Powerwave Technologies 5JS0044 Multi-Channel Power Amplifier User Manual sect 5
Powerwave Technologies Inc Multi-Channel Power Amplifier sect 5
sect 5
044-05073 Rev. A 5-1
MAINTENANCE
5-1. INTRODUCTION
This section contains periodic maintenance and performance test procedures for the Multicarrier
Cellular Amplifier. It also contains a list of test equipment required to perform the identified tasks.
NOTE
Check your sales order and equipment warranty
before attempting to service or repair the unit. Do
not break the seals on equipment under warranty or
the warranty will be null and void. Do not return
equipment for warranty or repair service until proper
shipping instructions are received from the factory.
5-2. PERIODIC MAINTENANCE
Periodic maintenance requirements are listed in Table 5-1. Table 5-1 also lists the intervals at
which the tasks should be performed.
WARNING
Wear proper eye protection to avoid eye injury
when using compressed air.
Table 5-1. Periodic Maintenance
TASK INTERVAL ACTION
Cleaning
Air Vents 30 Days Inspect and clean per paragraph 5-4
Inspection
Cables and
Connectors 12 Months Inspect signal and power cables for
frayed insulation. Check RF connectors
to be sure that they are tight.
Performance Tests 12 Months Perform annual test per paragraph 5-5.
5-3. TEST EQUIPMENT REQUIRED FOR TEST
Test equipment required to test the amplifier system is listed in Table 5-2. Equivalent test
equipment may be substituted for any item, keeping in mind that a thermistor type power meter is
required.
NOTE
All RF test equipment must be calibrated to 0.05
dB resolution. Any deviation from the nominal
attenuation must be accounted for and factored
into all output readings.
Section
5
044-05073 Rev. A 5-2
Table 5-2. Test Equipment Required
NOMENCLATURE MANUFACTURER MODEL
Signal Generator RDL IMD-801D-03A
30 dB Attenuator, 500 Watt Weinschel Corp. 53-30-34
10 dB Attenuator, 20 Watt
(2 each) Tenuline
Spectrum Analyzer H.P. 8560E
Coax Directional Coupler H.P. 778D
Power Meter/Sensor H.P. 437B/8481A
Network Analyzer H.P. 8753C
Current Probe
5-4. CLEANING AIR INLETS/OUTLETS
The air inlets and outlets should be cleaned every 30 days. If the equipment is operated in a
severe dust environment, they should be cleaned more often as necessary. Turn off DC power
source before removing fans. If dust and dirt are allowed to accumulate, the cooling efficiency
may be diminished. Using either compressed air or a brush with soft bristles, loosen and remove
accumulated dust and dirt from the air inlet panels.
5-5. PERFORMANCE TEST
Performance testing should be conducted every 12 months to ensure that the amplifier system
meets the operational specifications listed in table 5-3. Also verify system performance after any
amplifier module is replaced in the field. The test equipment required to perform the testing is
listed in table 5-2, and the test setup is shown in figure 5-1.
NOTE
The frequencies used in this test are typical for an amplifier with a
25 MHz band from 869 MHz to 894 MHz. Select evenly spaced
F1, F2, F3, and F4 frequencies that cover the instantaneous
bandwidth of your system.
5-5.1. AMPLIFIER SYSTEM PERFORMANCE TEST.
This test is applicable to the MCR20XX Series subrack with two plug-in G3S-800-150 amplifier
modules. To perform the test, proceed as follows:
1. Connect test equipment to the subrack as shown in figure 5-1.
NOTE
Do not apply any RF signals at this time.
2. Turn on signal generator and set frequency F1 to 880 MHz, F2 to 883 MHz, F3 to 886
MHz, and F4 to 889 MHz. Adjust each signal generator output so that the sum power
output from all four signal generators equals -4 dBm at the output of the 4-way combiner.
044-05073 Rev. A 5-3
Figure 5-1. Amplifier System Test Setup Diagram
SINGLE AMPLIFIER IMD TEST:
3. Adjust attenuator for an input signal at -l0 dBm. Turn on both amplifiers, and set RF ON
switch of amplifier number two to OFF. Reset first amplifier with the front panel RF ON
switch, and set switch to ON. Adjust variable attenuator to set amplifier power output on
power meter to 135 watts. Measure IMD on spectrum analyzer. IMD should be -65 dBc
min. Record test data in table 5-3. Set RF ON switch to OFF.
4. Repeat step 3 for amplifier number two.
TWO AMPLIFIER IMD AND CURRENT TEST:
5. Reset and turn on both amplifier modules. Adjust the variable attenuator to set power
output on power meter to 270 watts. Measure IMD on spectrum analyzer. IMD should be
-65 dBc min. Record test data in table 5-3.
