Powerwave Technologies 5JS0042 Linear Feed-Forward Power Amplifier User Manual Part 7

Powerwave Technologies Inc Linear Feed-Forward Power Amplifier Part 7

User Manual Part 7

044-05055 Rev. A 5-1MAINTENANCE5-1. INTRODUCTIONThis section contains periodic maintenance and performance test procedures for the MulticarrierCellular Amplifier System. It also contains a list of test equipment required to perform theidentified tasks.NOTECheck your sales order and equipment warrantybefore attempting to service or repair the unit. Donot break the seals on equipment under warranty orthe warranty will be null and void. Do not returnequipment for warranty or repair service until propershipping instructions are received from the factory.5-2. PERIODIC MAINTENANCEPeriodic maintenance requirements are listed in Table 5-1. Table 5-1 also lists the intervals atwhich the tasks should be performed.WARNINGWear proper eye protection to avoideye injury when using compressed air.Table 5-1. Periodic MaintenanceTASK INTERVAL ACTIONCleaningAir Vents 30 Days Inspect and clean per para. 5-4.InspectionCables andConnectors 12 Months Inspect signal and power cablesfor frayed insulation. Check RFconnectors to be sure that they aretight.Performance Tests 12 Months Perform annual test per para. 5-5.5-3. TEST EQUIPMENT REQUIRED FOR TESTTest equipment required to test the amplifier system is listed in Table 5-2. Equivalent testequipment may be substituted for any item; keep in mind that a thermistor type power meter isrequired.NOTEAll RF test equipment must be calibrated to 0.05 dBresolution. Any deviation from the nominal attenuation mustbe accounted for and factored into all output readings.Section5
044-05055 Rev. A 5-2Table 5-2. Test Equipment RequiredNOMENCLATURE MANUFACTURER MODELSignal Generator RDL IMD-801D-03A30 dB Attenuator, 500 Watt Weinschel Corp. 53-30-3410 dB Attenuator, 20 Watt(2 each) TenulineSpectrum Analyzer H.P. 8560ECoax Directional Coupler H.P. 778DPower Meter/Sensor H.P. 437B/8481ANetwork Analyzer H.P. 8753CCurrent Probe5-4. CLEANING AIR INLETS/OUTLETSThe air inlets and outlets should be cleaned every 30 days. If the equipment is operated in asevere dust environment, they should be cleaned more often as necessary. Turn off DC powersource before removing fans. If dust and dirt are allowed to accumulate, the cooling efficiencymay be diminished. Using either compressed air or a brush with soft bristles, loosen and removeaccumulated dust and dirt from the air inlet panels.5-5. PERFORMANCE TESTPerformance testing should be conducted every 12 months to ensure that the amplifier systemmeets the operational specifications listed in table 5-3. Also verify system performance after anyamplifier module is replaced in the field. The test equipment required to perform the testing islisted in table 5-2, and the test setup is shown in figure 5-1.NOTEThe frequencies used in this test are typical for an amplifier witha 25 MHz band from 869 MHz to 894 MHz. Select evenly spacedF1, F2, F3, and F4 frequencies that cover the instantaneousbandwidth of your system.5-5.1. AMPLIFIER SYSTEM PERFORMANCE TEST.This test is applicable to the MCR20XX Series (NTL107AC) subrack with two plug-in G3X-800Series (NTL107AA) 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 886MHz, and F4 to 889 MHz. Adjust each signal generator output so that the sum poweroutput from all four signal generators equals -4 dBm at the output of the 4-way combiner.
044-05055 Rev. A 5-3Figure 5-1. Amplifier System Test Setup DiagramSINGLE AMPLIFIER IMD TEST:3. Adjust attenuator for an input signal at -l0 dBm. Turn on both amplifiers, and set RF ONswitch of amplifier number two to OFF. Reset first amplifier with the front panel RF ONswitch, and set switch to ON. Adjust variable attenuator to set amplifier power output onpower meter to 100 watts. Measure IMD on spectrum analyzer. IMD should be -65 dBcmin. 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 poweroutput on power meter to 200 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 200 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 110 amps maximum. Record test data in table 5-3.
044-05055 Rev. A 5-4GAIN 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 gainacross 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 thegain 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 amplifiersshould be 3 dB higher than in steps 9 and 10. Record test data in table 5-3. HARMONICS TEST12. With the power set at 200 watts power output, use the spectrum analyzer and check thefrequency band from 869 MHz to 894 MHz for harmonics. Harmonics should be -45 dBcmaximum. Record test data in table 5-3.SPURIOUS TEST13. With the power amplifier set at 200 watts power output, use the spectrum analyzer andcheck the frequency band from 869 MHz to 894 MHz for spurious signals. Spurioussignals 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 returnloss measurement on network analyzer. Input return loss should be –14 dB minimum.Record test data in table 5-3.
044-05055 Rev. A 5-5Table 5-3. Multicarrier Cellular Amplifier System Test Data SheetDATE _________________________________MCR20XX SERIES (NTL107AC) SUBRACK S/N ______________________________________MODULE #1 S/N ________________________ MODULE #2 S/N ________________________TEST CONDITIONS:Load and Source Impedance: 50 OhmsVSWR: < 1.2:1Supply Voltage: +27 Vdc ±1.0 VdcTEST SPECIFICATION MIN MAX DATA4-TONE IMDOne ModuleVcc = 27 VdcPO = 100 WFreq.: 880, 883, 886, and 889MHz-65 dBc124-TONE IMDTwo ModulesVcc = 27 VdcPO = 200 WFreq.: 880, 883, 886, and 889MHz-65 dBc1,2RF GainOne ModuleVcc = 27 VdcPO = 100 WFreq. = 880 MHz 30 dB 50 dB 12RF GainTwo ModulesVcc = 27 VdcPO = 200 WFreq. = 880 MHz 30 dB 50 dB 1,2Gain Flatness Vcc = 27 Vdc ±1 VdcPO =200 W869-894 MHz Band -0.6 dB +0.6 dB 1,2Harmonics Vcc = 27 VdcPO = 200 W869-894 MHz Band -13 dBm 1,2Spurious Vcc = 27 VdcPO =200 W869-894 MHz Band -60 dBc 1,2Input ReturnLossVcc = 27 VdcPO = 200 W869-894 MHz Band -16 dB 1,2DC Power Vcc = 27 VdcPO = 200 W4 Tones110Amps1,2PASS _________________________________ FAIL _______________________________Tested by ______________________________
044-05055 Rev. A 5-65-6. FIELD REPLACEABLE PARTS AND MODULESThe following parts and modules can be replaced in the field on site by a qualified technician withexperience maintaining RF power amplifiers and similar equipment:1. G3X-800 Series (NTL107AA) power amplifier modules2. Cooling fans5-6.1. G3X-800 SERIES (NTL107AA) MODULETo 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 panelof 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 ofsubrack.CAUTIONWhen removing the amplifier from the subrack, it is veryimportant to support the amplifier such that the rear of themodule does not suddenly drop when it disengages from thetrack. A drop such as this could damage the module.5-6.2. COOLING FANSTo 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 powerconnector from amplifier module. 3. Install replacement in reverse order of steps 1 and 2 above.

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