EMCEE Broadcast TUA100FA UHF LPTV Power Amplifier User Manual TUA100F Mnl Cover Pg 1

EMCEE Broadcast Products UHF LPTV Power Amplifier TUA100F Mnl Cover Pg 1

TUA100FA Users Manual

P.O. Box 68, White Haven, PA 18661 Phone: (570) 443-9575 FAX: (570) 443-9257MDS  MMDS  ITFS  LPTVNorth America  South America  Europe  Asia  Australia  AfricaSince 1960TUA100FA100W SOLID STATEUHF POWER AMPLIFIER
TUA100FA100W SOLID STATEUHF POWER AMPLIFIERBROADCAST PRODUCTS04/99
TABLE OF CONTENTSI. THE TUA100FA POWER AMPLIFIER1.1 Introduction1.2 Specifications1.3 Installation1.4 Operation1.5 Warranty and Parts OrderingII. CIRCUIT DESCRIPTION2.1 Power Amplifier DrawerIII. MAINTENANCE3.1 Periodic Maintenance Schedule3.2 Recommended Test Equipment3.3 Troubleshooting Chart3.4 Alignment3.5 TTU100FA Transmitter Power Calibration3.6 TU100FA Translator Power Calibration3.7 Spare Modules and ComponentsIV. DATA PAKV. SCHEMATIC DIAGRAMS
iSECTION ITHE TUA100FA POWER AMPLIFIER1.1 Introduction ............................................................. 1611.2 Specifications ........................................................... 1611.3 Installation .............................................................. 1621.4 Operation ............................................................... 1631.4a TTU100FA Transmitter ............................................... 1631.4b TU100FA Translator ................................................. 1641.5 Warranty and Parts Ordering ............................................ 165
161SECTION ITHE TUA100FA POWER AMPLIFIER1.1 Introduction:The EMCEE model TUA100FA Power Amplifier is rated to provide 100 watts peak visual and10 watts average aural power on any FCC specified UHF channel extending from 470 to 806MHzwhen driven by the EMCEE TTU20F Transmitter or TU20F Translator. This compact, single drawerunit is completely solid-state and requires only minimal RF alignment, making it easy to service andmaintain.The TUA100FA was designed for the express purpose of broadcasting as authorized by the FederalCommunications Commission under Part 74, Subpart G of the FCC Rules and Regulations.1.2 Specifications:Output Power 100W peak visual10W average auralOutput Frequency Range 470-806MHz (FCC Ch. 14-69)Gain 12dBChannel Flatness ±0.5dBInput Impedance 50 ohms (N connector)Output Impedance 50 ohms (N connector)Spurious Products >50dB below peak syncHarmonics >60dB below peak syncIntermodulation Products (IM3) >52dB below peak syncDifferential Gain 5% maximumDifferential Phase 3E maximumColor Transmission Compatible with PAL, SECAM, and NTSCPower Requirements 115Vac ± 15%, 60Hz, 700W230Vac ± 15%, 50Hz (OPTIONAL)Ambient Temperature !30EC to +50EC
162Mechanical DimensionsPower Amplifier Drawer 5.25"H x 19"W x 27"DWeight 30 lb.1.3 Installation: 1. After unpacking the EMCEE Model TUA100FA Amplifier, a thorough inspection should beconducted to reveal any damage which may have occurred during shipment. If damage isfound, immediately notify the shipping agency and advise EMCEE Broadcast Products or itsfield representative. 2. Place the TUA100FA in a clean, weatherproof environment with adequate ventilation. Insurethat the amplifier’s ambient temperature does not exceed the !30EC and +50EC limits andcheck to see that nothing blocks the exhaust fan located on the rear of the unit.IMPORTANTDo not apply ac power to the amplifier at this time since its RF output must beproperly loaded before being placed in operation. 3. Place the amplifier in its permanent location near a 120Vac, 50 or 60Hz, single-phasereceptacle. Unless the customer has specifically requested 220Vac operation, the amplifierwill operate only from a 120Vac source. The ac source should have a minimum powercapacity of 700 watts. 4. Set all circuit breakers and switches, including the ac mains breaker, to the OFF position. Place an appropriate ac power line protector (surge suppressor) across the ac line thatsupplies the amplifier. 5. Connect the EMCEE supplied interconnect harness to the TTU20F Transmitter or TU20FTranslator CONTROL jack (J4) and the TUA100FA Amplifier CONTROL jack (J3). In thecase of a transmitter system, find the two video sense wires connected to the TTU/TU20FCONTROL jack (J4) end of the harness but broken out separately. If video sense output isprovided by the modulator, connect the striped white/orange/black wire to the video senseterminal and the black wire to the GND terminal on the modulator’s rear panel. Otherwise,clip off any bare conductor at the end of each wire and tie them back separately. For atranslator system, plug the 9-pin D connector into the Receiver CONTROL jack (J7). 6. Connect the EMCEE supplied RF cable (N connector to N connector) to the RF OUT jack(J2) on the rear panel of the TTU/TU20F and the INPUT jack (J1) on the TUA100FA PowerAmplifier's rear panel. 7. Connect the transmitting antenna cable to the Power Amplifier's RF OUT connector (J2).
