Ham Radio General Class Practice Test

Which of the following could be a cause of interference covering a wide range of frequencies?

1. Not using a balun or line isolator to feed balanced antennas

2. Lack of rectification of the transmitter's signal in power conductors

3. Arcing at a poor electrical connection

4. The use of horizontal rather than vertical antennas

The correct answer is: Arcing at a poor electrical connection

Interference covering a wide range of frequencies is often attributed to sudden, high-energy events that generate a broad spectrum of electromagnetic noise. Arcing at a poor electrical connection is one such event. When an electrical connection is faulty, it can create intermittent contact, leading to high-voltage arcs. These arcs produce a wide range of frequencies, often covering both radio and television bands, resulting in significant radio frequency interference. The nature of the interference from arcing is different from that created by the other options. For instance, the incorrect use of antennas or impedances might cause certain types of interference but is generally more confined to specific frequency bands rather than introducing random noise across a wide range. Lack of rectification in power conductors can cause power supply-related noise, but it is usually not as broad-spectrum as that produced by arcing. Similarly, the choice of horizontal versus vertical antennas would typically influence directivity and reception characteristics but would not inherently cause wide-spectrum interference. Thus, arcing stands out as a primary cause of interference that affects a broad range of frequencies.