CMRT Troubleshooting & Repair Techniques 4

Question 1

A technician notices radar performance degrades in rain but sea clutter appears normal. Which subsystem should be investigated first?

Accepted Answer

FTC (Fast Time Constant) / rain clutter circuit

Answer

Rain clutter suppression is handled by the FTC (differentiation) circuit; if it fails, rain returns are not suppressed while sea clutter performance remains normal.

Question 2

A ARPA (Automatic Radar Plotting Aid) is generating erratic target tracks. The radar bearings and ranges appear accurate. What is the most likely cause?

Accepted Answer

Speed or course input data error from the ship's sensors

Answer

ARPA target tracking relies on accurate speed and course inputs; erratic tracks with correct radar video indicate a sensor data error, not a radar RF problem.

Question 3

A radar technician suspects a failing diode in the duplexer (circulator). Which symptom would best confirm this diagnosis?

Accepted Answer

Receiver noise figure is degraded and transmitter power leaks into receiver path

Answer

A failed circulator diode allows transmit energy to leak into the receiver and degrades the noise figure, potentially damaging the receiver front end.

Question 4

During a radar alignment, a technician finds the antenna's horizontal beamwidth is wider than specification. What component is most likely at fault?

Accepted Answer

Damaged or corroded slotted waveguide array elements

Answer

The slotted waveguide array determines the horizontal beamwidth; damage or corrosion to the slots degrades the antenna pattern and widens the beam.

Question 5

A radar shows strong target returns but all targets appear at double their actual range. What is the most likely cause?

Accepted Answer

Timebase generator is running at half the correct frequency

Answer

If the timebase generator runs at half frequency, the sweep takes twice as long, making targets appear at double their actual range.

(CMRT) Certified Marine Radar Technician Practice Test

(CMRT) Certified Marine Radar Technician Practice Test

CMRT Troubleshooting & Repair Techniques 4