1631.4 Operation:1.4a TTU100FA Transmitter:Assuming the installation instructions of Section 1.3 have been completed and the transmitter isreceiving baseband video and audio signals, proceed with the following steps to place thetransmitter in operation. It is assumed that the TTU20F is being used as a driver. 1. Place the modulator (A1) power switch to ON and verify that it provides 87.5% videomodulation. If necessary, adjust the modulator for 87.5% video modulation as described inits instruction manual. 2. On the TTU20F Driver (A2), turn the POWER ADJUST control fully counterclockwise, placethe OPERATE/STANDBY switch to STANDBY, and place the OPERATE/ALIGN switch toOPERATE. Place the meter switch to FWD and the POWER circuit breaker to ON. Thenverify the following responses of the driver.a. The fans of the driver should be operating and exhausting air out the rear of the drawer.b. The driver OPERATE, SYNTH LOCK and DRIVER AMP indicators should beilluminated green.c. The TEMP EXCITER, ON, FINAL BIAS, and VSWR OVLD indicators should beextinguished. 3. Place the TUA100FA Amplifier (A3) POWER switch to ON and meter switch to FWD. Verifythe following responses of the amplifier drawer.a. The fans of the amplifier should be exhausting out the rear of the drawer.b. The FINAL ON and AMPL 1 indicators should be illuminated green and the TEMPindicator should be extinguished. 4. Place the driver OPERATE/STANDBY switch to OPERATE. Then verify the followingresponses of the driver.a. The OPERATE, SYNTH LOCK, and DRIVER AMP indicators should remainilluminated.b. The ON and FINAL BIAS indicators should be illuminated green while the VSWR OVLDand TEMP indicators remain extinguished. 5. Turn the POWER ADJUST control clockwise until a 100% indication appears on theTUA100FA % POWER meter. The % POWER meter on the TTU20F may indicate less than100% since a full 20W is not needed to drive the 100W amplifier. 6. Place both meter switches to REFLD and verify that neither % POWER meter indicates morethan 10% returned power. If either reflected power is more than 10%, shut down thetransmitter. Check the VSWR of the transmitting antenna and its associated cable or checkthe cable connecting the TTU20F Transmitter to the amplifier drawer. 7. Place the meter switches to FWD for constant monitoring of the transmitter’s output power.
164The transmitter is now in operation. Check its coverage area for clean, sharp television reception.If the reception or picture quality is unsatisfactory, examine the amount of power delivered to thetransmitting antenna and, if necessary, examine the antenna orientation, antenna VSWR, andtransmission line VSWR to insure maximum radiation in the proper direction.1.4b TU100FA Translator:Assuming the installation instructions of Section 1.3 have been completed and the translator isreceiving RF signals, proceed with the following steps to place the translator in operation. It isassumed that the TU20F is being used to drive the TUA100FA Power Amplifier. 1. Place the Receiver’s power switch to ON and its OPERATE/ALIGN switch to OPERATE.Verify the following responses.a. The CARRIER PRESENT indicator should be illuminated green, indicating that aVHF/UHF signal of correct frequency and sufficient amplitude is being received. 2. On the TTU20F Driver (A2), turn the POWER ADJUST control fully counterclockwise, placethe OPERATE/STANDBY switch to STANDBY, and place the OPERATE/ALIGN switch toOPERATE. Place the meter switch to FWD and the POWER circuit breaker to ON. Thenverify the following responses of the transmitter.a. The fans of the driver should be operating and exhausting air out the rear of the drawer.b. The driver OPERATE, SYNTH LOCK and DRIVER AMP indicators should beilluminated green.c. The TEMP EXCITER, ON, FINAL BIAS, and VSWR OVLD indicators should beextinguished. 3. Place the TUA100FA Power Amplifier (A3) power switch to ON and meter switch to FWD.Verify the following responses of the amplifier drawer.a. The fans of the amplifier should be exhausting out the rear of the drawer.b. The FINAL ON and AMPL 1 indicators should be illuminated green and the TEMPindicator should be extinguished. 4. Place the driver OPERATE/STANDBY switch to OPERATE. Then verify the followingresponses of the driver.a. The OPERATE, SYNTH LOCK, and DRIVER AMP indicators should remainilluminated.b. The ON and FINAL BIAS indicators should be illuminated green while the VSWR OVLDand TEMP indicators remain extinguished. 5. Turn the POWER ADJUST control clockwise until a 100% indication appears on theTUA100FA % POWER meter. The % POWER meter on the TTU20F may indicate less than100% which is appropriate.
