Question: In superhetrodyne receiver, the input at mixer stage is________________?

• 1. IF and RF
• 2. RF and AF
• 3. IF and AF
• 4. RF and local oscillator signal

Question: When the modulating signal controls the frequency of the carrier, we get______________?

• 1. Phase modulation
• 2. Amplitude modulation
• 3. Frequency modulation
• 4. May be any one of the above

Question: The IF is 455 kHz. If the radio receiver is tuned to 855 kHz, the local oscillator frequency is _______________?

• 1. 455 kHz
• 2. 1310 kHz
• 3. 1500 kHz
• 4. 1520 kHz

Question: The function of ferrite antenna is to_________________?

• 1. Reduce stray capacitance
• 2. Stabilise d.c. bias
• 3. Increase the Q of tuned circuit
• 4. Reduce noise

Question: A 100 V carrier is made to vary between 160 V and 40 V by the signal. What is the modulation factor ?

• 1. 3
• 2. 6
• 3. 5
• 4. None of the above

Question: If Amin = 40 and Amax = 60, what is the percentage of modulation?

• 1. 20 %
• 2. 40 %
• 3. 50 %
• 4. 10 %

Question: In a radio receiver, we generally use ………….. oscillator as a local oscillator.

• 1. Crystal
• 2. Wien-bridge
• 3. Phase-shift
• 4. Hartley

Question: A 50 kW carrier is to be amplitude modulated to a level of 85%. What is the carrier power after modulation ?

• 1. 50 kW
• 2. 5 kW
• 3. 8 kW
• 4. 25 kW

Question: As the modulation level is increased, the carrier power__________________?

• 1. Is increased
• 2. Remains the same
• 3. Is decreased
• 4. None of the above

Question: A high Q tuned circuit will permit an amplifier to have high __________________?

• 1. Fidelity
• 2. Frequency range
• 3. Sensitivity
• 4. Selectivity