What is a symptom of RF feedback in a transmitter or transceiver?

When considering the symptoms of RF feedback in a transmitter or transceiver, garbled, distorted, or unintelligible transmissions are a clear indicator. RF feedback occurs when radio frequency energy from the output stage of the transmitter leaks back into the input stage or other parts of the equipment. This feedback can create interference in the path of the audio or modulation signals, leading to poor-quality transmission that may sound distorted to those listening.

Such symptoms can frustrate communication as the signal becomes difficult for others to understand. Operators receiving the distorted signal might notice that the audio sounds unintelligible, which is a direct result of this feedback interfering with the modulation process. Recognizing this symptom helps operators identify and troubleshoot problems related to their equipment setup, antenna placement, or grounding issues to resolve the feedback effect.

In contrast, the other choices reflect other potential issues but do not directly relate to RF feedback. For example, excessive SWR at the antenna connection can indicate impedance mismatches rather than feedback, while the inability of the transmitter to stay on frequency often pertains to instability in the oscillator circuit, and blowing fuses typically points to overcurrent or other power supply issues not directly tied to RF feedback.