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WorksheetsOPMW UNIT 5
Total questions: 25
Worksheet time: 13mins
The production of power at higher frequencies is much simpler than production of power at low frequencies.
True
False
none of the above
Microwave tubes are power sources themselves at higher frequencies and can be used independently without any other devices.
True
False
None of the Above
Microwave tubes are grouped into two categories depending on the type of:
Power gain achieved
Amplification method
Electron beam field interaction
Construction methods
The klystron tube used in a klystron amplifier is a _________ type beam amplifier.
Linear Beam
Crossed field
Parallel field
None of the mentioned
________ is a single cavity klystron tube that operates as on oscillator by using a reflector electrode after the cavity.
Backward wave Oscillator
Reflex klystron
Travelling wave tube
Magnetrons
A major disadvantage of klystron amplifier is:
Low power gain
Low Bandwidth
High Source power
Design complexity
Klystron amplifiers have high noise output as compared to crossed field amplifiers.
True
False
None of the above
Magnetrons are microwave devices that offer very high efficiencies of about 80%.
False
True
Reflex klystron is a
Low Power Generator
High Power Generator
Low Gain Amplifier
Not an Oscillator
The modes in a reflex klystron
give the same frequency but different transit time
result from excessive transit time across the resonator gap
are caused by spurious frequency modulation
are just for theoretical considerations
In a travelling wave tube, the velocity of electron tube with respect to the axial velocity of RF field is kept as
Lower
Higher
Equal
Will Change
Travelling Wave Tube is sometimes preferred to the multicavity klystron amplifier, because it
has a greater bandwidth
is more efficient
has a higher number of modes
it produces a higher output power
In a travelling-wave tube, the purpose of helix structure is
to make-sure broadband operation
to minimise the noise figure
to minimise the RF field’s axial velocity
A microwave connector should have high SWR
True
False
Depends on Applications
Can’t say
Magnetron is a /an
i. O- tyoe tube
ii. a low power device
iii. a high-power device
iv. an oscillator
i and ii
ii and iv
iii and iv
i, ii and iv
Which device can be used to change the frequency of a coaxial magnetron by moving one of the end plates?
Coaxial cavity
Tuning piston
Coupling slots
Vanes
Magnetron can shift, almost unpredictably, from one mode to another because of change in
power
frequency
voltage
coupling
What is the preferred magnetron mode of operation?
Circular mode
Rectangular mode
σ mode
π mode
The power that can be produced by a magnetron depends on its ________
size
efficiency
output
speed
Both axial magnetic field and radial electric fields are used in the following vacuum tube
magnetron
a reflex klystron
multi cavity Klystron
traveling-wave tube
The following vacuum tube can be used as an oscillator and an amplifier?
TWT
Klystron
Magnetron
BWO
The transit time can be reduced in microwave tubes,
If electrodes are brought closer together
If a higher anode current is used
If multiple or coaxial leads are used
None
The purpose of attenuator in a travelling wave tube is
To increase gain
To help bunching
To prevent oscillation
To prevent saturation
In the following microwave tubes, RF energy travels at nearly the same speed as the electrons that are travelling from the cathode to the collector:
Magnetron
TWT
CFA
Klystron
A backward-wave oscillator is based on
Cross-field amplifier
Coaxial magnetron
Traveling-wave tube
Rising sun magnetron