165 6. Place both meter switches to REFLD and verify that neither % POWER meter indicates morethan 10% returned power. If either reflected power is more than 10%, shut down thetransmitter. Check the VSWR of the transmitting antenna and its associated cable or thecable connecting the TU20F Translator to the TUA100FA Amplifier drawer.. 7. Place the meter switches to FWD for constant monitoring of the transmitter’s output power.The translator is now in operation. Check its coverage area for clean, sharp television reception.If the reception or picture quality is unsatisfactory, examine the amount of power delivered to thetransmitting antenna and, if necessary, examine the antenna orientation, antenna VSWR, andtransmission line VSWR to insure maximum radiation in the proper direction.1.5 Warranty and Parts Ordering:Warranty – EMCEE warrants its equipment to be free from defects in material and workmanship fora period of one year after delivery to the customer. Equipment or components returned as defective(prepaid) will be, at our option, repaired or replaced at no charge as long as the equipment orcomponent part in question has not been improperly used or damaged by external causes (e.g.,water or lightning). Semiconductors are excepted from this warranty and shall be warranted for aperiod of not more than ninety (90) days from date of shipment. Equipment or component parts soldor used by EMCEE, but manufactured by others, shall carry the same warranty as extended toEMCEE by the original manufacturer.Equipment Returns – If the customer desires to return a unit, drawer, or module to EMCEE forrepair, follow the procedure described below: 1. Contact EMCEE Customer Service Department by phone or FAX for a Return AuthorizationNumber. 2. Provide Customer Service with the following information:Equipment model and serial numbers.Date of purchase.Unit input and output frequencies.Part number (PN) and Schematic Diagram designator if a module is being sent.Detailed information concerning the nature of the malfunction.The customer shall designate the mode of shipping desired (e.g., Air Freight, UPS, FED EX, etc.).EMCEE will not be responsible for damage to the material while in transit. Therefore, it is of utmostimportance that the customer insure the returned item is properly packed.Parts Ordering – If the customer desires to purchase parts or modules, utilize the followingprocedure: 1. Contact EMCEE Customer Service by phone or FAX indicating the customer's purchaseorder number. If the purchase order number is provided by phone, written confirmation ofthe order is required.
166 2. Also provide:The equipment model and serial number.The unit input and output frequencies.The quantity, description, vendor, number, and designation of the modules needed as foundin the Spare Modules Lists subsection of this manual.If a module is required, give the part number (PN) and Schematic Diagram designator(e.g., 20362238).Designate the mode of shipping desired (e.g., Air Freight, UPS, FED EX, etc.).Shipping and billing addresses.Spare and Replacement Modules and Components – The Spare Modules and Components sectionof this manual provides a listing of the modules and some discrete components contained withinthe amplifier. This list contains those modules or components considered to be essential bench-stock items and should be available to the maintenance technician at all times. The Schematic orInterconnection Diagram is the governing document of this manual. Should there be a discrepancybetween a modules or components list and a diagram, the diagram takes precedence. Such adiscrepancy is possible since manufacturing changes cannot always be incorporated immediatelyinto the instruction manual.Module Referencing – The transmitter consists of drawers containing modules and components. Each drawer is given a reference designator starting with A1. Components and modules locatedin a drawer are referred to by their respective designators, preceded by the designator of the drawerin which they reside. Hence, the designator A1PS2 refers to power supply PS2 in drawer A1. Thisstandard applies for all modular levels, i.e., A1A6A3 represents module A3, located in module A6,located in drawer A1. Components mounted directly to the cabinet take only a component referencedesignator. In the circuit description, Section 2, the full reference designator is given only with theschematic or interconnection diagram. In the text, the modules are referred to by their modulenumber only, unless a module is mentioned that is located in a different drawer. Moduledesignators on interconnect diagrams do not take the drawer designators.For EMERGENCY technical assistance, EMCEE offers a toll free, 24-hour,7-day-a-week customer service hot line: 1-800-233-6193.
