Key Topic 46: Equipment Faults-3

Question 1

8-46F1: Silicon crystals are used in RADAR mixer and detector stages. Using an ohmmeter, how might a crystal be checked to determine if it is functional?

A. Its resistance should be the same in both directions.
B. Its resistance should be low in one direction and high in the opposite direction.
C. Its resistance cannot be checked with a DC ohmmeter because the crystal acts as a rectifier.
D. It would be more appropriate to use a VTVM and measure the voltage drop across the crystal.

Answer 1

B. Its resistance should be low in one direction and high in the opposite direction.

Question 2

8-46F2: In a RADAR unit, if the crystal mixer becomes defective, replace the:

A. Crystal only.
B. The crystal and the ATR tube.
C. The crystal and the TR tube.
D. The crystal and the klystron.

Answer 2

C. The crystal and the TR tube.

Question 3

8-46F3: An increase in magnetron current that coincides with a decrease in power output is an indication of what?

A. The pulse length decreasing.
B. A high SWR.
C. A high magnetron heater voltage.
D. The external magnet weakening.

Answer 3

D. The external magnet weakening.

Question 4

8-46F4: It is reported that the RADAR is not receiving small targets. The most likely causes are:

A. Magnetron, IF amplifier, or receiver turning.
B. PFN, crystals, or processor memory.
C. Crystals, local oscillator tuning, or power supply.
D. Fuse blown, IF amp, or video processor.

Answer 4

A. Magnetron, IF amplifier, or receiver turning.

Question 5

8-46F5: A high magnetron current indicates a/an:

A. Defective AFC crystal.
B. Increase in duty cycle.
C. Defective external magnetic field.
D. High standing wave ratio (SWR).

Answer 5

C. Defective external magnetic field.

Question 6

8-46F6: Low or no mixer current could be caused by:

A. Local oscillator frequency misadjustment.
B. TR cell failure.
C. Mixer diode degradation.
D. All of the above.

Answer 6

D. All of the above.