G4C10 - What could be a symptom caused by a ground loop in your station’s audio connections?

General Questions
1

Question

What could be a symptom caused by a ground loop in your station’s audio connections?

Answer Options

  • A) You receive reports of “hum” on your station’s transmitted signal
  • B) The SWR reading for one or more antennas is suddenly very high
  • C) An item of station equipment starts to draw excessive amounts of current
  • D) You receive reports of harmonic interference from your station

Correct Answer: A

Explanation

A ground loop is a circular current path formed when interconnected equipment is grounded at multiple points with slightly different potential. When this occurs in the audio wiring between a microphone or sound card and the transceiver, the unwanted circulating current can induce 60 \text{Hz} (or 50 \text{Hz}) mains frequency noise into the audio signal path.

When this noisy audio is amplified and transmitted by the radio, the symptom is that you receive reports of ‘hum’ on your station’s transmitted signal. This hum is a low-frequency AC noise superimposed on your voice or data modulation, which is a classic indicator of an audio ground loop.

This topic was automatically created to facilitate community discussion about this exam question. Feel free to share study tips, memory tricks, or additional explanations!

2

Currently this question provides popup tooltip definitions for the word ‘ground’ and separately ‘loop’ in the question text. The definition for ground is correct but the definition used for loop refers to an antenna loop: “(1) An antenna with element(s) constructed as continuous lengths of wire or tubing. (2) A point of maximum voltage or current on an antenna.”

I’d suggest removing the two existing definitions and instead provide a single definition for the whole compound word ground loop, i.e., something about multiple paths to ground.

1 Like
3

I added a definition of “ground loop” to the glossary, so because the algorithm that automatically links terms to the glossary is “greedy” it now links to the right place.

Happy also to discuss improving the glossary entry!

1 Like