SBCA Equipment Setup 5 — Questions and Answers
Question 1: A Ku-band dish is experiencing rain fade during heavy storms. Which of the following is the most effective permanent mitigation strategy?
- Increase LNB gain by 3 dB
- Upgrade to a larger dish to increase antenna gain and link margin (Correct answer)
- Switch to horizontal polarization only
- Add a second LNB in parallel
Correct answer: Upgrade to a larger dish to increase antenna gain and link margin
A larger dish provides higher antenna gain, increasing the system's link margin and improving rain fade resilience without changing the satellite signal itself.
Question 2: What is the recommended torque specification approach when tightening F-connectors to satellite receiver input ports?
- Maximum hand-tight plus a quarter turn with pliers (Correct answer)
- Torque to exactly 20 ft-lbs with a torque wrench
- Finger-tight only to avoid stripping threads
- Use thread-locking compound and tighten fully
Correct answer: Maximum hand-tight plus a quarter turn with pliers
Industry practice calls for finger-tight plus a quarter turn with a wrench to achieve a weatherproof, mechanically secure connection without over-tightening and damaging threads.
Question 3: When installing a dish mount on a non-penetrating roof mount (NPRM) with ballast, what is the primary structural concern?
- RF interference from the metal ballast blocks
- Adequate weight distribution to prevent wind uplift without exceeding roof load limits (Correct answer)
- Corrosion of the galvanized steel ballast trays
- Height restriction limiting dish elevation angle
Correct answer: Adequate weight distribution to prevent wind uplift without exceeding roof load limits
NPRM installations must balance enough ballast to resist wind loads against the roof's maximum allowable dead load per square foot.
Question 4: Which signal parameter is used to verify correct satellite transponder lock on a professional satellite receiver display?
- Bit Error Rate (BER) and Eb/No or C/N (Correct answer)
- Peak voltage on the IF line
- LNB current draw in milliamps
- Dish surface temperature via IR sensor
Correct answer: Bit Error Rate (BER) and Eb/No or C/N
BER (Bit Error Rate) and carrier-to-noise (C/N or Eb/No) readings confirm that the receiver is locked to the correct transponder with sufficient signal quality.
Question 5: What is the purpose of inserting a DC blocking capacitor in a satellite IF coaxial line?
- Improve high-frequency signal response above 2 GHz
- Prevent DC voltage from the receiver from reaching components not designed to handle it (Correct answer)
- Reduce standing wave reflections at the LNB input
- Filter out interference from adjacent satellite channels
Correct answer: Prevent DC voltage from the receiver from reaching components not designed to handle it
A DC block prevents the 13/18 V DC supply voltage from the receiver from reaching downstream equipment such as splitters, meters, or other receivers not designed for powered lines.
Question 6: A technician is installing a dual-output LNB to feed two separate receivers. Both receivers require 18 V to select vertical polarization, but only one is receiving the correct signal. What is the most likely cause?
- The coaxial cable is too long for dual output
- One receiver is outputting 13 V instead of 18 V, selecting the wrong polarization (Correct answer)
- The LNB local oscillator has drifted out of specification
- Both receivers cannot simultaneously select the same polarization
Correct answer: One receiver is outputting 13 V instead of 18 V, selecting the wrong polarization
If one receiver outputs 13 V (horizontal selection) instead of 18 V (vertical selection), it selects the wrong LNB polarization output and receives the incorrect channel set.
Question 7: When running coaxial cable through an exterior wall penetration, which installation practice is required to prevent moisture migration into the structure?
- Use only rigid conduit through all wall penetrations
- Form a drip loop in the cable below the entry point before it enters the wall (Correct answer)
- Wrap the cable with electrical tape every 6 inches near the penetration
- Seal the penetration with steel wool to block rodent entry only
Correct answer: Form a drip loop in the cable below the entry point before it enters the wall
A drip loop routes the cable downward before it enters the wall so water runs off the cable rather than wicking into the building through the penetration.
SBCA Equipment Setup 5
A Ku-band dish is experiencing rain fade during heavy storms.
Which of the following is the most effective permanent mitigation strategy?