ITS information transmission systems CORPORATION TECHNICAL MANUAL EXHIBIT II (PRELIMINARY) ITS-5523 DIGITAL TRANSMITTER REV: 0 102 Rahway Road McMurray, PA 15317 USA Phone 412-941-1500 FAX 412-941-9421
ITS-5523 DIGITAL TRANSMITTER TABLE OF CONTENTS I. INTRODUCTION: II. SYSTEM ITS-5523: ......................................................................................................................................... 1555-1103 A. SYSTEM DESCRIPTION B. SPECIFICATIONS C. FRONT PANEL LED INDICATORS AND CONTROLS D. PRINTED CIRCUIT BOARD INDICATORS AND DESCRIPTIONS E. SYSTEM ALIGNMENT PROCEDURE F. REAR PANEL CONNECTIONS G. REMOTE CONTROL INTERFACE III. UPCONVERTER/AMPLIFIER SECTION: A. DRAWINGS: 1.
ITS-5523 SYSTEM DESCRIPTION The ITS-5523 Digital Transmitter is designed to operate in conjunction with a QAM digital IF modulator. The Modulator used with this model is a Comstream CM720M. The ITS-5523 incorporates Automatic Level Control (ALC) and Automatic Gain Control (AGC), which serve to maintain a constant output power level. Combining the latest in GaAsFET amplifier technology and space saving design, the ITS-5523 delivers an output power of 5 watts (average).
ITS-5523 THEORY OF OPERATION - Continued A L.O. (local oscillator) signal is generated on the UHF Generator Board. This Board is comprised internally of a voltage controlled crystal oscillator circuit and a x8 multiplier consisting of three x2 broadband doublers (23 = x8) which produces the local oscillator signal (L.O.) signal.. The oscillator circuit is a modified Colpitts design and the crystal is mounted in an oven set at 60° C and operates at 1/24 of the local oscillator frequency.
ITS-5523 THEORY OF OPERATION - Continued The Six Section Bias Board (1519-1136) supplies the two amplifier modules with both +10 VDC (operating voltage) and -5 VDC (bias voltage). The Transmitter Control Board (1555-1214) provides the capability to control and monitor the operating status of the transmitter. The board is designed to protect the transmitter in the event of the following faults: over temperature, loss or reduction in output power and loss of the -5 VDC GaAsFET bias voltage.
ITS-5523 THEORY OF OPERATION - Continued AC Voltage Source The transmitter may be configured to be powered by either a 115 VAC/60Hz or 230 VAC/50Hz by the following procedures. 230 VAC to 115 VAC Operation Locate the 10 position terminal block (TB1) within the transmitter. Referring to Interconnect drawing 15558102, remove the jumper between positions 2A and 3A. Remove the jumper between positions 4A and 5A. remove VR1 (250V), VR2 (275V), and VR4 (275V) from terminal block TB1.
ITS-5523 DIGITAL TRANSMITTER TRAY (11555-1102) SPECIFICATIONS Technical Specifications Type of Emissions........................................................................................................................... 6M00D7W Frequency Range ............................................2150 to 2162 and 2500 to 2686 MHz (any 6 MHz channel) Output Power Rating ..........................................................................................
ITS-5523 FRONT PANEL METER, CONTROLS, AND LED INDICATORS The ITS-5523 front panel provides operating controllability, metering capability and status indication. These features provide an effective means to determine the over-all operating status of the transmitter at a glance. Controls ON/OFF (Rear Panel) Provides control of AC to the tray as well as circuit protection. OPERATE (DS2) Places transmitter into the Operate mode. STANDBY (DS1) Places transmitter into the Standby mode.
ITS-5523 FRONT PANEL METER, CONTROLS, AND LED INDICATORS - Continued One front panel label is provided for channel indication. CHANNEL Indicates the operating channel. Two front panel sample ports provide for monitoring specific RF levels: CHANNEL OSCILLATOR Provides a sample from the channel oscillator. Nominal sample level is - 3 dBm.
ITS-5523 PRINTED CIRCUIT BOARD LED INDICATORS AND DESCRIPTIONS There are both red and green LED indicators located within the transmitter. The green LEDs, when lit, show that the function indicated is operating correctly. The red LEDs, when lit, show a malfunction of the function indicated.
ITS-5523 SYSTEM ALIGNMENT PROCEDURE Connect a suitable load to the output of the Upconverter/Amplifier tray. Turn the circuit breaker (CB1) located on the back of the tray to the on position. Place the Upconverter/Amplifier in standby by pressing the standby switch on the front panel. The amber front panel indicator will light indicating that the Upconverter/amplifier is in standby. Connect the output of the CM720M Modulator tray (J5) to the IF Input of the Upconverter/Amplifier tray (J2).
ITS-5523 SYSTEM ALIGNMENT PROCEDURE - Continued ALC/AGC Board (A6) 1022-1102 Adjust Inner Loop potentiometer R63 for 0.8 volts at TP7. Place switch SW2 into the AGC position. Adjust AGC potentiometer R96 for 100% on the front panel meter. Phase Corrector Board (A34) 1227-1250 The Phase Corrector Board corrects for phase non-linearities of the amplifier stages later in the system. This board has been factory aligned and should not be adjusted without the proper equipment.
