14 2-26.   What oscillator uses split capacitors for feedback? 1.   Hartley 2.   Colpitts 3.   Armstrong 4.   RC phase-shift _______________________________________ TO ANSWER QUESTIONS 2-27 THROUGH 2-29, SELECT THE CONFIGURATIONS IN COLUMN B THAT MATCH THE AMPLIFIER CHARACTERISTICS IN COLUMN A. CHOICES IN COLUMN B MAY BE USED ONCE, MORE THAN ONCE OR NOT AT ALL. A.  CHARACTERISTICS 2-27.   Voltage gain is less than unity 2-28.   Low power gain 2-29.   Feedback signal requires phase shift B.  CONFIGURATIONS 1.  Common-base 2.  Common-gate 3.  Common-emitter 4.  Common-collector ______________________________________ 2-30.   Which of the following statements best describes tank current in a series-fed oscillator? 1.   The dc path is through the tank circuit 2.   The dc path does not go through the tank circuit 3.   The ac path is through the tank circuit 4.   The ac path does not go through the tank circuit 2-31.   In a shunt-fed, tuned-collector Armstrong oscillator, what blocks the dc component from the tank circuit? 1.   A resistor 2.   A capacitor 3.   An inductor 4.   A transistor 2-32.   Which of the following circuit arrangements aid in the frequency stability of an oscillator? 1.   A regulated power supply 2.   A common bias source for the emitter and collector 3.   Both 1 and 2 above 4.   Separate bias sources Figure 2A.—Tuned-base Armstrong oscillator. IN ANSWERING QUESTIONS 2-33 THROUGH 2-37, REFER TO FIGURE 2A. 2-33.   The frequency of the output signal of the oscillator is determined by what components? 1.   R1 and L1 2.   L2 and C1 3.   L3 and C4 4.   R3 and C3 2-34.   Forward bias for the amplifier is developed by what component? 1. R1 2. R2 3. R3 4. L1