Question 8-23C1

A video amplifier is designed to amplify the baseband signal (the "video" or information component) that results after a radio frequency (RF) signal has been demodulated. * **Option C is correct:** In a superheterodyne receiver, the incoming RF signal is mixed down to an intermediate frequency (IF) and then amplified by the I.F. amplifier. After this, a demodulator extracts the baseband information. The video amplifier then takes this demodulated, baseband signal and amplifies it to a level suitable for driving a display system (like a television screen or a radar scope). This places the video amplifier directly between the IF amplifier (and subsequent demodulator) and the display. * **Option A is incorrect:** Between the mixer and the I.F. amplifier, the signal is still at the intermediate frequency, not yet demodulated into a video signal. * **Option B is incorrect:** Video signals are baseband signals, typically ranging from 0 Hz up to several megahertz (e.g., 4-6 MHz for broadcast television). 60 MHz to 120 MHz falls within the RF or IF range, not the baseband video range. * **Option D is incorrect:** The local oscillator generates a signal that combines with the incoming RF signal in the mixer. No video signal is present at this stage.