A received signal on a MF/HF transceiver breaks up rapidly and repeatedly. The signal alternates between mid scale and zero on the "Signal" meter. What is the most likely cause?
• MF/HF radio receiver functions: squelch, AGC (automatic gain control), and AF (audio frequency) amplifier • What the signal strength meter actually measures (RF input level, not audio output) • How a poor or intermittent antenna/coupler connection would appear on the signal meter vs audio quality
• Ask yourself: Does the signal meter jumping between mid-scale and zero indicate the RF signal itself is dropping in and out, or the audio after detection? • Which control or fault would cause the receiver to repeatedly mute/unmute or cut the RF input so that the meter follows it? • If the AGC failed, would you expect a steady but distorted/overloaded reading, or a complete drop to zero on the signal meter?
• Match each option to whether it affects RF input level (what the meter reads) or audio only (after detection). • Consider how squelch set too high behaves: does it change the incoming RF strength, or just when you can hear it? • Think about an intermittent antenna/coupler: would that cause the S-meter to swing between receiving a real signal and seeing no signal at all?
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