AR 10046249, Operating And Service Manual, Page: 46 / 58

Model 150/150AW1000
26 Rev C
4.3 TROUBLESHOOTING
CAUTION:
The microwave transistors used in the Model 150/150AW1000 amplifier
are GaN/GaAs FETs. These devices are very reliable when installed in a
suitable circuit, but they can be easily damaged by improper
troubleshooting or handling techniques.
The gate junctions of the GaN/GaAs FETs have a high input impedance
and are susceptible to static damage or damage due to the use of an
ungrounded soldering iron. Do not try to check the GaAs FETs with an
ohmmeter.
Use caution when troubleshooting the GaN/GaAs FETs; do not short the
gate to the ground or to the drain.
CAUTION:
Use care when unpacking new GaN/GaAs FETs. The GaN/GaAs FET
packaging should only be opened at Electrostatic Discharge (ESD)-
approved workstations, by individuals who are familiar with the handling
of microwave GaN/GaAs FETs and other ESD-sensitive devices.
Troubleshooting the Model 150/150AW1000 in a logical manner can speed the solution to a problem. The
settings of potentiometers (pots), capacitors (caps), or other variables should not be disturbed until other
problems have been eliminated. Comparing the measured DC voltages to those shown on the schematics can
solve many problems. Before measuring circuit voltages, first verify that the voltages to the circuits are correct.
Model 150/150AW1000 troubleshooting symptoms and remedies are described in the sections that follow

4.3.1 General Fault Reading

4.3.2 The Unit Cannot be Operated Remotely

4.3.3 Thermal Fault Lo Band

4.3.4 Thermal Fault Hi Band

4.3.5 Interlock Fault

4.3.6 PS1 Fault

4.3.7 PS2 Fault

4.3.8 PS3 Fault

4.3.9 Lo Band Amplifier Fault

4.3.10 Hi Band Amplifier Fault

4.3.11 Lo Band Low or No Power Output (DC Tests)

4.3.12 Hi Band Low or No Power Output (DC Tests)

4.3.13 Lo Band Low or No Power Output (RF Test)

4.3.14 Hi Band Low or No Power Output (RF Test)