491Microwave Tubes
cycle <1 s has also been reported. Their typical tuning range is reported to
be of the order of an octave at around 40 GHz.
As the beam velocity of this tube is controlled by varying the voltage, its
frequency of oscillation can be widely varied. This property makes the BWO
suitable to be used as a sweep oscillator. Further, by changing its beam cur-
rent, the amplitude of oscillation can be greatly reduced. This tube therefore
can also be used for amplitude modulation. Besides, it can be used as a volt-
age tunable bandpass amplier if its beam current does not exceed the oscil-
lation threshold level.
EXAMPLE 12.1
Find (a) the electron velocity leaving the cathode, (b) the gap transit
angle, (c) the beam coupling ...