Radio Receivers
In a broadcast superheterodyne receiver, the

Mixer input must be tuned to the signal frequency
Local oscillator operates below the signal frequency
Local oscillator frequency is normally double the IF
RF amplifier normally works at 455 kHz above the carrier frequency

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Radio Receivers
Show which of the following statements about the amplitude limiter is untrue:

The output must be tuned
Leak-type bias must be used
The circuit is always biased in class C, by virtue of the leak-type bias.
When the input increases past the threshold of the limiting, the gain decreases to keep the output constant.

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Radio Receivers
Indicate the false statement in connection with communications receivers.

The noise limiter cuts off the receiver’s output during a noise pulse.
A product demodulator could be used for the reception of Morse code.
Double conversion is used to improve image rejection
Variable sensitivity is used to eliminate selective fading

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Radio Receivers
In a ratio detector

the circuit is the same as in a discriminator, except that the diodes are reversed
the output is twice that obtainable from a similar phase discriminator
stabilization against signal strength variations is provided
the linearity is worse than in phase discriminator

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