Key Topic 56: Technology

Question 1

3-56G1: How can intermodulation interference between two transmitters in close proximity often be reduced or eliminated?

A. By using a Class C final amplifier with a high driving power.
B. By installing a terminated circulator or ferrite isolator in the feed line to the transmitter and duplexer.
C. By installing a band-pass filter in the antenna feed line.
D. By installing a low-pass filter in the antenna feed line.

Answer 1

B. By installing a terminated circulator or ferrite isolator in the feed line to the transmitter and duplexer.

Question 2

3-56G2: How can parasitic oscillations be eliminated in a power amplifier?

A. By tuning for maximum SWR.
B. By tuning for maximum power output.
C. By neutralization.
D. By tuning the output.

Answer 2

C. By neutralization.

Question 3

3-56G3: What is the name of the condition that occurs when the signals of two transmitters in close proximity mix together in one or both of their final amplifiers, and unwanted signals at the sum and difference frequencies of the original transmissions are generated?

A. Amplifier desensitization.
B. Neutralization.
C. Adjacent channel interference.
D. Intermodulation interference.

Answer 3

D. Intermodulation interference.

Question 4

3-56G4: What term describes a wide-bandwidth communications system in which the RF carrier varies according to some pre-determined sequence?

A. Spread-spectrum communication.
B. AMTOR.
C. SITOR.
D. Time-domain frequency modulation.

Answer 4

A. Spread-spectrum communication.

Question 5

3-56G5: How can even-order harmonics be reduced or prevented in transmitter amplifier design?

A by using a push-push amplifier.
B. By operating class C.
C. By using a push-pull amplifier.
D. By operating class AB.

Answer 5

C. By using a push-pull amplifier.

Question 6

3-56G6: What is the modulation type that can be a frequency hopping of one carrier or multiple simultaneous carriers?

A. SSB.
B. FM.
C. OFSK.
D. Spread spectrum.

Answer 6

D. Spread spectrum.