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. The output must be tuned When the input increases past the threshold of the limiting, the gain decreases to keep the output constant. Leak-type bias must be used TRUE ANSWER : ? YOUR ANSWER : ?
In a broadcast superheterodyne receiver, the Local oscillator frequency is normally double the IF RF amplifier normally works at 455 kHz above the carrier frequency Local oscillator operates below the signal frequency Mixer input must be tuned to the signal frequency TRUE ANSWER : ? YOUR ANSWER : ?
To prevent overloading of the IF amplifier in a receiver, one should use Double conversion Squelch Variable sensitivity Variable selectivity TRUE ANSWER : ? YOUR ANSWER : ?
The image frequency of a superheterodyne receiver Is independent of the frequency to which the receiver is tuned Is created within the receiver itself Is not rejected be the IF tuned circuits Is due to insufficient adjacent channel rejection TRUE ANSWER : ? YOUR ANSWER : ?
Indicate the false statement in connection with communications receivers. Double conversion is used to improve image rejection Variable sensitivity is used to eliminate selective fading 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. TRUE ANSWER : ? YOUR ANSWER : ?
When a receiver has good blocking performance, this means that Its detector suffers from burnout It is unaffected by AGC derived from nearby transmissions It does not suffer from double-spotting Its image frequency rejection is poor TRUE ANSWER : ? YOUR ANSWER : ?
If the intermediate frequency is very high (indicate false statement) Tracking will be improved The selectivity will be poor Image frequency rejection is very good The local oscillator need not be extremely stable TRUE ANSWER : ? YOUR ANSWER : ?
Indicate which of the following statements about the advantages of the phase discriminator over the slope detector is false: Fewer tuned circuits Much easier alignment Greater limiting Better linearity TRUE ANSWER : ? YOUR ANSWER : ?
The typical squelch circuit cuts off An IF amplifier when the AGC is maximum An IF amplifier when the AGC is minimum an audio amplifier when the carrier is absent RF interference when the signal is weak TRUE ANSWER : ? YOUR ANSWER : ?
If a FET is used as the first AF amplifier in a transistor receiver, this will have the effect of Reducing the effect of noise at low modulation depths Reducing the effect of negative-peak clipping Improving the selectivity of the receiver Improving the effectiveness of the AGC TRUE ANSWER : ? YOUR ANSWER : ?