Radio Receivers
In a broadcast superheterodyne receiver, the

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

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Radio Receivers
In a ratio detector

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

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

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

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Radio Receivers
The local oscillator of a broadcast receiver is tuned to a frequency higher than the incoming frequency

Because otherwise an intermediate frequency could not be produced
To help the image frequency rejection
To allow adequate frequency coverage without switching
To permit easier tracking

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