HIGH POWER SYSTEMS FOR WIND PROFILER K. P. Ray K. P. Ray Society for Applied Microwave Electronics...
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Transcript of HIGH POWER SYSTEMS FOR WIND PROFILER K. P. Ray K. P. Ray Society for Applied Microwave Electronics...
HIGH POWER SYSTEMS FOR WIND PROFILER HIGH POWER SYSTEMS FOR WIND PROFILER
K. P. RayK. P. Ray
Society for Applied Microwave Electronics Engineering & Research IIT campus, Powai, Mumbai-400 076.
1.HIGH POWER TRANSMITTER
2.DUPLEXER
Transmitter Specifications:
Frequency : 404.37 MHzBandwidth : 500 kHzOutput power : 16 kW peakDuty cycle : 10 % maximumPulse Width : 2 -16 sPulse Repetition Time : 100 - 160sHarmonics : -30 dBc or betterSpurious : -40 dBcCooling : Forced air
Main Subsystems:
1.HIGH POWER RF AMPLIFIERS
2.HIGH AND LOW VOLTAGE POWER
SUPPLIES
3. RF CONTROL CIRCUITS AND DUAL
DIRCTIONAL COUPLER
4. CONTROL AND INTERLOCK
CIRCUITS
BLOCK DIAGRAM FOR 16 kW PULSED TRANSMITTER
HIGH POWER RF
AMPLIFIERS
DR HPA
~10.5 dB ~9.5 dB ~9 dB
16kW1mW
43dB
20W 2kW225W
FIRST OPTION OF 16 kW PULSED TRANSMITTER
SSA PDR
DR HPA
~11 dB ~12 dB
16kW1mW
50 dB
100W 1kWSSA
SECOND OPTION ….
BLOCK DIAGRAM FOR SOLID STATE AMPLIFIER
MSA 1101MSA 0520
MHW 720A1 MRF 393
SOLID STATE AMPLIFIER
Frequency Response of SSA
Measured values of Parameters for Solid State Amplifier
• Output power : 100W Pulsed
• Gain : 50 db
• 3 db Bandwidth : >+/- 3 MHz
• Efficiency : approx 40%
• Harmonics/spurious : -40db
• Dynamic range : > 5 db
Reactance provided by the tube capacitance
Xc = j Zo tan (2/) L
The length 'L' of the tuned co-axial line is given by:
L = /2 tan-1 Xc / Zo
Where = wavelength in cm
Xc = reactance due to the inter-electrode capacitance
Zo = characteristic impedance of the line (ohm)
The 50 ohm matching point to tap-out the output power is given by:
L2 = /2 Ri/Rg . [Xc/(Xc2 + Zo
2)1/2] cm
Where L2 = distance from the short circuited end to the matching
point.
Ri = Output resistance (50 ohm in this case)
Rg = grid resistance in ohms.
Co-axial structure with centre conductor having circular cross-section and outer conductor of rectangular cross section are commonly used.
Design Philosophy of Distributed Matching Network for Triode Amplifiers
FREQUENCY TUNING BY VARYING LENGTH
FREQUENCY TUNING BY VARYING IMPEDANCE
BIASING OF 2 kW TRIODE DRIVER AMPLIFIERGrounded Grid Configuration
SCHEMATIC OF TRIODE AMPLIFIERS
DRIVER AMPLIFIER CAVITY
3CPX800A7
Frequency Response of a Driver Amplifier
Pulse Response of a Driver Amplifier
Harmonic Content of a Driver Amplifier
HIGH POWER AMPLIFIER CAVITY
3CPX3500U7
Frequency Response of High Power Amplifier
Pulse Response of High Power Amplifier
Harmonic Content of High Power Amplifier
HIGH VOLTAGE AND LOW
VOLTAGE POWER SUPPLIES
Power Supply Requirement for Various Amplifier Stages
Solid State Amplifier:
28 Volts DC Regulated
12 Volts DC Regulated
Driver Amplifier:
Plate Voltage: 3.5 kV DC
Cathode Voltage: 10.0 Volts DC
Filament Voltage: 13.5 Volts AC, 3.5 Amps
High Power Amplifier:
Plate Voltage: 6.4 kV DC
Cathode Voltage: 63.0 Volts DC
Filament Voltage: 15.0 Volts AC, 13 Amps
LOW POWER RF CONTROL CIRCUITS AND DUAL DIRCTIONAL COUPLER
oOutput power of an amplifier may change due to:
1)Change in ambient temperature,
2)Change in supply voltages.
