Explanation: A dummy load is a non-radiating resistive component designed to safely absorb RF power from a transmitter for testing purposes. When a transceiver is connected to a dummy load instead of an antenna, its receiver input is effectively terminated into this device. While the transceiver's audio frequency (AF) output stage itself might be fully functional (producing strong background hiss or noise if the squelch is open), no external RF signals can be picked up from the air because the dummy load does not act as an antenna. Consequently, no signals are demodulated and passed to the AF output. A high Standing Wave Ratio (SWR) (B) primarily indicates an inefficient antenna system for transmission, but an antenna with high SWR would still pick up *some* signals. A "crowbar" circuit (C) in the power supply would completely shut down the transceiver, preventing any output. A failed squelch circuit (D) might either constantly mute signals or produce continuous noise, but wouldn't prevent the *reception* of RF signals by an actual antenna.