Which of the following can be a cause of radio frequency interference?

• A. Noise from computers
• B. Use of outdated equipment
• C. Fundamental overload, harmonics, and spurious transmissions
• D. Weak signal reception

Answer: (C)

Radio frequency interference (RFI) can arise from various sources, and fundamental overload, harmonics, and spurious transmissions represent significant contributors to this phenomenon.

Fundamental overload occurs when a radio receiver is exposed to a signal that is too strong, causing distortion or interference with the desired signal. This can happen if nearby transmitters are operating at high power levels on the same or adjacent frequencies.

Harmonics result from non-linearities in electronic circuits, which can cause signals to generate additional frequencies that are integer multiples of the original frequency. When these harmonic frequencies fall within the range of other radio services, they can interfere with legitimate communications.

Spurious transmissions are unwanted signals that can occur from a transmitter due either to design flaws or poor operating conditions. These signals might appear at frequencies other than the one intended for transmission, impacting other users on the band.

Together, these factors can create a significant interference challenge for radio operators, affecting the clarity and quality of communications. Understanding these sources is critical for operating effectively in the ham radio environment and being able to troubleshoot and reduce interference.