Key Topic 24: Automatic Frequency Control -AFC

Question 1

8-24C1: The AFC system is used to:

A. Control the frequency of the magnetron.
B. Control the frequency of the klystron.
C. Control the receiver gain.
D. Control the frequency of the incoming pulses.

Answer 1

B. Control the frequency of the klystron.

Question 2

8-24C2: A circuit used to develop AFC voltage in a RADAR receiver is called the:

A. Peak detector.
B. Crystal mixer.
C. Second detector.
D. Discriminator.

Answer 2

D. Discriminator.

Question 3

8-24C3: In the AFC system, the discriminator compares the frequencies of the:

A. Magnetron and klystron.
B. PRR generator and magnetron.
C. Magnetron and cyrstal detector.
D. Magnetron and video amplifier.

Answer 3

A. Magnetron and klystron.

Question 4

8-24C4: An AFC system keeps the receiver tuned to the transmitted signal by varying the frequency of the:

A. Magnetron.
B. IF amplifier stage.
C. Local oscillator.
D. Cavity duplexer.

Answer 4

C. Local oscillator.

Question 5

8-24C5: A RADAR transmitter is operating on 3.0 GHz and the reflex klystron local oscillator, operating at 3.060 GHz, develops a 60 MHz IF. If the magnetron drifts higher in frequency, the AFC system must cause the klystron repeller plate to become:

A. More positive.
B. More negative.
C. Less positive.
D. Less negative.

Answer 5

B. More negative.

Question 6

8-24C6: What component is block 50 in Fig. 8A1?

A. IF amplifier.
B. AFC Amplifier.
C. Discriminator.
D. Crystal detector.

Answer 6

C. Discriminator.