CMRT Troubleshooting & Repair Techniques 5

Question 1

A radar technician is troubleshooting a system where the display shows no video but the timebase sweep is visible. What does this indicate?

Accepted Answer

The video signal path from receiver to display has a fault

Answer

A visible sweep with no video indicates the timing and display hardware work but the video signal from the receiver is not reaching the display.

Question 2

When performing a radar power output measurement using a calibrated power meter, what safety precaution is MOST important?

Accepted Answer

Ensure the power meter is rated for the radar's peak pulse power, not just average power

Answer

Radar peak pulse power can be hundreds of kilowatts even though average power is low; using an undersized power meter will damage it and give incorrect readings.

Question 3

A technician finds corrosion inside a coaxial connector between the transceiver and antenna. After cleaning, what test should be performed before returning the system to service?

Accepted Answer

VSWR measurement to confirm acceptable impedance match

Answer

After cleaning and reconnecting a coaxial connector, VSWR must be measured to verify the connector provides a good impedance match and has not introduced reflections.

Question 4

A radar technician is using a substitution method to isolate a fault. This technique involves:

Accepted Answer

Replacing suspected faulty modules with known-good units to identify the defective stage

Answer

Substitution troubleshooting replaces suspect modules with confirmed-good spares to isolate the defective stage quickly without detailed circuit analysis.

Question 5

A radar's performance monitor shows a decrease in the sensitivity level (MDS — minimum detectable signal) over time. What is the most common cause?

Accepted Answer

Gradual magnetron frequency drift or aging reducing receiver-to-transmitter coupling efficiency

Answer

As a magnetron ages, its frequency can drift, reducing AFC lock quality and degrading receiver sensitivity as the IF passband becomes misaligned.

(CMRT) Certified Marine Radar Technician Practice Test

(CMRT) Certified Marine Radar Technician Practice Test

CMRT Troubleshooting & Repair Techniques 5