Nautel XL12 Technical Instructions

Contents

12 000 WATT AM BROADCAST TRANSMITTERXL12Page 3-1001 January 2002Table 3-1 Control/Monitor Panel Controls and Indicators (Continued)PANEL MARKING/REF FIG NOMENCLATURE FUNCTIONDES NO. USED IN TEXTA1A3S1 MD-3 ♦ CONTROL - ∧∧(INCR RF PWR)Push button switch that causes an incremental increase inthe RF output level (total of 1000 increments from zero tomaximum), by controlling the magnitude of the PDM'scarrier reference voltage, when it is depressed (integrallamp will turn on while held depressed). The first incrementoccurs 0.25 seconds after actuation. If the switch ismomentarily pressed and released the RF output willincrease by one increment. If the switch is held depressed,the RF output will increase to a nominal maximum of13.5kW. The RF output will remain at the level presentwhen the switch is released and will become the presetlevel for the current preset RF power level selection.NOTESwitch actuation will increase the carrier referencevoltage, for the selected preset RF power level, even if theRF power stage is off (not producing an RF output).When the RF power stage is turned on, the RF output willbe greater than the last established level for that presetpower level.In addition to increasing the carrier reference voltage (RFoutput), the CONTROL - ∧∧ switch will/may cause thefollowing to occur:If it is not released prior to attaining a carrier referencevoltage that corresponds to 13.5kW, the increase integrallamp will extinguish. The power will not continue toincrease. This status will be maintained until the carrierreference voltage is reduced by pressing the CONTROL - ∨∨(DECR RF PWR) switch or it is reset to zero bysimultaneously pressing and releasing CONTROL - ∧∧ andCONTROL - ∨∨ switches.If the CONTROL - ∨∨ and CONTROL - ∧∧ switches aresimultaneously actuated, the carrier reference voltage andtherefore the RF output level will be set to zero. All six ofthe preset power level selections will be affected (set tozero).If it is actuated when the RF output is reduced (cutback)because a protection circuit has automatically reduced it toa safe operating level (the RF POWER - CUTBACK statusindicator's display is red), the RF output will be restored tothe original preset power level in one step.