iiSECTION IICIRCUIT DESCRIPTION2.1 Power Amplifier Drawer ................................................... 2612.1a 100W UHF Amplifier Module ............................................ 2612.1b UHF Notch Filter ..................................................... 2622.1c Metering Coupler ..................................................... 2622.1d Metering Detector .................................................... 2622.1e Metering Display Assy ................................................. 2632.1f Indicator Circuit ...................................................... 2642.1g 32V Power Supply .................................................... 264
261SECTION IICIRCUIT DESCRIPTIONS2.1 Power Amplifier Drawer:Interconnection Diagram 30383170/Rev 53 ò A3RF OUT (J2) 100W (+50dBm) peak visual10W (+40dBm) average auralDrawer Gain (J1-J2) 12dB MinimumThe Power Amplifier drawer (A3) amplifies the composite RF output signal from the TTU20FTransmitter or the TU20F Translator (A2) to obtain 100 watts peak visual output with 10 watts ofaverage aural. The drawer consists of an RF amplifier chain, a power detection/metering circuitryand an indicator circuit. Some monitoring and control of this drawer is also performed by theTTU/TU20F Driver. The RF amplifier chain is made up of a single LDMOS 100W UHF Amplifiermodule (A1), a 4.5MHz UHF Notch Filter (FL1) and a UHF Metering Coupler (DC1). The powerdetection/metering circuitry includes a Metering Detector (A2), Metering Switch (PC2), MeteringDisplay Assembly (PC1) and an Indicator Circuit (PC3). The amplifier drawer has an internal 32VPower Supply (PS1) and slaves ±15V and +5V from the ±15V/+5V Power Supply (A2PS2) in theTTU/TU20F Upconverter/Amplifier Drawer.The drawer’s front panel provides a display of the amplifier’s % POWER using the MeteringDisplay Assembly (PC1), which is a 30-segment LED bar array driven by information via theMetering Switch (PC2). Also on the front panel is the Indicator Circuit (PC3) which has three LEDsto indicate if the drawer is operational, the power amplifier has overheated, or if the amplifiermodule (A1) has experienced a fault.2.1a 100W UHF Amplifier:Schematic Diagram 40383163/Rev 54 ò A3A1Gain 13dBThe TUA100FA contains a single 100 watt UHF power amplifier module (A1) having a nominalgain of 13dB in the UHF frequency band of 470 to 806MHz. The gain is derived from two parallel,class AB push-pull, LDMOS transistors (Q1, Q2) operating at 32Vdc.The RF signal enters the module through connector J1 and is split by a 90E hybrid, HY1. Eachsignal is then brought to separate coaxial baluns (Z1/Z2) both providing two signals that are 180Eout of phase at the gates of their respective transistor pairs. The gate-source bias voltages for Q1and Q2 are generated by monolithic voltage regulators U1 and U2 which are fed directly by 32Vat pins 11 and 12. Potentiometers R8 and R12, in conjunction with resistors R7, R9, R11 and R13,control the outputs of U1and U2 and are typically set for a 10V at pin 10 of each regulator.Potentiometers R6 and R15 along with R4, R5, R16 and R17 provide individual fine adjustmentfor the gate-source biases of Q1 and Q2, a potential of approximately 4V. Input matching andsignal coupling for each transistor are provided by capacitors C1-C6 with C25 for Q1, and C13-C18
262with C36 for Q2. The outputs of each transistor pair are transformed into combined signals bycoaxial baluns Z3 and Z4. These two signals are then combined again by 90E hybrid HY2 anddelivered to the module output at J2. Output matching and coupling for each transistor pair arefurnished by capacitors C8-C12, C62 for Q1, and C20-C24, C63 for Q2. Inductors L1 through L6are employed as RF chokes with the remaining capacitors used for RF bypass.If a fault occurs in either transistor pair, the difference in power at the hybrid HY2 inputs will createan imbalance causing excessive power to appear at the HY2 ISOlation port. To monitor this fault,a power detection circuit, centered around diode CR1, transforms this excess power into a DCvoltage which appears as a TTL high at terminal E11. On the Indicator Circuit (PC3) board thislogic level high will change the front panel AMPL 1 status LED from green to red.2.1b UHF Notch Filter:Schematic Diagram N/A ò A3FL1Insertion Loss 0.5dB maximumNotch Depth !12dB minimumNotch Frequency Visual Carrier !4.5MHzAural Carrier +4.5MHzThis filter is a tunable two-section notch filter that removes the spurious products created throughcommon amplification 4.5MHz below the visual carrier and above the aural carrier of thetransmitted channel. Each notch has a minimum attenuation of 12dB, with the insertion loss of thepassband at 0.5dB maximum.2.1c Metering Coupler:Schematic Diagram 10199178/Rev 52 ò A3DC1Insertion Loss (J1-J2) <0.5dBFWD Coupling (J1-J3) 30dBREFL Coupling (J1-J4) 30dBThe Metering Coupler is a four port device designed to provide forward and reflected RF samplesto the Metering Detector (A2) with minimal loss to the output signal. The RF signal from the NotchFilter is applied to the coupler’s input port (J1) and exits the coupler at J2 with a maximum of 0.5dBof loss. A !30dB sample of the signal’s forward power is provided at J3, and a !30dB sample ofthe reflected power is provided at J4. These two signals are connected through 6dB attenuators(AT3, AT4) to the metering detector which then provides DC signals, proportional to the amplifier’soutput power, to the Control Board, AGC circuit, and Metering Switch.
