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M 1021 M 1021
1
Description of Operation

1
This Description of Operation also applies to M1000, M1001, M1020, M1025, M1030, M1040, M1125 and M1021
The M1021 Microwave Power Module is a fully
integrated microwave amplifier. Integral to the M1021 is
a Vacuum Power Booster (VPB), a high voltage power
supply and a 115 VAC 60 Hz AC to DC converter. The
VPB is a high-efficiency mini traveling wave tube, which
serves as the microwave amplifier. The high voltage
power supply converts the output voltage from the AC to
DC converter to the levels required to power the VPB. A
logic circuit, built into the high voltage power supply,
functions as the user interface of the M1021.
Upon application of prime power (by plugging the M1021
into a 115 VAC 60Hz source) the internal low voltage
power supply is enabled and the MPM enters the warm-
up state, which lasts approximately two minutes. While
in the warm-up state the Warm-Up indicator (pin 11) is
active. In this mode the MPM ignores the RF On/Off
input command (pin 3).
Once the MPM completes the warm-up cycle, the Warm-
up indicator becomes inactive and the MPM reacts to the
RF On/Off Input command. Application of a RF On
command results in the high voltage being applied to the
VPB, turning the VPB on and allowing RF amplification
to occur. In this mode the HV On indicator (pin 12) is
active. The M1021 has no internal gain equalizer and
therefore requires variable drive across the operating
band. Generally, input power levels between 18 dBm and
30 dBm, depending upon the frequency of operation, will
saturate the VPB. The final test data, supplied with each
MPM, defines the drive level versus frequency to reach
saturated output power. Drive data is taken every 500
MHz and requires linear interpolation between points. Do
not exceed these drive levels by more than 1 dB.
When in the fault mode, the High Voltage On indicator is
inactive and the Fault indicator (pin 6) is active. For helix
over current fault, prime power over current fault and
temperature fault, the MPM immediately reverts to the
fault state for approximately one second and then
automatically recycles back into the state defined by the
RF On command. If approximately four successive faults
are detected, the MPM latches in the fault state and the
unit must be reset to clear the fault. The MPM can be
reset by cycling the RF On/Off command from On to Off
and then back On. The line voltage fault causes the MPM
to remain in the fault mode until the fault disappears.
A helix current monitor (pin 15) is also provided at the
MPM interface connector. The helix current monitor is a
voltage proportional to the helix current. The helix
current of the VPB is sensed through a 200 ohm resistor
in the power supply, therefore the scale is .2 volts/mA.
Under normal operation the voltage across the resistor
should not exceed 2.0 volts.
The M1021 is configured for conduction cooling with
baseplate temperatures between -40
�C and +55�C.
Maintaining a +55
�C baseplate will generally require
active cooling, such as using a finned-extrusion and
forced air cooling. An example fin configuration is .125"
wide, .75" long with .2" spacing, covering the entire
M1021 baseplate. The fan should be capable of
approximately 100 CFM.
Electron Devices Division
960 Industrial Road
San Carlos, CA 94070
650-591-8411
Fax 650-508-1956 M1021 - Interface Signals
Input Connector: D-subminiature 15 pin male
Pin Number
Function
Signal Format
Note
1
Spare
2
Spare
3
RF On/Off
TTL
Logic 1 = RF On
4
Spare
5
Spare
6
Fault Indicator
TTL
Logic 1 = Fault
(RF Disabled)
7
+5V, 100mA
Logic Power
8
Signal Return
Ground
9
Spare
10
Spare
11
Warm-Up Indicator
TTL
Logic 1 = Warmup
12
High Voltage
Indicator
TTL
Logic 1 = HV On
13
Spare
14
Spare
15
Helix Current
Monitor
Analog
200mV = 1mA
960 Industrial Road, San Carlos, CA 94070, 650-591-8411; Fax 650-508-1956