Subelement F: Installation, Maintenance & Repair— Topic 45: Equipment Faults-2
Question 8-45F2
Element 8 (RADAR)A defective crystal in the AFC section will cause:
Explanation
A defective crystal in the Automatic Frequency Control (AFC) section compromises the receiver's ability to maintain a precise frequency lock. In radar systems, which often use a Plan Position Indicator (PPI) display, this frequency stability is critical for accurately processing target echoes.
If the AFC crystal fails, the receiver's Intermediate Frequency (IF) will drift or become unstable. This results in the radar intermittently losing its "tune" to the incoming signals. On a PPI display, this manifests as "bright flashing pie sections," indicating sectors where the radar is temporarily unable to properly detect and display targets due to the frequency instability. The radar loses its coherent processing in these areas, rather than showing a stable, accurate picture.
The other options are incorrect: A defective crystal in a critical control circuit like AFC would indeed cause serious operational problems, not "no serious problems." Spiking (C and D) typically relates to noise, interference, or specific display synchronization issues, not the broad frequency instability caused by AFC failure.
Related Questions
8-44F6 The raster scan RADAR display has missing video in a rectangular block on the screen. Where is the most likely problem area?8-45F1 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:8-45F3 The RADAR display has sectors of solid video (spoking). What would be the first thing to check?8-45F4 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?8-45F5 If the TR tube malfunctions: