Key Topic 12: Magnetrons

Question 1

8-12B1: High voltage is applied to what element of the magnetron?

A. The waveguide.
B. The anode.
C. The plate cap.
D. The cathode.

Answer 1

D. The cathode.

Question 2

8-12B2: The characteristic of the magnetron output pulse that relates to accurate range measurement is its:

A. Amplitude.
B. Decay time.
C. Rise time.
D. Duration.

Answer 2

C. Rise time.

Question 3

3-12B3: What device is used as a transmitter in a marine RADAR system?

A. Magnetron.
B. Klystron.
C. Beam-powered pentode.
D. Thyratron

Answer 3

A. Magnetron.

Question 4

3-12B4: The magnetron is:

A. A type of diode that requires an internal magnetic field.
B. A triode that requires an external magnetic field.
C. Used as the local oscillator in the RADAR unit.
D. A type of diode that requires an external magnetic field.

Answer 4

D. A type of diode that requires an external magnetic field.

Question 5

3-12B5: A negative voltage is commonly applied to the magnetron cathode rather than a positive voltage to the magnetron anode because:

A. The cathode must be made neutral to force electrons into the drift area.
B. A positive voltage would tend to nullify or weaken the magnetic field.
C. The anode can be operated at ground potential for safety reasons.
D. The cavities might not be shock-excited into oscillation by a positive voltage.

Answer 5

C. The anode can be operated at ground potential for safety reasons.

Question 6

3-12B6: The anode of a magnetron is normally maintained at ground potential:

A. Because it operates more efficiently that way.
B. For safety purposes.
C. Never. It must be highly positive to attract the electrons.
D. Because greater peak-power ratings can be achieved.

Answer 6

B. For safety purposes.