UBS Axcera 325A 500-Watt VHF Low-band Television Transmitter User Manual

UBS-Axcera 500-Watt VHF Low-band Television Transmitter Title Page

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Chapter 5

500-Watt VHF Low Band Transmitter Chapter 5, Detailed Alignment Procedures325A, Rev. 0 5-1Chapter 5Detailed Alignment ProceduresThe 325A transmitter was aligned at thefactory and should not require additionalalignments to achieve normal operation.This transmitter operates using thebaseband audio and video inputs or, ifthe (optional) 4.5-MHz composite inputkit is purchased, either a singlecomposite video + 4.5-MHz input orseparate baseband video and audioinputs.Check that the RF output at J2 of (A9-A5)the coupler is terminated into a dummyload of at least 500 watts. Whileperforming the alignment, refer to theTest Data Sheet for the transmitter andcompare the final readings from thefactory with the readings on each of thetrays. They should be very similar. If areading is off by a significant amount, theproblem is likely to be in that tray.Switch on the main AC and the VHFexciter circuit breakers on the ACdistribution panel behind the rear cabinetdoor.5.1 (A4) VHF Low-Band Exciter Tray(1070820; Appendix C) withBaseband Video and Audio InputsThe (A4) low-band VHF exciter tray(1070820) has adjustments for videolevels, audio modulation levels, and otherrelated parameters.Connect an NTSC baseband video testsignal input (1 Vpk-pk) to the transmittervideo input jack J2 on the (A12) remoteinterface panel. Jacks J1 and J2 on theVHF exciter tray are loop-throughconnected and the unused jack can beused as a video source for anothertransmitter by removing jumper W4 onjack J3 on (A5) the sync tip clampmodulator board (1265-1302). Connect abaseband audio input (+10 dBm) to thebalanced audio input terminal block TB1-1 (+), TB1-2 (-), and TB1-3 (ground). Ifstereo/composite audio is provided,connect it to BNC jack J6, the compositeaudio input jack on the remote interfacepanel. Jacks J3 and J13 on the rear of theexciter panel are loop-through connectedand the unused jack can be used as anaudio source for another transmitter byremoving jumper W1 on jack J15 on theaural IF synthesizer.Look at the front panel meter on the VHFexciter tray. In the Video position, themeter indicates active video from 0 to 1Vpk-pk. The normal video input level is 1Vpk-pk on the meter. If this reading isnot at the proper level, the overall videolevel can be changed by adjusting videolevel control R12 on the sync tip clamp/modulator board.Switch the meter to the Audio position toshow the audio deviation (modulationlevel) of the signal from 0 to 100 kHz.The aural IF synthesizer board wasfactory set for a ±25 kHz deviation with abalanced audio input of +10 dBm. If thereading is at not the correct level, adjustbalanced audio gain pot R13 on the auralIF synthesizer board, as needed, to attainthe ±25 kHz deviation. The aural IFsynthesizer board was factory set for a±75 kHz deviation with a compositeaudio input of 1 Vpk-pk. If this reading isnot correct, adjust composite audio gainpot R17 on the aural IF synthesizerboard, as needed, for the ±75 kHzdeviation.5.2 (A4) VHF low-Band Exciter Tray(1070820; Appendix C) with the 4.5-MHz Composite Input KitWith the 4.5-MHz composite input kit,the (A4) VHF exciter tray is able tooperate using either the separate videoand audio baseband inputs or the single4.5-MHz composite input.
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Document ID265277
Application IDx4m/3vp4IYWlMuqAIdiA0Q==
Document DescriptionChapter 5
Short Term ConfidentialNo
Permanent ConfidentialNo
SupercedeNo
Document TypeUser Manual
Display FormatMicrosoft Word - pdf
Filesize10.2kB (127468 bits)
Date Submitted2002-08-23 00:00:00
Date Available2002-10-16 00:00:00
Creation Date2002-08-23 10:49:11
Producing SoftwareAcrobat Distiller 4.0 for Windows
Document Lastmod2002-08-23 10:49:13
Document TitleChapter 5
FCC ID Filing: OUS325A

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