Nautel XL12 Technical Instructions

Contents

12 000 WATT AM BROADCAST TRANSMITTERXL12Page 5-301 January 20025.5.1 RF POWER MODULES ALARM: AnRF POWER MODULES alarm indicates a failurein one or more RF power modules.NOTEIt is permissible to operate the transmitter with adefective or missing RF power module.Do not attempt to compensate for any RF powerreduction caused by RF amplifier assemblyfailures by adjusting RF power level controls.(a) Select forward power to be displayed on thecontrol/monitor panel's RF KILOWATTS meter(FORWARD POWER lamp shall be on). Recordforward power reading.(b) If forward power reading in step (a) is lessthan the preset level, one or more RF powermodules are defective. Proceed to paragraph5.5.1.1.(c) If forward power reading in step (a) is normal,the alarm is probably false. Press ALARMRECALL switch to check for other alarms thatmay have triggered the RF power modulealarm. Press/release SYSTEM RESET.5.5.1.1 RF Power Module Fault Validation:Verify one or more RF power modules are defective,isolate the defective module and the nature of thedefect as follows:NOTEA defective RF power module can be removed forrepair, without turning off the transmitter asdescribed in paragraph 5.6. The transmitter canbe operated at a reduced output power level withan RF power module removed.(a) Open the front doors and note which RF powermodule(s) indicate a fault (alarm lamp is on).Record which RF power module is displayingan alarm and which alarm lamps are on.(b) Attempt to reset the RF power module bypressing RESET on its front panel. If itsuccessfully resets, the alarm indication mayhave been false. If the alarm does not reset orit returns, remove the RF power module fortrouble shooting.NOTEThe RF power module's TEMPERATURE alarm canoccur when the 'D' connector is removed fromA1J1 of the RF power module.5.5.1.2 RF Power Module Trouble Shooting:Refer to paragraph 5.6 for removal and installationinstructions and then refer to the RF power moduleservice instruction manual for detailed troubleshooting information.5.5.2 EXTERNAL INTERLOCK ALARM:An RF INTERLOCKS - EXTERNAL alarm indicates anexternal interlock is open. It will be accompanied bya SHUTBACK alarm.(a) Connect a digital multimeter (set to measureDC) between TB1-25 (INTLK OPEN) (+) of theremote interface PWB and ground.(b) If +24 VDC is present on TB1-25, the externalinterlock circuit is intact and the probable causeof the alarm is a defective monitoring circuit.Suspect U7 on remote interface PWB andU23/U24 on the system control PWB.(c) If +24 VDC is not present on TB1-25,determine voltage between TB1-26 (+24VINTLK) of remote interface PWB and ground.(d) If +24 VDC is present on TB1-26, the externalinterlock circuit is open (normally caused by anopen interlock switch).(e) If +24 VDC is not present on TB1-26, theprobable cause is a defective unregulated +24VDC power supply.5.5.3 INTERNAL INTERLOCK ALARM:An RF INTERLOCKS - INTERNAL alarmindicates a ground wand has not been properlystored. It will be accompanied by a SHUTBACKalarm.