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WorksheetsMicrowave Tubes
Total questions: 10
Worksheet time: 5mins
A microwave tube amplifier uses an axial magnetic field and a radial electric field. This is the
reflex klystron
coaxial magnetron
traveling wave magnetron
CFA
One of the reasons why vacuum tubes eventually fail at microwave frequencies is that their
noise figure increases
transit time becomes too short
shunt capacitive reactances become too large
series inductive reactances become too small
One of the following is unlikely to be used as a pulsed device. What is it?
multicavity klystron
BWO
CFA
TWT
Indicate the false statement.
Transit time in microwave tubes will be reduced if
the electrodes are brought closer together
a higher anode current is used
multiple or coaxial leads are used
the anode voltage is made larger
The multicavity klystron
is not a good low level amplifier because of noise
has a high repeller voltage to ensure a rapid transit time
is not suitable for pulsed operation
needs a long transit time through the buncher cavity to ensure current modulation
Indicate the false statement.
Klystron amplifiers may use intermediate cavities to
prevent the oscillations that occur in two-cavity klystrons
increase the bandwidth of the device
improve the power gain
increase the efficiency of the klystron
The TWT is sometime preferred to the multicavity klystron amplifier, because it
is more efficient
has a greater bandwidth
has a higher number of modes
produces a higher output power
The cavity magnetron uses strapping to
prevent mode jumping
prevent cathode back heating
ensure bunching
improve the phase focusing effect
To avoid difficulties with strapping at high frequencies, the type of cavity structure used in the magnetron is the
hole and slot
slot
vane
rising sun
The primary purpose of the helix in a traveling wave tube is to
prevent the electron beam from spreading in the long tube
reduce the axial velocity of the RF field
ensure broadband operation
reduce the noise figure
