7. The major advantage of using an IF frequency amplifier in a superheterodyne r
ID: 2249854 • Letter: 7
Question
7. The major advantage of using an IF frequency amplifier in a superheterodyne receiver is the amplification of A. the signal minus image frequencies. B. the mixer’s RF frequency components along with the LO components. C. a constant information bandwidth over a fixed carrier frequency. D. the AGC voltage levels along with the signal levels.
8. A receiver uses a 455-kHz IF frequency and is tuned to a station at 720 kHz. What is the image frequency? A. 1175 kHz C. 1630 kHz B. 1325 kHz D. 1780 kHz
9. The type of transistor normally used in the RF amplifier of an AM receiver is a A. BJT. C. MOSFET. B. Darlington pair. D. V-FET.
10. When no stations are heard on the radio from the mid-to-high AM band, you would typically suspect a faulty A. AGC circuit. C. RF circuit. B. LO circuit. D. IF circuit.
11. One method of quickly checking the audio amplifier section of an AM receiver is to A. inject ripple into the power supply. B. connect the RF stage to the IF stage, bypassing the mixer. C. touch the middle terminal of the volume control with a screwdriver. D. use a second audio signal source after the final IF amp.
12. A type of diode that can be used for RF tuning in place of a mechanically operated tuning capacitor is the A. point-junction diode. C. varactor diode. B. broad-range diode. D. range detection diode.
13. An FET-type transistor may use internal back-to-back Zener diodes for A. electronic tuning applications. B. AGC voltage injection inputs. C. power supply regulation. D. protection of the fragile internal junctions.
14. IF transformers are tuned to operate at their center IF frequency by A. adjusting the input capacitor. B. moving a slug in the transformer’s core. C. adjusting the output trimmer capacitor. D. adjusting the AGC bias voltage potentiometer.
15. The time constant of the RC network used for AGC voltage generation should be about A. 0.1 second. C. 1.0 second. B. 0.25 second. D. 2.5 seconds.
16. The typical IF frequency of a standard AM band receiver is A. 220 kHz. C. 1 MHz. B. 455 kHz. D. 2 MHz.
17. A diode detector has a short time constant at audio frequencies. This short time constant RC network is called a(n) A. cascading filter. C. envelope detector. B. harmonic filter. D. audio filter.
18. You’re looking at the output of a regulated power supply in an AM receiver, using an oscilloscope. A large amount of ripple is noticed. The most likely cause of this excess ripple is a(n) A. shorted diode. C. open diode. B. failed regulator. D. failed resistor.
Explanation / Answer
7. The IF amplifier amplifies the signal from the mixer circuit. For mixer the inputs are RF amplified signal and local oscillator frequency signal.
Hence, the correct option is B.
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