2632.1d Metering Detector:Schematic Diagram 30368024/Rev P ò A3A2The Metering Detector contains three circuits for monitoring signal levels. Each of these circuitscan take an RF signal at its input and provide a DC voltage at its output proportional to the inputsignal’s strength. Only two of the detector circuits are used in this application. From the MeteringCoupler (DC1) a sample of the amplifier’s forward signal is supplied to the VISual port of thedetector, and a sample of the reflected power is provided to the detector’s REFLected input. Thefront end or detector portion of each circuit is basically the same. Diodes CR2 and CR4, togetherwith their surrounding components, convert the sampled on-channel RF signals to positive dcvoltages proportional to the detected RF power. Detection of the sampled forward output isaccomplished by CR2 in conjunction with R4 and C2 which form a time constant of 1 second. R4is the dc load while C1 and C11 form the RF ground of the visual power detector. Detection of thesampled reflected signal is the same except for a faster time constant, as R22/C6 form a timeconstant of 1 millisecond. The positive dc voltages from the visual and reflected power detectorsare processed by buffer amplifiers U1 and U2 which provide voltage gains of 1V/V and 2V/V,respectively. These buffer amplifiers also provide isolation between the % POWER meter and thedetectors. The settings of potentiometers R9 and R27 determine the voltage level applied to the% POWER meter when the meter switch (A3PC2) is in its FWD or REFL position. Since commonamplification of the visual and aural carriers is provided in this amplifier, the AURal detector circuitis not used.A dc voltage proportional to the amplifier's output power is applied to pin 5 of connector J4,designated VIS PWR REF. This power reference is fed back to the driver's (A2A1) AGC circuitcontained in the IF/Upconverter. This voltage ultimately controls the attenuation of the compositeIF carrier so that the amplifier's output is automatically maintained at its rated value.A dc voltage proportional to the amplifier's reflected output power is fed to pin 10 of comparatorU2. This voltage is compared to a reference voltage at pin 9 whose magnitude is determined bypotentiometer R30. With R30 properly set (see paragraph 3.5b), the voltage on pin 10 will begreater than the reference voltage whenever the amplifier's reflected power is more than 10% ofits rated forward power. As a result, the output of the comparator saturates in the positive modeapplying approximately +4Vdc to the VSWR OVLD line. This voltage instructs the Control Board(A2PC1) in the transmitter/driver that a VSWR overload condition has been detected. When theamplifier's reflected power is less than 10% of its rated forward power, the voltage on pin 10 ofcomparator U2 will be less than the reference voltage. As a result, the comparator saturates in thenegative mode, diode CR1 is forward biased, and approximately !0.7Vdc is applied to pin 7 ofconnector J4. This voltage instructs the Control Board that no VSWR overload condition exists.2.1e Metering Display Assy:Schematic Diagram 20362238/Rev 54 ò PC1The Metering Display (PC1) consists of three 10-segment LED bar graphs (DS1, DS2, and DS3)and their drivers (U1, U2 and U3). Light Emitting Diodes DS1 and DS2 are green with DS3 coloredred. The drivers are scaled so that at 100% forward output power all segments of DS1 and DS2should be illuminated and at 50% only segments of DS1 should be illuminated. When the amplifieris operating at more than 100%, all segments of DS1 and DS2 will be lit with some or all portionsof DS3 illuminated depending on the amount of output power over 100%.
2642.1f Indicator Circuit:Schematic Diagram 20383174/Rev 53 ò A3PC3The Indicator Circuit (PC3) is mounted to the front panel and contains three indicator LEDs. TheFINAL ON indicator illuminates when the power switch is turned on and the 32V Power Supply(PS1) distributes power throughout the drawer. The TEMP LED illuminates when the thermostat,mounted on the heat sink of the power amplifier module, detects excessively high temperatures(175EF/80EC). When the 100W UHF Power Amplifier (A1) module is functioning properly, a logic"0/ " is present on J2-A causing inverter U1 in the AMPL 1 status circuit to output a logic "1", placingapproximately 5V across the green section of LED DS1. Buffer U2 essentially passes the logic"0/ " bypassing the red section of the LED to ground, thus extinguishing it. If the amplifier moduleexperiences a fault, a logic "1" is put on the AMPL 1 STATUS input J2-A, and the green LEDsection extinguishes while the red section illuminates. 32V is converted to +5V on this board byregulator U3 for use by inverters and buffers U1 and U2.2.1g 32V Power Supply:Schematic Diagram N/A ò A3PS1Output 32V @ 18.7A MaxA +32V, 600 watt high performance, high efficiency power supply is used to power the 100W UHFPower Amplifier module. The supply is a single output, power factor corrected switching type.The 32V Power Supply is not field repairable. If defective, it should be returned to EMCEE forrepair or replacement.
