13.
One difference between a klystron and a traveling-wave tube (TWT) is simply that the klystron
a.
uses a standing wave to influence the signal, and the TWT uses a traveling wave to influence the
signal.
b.
acts as a capacitive reactance, and the TWT acts as an inductive reactance.
c.
is velocity-modulated, and the TWT is space-charge modulated.
d.
is an amplifier, and the TWT is an oscillator.
14.
Amplification in a TWT is accomplished through the interaction of the RF signal and the electron stream
in the slow-wave structure of the TWT. The weak RF signal to be amplified by the TWT is applied to the
electrode that is identified as the
a.
helix.
c.
resonant cavity.
b.
control grid.
d.
accelerating anode.
15.
Direct-pin coupling is generally NOT used as a means of coupling from a TWT because it
a.
is a complex coupling system.
b.
handles only low-power signals.
c.
has standing waves that generate heat.
d.
reduces the effects of the focusing field.
16.
If the temperature of a TWT's helix increases, the helix becomes distorted. Operation of a TWT with a
distorted helix can cause the TWT to
a.
become an oscillator.
b.
fail at some frequencies.
c.
become a broadband amplifier.
d.
conduct in a reverse direction.
17.
In a parametric amplifier, amplification is produced by varying a parameter of the diode with a
a.
refrigerant.
c.
magnetic field.
b.
traveling wave.
d.
pump frequency.
344 L1
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