Question T4A11
From subelement T4 - T4A
Where should the negative power return of a mobile transceiver be connected in a vehicle?
Why is this correct?
The negative power return must connect at the 12-volt battery chassis ground to ensure proper electrical reference and avoid ground loops. Connecting to random metal parts (C) can cause poor grounding and alternator whine. The antenna mount (B) and mounting bracket (D) aren't designed for power connections and could create voltage differences that introduce noise and operational problems.
Memory tip
Look for the most direct path to the vehicle's electrical system ground reference point. In mobile power questions, the battery or primary chassis ground is always the safest, most reliable connection point—avoid shortcuts to random metal parts.
Learn more
Proper mobile grounding prevents RF interference and protects equipment during electrical faults. Many installations run dedicated positive and negative leads directly to the battery with fuses on both lines. The negative fuse protects against reverse current during improper jump-starts. This direct connection eliminates ground potential differences that cause alternator whine and other noise issues common in mobile operations.
Think about it
Why do you think connecting the ground to random metal parts might work initially but cause problems later as the vehicle ages?