CMRT Troubleshooting & Repair Techniques 2

Question 1

A marine radar displays a 'heading line' that drifts slowly over time. What is the most likely cause?

Accepted Answer

Gyrocompass or heading sensor drift

Answer

Heading line drift is caused by drift in the gyrocompass or heading sensor feeding data to the radar.

Question 2

When testing a radar's TR (transmit/receive) limiter, a technician finds it has high insertion loss in the receive path. What symptom will this cause?

Accepted Answer

Reduced receiver sensitivity and poor target detection

Answer

High insertion loss in the TR limiter attenuates the received signal, reducing receiver sensitivity and degrading target detection.

Question 3

A radar technician measures abnormally high anode current on the magnetron. What should be checked first?

Accepted Answer

Modulator pulse width and peak voltage

Answer

High anode current is typically caused by incorrect modulator pulse width or excessive peak voltage applied to the magnetron.

Question 4

A radar system exhibits 'ringing' artifacts — bright concentric rings near the center of the display. What is the most probable cause?

Accepted Answer

Poor transmitter-to-antenna impedance match causing reflections

Answer

Ringing artifacts are caused by impedance mismatches in the waveguide or antenna, creating internal reflections that appear as concentric rings.

Question 5

After replacing a radar display unit, the technician notices the range rings are no longer accurate. What is the most likely calibration step needed?

Accepted Answer

Calibrate the timebase (sweep) generator

Answer

Range ring accuracy depends on the timebase generator; calibrating it ensures range rings correctly represent true distances.

(CMRT) Certified Marine Radar Technician Practice Test

(CMRT) Certified Marine Radar Technician Practice Test

CMRT Troubleshooting & Repair Techniques 2