Why should DC power for a 100-watt HF transceiver not be supplied by a vehicle’s auxiliary power socket?

A typical 100-watt HF transceiver draws approximately 20 to 25 amps of current during transmit. Standard vehicle auxiliary power sockets (often referred to as cigarette lighters) are usually wired with thin-gauge wire and fused for a maximum of 10 to 15 amps. If you attempt to pull 20+ amps through this under-rated socket, you will cause a severe voltage drop. This drop can cause the transceiver to shut down, distort your audio, or behave erratically. More importantly, it can overheat the vehicle's internal wiring or instantly blow the auxiliary circuit's fuse. The other options are incorrect: auxiliary sockets do not have reversed polarity by default, pulling power from them will not overheat the engine, and RF-shielded power cables are not the primary concern here compared to sheer current capacity.