Troubleshooting & Repair Techniques Flashcards

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

Answer: FTC (Fast Time Constant) / rain clutter circuit

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

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

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

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.

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

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

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

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

Answer: Damaged or corroded slotted waveguide array elements

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

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

Answer: Timebase generator is running at half the correct frequency

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

A vessel's radar shows intermittent loss of synchronization between the sweep and the antenna bearing. What component should be inspected?

Answer: Azimuth encoder or bearing pulse generator on the antenna pedestal

The azimuth encoder generates bearing pulses that synchronize the display sweep with antenna rotation; a faulty encoder causes bearing sync loss.

After a lightning strike near a vessel, the radar receiver is completely dead but the transmitter still functions. Which component is most likely damaged?

Answer: Low-noise amplifier (LNA) or receiver front-end diode mixer

Lightning-induced transients most commonly destroy the sensitive LNA or front-end mixer diodes in the receiver, which are not protected by the TR limiter against an external surge.