Transcript Document 7636436

HIGH POWER SYSTEMS FOR WIND PROFILER
K. P. Ray
Society for Applied Microwave Electronics Engineering & Research
IIT campus, Powai, Mumbai-400 076.
1.HIGH POWER TRANSMITTER
2.DUPLEXER
Transmitter Specifications:
Frequency
Bandwidth
Output power
Duty cycle
Pulse Width
Pulse Repetition Time
Harmonics
Spurious
Cooling
:
:
:
:
:
:
:
:
:
404.37 MHz
 500 kHz
16 kW peak
10 % maximum
2 -16 s
100 - 160s
-30 dBc or better
-40 dBc
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
FIRST OPTION OF 16 kW PULSED TRANSMITTER
43dB
~9.5 dB
~10.5 dB
1mW
20W
SSA
PDR
225W
DR
~9 dB
2kW
16kW
HPA
SECOND OPTION ….
50 dB
~11 dB
1mW
100W
SSA
DR
~12 dB
1kW
16kW
HPA
BLOCK DIAGRAM FOR SOLID STATE AMPLIFIER
MSA 1101
MSA 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
Design Philosophy of Distributed Matching
Network for Triode Amplifiers
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 + Zo2)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 crosssection and outer conductor of rectangular cross section are
commonly used.
FREQUENCY TUNING BY VARYING LENGTH
FREQUENCY TUNING BY VARYING IMPEDANCE
BIASING OF 2 kW TRIODE DRIVER AMPLIFIER
Grounded 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
AUTOMATIC LEVEL CONTROL
Output power of an amplifier may
change due to:
o
1)Change in ambient temperature,
2)Change in supply voltages.
Requirement :
Level Stability : < 0.1 dB for 1 dB
change in amplifier gain
BLOCK DIAGRAM FOR AUTOMATIC LEVEL
CONTROL CIRCUIT
FINAL 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
•
•
Display Indicators :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
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
Specifications of 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
leakage (isolation)
:
50.0 dB Min.
Recovery time
:
3 µs, however effort will
Transmit mode
be put to achieve 1 µs
HIGH POWER BALANCED DUPLEXER
HIGH POWER BALANCED DUPLEXER
WITH INCREASED ISOLATION
CIRCULATOR AND DUPLEXER
Antenna
Rx
NC
Tx
+72dBm
BS
+72dBm
16kW
DUPLXER
LOAD
LNA
CIRCULATOR, DUPLEXER AND LIMITER
Antenna
LOAD
Rx
Tx
NC
+55dBm
LIMITER
+72dBm
16kW
~ 300W
DUPLXER
BS
LNA
THANK YOU