Requirement :
Level Stability : < 0.1 dB for 1 dB change in amplifier gain
AUTOMATIC LEVEL CONTROL
BLOCK DIAGRAM FOR AUTOMATIC LEVEL CONTROL CIRCUIT
FINAL OUTPUT RESPONSE OF THE TRANSMITTERFINAL OUTPUT RESPONSE OF THE TRANSMITTER
DUAL DIRECTIONAL COUPLER
CONTROL AND INTERLOCK CIRCUITS
SAFETY INTERLOCKS FOR TRANSMITTER
AIR FLOW
CATHODE SUPPLY
PLATE VOLTAGE
EXCESS PLATE CURRENT
SSA OVERLOAD
DOOR
EXCESS REFLECTION
Interlock Scheme for the Transmitter
S.NO. Failure RF drive HT supply Filament
supply
1. Tube cooling
blower
• • •
2. Rack exhaust fan • • •
3. Cathode supply • • •
4. Excess anode current • •
5. Reflected power (VSWR) •
6. Duplexer •
7. Door/Panel • •
Sr. No. Parameters Indications Location
1. Anode voltage (HPA) Analog meter Display Panel
2. Anode current (HPA) Analog meter Display Panel
3. Grid current (HPA) Analog meter Display Panel
4. Anode voltage (Driver) Analog meter Display Panel
5. Anode current (Driver) Analog meter Display Panel
6. Grid current (Driver) Analog meter Display Panel
7. Forward Power Analog meter Display Panel
8. Reflected Power Analog meter Display Panel
9. Mains Supply (R, Y, B) Lamps Mains Panel
10. EHT Timer Lamps Mains Panel
11. Filament Timer Lamps Mains Panel
12. Elapsed Time Time Totalized meter Back Panel
13. DC Voltages (LVPS) Analog meter LVPS Plug in
14. DC Currents (LVPS) Analog meter LVPS Plug in
Display Indicators :-
TEST RESULTS OF TRANSMITTER
Parameters Specified values Measured values
Output power: 16 kW peak >16 kW peak
Bandwidth: 0.5 MHz > 1 MHz
Harmonics: -30 dBc > -38 dBc
Spurious Level: -40 dBc -55dBc
16 kW PULSED TRANSMITTER
DUPLEXER
Total input power : 16 kW peak
Average power : 1.6 kW
Pulse width : 2 µs & 16 µs (coded)
Transmit port Return loss : > 18.0 dB
Transmit mode insertion loss : < 0.5 dB
Receive mode insertion loss : <1.0 dB
Transmit mode
leakage (isolation) : 50.0 dB Min.
Recovery time : 3 µs, however effort will
be put to achieve 1 µs
Specifications of Duplexer
HIGH POWER BALANCED DUPLEXER
HIGH POWER BALANCED DUPLEXER
WITH INCREASED ISOLATION
CIRCULATOR AND DUPLEXER
LOAD
LNABS
DUPLXER
Rx
Antenna
Tx
+72dBm
+72dBm
16kW
NC
CIRCULATOR, DUPLEXER AND LIMITER
BS
DUPLXER
Rx
Antenna
Tx
+72dBm
+55dBm
16kW
NC
~ 300W
LOAD
LIMITER LNA
THANK YOU