8-12B: 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

ANSWER D
High voltage is found within the heart of the magnetron on the sealed cathode. Cathode current is several amps, and the cathode is large so that it can withstand the tremendous amount of heat that develops. Keep metal tools well away from the magnetron because of its large permanent magnet. The exposed anode is at ground potential, and a large megative voltage of several kilovolts is applied to the cathode during the magnetron’s oscillating state.

Question 2

8-12B4

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 2

ANSWER D
The magnetron is a diode with a magnetic field between the cathode and the anode; the magnetic field controls the tube. When the magnet gets weak, the magnetron must be replaced.