Chapter 3 - Routine Maintenance
Confidential and Proprietary Information of ZTE CORPORATION 69
Measuring Amplifier Output Power
[
Instruments and meters
]
1.
One set of 3 1/2 digital multimeter;
2.
One set of 150 W thru-line power meter;
3.
Multiple RF cables;
4.
Other hardware.
[
Test procedure
]
1.
Shut off the power on PSM related to the ETRM module.
2.
When the power supply is cut off and ETRM has no output power,
loosen the cable connectors from the amplifier output terminal to the
AEM module, and connect them with a thru-line power meter and a
large-power load.
Notes:
When it is not connected with an antenna, a 100 W microwave power load
is needed but it is not necessary when it is not connected with an antenna.
3.
Turn on the power and add the excitation (ETRM has output power),
then read the power of the set band (GSM900: 925 MHz ~ 960 MHz;
GSM1800: 1805 MHz ~ 1880 MHz). In the case of full power, read the
output power and the gain flatness.
[
Normal result
]
It is required the output power should be larger than 40 W with the gain
flatness of less than ±0.5 dB.
[
Troubleshooting
]
1.
For a 60 W BS21 (V2.2), if the amplifier output power does not meet
the technical specifications, check whether the ETRM output level is
within the allowed range. If it is normal, the fault may lie in the
amplifier.
2.
Common problems of a power amplifier include power amplifier (front
end) and amplifier tube (rear end) damage. It is manifested in low
gains and decreased output power. If the fault is in the amplifier,
replace the ETRM.
[
Recovery after test
]
Release the connection between the thru-line power meter, large power
load and the amplifier output terminal. Re-establish the connection
between the amplifier output terminal and the AEM module.
Measuring SWR of Antenna Feeder
[
Instruments and meters
]
A SiteMaster tester and a testing cable.
