The E/F-Band RF transmitter test bed system is available for testing various RF products to meet high power operating parameters. This system allows research and development, prototype testing, and production testing. It is configured to run short and long term duration of unique RF operating parameters for waveguides, dummy loads, circulators, serpentines and associated components. Units undergoing test are checked for internal RF arcing, ability to handle long tern RF operations, assuring the customer receives the best value component.

Using the test mode of fixed frequencies from 2900 MHz to 3100 MHz and a fixed pulse recurrence frequency (PRF) from 100 to 799 Pulses per second (PPS)., exact RF measurements can be made and the exact power requirements can be calculated for the current test in progress. Multiple frequencies are available at the output port of the transmitter for specific tests. The resonate ring has the capability to resonant selected frequencies in the 2900 to 3100 MHz ranges with increased peak power levels (5.0 MW).

The test transmitter has the flow capacity to cool high power components with up to 25+ GPM of distilled water with nominal resistivity of 2 M-Ohms.

TRANSMITTER SYSTEM AN SPS-48C E/F-Band Test Bed

The transmitter system is composed of four RF stages and a transmitter control unit. The frequency synthesizer RF pulse groups (frequency range of 2900 to 3100 MHz) are amplified by the four RF stages and applied via waveguide to the antenna. The RF nominal pulse width is 27 µs at the final stage output. Each of the four RF stages is composed of an RF amplifier, a modulator and a high voltage power supply. In this test bed, certain test power levels are available using selected stages. The transmitter control unit synchronizes the transmitter timing and provides transmitter circuit monitoring and protection. The computer system applies the control triggers to the transmitter control unit for synchronization of the transmitter.

FIRST RF STAGE

The first RF stage utilizes a traveling wave tube (TWT) for RF amplification. The frequency synthesizer output pulse groups are amplified in the first RF stage to 2.8 kW peak power. The first RF stage is triggered to transmit in all pulse transmissions.

SECOND RF STAGE

The second RF stage also utilizes an amplitron RF amplifier and amplifies the first stage output to 57 kW peak power. The second RF stage is also triggered during all pulse transmissions.

DRIVER RF STAGE

The driver RF stage also utilizes an amplitron RF amplifier and, when triggered, amplifies the second RF stage output to a 600 kW peak power level. The driver RF stage is triggered to operate only during medium power (600 kW) pulse transmissions and high power (final RF stage operation) pulse transmissions. During low power pulse transmissions the driver RF stage amplitron is not triggered and presents extremely low (approximately 1.0 dB) attenuation in the non-triggered state, thereby allowing preceding stage power to pass through without appreciable loss.

FINAL RF STAGE

The final RF stage also utilizes an amplitron RF amplifier and, when triggered, amplifies the 600 kW output of the driver stage to a peak power level of 2.2 megawatts. The final RF stage is triggered only during high power transmissions. The final RF stage amplitron, like the driver, presents virtually no attenuation (1.0 dB) when non-triggered, and appears as a waveguide section to RF pulses. The resonant ring is an additional unit used to increase RF peak power levels to 5 MW for controlled tests.

TRANSMITTER CONTROL UNIT

The transmitter control unit synchronizes each of the four RF stage modulators to trigger in accordance with the computer commands. Pulse forming network circuits are employed which establish modulator trigger duration for the respective stage when the applicable computer-timed trigger is applied. In addition to timing, the transmitter control unit also contains monitoring and fault detection circuits which indicate transmitter operating status.

TRANSMITTER TIMING

The transmitter control unit receives the transmitter power triggers from the test generator system and applies these to the RF modulators. The timing of each modulator is therefore synchronized with the applied RF at the TWT or amplitron.

MONITORING AND FAULT DETECTION CIRCUITS

The transmitter system contains status and fault indicating circuits for each of the four RF stages. Each RF stage has front panel meters for monitoring RF power and high voltage. Test jacks and test points are provided to facilitate testing the overall operation of each RF stage. Each RF stage also has fault-detection circuitry incorporated for fault isolation. The fault-detection circuitry is tied into the transmitter interlock system, so that fault-detected malfunctions disable the affected stage and prevent potential damage to components.

TRANSMITTER COOLING

Because of the high temperatures normally generated by high power components of the transmitter, direct and indirect water cooling is utilized to dissipate heat. All major components of the final stage plus the RF amplifiers and modulators in the first, second and driver stages utilize direct water cooling. The additional resonate ring also has cooling chambers to maintain consistent temperature for power measurements.

Waveguides

Antennas

Rotary Couplers

Dummy Loads

RF Serpentines

Waveguide Switches

Circulator

Attenuators