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2-45. Keep-alive voltage is applied to the tr
tube for which of the following reasons?
1. To maintain ionization within the
tube after the breakdown voltage is
removed
2. To ensure that the tube will rapidly
return to the deionized state
3. To maintain a glow discharge within
the tube so that firing will occur
rapidly
4. To prevent breakdown within the
tube prior to pulse transmission so
that firing will not be premature
2-46. Atr tubes generally have a longer duty
life than tr tubes because atr tubes do
NOT use
1. radioactive materials and chemically
active gas
2. chemically active gas and keep-alive
voltages
3. keep-alive voltages and radioactive
materials
4. keep-alive voltages and pure inert gas
2-47. In a series-connected duplexer, what
spark gap, if any, fires during reception?
1. The tr only
2. The atr only
3. Both the tr and atr
4. None of the above
2-48. Indirectly coupled waveguide duplexers
are normally connected to the main
waveguide by which of the following
devices?
1. A two-wire line
2. A coaxial cable
3. A short quarter-wave stub
4. A short section of waveguide
2-49. The direct-coupled waveguide duplexer
is connected to the waveguide at the
location of
1. minimum current flow
2. minimum magnetic field intensity
3. maximum magnetic field intensity
4. maximum electric field intensity
2-50. In a hybrid-ring duplexer, the fields at
the entrance of an arm must have what
phase relationship to propagate energy
down the arm?
1. 0 degrees
2. 90 degrees
3. 180 degrees
4. 270 degrees
2-51. Which of the following are requirements
of a microwave receiver?
1. Amplify extremely high-frequency
pulses
2. Detect and amplify pulses in the
microvolt range
3. Detect pulses with a duration of a
few microseconds
4. All of the above
2-52. The maximum range at which a radar
receiver can detect an object is limited by
which of the following factors?
1. Noise
2. Signal distortion
3. Receiver bandwidth
4. Transmitter frequency
2-53. An effective radar receiver should have a
gain factor that is in which of the
following ranges?
1. 101 to 102
2. 103 to 104
3. 106 to 108
4. 109 to 1010