6. With the amplifier modules set at 270 watts power output, use the current probe
(magnetic field type) and measure the dc current flow from the +27 Vdc power source.
Current should be 120 amps maximum. Record test data in table 5-3.
044-05073 Rev. A 5-4
GAIN TEST:
7. Disconnect spectrum analyzer from test setup, and connect the network analyzer.
8. Set network analyzer as follows:
• Power output to 5 dBm.
• Frequency start to 869 MHz.
• Frequency stop to 894 MHz.
• Normalize the network analyzer for gain and return loss.
9. Reset and turn on the channel 1 amplifier; turn off channel 2 amplifier. Check the gain
across the band from 869 MHz to 894 MHz. Gain should be between 30 and 50 dB.
Record test data in table 5-3.
10. Turn off the channel 1 amplifier and reset and turn on the channel 2 amplifier. Check the
gain across the band from 869 MHz to 894 MHz. Gain should be between 30 and 50 dB.
Record test data in table 5-3.
11. Reset and turn on both amplifier modules and check the gain. The gain of both amplifiers
should be 3 dB higher than in steps 9 and 10. Record test data in table 5-3.
HARMONICS TEST
12. With the power set at 270 watts power output, use the spectrum analyzer and check the
frequency band from 869 MHz to 894 MHz for harmonics. Harmonics should be -45 dBc
maximum. Record test data in table 5-3.
SPURIOUS TEST
13. With the power amplifier set at 270 watts power output, use the spectrum analyzer and
check the frequency band from 869 MHz to 894 MHz for spurious signals. Spurious
signals should be -60 dBc maximum. Record test data in table 5-3.
INPUT RETURN LOSS TEST:
14. Reset and turn on both amplifier modules in the subrack. Read and record the S11 return
loss measurement on network analyzer. Input return loss should be –14 dB minimum.
Record test data in table 5-3.
044-05073 Rev. A 5-5
Table 5-3. Multicarrier Cellular Amplifier System Test Data Sheet
DATE _________________________________
SUBRACK S/N __________________________
MODULE #1 S/N ________________________ MODULE #2 S/N _________________________
TEST CONDITIONS:
Load and Source Impedance: 50 Ohms
VSWR: < 1.2:1
Supply Voltage: +27 Vdc ±1.0 Vdc
TEST SPECIFICATION MIN MAX DATA
4-TONE IMD
One Module
Vcc = 27 Vdc
PO = 135 W
Freq.: 880, 883, 886, and 889
MHz
-65 dBc
12
4-TONE IMD
Two Modules
Vcc = 27 Vdc
PO = 270 W
Freq.: 880, 883, 886, and 889
MHz
-65 dBc
1,2
RF Gain
One Module
Vcc = 27 Vdc
PO = 135 W
Freq. = 880 MHz 30 dB 50 dB 12
RF Gain
Two Modules
Vcc = 27 Vdc
PO = 270 W
Freq. = 880 MHz 30 dB 50 dB 1,2
Gain Flatness Vcc = 27 Vdc ±1 Vdc
PO =270 W
869-894 MHz Band -0.6 dB +0.6 dB 1,2
Harmonics Vcc = 27 Vdc
PO = 270 W
869-894 MHz Band -13 dBm 1,2
Spurious Vcc = 27 Vdc
PO =270 W
869-894 MHz Band -60 dBc 1,2
Input Return
Loss
Vcc = 27 Vdc
PO = 270 W
869-894 MHz Band -16 dB 1,2
DC Power Vcc = 27 Vdc
PO = 270 W
4 Tones
120
Amps
1,2
PASS _________________________________ FAIL ________________________________
Tested by ______________________________
044-05073 Rev. A 5-6
5-6. FIELD REPLACEABLE PARTS AND MODULES
The following parts and modules can be replaced in the field on site by a qualified technician with
experience maintaining RF power amplifiers and similar equipment:
1. G3S-800-150 power amplifier modules
2. Cooling fans
5-6.1. G3S-800-150 POWER AMPLIFIER MODULE
To replace a power amplifier module, proceed as follows:
1. Set both the RF ON On/Off/Reset switch and the power ON/OFF switch on the front panel
of the amplifier module to OFF.
2. Loosen two screws that secure amplifier module to subrack.
3. Use handle on front of module, and with a steady even pressure, pull module out of
subrack.
CAUTION
When removing the amplifier from the subrack, it is very important
to support the amplifier such that the rear of the module does not
suddenly drop when it disengages from the track. A drop such as
this could damage the module.
5-6.2. COOLING FANS
To replace a cooling fan, proceed as follows:
1. Remove amplifier module from subrack; see paragraph 5-6.1 preceding.
2. Loosen four snap fasteners that secure fan to amplifier module. Disconnect fan power
connector from amplifier module.
3. Install replacement in reverse order of steps 1 and 2 above.