Nautel V10 User's Installation And Operation Manual

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Nautel V10 User's Installation And Operation Manual Manual pdf 121 page image

V10/V7.5/V5/V3.5 Installation and Operation Manual Page 5-17Section 5 System Level Troubleshooting Issue 3.5• Visually inspect the antenna system forice buildup.• If no ice is present, the problem islikely the fault detection circuitry on thecontrol/display PWB (A43).Possible Associated Faults:- SWR Foldback5.5.3.3 SWR Shutback/Cutback LevelAn SWR Shutback alarm occurs whenthe transmitter’s peak reflected powerexceeds the SWR shutback threshold (2:1SWR) due to a transient SWR condition(arc or lightning) within the outputtransmission line or antenna system [SWRShutback threshold is user definable, but isdefaulted to 1,200 W for V10, 900 W forV7.5, 600 W for V5 or 450 W for V3.5, forall modes]. To reset the latched conditionimmediately (clear the cutback levels),press the Reset soft key in the Statusscreen. Troubleshoot an SWR Shutbackalarm as follows:NOTEUnder excessive reflected power, thetransmitter shuts back and recovers to aseries of cutback levels. Each levelrepresents a 1/8th reduction in forwardpower from the preset power. Thetransmitter sequentially attempts torecover to the highest level that yieldsacceptable reflected power. The leveldepends on the extent of damage to theoutput transmission line or antennasystem. The recovery time is dependentupon the cutback level.• Inspect the output transmission line forpunctures and/or damage.• If no damage can be found with theoutput network, the problem is likelywith the fault detection circuitry on thecontrol/display PWB (A43).Possible Associated Faults:- SWR Shutback- Cutback Level 1 - 75.5.3.4 SWR ShutdownAn SWR Shutdown alarm occurs whenthe transmitter tries to reduce the forwardpower below 1630 W (V10)/1223 W(V7.5)/815 W (V5)/612 W (V3.5) (FMmode), 1164 W (V10)/873 W (V7.5)/582 W(V5)/437 W (V3.5) (FM+HD mode), or465 W (V10)/349 W (V7.5)/232 W (V5)/174 W (V3.5) (HD mode) due to repeatedSWR Foldback alarms. The transmitterlatches off. To reset, press the Reset softkey in the Status screen. Whentroubleshooting an SWR Shutdownalarm, refer to the troubleshooting tips foran SWR Foldback alarm (see 5.5.3.2) orcheck the control/display PWB (A43)detection circuitry.Possible Associated Faults:- SWR Shutdown5.5.3.5 High Forward Power andForward Power LimitingA High Fwd Pwr alarm occurs when thetransmitter average forward powerexceeds the high threshold (High ForwardPower threshold is 1.036 times themaximum power setting for all modes; e.g.,11,396 W for a V10 in FM mode). SeeTable 1-1 for maximum power capability.This alarm only occurs if ALC is disabledor cannot respond fast enough totransmitter load changes. Troubleshoot aHigh Fwd Pwr alarm as follows:NOTEOnce this alarm is active, the transmitterprepares to fold back the forward power ifthe forward power limiting threshold isexceeded. The forward power limitingthreshold is 1.063 times the maximumanalog power setting for FM mode (e.g.,11,693 W for a V10, the max hybrid powersetting for FM+HD mode, and the max all-digital power setting for HD mode.• Verify ALC is enabled.• If ALC is enabled, suspect the faultdetection circuitry on the control/display PWB (A43).