17. The mixer shown in figure 2-2 of the attached memorandum must operate on the
nonlinear portion of its characteristic to achieve efficient mixing action.
Efficient mixing action is therefore achieved when the
a. incoming signal voltage exceeds the bias voltage.
b. incoming signal voltage exceeds the local oscillator output voltage.
c. negative peaks from the local oscillator drive the transistor into heavy
conduction.
d. positive voltage peaks of the combined RF and local oscillator signals
cause heavy conduction to occur.
18. Transformer T1 in figure 2-2 selects only the IF from all the frequencies
generated during the mixing process.
The IF in the receiver can be simply
described as the
a. difference between the RF input and local oscillator signals.
b. difference between the two sidebands of modulation.
c. sum of the local oscillator and input RF signals.
d. sum of the two sidebands of modulation.
19. To sustain oscillations in an oscillator, there must be some regenerative
feedback.
In the circuit shown in figure 2-4, regenerative feedback is
accomplished
a. by L1.
c. by C6 and R1.
b. by C2 and R1.
d. through the power supply.
20. Degeneration in the local
oscillator circuit
of figure 2-4 aids
in
maintaining oscillator stability.
This degenerative
voltage is developed
by
resistor
a. R1.
c. R3.
b. R2.
d. R4.
CHECK YOUR ANSWERS WITH LESSON SOLUTIONS ON PAGE 50.
322 L2
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