iiiSECTION IIIMAINTENANCE3.1 Periodic Maintenance Chart ............................................. 3613.2 Recommended Test Equipment .......................................... 3613.3 Troubleshooting Chart ................................................... 3623.4 Alignment ............................................................... 3643.4a UHF Notch Filter .................................................... 3643.5 TTU100FA Transmitter Power Calibration ................................ 3643.5a Forward Power ...................................................... 3643.5b Reflected Power .................................................... 3653.6 TU100FA Translator Power Calibration ................................... 3663.6a Forward Power ...................................................... 3663.6b Reflected Power .................................................... 3673.7 Spare Modules and Components ........................................ S61
361SECTION IIIMAINTENANCE3.1 Periodic Maintenance Schedule:OPERATION RECOMMENDATIONALIGNMENT Upon installation and at one-year intervalsthereafter (see subsection 3.4).OUTPUT POWER CALIBRATION Same as above (see subsection 3.5).FANS Inspect as often as possible (at least monthly)and clean when necessary. No lubricationneeded.3.2 Recommended Test Equipment:EQUIPMENT MANUFACTURER MODEL #Digital Multimeter HEWLETT PACKARD E2378AOscilloscope TEKTRONIX 2232VHF Sweep Generator WAVETEK 200150 Ohm RF Detector TELONIC BERKELEY 855330dB 150W Attenuator NARDA 769-30Power Meter HEWLETT PACKARD 435BStep Attenuator KAY 1/432Frequency Counter HEWLETT PACKARD 5386ASpectrum Analyzer HEWLETT PACKARD 8594ENTSC Video Generator TEKTRONIX TSG100Television Modulator EMCEE EM1Mixer MINI-CIRCUITS ZP-2
3623.3 Troubleshooting Chart:The following chart is an aid to determining and correcting the causes of faults that may occur in thisamplifier. Under normal operating conditions, the FINAL ON indicator should be illuminated greenwith the TEMP and AMPL 1 indicators unlit. If a problem develops, note the type of problem, thestate of the indicator LEDs and % POWER meter and compare them to this chart. Refer to theTroubleshooting Chart in the TTU20F Transmitter or TU20F Translator manual as necessary.TROUBLESHOOTING CHARTPROBLEM INDICATORS CAUSE SOLUTIONNO OUTPUTPOWER ALL LEDs UNLIT No 32V or 5V available Check plug connectionsP9/P10 and 5V regulator(U3) output on Indicator Circuit board PC3.Faulty module or 32VPower Supply Shut off Xmtr/Xltr RFdrive. While monitoringthe 32V supply, removethe dc plug from eachmodule and PC board inthe drawer and the wireharness to the driver. Ifthe 32V returns when aplug is removed, replacethe associated module. If32V does not return withall plugs removed,replace power supply.TEMP YELLOWAMPL 1 GREENFINAL ON GREEN% POWER 0DRIVER STBYHigh ambient temperatureinside drawer Ensure fans are opera-tional and are notblocked.Faulty thermostat If amplifier A1 is cool,measure resistanceacross the thermostat. Replace thermostat if ashort is present.LOW OUTPUTPOWER ORDISTORTEDOUTPUTAMPL 1 RED Faulty amplifier module Replace amplifier module.NO fault indicated Output power calibrationis incorrect See Section 3.5 or 3.6.
TROUBLESHOOTING CHARTPROBLEM INDICATORS CAUSE SOLUTION363LOW OUTPUTPOWER ORDISTORTEDOUTPUTNO fault indicated Notch Filter misaligned See Section 3.4a.Xmtr/Xltr Drivermisaligned Refer to the TTU/TU20FInstruction Manual.
3643.4 Alignment:3.4a UHF Notch Filter: 1. Place the Amplifier Drawer POWER ON switch to off. Disconnect the input cable from theNotch Filter and connect the filter’s input directly to the sweep generator's RF output. 2. Place the RF Detector directly on the RF OUTPUT connector (J2) of the transmitter. 3. Tune the sweep generator to the center frequency of the transmitter's output channelemploying a 20MHz sweep width display on the oscilloscope. Display the 1MHz markers. 4. The filter adjustments are the two threaded rods located on the short side of the filteraccessible through the left side panel toward the rear of the drawer. If they are not marked,slowly adjust one and observe which notch moves on the scope and set accordingly. Do notswitch the positions of the individual notches.Set the lower notch to (Visual Carrier Frequency ! 4.5MHz).Set the upper notch to (Aural Carrier Frequency + 4.5MHz).The visual carrier frequency for the appropriate UHF channel can be found inSection 4, the Data Pak, or in Table 261. 5. Remove the sweeper cable from the filter input and the RF Detector from the drawer output.Replace the Notch Filter input cable.3.5 TTU100FA Transmitter Power Calibration:To ensure proper transmission, the output power level and % Power Meter calibration should bechecked once every year. With the meter switch in the FWD position, the % Power Meter has beenfactory calibrated for 100% with the transmitter providing 100 watts peak visual and 10 wattsaverage aural. The following calibration procedure assumes that the visual carrier has 87.5% videomodulation and 0% average picture level (APL). In the following steps, the power levels stated arethose expected at the output of the transmitter. Therefore, when measuring these power levels asshown in Figure 366, be sure to take into account the 30dB factor provided by the attenuator. Powerlevels at 50% APL (stair steps) are included in brackets following the power levels at 0% APL (SYNConly).3.5a Forward Power: 1. With the TTU20F in STANDBY and the TUA100FA Amplifier off (POWER ON circuit breakerdown), set up the test equipment as shown in Figure 366.
