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3469 Series

Magnetron Transmitters

FEATURES:

• Up to 400 kW peak power RF output

• Air cooled

• Built in diagnostics and BIT for local or

remote troubleshooting

• Compact design for remote operation

BENEFITS:

• CPI BMD magnetrons and modulators ensure

compatible performance

• Operates in all orientations and during vibration

APPLICATIONS:

• Weather radar systems

• Surveillance radar systems

Communications & Power Industries Magnetron Transmitters

The 3469 Series Magnetron Transmitters are developed as a

fully integrated magnetron system for use as a high power

source of RF power for outdoor-mounted radar applications.

This microwave transmitter uses the CPI coaxial Magnetron

as its RF output device. The enclosure is made for use inside

of an antenna pedestal or similar environments. CPI is able

to furnish a compact, user-friendly, microwave power source

that allows for the antenna environment.

The transmitter cabinet contains the high voltage power

supply, solid-state switch, and the high voltage tank assem-

bly which includes the pulse transformer, energy storage

high voltage capacitor, and ﬁlament power supply.

The high voltage power supply (HVPS) is contained inside

the enclosure. It is completely self-protected with over

current and input under/over voltage circuits. The high

voltage power supply converts input AC into DC then

switches it utilizing a short-circuit proof series resonant

inverter. The ﬁlament power supply needed to operate the

magnetrons is contained in this unit. All external interface

and control is done in this supply.

Cathode pulsing is done by a solid state array of IGBT switch

boards that is driven by the control interface board in the

high voltage power supply. This switch inherently limits

current and pulse by design, no external circuitry is required

for these functions. The IGBT switch is a current controlled

switch, set by a bias voltage from the high voltage power

supply control interface board. The voltage across the

switch will automatically change as the voltage across the

magnetron changes due to frequency and temperature

changes. Replacing a magnetron only requires an adjust-

ment of the drive voltage. This switch will inherently limit arc

current in the event of a magnetron high voltage arc. The

limit is less than twice the normal operating current in the

event of a complete short circuit. The switch assembly is

conduction cooled to the heat exchanger.

All high voltage is contained in a sealed tank. The pulse

transformer that steps up the high voltage power supply

output to the voltage that the magnetron requires; the

storage capacitor bank to supply the energy during the

pulse; and the magnetron ﬁlament connections are all

contained in this tank. This tank is sealed so that it can func-

tion in any orientation and so that it is not affected by

normal acceleration levels. The magnetrons are mounted

on the side of the enclosure for easy access. An external fan

is required to cool the magnetrons.

3469 Series

Magnetron Transmitters pg. 2

Cooling

Cooling is accomplished by fans internal to the enclosure.

The air ﬂows through a plenum and heat exchanger to which

all of the heat generating components are connected. The

electronics and voltage carrying devices are not subject to

outside air and therefore protected from the environmental

conditions.

Instrumentation and Control

The magnetron transmitter has an Ethernet connector that

accepts control inputs and provides status, fault and alarm

conditions, and metered parameter information. The table

on page 3 deﬁnes the speciﬁc control functions, monitored

test points, transmitter operating status, fault and alarm

conditions, and metered voltages, currents, and operating

times.

CPI can provide a GUI or the software protocol that allows

for operation remotely through the Ethernet connection.

The remote interface utilizes an Ethernet IP address with CPI

standard protocol and command set. Analog test points are

available for diagnostic and performance assessment on the

side panel. These test points are buffered to allow the use

of standard test equipment such as oscilloscopes.

Pulsed operation and timing are derived from an externally

supplied modulator gate signal. This gate will determine

the duration of the output RF and pulse repetition frequency

(PRF). Internal monitoring circuits will ensure that the

acceptable pulse width, PRF, and duty cycle limits of the

transmitter are not exceeded. This modulator gate signal is

not part of the Ethernet interface and must be supplied

separately via a dedicated low impedance driver.

Speciﬁcation

Modulator type

Frequency

RF Output Power

RF Duty Cycle

Pulse Width

PRF

RF Droop within pulse

RF Rise time

RF Fall time

Operating Temperature

Cooling

Input voltage

Dimensions

Weight

Vibration

Description

Solid state

1 GHz to 35.56 GHz

400 kW (max.)

Up to 0.001

Adjustable

0.4 µs to 2 µs

Maximum: 2 kHz

0.5 dB max. at max PW

50 ns (typical)

250 ns (typical)

–40°C to +60°C ambient

Air cooled

208 vac 3 phase, 50/60 Hz, ±5%

23 x 11 x 18 inches

150 pounds (approx.)

MIL-STD-810G method 514.7

Annex C category 4

Comments

IGBT switch modulator current controlled

Dependent on magnetron

The pulse width is continuously variable based on

input gate.

Must maintain 0.001 duty limits set by magnetron

Forced air with integral fans

Other input voltages are available as options.

(0.85 power factor minimum)

(depth x height x width)

Depends on the magnetron selected

Vertical 1.07 grms, horizontal 0.76 grms,

longitudinal 0.76 grms

SPECIFICATIONS

CPI Magnetron Transmitters