% FILENAME = N18.TXT % Transmitter Block Diagrams % Release version 3, October 2001 %Question 1 #18.1 In the transmitter block diagram shown, the "oscillator":

is variable in frequency generates an audio frequency tone during tests uses a crystal for good frequency stability may have a calibrated dial % ans 3 %Question 2 #18.2 In the transmitter block diagram shown, the "balanced modulator":

balances the high and low frequencies in the audio signal performs double sideband suppressed carrier modulation acts as a tone control balances the standing wave ratio % ans 2 %Question 3 #18.3 In the transmitter block diagram shown, the "filter":

removes mains hum from the audio signal suppresses unwanted harmonics of the RF signal removes one sideband from the modulated signal removes the carrier component from the modulated signal % ans 3 %Question 4 #18.4 In the transmitter block diagram shown, the "mixer":

adds the correct proportion of carrier to the SSB signal mixes the audio and RF signals in the correct proportions translates the SSB signal to the required frequency mixes the two sidebands in the correct proportions % ans 3 %Question 5 #18.5 In the transmitter block diagram shown, the "linear amplifier":

has all components arranged in-line amplifies the modulated signal with no distortion aligns the two sidebands correctly removes any unwanted amplitude modulation from the signal % ans 2 %Question 6 #18.6 In the transmitter block diagram shown, the "VFO" is:

a voice frequency oscillator a varactor fixed oscillator a virtual faze oscillator a variable frequency oscillator % ans 4 %Question 7 #18.7 In the transmitter block diagram shown, the "master oscillator" produces:

a steady signal at the required carrier frequency a pulsating signal at the required carrier frequency a 800 Hz signal to modulate the carrier a modulated CW signal % ans 1 %Question 8 #18.8 In the transmitter block diagram shown, the "driver buffer":

filters any sharp edges from the input signal drives the power amplifier into saturation provides isolation between the oscillator and power amplifier changes the frequency of the master oscillator signal % ans 3 %Question 9 #18.9 In the transmitter block diagram shown, the "Morse key":

turns the DC power to the transmitter on and off allows the oscillator signal to pass only when the key is depressed changes the frequency of the transmitted signal when the key is depressed adds an 800 Hz audio tone to the signal when the key is depressed % ans 2 %Question 10 #18.10 In the transmitter block diagram shown, the "power amplifier":

need not have linear characteristics amplifies the bandwidth of its input signal must be adjusted during key-up conditions should be water-cooled % ans 1 %Question 11 #18.11 In the transmitter block diagram shown, the "speech amplifier":

amplifies the audio signal from the microphone is a spectral equalization entropy changer amplifies only speech, while discriminating against background noises shifts the frequency spectrum of the audio signal into the RF region % ans 1 %Question 12 #18.12 In the transmitter block diagram shown, the "modulator":

is an amplitude modulator with feedback is an SSB modulator with feedback causes the speech waveform to gate the oscillator on and off causes the speech waveform to shift the frequency of the oscillator % ans 4 %Question 13 #18.13 In the transmitter block diagram shown, the "oscillator" is:

an audio frequency oscillator a variable frequency RF oscillator a beat frequency oscillator a variable frequency audio oscillator % ans 2 %Question 14 #18.14 In the transmitter block diagram shown, the "frequency multiplier":

translates the frequency of the modulated signal into the RF spectrum changes the frequency of the speech signal produces a harmonic of the oscillator signal multiplies the oscillator signal by the speech signal % ans 3 %Question 15 #18.15 In the transmitter block diagram shown, the "power amplifier":

increases the voltage of the mains to drive the antenna amplifies the audio frequency component of the signal amplifies the selected sideband to a suitable level amplifies the RF signal to a suitable level % ans 4 %Question 16 #18.16 The signal from an amplitude modulated transmitter consists of: a carrier and two sidebands a carrier and one sideband no carrier and two sidebands no carrier and one sideband % ans 1 %Question 17 #18.17 The signal from a frequency modulated transmitter has: an amplitude which varies with the modulating waveform a frequency which varies with the modulating waveform a single sideband which follows the modulating waveform no sideband structure % ans 2 %Question 18 #18.18 The signal from a balanced modulator consists of: a carrier and two sidebands a carrier and one sideband no carrier and two sidebands no carrier and one sideband % ans 3 %Question 19 #18.19 The signal from a CW transmitter consists of: a continuous, unmodulated RF waveform a continuous RF waveform modulated with an 800 Hz Morse signal an RF waveform which is keyed on and off to form Morse characters a continuous RF waveform which changes frequency in synchronism with an applied Morse signal % ans 3 %Question 20 #18.20 The following signal can be amplified using a non-linear amplifier: SSB FM AM DSBSC % ans 2