ITS-5523 SYSTEM ALIGNMENT PROCEDURE – Continued UHF Generator Board (A15-A1) 1512-1101 1. Connect the main output from the channel oscillator section of the UHF Generator Board (J1) to a spectrum analyzer, tuned to the crystal frequency and peak the tuning capacitors C6 and C11 for maximum output. Tune L3 and L2 for maximum output. The output level should be +5 dBm ±2 dB. While monitoring with a DVM, maximize each of the following test point voltages by tuning the broadband multipliers in sequence. 2.
MMDS PROGRAMMING CHART FOR VHF GENERATOR CONTROL BOARD (1555-1214) CHANNEL NUMBER VISUAL CARRIER (MHz) L.0. = (FV+45.75 MHz) OSCILLATOR FREQUENCY = (L.O./24 MHz) (1 = HIGH) (0 = LOW) (S1) (S2) (S3) (S4) A1 A2 A3 A4 2501.25 2513.25 2525.25 2537.25 2547.00 2559.00 2571.00 2583.00 106.125 106.625 107.125 107.625 1101 1111 1100 1110 1000 1000 0100 0100 1100 1100 1100 1100 1111 1101 1110 1100 B1 B2 B3 B4 2507.25 2519.25 2531.25 2543.25 2553.00 2565.00 2577.00 2589.00 106.375 106.875 107.
MDS PROGRAMMING CHART FOR VHF GENERATOR CONTROL BOARD (1555-1214) CHANNEL NUMBER VISUAL CARRIER (MHz) L.0. = (FV+44.75 MHz) OSCILLATOR FREQUENCY = (L.O./24 MHz) (1 = HIGH) (0 = LOW) (S1) (S2) (S3) (S4) MDS1 MDS2 2151.25 2157.25 2196.00 2203.00 87.875 88.
ITS-5523 SYSTEM ALIGNMENT PROCEDURE – Continued Upconverter Board (A4) 1519-1125 This board does not contain any RF tuning adjustments. The Upconverter Module produces an RF output at J2 by mixing two input signals (L.O. and I.F.) which are applied to J1 and J4 respectively. The L.O. signal (+3 dBm) enters the module at J1 and is split into (2) separate and equal signals by a Wilkinson splitter. One output from the splitter is amplified to provide a buffered output sample (0 dBm) at J3.
ITS-5523 SYSTEM ALIGNMENT PROCEDURE – Continued 50 Watt Amplifier Module (A10-A3) 1512-1107 This Amplifier module does not contain any RF tuning adjustments. The module contains two cascaded broadband GaAs FET amplifier stages (FLL200-3 driving four parallel FLL200-3 's) providing a nominal gain of 18 dB.
ITS-5523 REAR PANEL CONNECTIONS The rear panel of the ITS-5523 provides quick and easy access to all of the external connections necessary to interface the transmitter to the outside world. CONNECTOR NUMBER CONNECTOR TYPE AC . transmitter . . . J1 . IEC . Provides IF INPUT . . . J2 . BNC . Provides an external IF input from the MMDS Receiver tray (50 Ω impedance) L.O. OUTPUT . . . J6 . BNC . Provides an L.O. output to a Modulator. EXT. 10 MHz REF. INPUT . J7 . BNC .
ITS-5523 REMOTE CONTROL INTERFACE All remote/control functions are accessed through a 37 position "D" connector (J12) and two RJ45 connectors and J17) located on the rear panel of the Upconverter/Amplifier. CONNECTION Control: REMOTE OPERATE . . . . . . . J16 REMOTE STANDBY . . . . . . . J16 EXTERNAL OPERATE COMMAND . . . . . J12 Metering: FWD POWER . . . . . . . . J16 REFL POWER . . . . . . . . J16 ALC INPUT . . . . . . . . J12 . . . . . . .
ITS-5523 DIGITAL TRANSMITTER DRAWING LIST UPCONVERTER/AMPLIFIER TRAY The UPCONVERTER/AMPLIFIER TRAY consist of the following boards/modules: x3 Multiplier Assembly..................................................................................................................................................... 1003-1004 UHF Generator Board .......................................................................................................................................................
ITS-5523 DIGITAL TRANSMITTER DRAWING LIST UPCONVERTER/AMPLIFIER TRAY Upconverter Board............................................................................................................................................................ 1555-1225 Schematic ....................................................................................................................................................................... 1555-3225 SCADA Controller Board.................................................
MAINTENANCE AND TROUBLESHOOTING Problem Analysis In most cases, the performance of a GaAsFET transistor is closely tied to the DC operation of the system. Any degradation in signal quality, gain or power is usually related to a corresponding change in a DC parameter somewhere in the system. An exception may be a defective RF input or output connection, which can result in poor performance of the amplifier with all DC parameters appearing normal.
The amount of cleaning necessary depends greatly on the conditions in the translator room. While the electronics have been designed to function well even if covered with dust, heavy buildups of dirt and insects will impede the effectiveness of the cooling and lead to shutdown or premature failure. When it is apparent that the front panel is becoming dust covered, the top cover should be opened and the accumulated foreign material removed.
