FCC Commercial Element 8 pool, section 45

Subelement F

Installation, Maintenance & Repair

Section 45

Equipment Faults-2

845F1

A circuit card in a RADAR system has just been replaced with a spare card. You notice the voltage level at point E in Fig. 8F12 is negative 4.75 volts when the inputs are all at 5 volts. The problem is:

A.
The 25 K resistor is open.
B.
The 100 K resistor has been mistakenly replaced with a 50 K resistor.
C.
The op amp is at the rail voltage.
Correct Answer
D.
The 50 K resistor has been mistakenly replaced with a 25 K resistor.

845F1

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845F2

A defective crystal in the AFC section will cause:

A.
No serious problems.
Correct Answer
B.
Bright flashing pie sections on the PPI.
C.
Spiking on the PPI.
D.
Vertical spikes that constantly move across the screen.

845F2

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845F3

The RADAR display has sectors of solid video (spoking). What would be the first thing to check?

A.
Antenna information circuits failure.
B.
Frequency of raster scan.
Correct Answer
C.
For interference from nearby ships.
D.
Constant velocity of antenna rotation.

845F3

When the RADAR display shows sectors of solid video in a spoked pattern, it may indicate interference from nearby ships. The spoking effect can occur when the RADAR signals bounce off the metallic structures of nearby vessels, creating echoes that appear as solid sectors on the display.

Mnemonic: "SAIL - Spoking, Antenna, Interference, Local vessels"

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845F4

In the circuit contained in Fig. 8F12, there are 5 volts present at points B and C, and there are zero volts present at points A and D. What is the voltage at point E?

Correct Answer
A.
-1.5 Volts.
B.
3.75 Volts.
C.
23.75 Volts.
D.
4.5 Volts.

845F4

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845F5

If the TR tube malfunctions:

A.
The transmitter might be damaged.
Correct Answer
B.
The receiver might be damaged.
C.
The klystron might be damaged.
D.
Magnetron current will increase.

845F5

If the TR tube malfunctions:

The receiver might be damaged.

TR Tube - The Receiver might be damaged.

A malfunctioning TR tube can lead to the receiver being damaged due to the inadvertent transfer of high-power energy from the transmitter during the receive phase.

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845F6

The indicated distance from your own vessel to a lighthouse is found to be in error. What circuit would you suspect?

Correct Answer
A.
Range ring oscillator.
B.
Video amplifier.
C.
STC circuit.
D.
FTC circuit.

845F6

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