🔍 Key Concepts

• Inmarsat-C above deck equipment (ADE) design: how DC power is sent to the antenna/LNA via the coax center conductor • Difference between terminal DC supply fuse and antenna power fuse and where each one is located in the system • Function of a Low Noise Amplifier (LNA) versus mechanical parts like AZ/EL motors in relation to DC voltage on the feed line

💭 Think About

• If there is no DC voltage on the antenna center pin, which single failed component or protection device would most directly interrupt that DC feed? • Which option would affect only the receive signal path, and which would also affect or be unrelated to the DC voltage going up the coax? • Would a purely mechanical failure (like an AZ/EL motor) normally remove DC power from the antenna feed, or just affect pointing/tracking?

✅ Before You Answer

• Verify which fuse specifically protects the DC power feed to the antenna/LNA over the coax center conductor. • Check whether a defective LNA would usually cause loss of DC voltage on the center pin or instead draw too much current and blow a protection device. • Confirm that a blown terminal main DC line fuse would affect power to the entire terminal, not just the receive section.