Key Topic 21: Local Oscillators

Question 1

8-21C1: The error voltage from the discriminator is applied to the:

A. Repeller (reflector) of the klystron.
B. Grids of the IF amplifier.
C. Grids of the RF amplifiers.
D. Magnetron.

Answer 1

A. Repeller (reflector) of the klystron.

Question 2

8-21C2: In a RADAR unit, the local oscillator is a:

A. Hydrogen Thyratron.
B. Klystron.
C. Pentagrid converter tube.
D. Reactance tube modulator.

Answer 2

B. Klystron.

Question 3

3-21C3: What component of a RADAR receiver is represented by block 48 in Fig. 8A1?

A. Klystron (local oscillator).
B. Discriminator.
C. IF amplifier.
D. Crystal detector.

Answer 3

A. Klystron (local oscillator).

Question 4

3-21C4: What device(s) could be used as the local oscillator in a RADAR receiver?

A. Thyratron.
B. Klystron.
C. Klystron and a Gunn Diode.
D. Gunndiode.

Answer 4

C. Klystron and a Gunn Diode.

Question 5

3-21C5: The klystron ocal oscillator is constantly kept on frequency by:

A. Constant manual adjustments.
B. The automatic Frequency Control circuit.
C. A feedback loop from the crystal detector.
D. A feedback loop from the TR box.

Answer 5

B. The automatic Frequency Control circuit.

Question 6

3-21C6: How may the frequency of the klystron be varied?

A. Small changes can be made by adjusting the anode voltage.
B. Large changes can be made by adjusting the frequency.
C. By changing the phasing of the buncher grids.
D. Small changes can be made by adjusting the repeller voltage and large changes can be made by adjusting the size of the resonant cavity.

Answer 6

D. Small changes can be made by adjusting the repeller voltage and large changes can be made by adjusting the size of the resonant cavity.