What kind of interference will a 13.345 MHz signal cause in a receiver mixing a 13.8 MHz VFO with a 14.255 MHz input?

The correct answer pertains to the concept of "image response," which refers to a specific type of interference that occurs in radio receivers due to the way they process signals at different frequencies. In a superheterodyne receiver, signals are mixed with a local oscillator (VFO) to create intermediate frequencies.

When mixing a 13.8 MHz VFO with a 14.255 MHz input signal, the receiver is tuned to respond to a frequency determined by the difference between these two frequencies — which, in this case, is 455 kHz. However, because of the nature of the mixing process, signals that are spaced by twice the intermediate frequency (in this case, approximately 910 kHz away from the desired signal) can also produce a response.

The 13.345 MHz signal's frequency is nearly the same distance away from the VFO as the desired signal, thus falling within the receiver's response range and leading to potential interference. This scenario exemplifies image response interference, as the receiver may inadvertently pick up this unintended signal along with the desired one, disrupting the clarity and quality of the information being received.

This understanding of image response helps in the design and operation of receivers, emphasizing the importance of selecting appropriate front-end filtering to