11
2-19. In a reflex klystron, what type(s) of
electrical charge, if any, does the repeller
have?
1. Positive only
2. Negative only
3. Alternately positive and negative
4. None
2-20. In a reflex klystron, the length of time a
constant speed electron remains in the
space separating the grid and repeller is
determined by which of the following
factor(s)?
1. Repeller voltage
2. Electron velocity
3. Both 1 and 2 above
4. The distance between grid and
repeller
2-21. A reflex klystron in which the constant-
speed electrons remain in the repeller
field for 3/4 cycle is operating in what
mode?
1. Mode 1
2. Mode 2
3. Mode 3
4. Mode 4
2-22. In a reflex klystron, the choice of
operating mode is determined by which
of the following circuit factors?
1. The voltage required
2. The power available
3. The frequency range available
4. Both 2 and 3 above
2-23. In the higher modes, power and
amplitude limitations in a reflex klystron
are caused by which of the following
actions?
1. Electron debunching
2. Frequency fluctuation
3. Decreasing transit time
4. Increasing electron density
2-24. The term "bel" is a unit of measurement
that expresses which of the following
relationships?
1. Ratio of voltage and resistance
2. Logarithmic ratio between input and
output
3. Geometric progression from input to
output
4. Ratio of voltage to current
2-25. The term "dBm" is based on what
standard reference level?
1. 1 watt
2. 1 volt
3. 1 milliwatt
4. 1 millivolt
2-26. Which of the following twt
characteristics makes it ideal for use as
an rf amplifier?
1. High-noise and narrow-bandwidth
2. Low-noise and wide-bandwidth
3. High-noise and wide-bandwidth
4. Low-noise and narrow-bandwidth
2-27. In a twt, what is the primary purpose of
the helix?
1. To increase the forward velocity of
the input
2. To decrease the forward velocity of
the input
3. To decrease the reflected velocity of
the output
4. To increase the reflected velocity of
the output
2-28. Velocity modulation of the electron beam
in a twt is achieved by what action?
1. By the action of resonant cavities
2. By interaction of the electron beam
with the permanent magnet field
3. By interaction of the electron beam
with the electric field in the helix
4. All of the above
