DOORDARSHAN

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Training Company :- DOORDARSHAN HPT BUNDI (RAJ). , Submitted by : Chandresh bhanawat B TECH, IV Year ( E lectronics & communication )

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PRASAR BHARTI (BROADCASTING CORPORATION OF INDIA) DOORDARSHAN HPT, BUNDI, (RAJ.)

CONTENTS:

CONTENTS THEORY WORKING SEQUENCE MODULE MECHENICAL & GEOGRAPHIAL MEASUREMENTS 1 KW VISION RACK TECHNICAL DATA SOLID STATE EXCITER POWER SUPPLY UNIT CORRECTOR & DIVIDER UNIT CONTROL CONSOLE PANEL 80 WATT AMLIFIER UNIT 2 WAY COMBINER UNIT VISION MONITORING UNIT ASSEMBLY & INSTALLATION DAILY MAINTAINENCE

INTRODUCTION TO 10 kW TV TRANSMITTER HVV-138 :

INTRODUCTION TO 10 kW TV TRANSMITTER HVV-138 The transmitter system consists of the following main units : exciters(main & backup) selector unit Audio processing unit Video processing unit solid state power amplifier(s) unit. The 1KW solid state valve to the left & 10KW valve stage to the right.

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130 W (sync-peak) solid state amplifier in the vision chain (drives a valve stage to obtain about 1 KW output) The vision output stage uses BEL 15000CX VALVE to generate 10 KW output.

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TRANSMISSION WORKING SEQUENCE OF ALL MODULES OF HTP BUNDI RECEIVER SECTION CONTROL CONSOLE LINE SELECTION EXCITER POWER AMPLIFIER COMBINER DEPLEXER DISH ANTENA TO UP LINK ON AIR

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MECHENICAL AND GEOGRAPHICAL MEASUREMENTS WIDTH : 2400mm DEPTH : 1100mm HEIGHT : 2150mm WEIGHT : 1500Kg LATTITUDE : 25deg.,27min.,09sec. LONGITUDE : 75deg.,38min.,05sec. POWER OF TRANSMITTER : 10KW CHANNEL : #12(-) FREQUENCY : 223-230MHz TRANSMITTER TYPE : BEL-TYPE HVV 138 HIEGHT OF TOWER : 150 mtr . AREA OF SITE : 1.12 HECTERES DATE OF COMMISIONING : 27 APRIL,1993

1 KW VISION RACK:

1 KW VISION RACK 1 KW vision rack houses The solid state exciter Standby exciter Exciter input-output selector Transmitter control unit Corrector/divider unit 130 W amplifier chain RF monitoring unit 1 KW vision cavity & Power supply unit. Linear detector & peak power measuring unit are also mounted on this…

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AURAL MIXER 2 WAY DIVIDER DUAL DRIVER AMPLIFIER 200 W POWER AMPLIFIER 3 WAY OUTPUT DIVIDER 400 W AURAL AMPLIFIER 400 W AURAL AMPLIFIER 400 W AURAL AMPLIFIER 3 WAY OUTPUT COMBINER to 1kW valve AUDIO PROCESSING SEQUENCE

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VSBF & MIXER CORRECTOR & DIVIDER DUAL DRIVER UNIT 80 W POWER AMPLIFIER 80 W POWER AMPLIFIER 2 WAY COMBINER VIDEO PROCESSING SEQUENCE To 1 kW power valve

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TECHNICAL DATA VISUAL TRANSMITTER: TYPE OF EMISSION : C3F OUTPUT POWER : 10KW(SYNC PEAK) : 6.0 KW FREQ. STABLITY : +-300Hz or LESS FREQ. RANGE : 174-230MHz DIFF. GAIN : <=(+-)3% DIFF. PHASE : <=(+-) 3deg. O/P IMPEDENCE : 50 ohms PEAK POWER STABLITY : 10% or less VIDEO I/P LEVEL : 0.5-1.5 V (P-P) VIDEO I/P IMPEDENCE : (nominal) 75 ohms RISE TIME OF PULSE : 250 nano sec RANDOM NOISE IN VIDEO : <= -56 dB (un weighted) BAND OF(10KHz-5MHz) : <= -63 dB (weighted) HUM & LOW FREQ NOISE (<=1KHz) : <= -43 dB

