07-02-2013, 10:51 AM
MICROWAVE TUBES
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TYPES OF RADAR TRANSMITTER:
POWER AMPLIFIER ( KLYSTRON)
SELF EXCITED OSCILLATOR (MAGNETRON)
TYPES OF MICROWAVE TUBES
GRIDDED TUBES - TRIODE
KLYSTRON – BRIEF INTERACTION TAKES PLACE BETWEEN AN ELECTRON BEAM AND AN RF VOLTAGE
TWT – INTERACTION BETWEEN ELECTRON BEAM AND RF FIELD IS CONTINUOS
MAGNETRON – INTERACTION BETWEEN ELECTRON BEAM AND RF FIELD IS ENSURED BY A MAGNETIC FIELD
KLYSTRON
A POWER AMPLIFIER TUBE USED TO AMPLIFY WEAK MICROWAVE ENERGY (PROVIDED BY A RADIO- FREQUENCY EXCITER) TO A HIGH POWER LEVEL FOR A RADAR TRANSMITTER
A KLYSTRON IS CHARACTERIZED BY :
HIGH POWER
LARGE SIZE
HIGH STABILITY
HIGH GAIN
AND HIGH OPERATING VOLTAGES.
REFLEX KLYSTRON
PRODUCE OSCILLATIONS IN A KLYSTRON WHICH HAS ONLY ONE CAVITY THROUGH WHICH ELECTRON PASS TWICE
LOW POWER,LOW EFFICIENCY MICROWAVE ILLUSTRATOR
BEAM IS ACCELERATED TOWARD THE CAVITY WHICH HAS HIGH POSITIVE VOLTAGE APPLIED TO IT ACT AS THE ANODE
THE ELECTRONS OVERSHOOT THE GAP IN THIS CAVITY AND CONTINUE ON TO THE NEXT ELECTRODE WHICH THEY NEVER REACH
THIS REPELLER ELECTRODE HAS A FAIRLY HIGH NEGATIVE VOLTAGE APPLIED TO IT AND PRECAUTIONS ARE TAKEN TO ENSURE THAT I IS NOT BOMBARDED BY THE ELECTRONS