11 2-11. Which of the following is an advantage of the variable-mu tube over conventional tubes?   1.  It can be driven into cut-off by remote signals   2.  It can be saturated quickly with a small input signal   3.  It can amplify small input signals without distortion   4.  It can amplify large input signals without distortion 2-12. What is the only difference between a remote-cutoff tube and a sharp-cutoff tube?   1.    The spacing of the grid wires   2.    The number of grids in each tube   3.    The bias voltage used for conduction   4.    The potential on the elements of each tube 2-13. Which of the following is the BEST method for reducing transit time in uhf tubes?   1.    Placing the elements very close together   2.    Increasing the voltage on the electrodes   3.    Increasing the velocity of electrons   4.    Placing the elements far apart 2-14. Which of the following is a disadvantage of uhf tubes?   1.  Interelectrode capacitance is reduced   2.  They are manufactured without socket bases   3.  All the physical dimensions are scaled small   4.  They have reduced power-handling capabilities 2-15. What is the only physical difference between the doorknob tube and the acorn tube?   1.    Size   2.    Base design   3.    Filament material   4.    Power-handling capability 2-16. How does the construction of a planar tube differ from that of a concentric tube?   1.  Concentric tubes use filaments while planar tubes do not   2.  Planar tubes use filaments while concentric tubes do not   3.  The electrodes of the planar tubes are parallel to each other while those in concentric tubes are not 2-17. Why is the metallic ring of the planar tube grounded?   1.    To eliminate shock hazards   2.    To eliminate unwanted rf signals   3.    To make removing the tube easier   4.    To shunt the cathode current to ground 2-18. The metallic shell capacitive ground of a planar tube serves as what kind of capacitor in a cathode-bias circuit?   1.    Grid   2.    Bypass   3.    Coupling   4.    Plate-to-cathode 2-19. What is the major difference between the oilcan tube and the lighthouse tube?   1.    The oilcan tube has cooling fins; the lighthouse tube does not   2.    The oilcan tube functions as a triode   3.    The lighthouse tube can handle more power   4.    The lighthouse tube is a diode-type tube