365 2. Verify that the modulator is operating and providing 87.5% video modulation. Place the100 Watt Amplifier POWER switch to ON and make sure the Amplifier’s Meter Switch is inthe FWD position. Place the TTU20F Transmitter STANDBY switch to OPERATE. 3. To set the output power, adjust the TTU20F POWER ADJUST for an external power meterreading of 69.5W [44W]. Note that 100W peak visual at 0% [50%] APL and 87.5%modulation plus 10W average aural equals 69.5W [44W] average power. 4. To check or adjust the visual to aural carrier ratio, replace the power meter in Figure 366 witha spectrum analyzer. Adjust the aural carrier level on the modulator for the desired ratio.Remove the spectrum analyzer and return the power meter to the Transmitter’s output andreset the output power for an external power meter reading of 69.5W [44W]. 5. With the external power meter showing the correct power, place the meter switch to FWDand check the TUA100FA front panel % Power Meter for a 100% indication. If this readingis not obtained, adjust potentiometer R9 of the Metering Detector (A3) for a 100% indication.The Metering Detector is mounted on the right-hand side wall near the front of the amplifierdrawer and is accessible through the holes in the side wall. The % Power Meter on theTTU20F Transmitter/Driver will indicate less than 100% which is an appropriate reading.3.5b Reflected Power (OPTIONAL): 6. On the right side wall of the TUA100FA Power Amplifier drawer, adjust potentiometer R30of the Metering Detector fully clockwise to disable the VSWR overload detection circuit.Place the amplifier drawer meter switch to REFL. 7. Place the Transmitter/Driver OPERATE/STANDBY switch to STANDBY and the OPERATE/ALIGN switch to ALIGN. Remove and reverse the forward power (J3) and reflected power(J4) coupling port cables on the Metering Coupler (DC1). J1 and J3 of the Metering Detector(A3) should now be connected to J4 and J3 of the Metering Coupler (DC1), respectively.This simulates an open circuit at the amplifier's RF OUTput (J2) delivering maximumreturned power to the REFL port of the Metering Detector. Insert a step attenuator betweenthe modulator's IF OUTPUT and the transmitter's IF INPUT and set the step attenuator for10dB attenuation. 8. Place the Transmitter/Driver OPERATE/STANDBY switch to OPERATE. Remove theattenuation from the step attenuator for an external power meter reading of 69.5W [44W].Check the amplifier drawer's front panel REFL meter for a 100% [70%] reading. Ifnecessary, adjust potentiometer R27 of the amplifier Metering Detector for the properreading. R7 is accessible through the right-hand side wall of the drawer. 9. Decrease the transmitter's power to 50% by increasing the step attenuator 3dB for anexternal power meter reading of 34.75W [22W]. This power level is used for setting the trippoint of the VSWR overload detection circuit. Adjust R30 of the amplifier’s Metering Detectorslowly counterclockwise until the front panel VSWR OVLD indicator illuminates red and theTransmitter/Driver is placed in standby.
36610. Check the VSWR OVLD trip point by setting the step attenuator for an additional 1dB ofattenuation. Press the momentary VSWR RESET switch to reset the transmitter andremove the additional 1dB of attenuation from the step attenuator. The VSWR OVLD circuitshould again trip. If it does not, repeat this section beginning at step #6.11. Place the OPERATE/STANDBY switch to STANDBY. Return the Metering Coupler cablesto their original ports, J3 and J4. Reinstall the top cover, slide the drawer back into thecabinet and secure it properly. Properly load the transmitter and place the Driver OPERATE/ALIGN and OPERATE/STANDBY switches to OPERATE.3.6 TU100FA Translator Power Calibration:To ensure proper transmission, the output power level and % Power Meter calibration of thetranslator should be checked once every year. With the meter switch in the FWD position, theTUA100FA Amplifier % Power Meter has been factory calibrated for 100% with the translatorproviding 100 watts peak visual and 10 watts average aural. The following calibration procedureassumes that the composite signal received by the translator has the aural carrier 10dB down fromthe visual with the visual carrier having 87.5% video modulation and 0% average picture level (APL).In the following steps, the power levels stated are those expected at the output of the translator.Therefore, when measuring these power levels as shown in Figure 367, be sure to take into accountthe 30dB factor provided by the attenuator. Power levels at 50% APL (stair steps) are included inbrackets following the power levels at 0% APL (SYNC only).This procedure also assumes the setup in Figure 367 is being used and that the output of thereceiver drawer has been correctly calibrated. If the received broadcast channel frequency is in theVHF band (Ch.2-13), the mixer can be deleted from the test setup and a VHF agile modulator seton the correct channel may be connected directly to the RF INput (J1) of the Receiver drawerthrough an attenuator.3.6a Forward Power: 1. With the TU20F Translator drawer in STANDBY and the TUA100FA Amplifier POWER ONcircuit breaker switch open (down), set up the test equipment as shown in Figure 367. 2. Verify that the modulator is providing 87.5% video modulation with the aural 10dB below thevisual and that the input signal is at the correct frequency (Receiver’s input channel) and atan amplitude between !40dBm to !47dBm. Place the TUA100FA 100 Watt Power Amplifierinto operation and make sure the Meter Switch is displaying FWD power. Turn the TU20FTransmitter/Driver ON and place both the OPERATE/STANDBY and OPERATE/ALIGNswitches to OPERATE. 3. To set the output power, adjust the Driver’s POWER ADJUST control for an external powermeter reading of 69.5W [44W]. Note that 100W peak visual at 0% [50%] APL and 87.5%modulation plus 10W average aural equals 69.5W [44W].