SOLID STATE EXCITER UNIT:

SOLID STATE EXCITER UNIT DP/DG CORRECTOR LOW PASS FILTER DELAY EQUALIZER VISUAL MODULATOR IF OSCILLATOR LOCAL OSCILLTOR AURAL MIXER VSBF & MIXER AURAL MODULATOR POWER SUPPLY UNIT There is also an exciter provided called a backup exciter used at the time of failure of main exciter. Both exciters are brought into line up by keyboard selection on the control panel

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EXCITER CHAIN DIAGRAM

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EXCITER PICTURE EXCITER STAND BY EXCITER

POWER SUPPLY:

POWER SUPPLY Power supply used for running the transmitter is about 11000 volts. The ac voltage at 240V single phase is fed to the power transformer. Each o/p is provided with a over voltage protector. The front panel LEDs at the control console indicates the status of the power supply(s). POWER TRANSFORMER 11000 VOLTS SUPPLY

POWER SUPPLY CONTROLS:

POWER SUPPLY CONTROLS

CORRECTOR/DIVIDER UNIT:

CORRECTOR/DIVIDER UNIT This unit comprises of 2 sections, namely the linearity corrector unit & the 2 way hybrid divider . The o/p of the exciter is fed to linearity corrector. 1 signal is fed to a linear amplifier part & the other is passed through the non-linear section. These two are combined to produce the non-linearity req. to compensate for the non-linearity that will occur in the solid state power amplifier stages. The pre-corrected RF signal is fed to the 2 way hybrid divider which gives two o/p(s) which are at 90 degree phase diff. at the i/p level.

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CORRECTOR & DIVIDER CORRECTOR & DIVIDER BLOCK

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VALVE PICTURE

CONTROL CONSOLE PANEL:

CONTROL CONSOLE PANEL

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THE WHOLE LOOK AT THE EXCITER & AMPLIFIER UNITS: CONSISTS OF :- CONTROL UNIT EXCITER UNIT STAND BY EXCITER UNIT DUAL DRIVER AMPLIFIER UNIT AMPLIFIER UNIT CORRECTOR & DIVIDER UNIT 2 WAY COMBINER UNIT 3 WAY COMBINER UNIT

80 WATT AMPLIFIER UNIT:

80 WATT AMPLIFIER UNIT This unit is driven by the o/p(s) of dual driver unit. It works in class A configuration. The 1 st o/p of the dual driver is fed into the 1 st 80 watt PA unit. The other 80W PA unit is fed from the 2 nd o/p of the dual driver unit. The resultant of 80 W power level is in phase with respect to the i /p. The current consumption of each 80W is about is 8A. The dual driver and 80 W operates from a +28 V power supply.

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2 WAY COMBINER UNIT The o/p from the exciter splits into 2 paths with a 90deg. phase shift in the corrector divider unit & these are fed to 2 chain amplifiers. The hybrid combiner in the 2 way combiner unit combines the 80W units o/p to give around 130W(sync peak) vision RF o/p. T his signal is passed through a directional coupler to get sample RF signal for monitoring purpose. VISION MONITORING UNIT This houses the analog metering ckt . A +5V power supply which is used for operation of peak power circuits . Special meters & switches are provided on the main control console for monitoring..

ASSEMBLY AND INSTALLATIONS:

ASSEMBLY AND INSTALLATIONS Before re-assembly & installation of the transmitter , building is cleaned where the equipments are to be installed. install the blower & blower ducts. Place the instruments & modules as per selected. make interconnections as per station wiring & drawing. DELAY MAINTAINENCE Check the video i/p before the transmission ON record the current & voltage indicated by the panel meters only

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t hank you

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