Nautel VS2.5 Troubleshooting Manual

Also see for VS2.5: Installation manual Installation manual Troubleshooting manual

Contents

VS2.5 Troubleshooting Manual Responding to alarmsIssue 4.0 2012-12-01 Page 1-15Forward PowerLow(Fwd PowerLow)Output Network(amber)This alarm occurs if the transmitter's average forward power fallsbelow the low forward power threshold (defaulted to 50% of thepreset power level and is user adjustable) due to PA failures, fanfailures, SWR foldback or a pre-amp/IPA failure. The VS2.5 takesno action on this alarm. Check for associated alarms, and followthe associated troubleshooting procedure if present. If no otheralarms are being indicated, with RF turned on, use a digitalmultimeter to measure the voltage between pad V and pad W onany PA. If the voltage does not fall within an acceptable range(between 2.3 V and 3 V), suspect the exciter/control PWB (A1). Ifthe voltage is within this range, suspect the combiner interfacePWB (A12) (see “Combiner Interface PWB Replacement” onpage 1-43).Forward PowerShutdown(Fwd PowerShutdown)Output Network(red)This alarm occurs if the transmitter tries to reduce the forwardpower below minimum (64 W) due to repeated Forward PowerLimiting alarms. The transmitter latches off. See Forward PowerLimiting for troubleshooting tips.Forward PowerVery Low(Fwd PowerVery Low)Output Network(amber)This alarm occurs if the transmitter's average forward power fallsbelow the very low forward power threshold (defaulted to 12.5% ofthe preset power level and is user adjustable) due to PA failures,fan failures, or SWR foldback. The VS2.5 takes no action on thisalarm. See Forward Power Low for troubleshooting tips.High ForwardPower(High FwdPower)Output Network(amber)This alarm occurs if the transmitter's average forward powerexceeds the high forward power threshold (1.036 times themaximum power setting; 2901 W). This alarm occurs only if theexciter ALC cannot respond fast enough to transmitter loadchanges. The VS2.5 takes no action on this alarm. Check forassociated alarms and follow the associated troubleshootingprocedure, if present. If no other alarms exist, inspect the antennanetwork attached to the transmitter. If there are no major issueswith the antenna network that would cause an impedance change(icing for example) suspect the combiner interface PWB (A12)(see “Combiner Interface PWB Replacement” on page 1-43).High Reject Output Network(amber)This alarm occurs if the control system determines that thecalculated power in any reject resistor exceeds the high rejectpower threshold (320 W). The VS2.5 takes no action on thisalarm. Check for associated alarms, and follow the associatedtroubleshooting procedure if present. Typically, high reject poweris the result of a PA failure or removal. If no other alarms are beingindicated, contact Nautel for further support.Alarm NameAUI and(Front Panel)Front PanelLED (color) Description and Troubleshooting Action