3-F-042: RF Amplifiers
3-42F1:
How can selectivity be achieved in the front-end circuitry of a communications receiver?
By using a preselector.
By using an audio filter.
By using an additional RF amplifier stage.
By using an additional IF amplifier stage.
3-42F2:
What is the primary purpose of an RF amplifier in a receiver?
To improve the receiver’s noise figure.
To provide most of the receiver gain.
To vary the receiver image rejection by utilizing the AGC.
To develop the AGC voltage.
3-42F3:
How much gain should be used in the RF amplifier stage of a receiver?
Sufficient gain to allow weak signals to overcome noise generated in the first mixer stage.
As much gain as possible short of self oscillation.
Sufficient gain to keep weak signals below the noise of the first mixer stage.
It depends on the amplification factor of the first IF stage.
3-42F4:
Too much gain in a VHF receiver front end could result in this:
Susceptibility of intermodulation interference from nearby transmitters.
Local signals become weaker.
Difficult to match receiver impedances.
Dramatic increase in receiver current.
3-42F5:
What is the advantage of a GaAsFET preamplifier in a modern VHF radio receiver?
High gain and low noise floor.
Increased selectivity and flat gain.
Low gain but high selectivity.
High gain with high noise floor.
3-42F6:
In what stage of a VHF receiver would a low noise amplifier be most advantageous?
Front end RF stage.
IF stage.
Audio stage.
Power supply.
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