystal’s stability

Answer 1

C. It is stable.

Question 2

3-43F2: What is the oscillator stage called in a frequency synthesizer?

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

Answer 2

A. VCO.

Question 3

3-43F3: 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.
D. Colpitts, Hartley, and Pierce.

Answer 3

D. Colpitts, Hartley, and Pierce.

Question 4

3-43F4: Which type of oscillator circuit is commonly used in a VFO (variable frequency oscillator)?

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

Answer 4

A. Colpitts.

Question 5

3-43F5: 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.
D. Have sufficient positive feedback.

Answer 5

D. Have sufficient positive feedback.

Question 6

3-43F6: In Figure 3F15, which block diagram symbol (labeled 1 through 4) is used to represent a local oscillator?

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

Answer 6

B. 2