Ham Radio General Class Practice Test

What could be a symptom of a ground loop somewhere in your station?

1. You receive reports of "hum" on your station's transmitted signal

2. The SWR reading for one or more antennas is suddenly very high

3. An item of station equipment starts to draw excessive amounts of current

4. You receive reports of harmonic interference from your station

The correct answer is: You receive reports of "hum" on your station's transmitted signal

A symptom of a ground loop in your station is often a "hum" that can be heard on your transmitted signal. Ground loops occur when there are multiple grounding points in a system that result in differences in ground potential. When this happens, stray currents can flow between these points, which can introduce interference into audio signals. The hum is typically at a frequency of 60 Hz (or 50 Hz in some regions), corresponding to the power line frequency, and is caused by the electromagnetic interference from the AC mains. This unwanted noise can be particularly noticeable when you’re transmitting and can affect the quality of your communications, prompting reports from others who hear the signal. The other options might indicate various types of problems, but they do not specifically relate to the symptoms typically caused by ground loops. For instance, high SWR can point to issues such as mismatched impedance or faulty antenna elements, excessive current draw might signify a faulty or overloaded piece of equipment, and harmonic interference typically indicates problems with the station's transmission circuitry or filters rather than grounding issues.