May 9, 2014

FCC Technician Exam Question Of The Day (T7B11)

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

A) Reports of garbled, distorted, or unintelligible transmissions

NJ2X Notes:
RF feedback is caused when RF finds its way back into the shack and into the audio circuit.  Under ideal conditions, all RF is radiated from the antenna (not from the chassis or coax).  RF feedback can be a problem with end-fed antennas, poor grounding, poor match between antenna and feed line impedance, and random wire antennas.  There are several effective techniques for eliminating or reducing RF feedback including: improving your station grounding, improving your antenna counterpoise, improving the match between your feed line and antenna, and using a common-mode RF isolation choke (also known as a current balun).

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