Axcera 79XITS-7029 Benutzerhandbuch
MAINTENANCE AND TROUBLESHOOTING
Problem Analysis
In most cases, the performance of a GaAsFET transistor is closely tied to the DC operation of the system. Any
degradation in signal quality, gain or power is usually related to a corresponding change in a DC parameter
somewhere in the system. An exception may be a defective RF input or output connection, which can result in poor
performance of the amplifier with all DC parameters appearing normal.
The first step of analysis is therefore to carefully measure all DC parameters and compare these to the numbers
indicated on the schematics, block diagrams, and factory test data sheet. Each GaAsFET operates with – .5V of bias
on the gate and about +10.2V maximum volts on the drain. The static current of a GaAsFET is determined by
measuring across associated .05 ohm resistor, located on the bias protection board and using Ohm’s Law.
If all DC parameters are normal, an RF intermittency should be suspected. Follow the RF path from input to output
and apply a small physical force on all connectors while observing the output power. If an intermittency is detected, a
simple re-soldering can be attempted.
While following these procedures, it is important to maintain terminations on all amplifier circuits to avoid VSWR
damage. Before a fan fails, it normally begins to exhibit noisy operation. Always check for free fan blade movement
and p rocure a replacement fan if fan-bearing noise is evident.
Repair Procedures
Repair of this transmitter normally involves module level replacement. ITS Corporation maintains an adequate stock
of replacement modules. If you have determined that a particular subassembly is defective and that it cannot be
easily repaired at your facility, please contact the ITS Customer Services Department. An effort will be made to
provide a module on an exchange basis. It is often possible to ship replacement modules counter-to-counter or one-
day UPS/Federal Express to expedite delivery.
On some occasions it is necessary to perform component level repairs. In many cases failures can be a result of poor
connections somewhere in the system. Poor connections can generally be repaired with a suitable, small, grounded
soldering iron. A spare parts kit of standard components is available for this booster. Please contact the ITS
Marketing Department for the price and availability of the spare parts kit. Individual components can also be ordered
from the Customer Services or Marketing departments of ITS. The fuses are standard and generally available at local
parts distributors. The parts list provides complete manufacturer's information and part number for all standard
electrical components. These components can often be obtained from local distributors. An effort has been made to
select standard (off-the-shelf) components whenever possible in the product design. Replacement of the GaAsFET
transistors in the field is not recommended unless performed by an experienced technician. It is important to realize
that each GaAs FET operates at a specific bias voltage that must be preset before t he main power supply is switched
on. Failure to provide the proper bias voltage will result in rapid GaAsFET destruction. Please refer to the ITS
Warranty and Material Return Authorization procedures for additional information concerning repair parts.
Periodic Procedures
This transmitter is designed with components that require no periodic maintenance except for cleaning and record
keeping.
Problem Analysis
In most cases, the performance of a GaAsFET transistor is closely tied to the DC operation of the system. Any
degradation in signal quality, gain or power is usually related to a corresponding change in a DC parameter
somewhere in the system. An exception may be a defective RF input or output connection, which can result in poor
performance of the amplifier with all DC parameters appearing normal.
The first step of analysis is therefore to carefully measure all DC parameters and compare these to the numbers
indicated on the schematics, block diagrams, and factory test data sheet. Each GaAsFET operates with – .5V of bias
on the gate and about +10.2V maximum volts on the drain. The static current of a GaAsFET is determined by
measuring across associated .05 ohm resistor, located on the bias protection board and using Ohm’s Law.
If all DC parameters are normal, an RF intermittency should be suspected. Follow the RF path from input to output
and apply a small physical force on all connectors while observing the output power. If an intermittency is detected, a
simple re-soldering can be attempted.
While following these procedures, it is important to maintain terminations on all amplifier circuits to avoid VSWR
damage. Before a fan fails, it normally begins to exhibit noisy operation. Always check for free fan blade movement
and p rocure a replacement fan if fan-bearing noise is evident.
Repair Procedures
Repair of this transmitter normally involves module level replacement. ITS Corporation maintains an adequate stock
of replacement modules. If you have determined that a particular subassembly is defective and that it cannot be
easily repaired at your facility, please contact the ITS Customer Services Department. An effort will be made to
provide a module on an exchange basis. It is often possible to ship replacement modules counter-to-counter or one-
day UPS/Federal Express to expedite delivery.
On some occasions it is necessary to perform component level repairs. In many cases failures can be a result of poor
connections somewhere in the system. Poor connections can generally be repaired with a suitable, small, grounded
soldering iron. A spare parts kit of standard components is available for this booster. Please contact the ITS
Marketing Department for the price and availability of the spare parts kit. Individual components can also be ordered
from the Customer Services or Marketing departments of ITS. The fuses are standard and generally available at local
parts distributors. The parts list provides complete manufacturer's information and part number for all standard
electrical components. These components can often be obtained from local distributors. An effort has been made to
select standard (off-the-shelf) components whenever possible in the product design. Replacement of the GaAsFET
transistors in the field is not recommended unless performed by an experienced technician. It is important to realize
that each GaAs FET operates at a specific bias voltage that must be preset before t he main power supply is switched
on. Failure to provide the proper bias voltage will result in rapid GaAsFET destruction. Please refer to the ITS
Warranty and Material Return Authorization procedures for additional information concerning repair parts.
Periodic Procedures
This transmitter is designed with components that require no periodic maintenance except for cleaning and record
keeping.