System Maintenance Flashcards
7 cards from real SBCA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 System Maintenance flashcards as text
What safety precaution is mandatory before performing maintenance on a high-power amplifier (HPA) in a satellite uplink facility?
Answer: Confirm the HPA is inhibited and follow lockout/tagout procedures before opening the unit
HPAs contain high voltages that are lethal; lockout/tagout procedures ensure the unit is de-energized and cannot be accidentally re-energized during maintenance.
A TVRO (Television Receive Only) system shows good signal during clear weather but the signal drops during heavy rain. What phenomenon is occurring?
Answer: Rain fade, caused by atmospheric attenuation of satellite signals by precipitation
Rain fade is the attenuation of satellite signals (especially Ku-band and Ka-band) by water droplets in the atmosphere, which absorb and scatter RF energy.
Which test verifies that a satellite dish's surface accuracy (RMS error) meets manufacturer specifications for its intended frequency band?
Answer: Microwave holography or photogrammetry surface measurement
Microwave holography or photogrammetry precisely measures reflector surface deviations, verifying that RMS surface errors are within acceptable limits for the operating frequency.
What does a rising trend in block upconverter (BUC) temperature readings during maintenance monitoring indicate?
Answer: Possible cooling system failure or excessive thermal load requiring investigation
Consistently rising BUC temperatures suggest the cooling system (fan or heatsink) may be failing, risking thermal shutdown or reduced component lifespan.
In a satellite uplink facility, why is dry nitrogen used to pressurize waveguide runs?
Answer: To displace moisture and prevent condensation, which can cause arcing and signal loss
Dry nitrogen is an inert, moisture-free gas that prevents condensation inside waveguides, which would otherwise cause corrosion, arcing, and significant signal attenuation.
A satellite technician is conducting a link budget verification after maintenance. The measured C/N is 3 dB lower than calculated. What is the most systematic next step?
Answer: Methodically measure each component's insertion loss and gain to identify the discrepancy
A systematic component-by-component measurement isolates whether the deficit is from path loss, component gain reduction, or noise degradation rather than replacing parts blindly.
What is the correct procedure when a satellite system's SCPC (Single Channel Per Carrier) modem reports a frequency offset error after routine maintenance?
Answer: Verify and reconfigure the modem's reference frequency and check the frequency standard (reference oscillator) accuracy
Frequency offset errors typically result from a mismatched or drifted reference oscillator; verifying the frequency standard and modem configuration corrects the offset.