AdvancedA-006-002-010
Which two stages in a superheterodyne receiver have input tuned circuits tuned to the same frequency?
A
Answer
Propagation and operating practice
Type
A
RF and first mixer
B
RF and local oscillator
C
IF and local oscillator
D
RF and IF
Answer Notes
In a superheterodyne receiver, both the RF amplifier and the first mixer sit at the "front end" of the receiver chain. Their primary job is to capture and selectively process the desired incoming signal straight from the antenna.
Because they are both handling the exact same incoming radio frequency, their input tuned circuits must be tuned to that identical frequency. This ensures maximum signal transfer and helps reject out-of-band interference before any frequency conversion happens.
Distractors involving the local oscillator (LO) or intermediate frequency (IF) are incorrect because the LO is intentionally tuned to a frequency offset from the RF by the IF amount, and the IF stage operates at the fixed converted frequency rather than the incoming RF.
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What receiver stage combines a 14.25-MHz input signal with a 13.795-MHz oscillator signal to produce a 455-kHz intermediate frequency (IF) signal?
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The mixer stage of a superheterodyne receiver: