🔍 Key Concepts

• Superheterodyne receiver basic blocks: RF amplifier, local oscillator, mixer, IF (intermediate frequency) amplifier • What it means for a signal to be "very near the IF frequency" and how that relates to where selectivity (filtering) mainly occurs • How signals can sometimes bypass the mixer and appear directly at the IF amplifier input

💭 Think About

• Draw a simple block diagram of a superheterodyne receiver and mark where the IF amplifier is located. Ask yourself: if a signal is already close to the IF frequency when it enters the set, what path might it take? • Think about which stages provide most of the selectivity: is it the RF/oscillator tuning, or the IF filters? What happens to a signal that shows up right at the IF frequency before any frequency conversion? • Which choice best describes a situation where the unwanted signal gets through too easily, with little or no rejection from the tuned stages in front?

✅ Before You Answer

• Be clear on the job of the RF stage (to select the incoming band) versus the IF amplifier (to amplify a fixed, narrow band). • Ask: would a frequency already at or near IF need to be mixed/converted, or could it appear directly in the IF chain? What does that imply? • Verify which option correctly describes an unwanted, insufficiently filtered signal getting into the IF amplifier, rather than being blocked by earlier tuned circuits.