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2-37. Unwanted oscillations in an rf amplifier
transmitter are prevented because of
which of the following pulse
relationships?
1. The rf pulse is wider than the
modulator pulse
2. The rf pulse is narrower than the
modulator pulse
3. The rf pulse frequency is equal to the
local oscillator frequency
4. The rf pulse frequency is less than
the local oscillator frequency
2-38. A power-amplifier transmitter that
transmits a broad band of frequencies
typically uses which of the following
tubes as the final stage?
1. A crossed-field amplifier
2. A multicavity klystron
3. A magnetron
4. A twt
2-39. What is the primary function of the radar
duplexing system?
1. To prevent the formation of standing
waves in the waveguide system
2. To permit the use of one antenna for
transmission and reception
3. To increase the effective range of the
radar
4. To increase antenna directivity
2-40. A defective duplexer in a radar will most
likely cause damage to which of the
following components?
1. The receiver
2. The waveguide
3. The magnetron
4. The local oscillator
2-41. Why is it desirable that the duplexer
quickly connect the receiver to the
antenna after the transmitted pulse?
1. So that line-match will remain
balanced
2. So that the transmitter power
dissipated will be minimum
3. So that echoes from nearby targets
will be received
4. So that echoes from nearby targets
will not prolong ionization
2-42. The action of tr-atr circuits depends upon
the impedance characteristics of which of
the following lengths of transmission line
segments?
1. 1 wave length
2. 1/2 wave length
3. 1/4 wave length
4. 1/8 wave length
2-43. Which of the following requirements
is/are essential for proper tr spark gap
operation?
1. High impedance during arc time
2. Low impedance during arc time
3. High impedance prior to arc time
4. Both 2 and 3 above
2-44. What is the purpose of introducing water
vapor into a tr tube?
1. It increases recovery time
2. It prevents early ionization
3. It decreases deionization time
4. It increases the gap breakdown
potential
