UBS Axcera 835A-6 6000-Watt UHF Transmitter User Manual 835A

UBS-Axcera 6000-Watt UHF Transmitter 835A

Specifications

UHF Solid State Transmitters835A-3, 835A-4, 835A-5, 835A-6The 835A represents the state of the art insolid state UHF transmitters. Highperformance, redundancy, and simplicity arecombined in a very reliable unit.Using parallel high gain amplifiers, the 835Acan be configured for 3kW, 4kW, 5kW, or6kW operation. Combined aural/visualamplification is achieved with very goodintermodulation performance, thanks tohighly linear amplifiers and extensivecorrection capability.Front panel samples, status, and metering,most of which are remote controllable, allowfor convenient system monitoring. As with allAxcera products, servicing is made easy withslide out assemblies that require no extendercards. This allows the circuits to be accessedfor maintenance or adjustments even whileon the air.
www.axcera.com • 724-873 -1500UHF Solid State TransmittersHigh PerformanceExciterThe exciter, designed andbuilt by Axcera, contains thecircuitry to convert the inputvideo and audio signals to acombined, modulated RFsignal which drives two verylinear phase and gainmodules. An optionalsecond exciter withautomatic exciter switcher isavailable for addedredundancy.Video/Visual ModulationThe video signal is processedin several ways prior tomodulation. Sync tipclamping is provided torestore proper DC level.Sync and white clipping arealso included to limit videotransient faults. Back porchclamping is also available forsome scrambling systems.The video signal is thenapplied to a doublebalanced diode modulator,providing modulationUHF Solid State Transmitterscapability to 1% at standardintermediate frequency (IF).A SAW filter is employedfor precise sidebandfiltering with minimal groupdelay error.Audio/Aural ModulationThe audio signal is applied toa very wideband, linear FMmodulator which operates atintercarrier frequency (4.5MHz for system M). Thehigh performance modulatoraccepts a full range ofmultichannel audio includingstereo, mono, and secondaudio programming (SAP).Standard aural IF is achievedby heterodyne conversion ofthe modulated intercarriersignal with the visual IF.IF ProcessingThe visual and auralmodulated IF signals arecombined and applied to IFprocessing stages. Thesestages provide outstandingsignal precorrection to yielda very linear transmitteroutput. Amplitudelinearity, incidental carrierphase modulation (ICPM),and frequency responsecorrection are alladjustable.UpconversionThe IF signal is upconvertedto final channel frequencythrough heterodyning with avery stable local oscillator.The oscillator is crystal andoven temperature controlledfor excellent frequencystability. The exciter iscontrolled with an AutomaticLevel Control (ALC) loopwhich ensures stable signallevels. After upconversionthe signal is amplified toprovide the exciter output.Power AmplifiersThe parallel 600 wattpower amplifiers are highgain units (45-50 dB),which provide redundantpaths from the exciter to theoutput. Redundancy isenhanced with independentpower supplies and coolingfor each amplifier assembly.The output stage of eachamplifier module utilizeseight transistors in parallel foradded redundancy and on-airreliability.A high degree of protectionis provided with eachamplifier. Individualcirculators, overdriveprotection, VSWR cutback,and overtemperatureprotection are all included.Automatic Gain Controlaround each amplifierensures that the transmitteroutput remains stable.The output of each RFcabinet is fed into a low losshybrid combiner. Outputbandpass and trap filtering isincluded to provide superiorout of band rejection.
www.axcera.com • 724-873 -1500UHF Solid State TransmittersFeatures and Benefits24 Hour Field SupprtStandard with all Axcera products is 24 hour/day, 7 day/week field support. This serviceoperates as a direct telephone line during business hours, and on a pager system at all othertimes. Since all our products are designed and built at our facility just south of Pittsburgh,Pennsylvania, we are able to offer quick turnaround on most replacement modules, andtimely shipping from the Pittsburgh International Airport.■Utilizes 100% solid state circuitry for high reliability and low maintenance costs■Configured with parallel high gain amplifiers for total system redundancy and maximumon-air reliability, including driver stages■Provides standard ±1 kHz frequency stability for stations with an offset frequency■Independent power supplies and cooling for cost-effective and reliable operation■Configured with broadcast quality exciter that includes full BTSC soundcapability■Provides output circulator amplifier protection and isolation for high VSWR conditions■Experienced field service/support team is ready to help you 24 hours a day, 7 days a weekPAPAPAPAPAPAPAPAPAPASplitter 5-WayCombinerIPASplitterHybridCombinerSplitter 5-WayCombinerIPAExciterSwitcherExciterExciterBandpass/Trap FilterOptional SecondExciter withAutomatic ExciterSwitcherCombined RFCombined RF RF Output 5kW Peak Visual500W Average AuralVideoAudioVideoAudioUHF Solid State TransmittersBlock Diagram - 835A UHF 5kW Transmitter
B0008 1101R1-E835A-3, 835A-4, 835A-5, 835A-6Visual PerformancePower Output (Peak) 3000, 4000, 5000, or 6000wattsOutput Impedance 50 ohmsOutput Connector 3 1/8" EIAFrequency Range 470 to 860 MHzCarrier Stability ±1 kHz (standard)±350 Hz (optional)Regulation of RF Output Power 3%Output Variation (over 1 frame) 2%Sideband Response (System M/N-others on request)-3.58 MHz -42 dB-1.25 MHz and below -20 dB-0.5 to +3.58 MHz ±0.5 dB3.58 MHz to 4.18 MHz +0.5, -1.0 dBFreq Response vs. Brightness ±0.5 dBVisual Modulation Capability 1%Differential Gain 5%Incidental Phase Modulation ±3°Linearity (Low Frequency) 5%Differential Phase ±3°Signal-to-Noise Ratio 55 dB2t K-Factor 2%Env. Delay Per CCIR or FCC StandardVideo Input 75 ohms (loop through)Video AGC Range 1V, ±6 dBHarmonics -60 dB or betterIntermodulation Products -52 dB or betterSpurious -60 dB or better(>3 MHz from channel edge)Aural PerformancePower Output (Average) 300, 400, 500, or 600 WFrequency Deviation Capability ±75 kHzDistortion 0.5%FM Noise -60 dBAM Noise -50 dBAural to Visual Separation 4.5 MHz, ±100 HzComposite Audio Input (multi-channel sound)Input Level 1V peak, nominalInput Impedance 75 ohms, unbalancedFrequency Range ±0.1 dB response 50 Hz to 50 kHz ±0.5 dB response 30 Hz to 120 kHzMonaural Audio InputInput Level 0 to +10 dBmInput 600 ohms, balancedFreq Range (±0.5 dB resp.) 30 Hz to 15 kHzPre-emphasis 75µsSubcarrier InputInput Level 1V peak, nominalInput Impedance 75 ohms, unbalancedFreq Range (±0.5 dB resp.) 20 kHz to 120 kHzGeneralOperational Temperature Range 0°C to +50°COperational Humidity Range 0% to 95%Altitude 8,500 feetLine Voltage 230V, ±10%,1 phase or 3 phase,50/60 HzPower Factor 0.95835A-3Size (H x W x D) 80" x 44" x 34"Weight 1150 lbsPower Consumption 10,300 W (50% APL)835A-4Size (H x W x D) 80" x 66" x 34"Weight 1350 lbsPower Consumption 13,700 W (50% APL)835A-5Size (H x W x D) 80" x 66" x 34"Weight 1500 lbsPower Consumption 17,000 W (50% APL)835A-6Size (H x W x D) 80" x 66" x 34"Weight 1650 lbsPower Consumption 20,200 W (50% APL)

Navigation menu