367 4. With the external power meter reading the correct output power, place the meter switch toFWD and check the TUA100FA Amplifier front panel % Power Meter for a 100% indication.If this reading is not obtained, adjust potentiometer R9 of the Metering Detector (A3) for a100% indication. The Metering Detector is mounted on the right-hand side wall near the frontof the amplifier drawer and is accessible through the holes in the side wall. The % PowerMeter on the TU20F Driver will read less than 100% which is an appropriate indication.3.6b Reflected Power (OPTIONAL): 5. On the right side wall of the 100W Power Amplifier drawer, adjust potentiometer R30 of theMetering Detector fully clockwise to disable the VSWR overload detection circuit and placethe meter switch to REFL. 6. Place the Transmitter/Driver OPERATE/STANDBY switch to STANDBY and the OPERATE/ALIGN switch to ALIGN. In the amplifier drawer remove and reverse the forward power (J3)and reflected power (J4) coupling port cables on the Metering Coupler (DC1). J1 and J3 ofthe Metering Detector (A3) should now be connected to J4 and J3 of the Metering Coupler(DC1), respectively. This simulates an open circuit at the amplifier’s RF OUTput (J2)delivering maximum returned power to the REFL port of the Metering Detector. Insert a stepattenuator between the Receiver’s IF OUTPUT and the Transmitter’s IF INPUT and set thestep attenuator for 10dB attenuation. 7. Place the Transmitter’s OPERATE/STANDBY switch to OPERATE. Remove attenuationfrom the stepper for an external power meter reading of 69.5W [44W]. Check the amplifierdrawer's front panel meter for a 100% [70%] reading and, if necessary, adjust potentiometerR27 of the Amplifier’s Metering Detector for the proper reading. R27 is accessible throughthe right-hand side wall of the drawer. 8. Decrease the translator's power to 50% by increasing the step attenuator 3dB for an externalpower meter reading of 34.75W [22W]. This power level is used for setting the trip point ofthe VSWR overload detection circuit. Adjust R30 of the Amplifier’s Metering Detector slowlycounterclockwise until the front panel VSWR OVLD indicator illuminates red and theTranslator/Driver drops into standby. 9. Check the VSWR OVLD trip point by increasing the step attenuator an additional 1dB. Pressthe momentary VSWR RESET switch to reactivate the Translator and remove the additional1dB of attenuation from the attenuator. The VSWR OVLD circuit should again trip. If it doesnot, repeat this section beginning at step #5.10. Place the OPERATE/STANDBY switch to STANDBY. Return the Amplifier Metering Couplercables to their original ports, J3 and J4. Reinstall the top cover, slide the drawer back intothe cabinet and secure it properly. Properly load the Translator and place both theOPERATE/ALIGN and the OPERATE/STANDBY switches to OPERATE.
S613.7 Spare Modules and Components:The following contains the description, vendor, part number, and designator of each module foundin the TUA100FA Amplifier which EMCEE considers to be essential bench-stock items. Thesemodules should be available to the technician at all times.TUA100FA SPARE MODULES LISTINTERCONNECTION DIAGRAM 30383170 (REV 53)DESCRIPTION VENDOR/PART # DESIGNATORUHF Power Amplifier EMCEE/40383176-2 A132V Power Supply ASTEC/MP6-3T-00 PS1Metering Detector EMCEE/60368050-1 A2Metering Display EMCEE/60362240-1 PC1Indicator Circuit EMCEE/20383186-1 PC3Fans EMCEE/A2000-5 B1, B2RF Cable EMCEE/A288-048-36Interconnect Harness TTU100FATransmitter EMCEE/60383052-1ORInterconnect Harness TU100FA Translator EMCEE/60383092-1Surge Suppressor GE/V150LA10A E3, E4

Navigation menu