Larcan MX Series, Manual

Page 1: ...r the 1W Amplifier 6 5 Production Changes 6 GENERAL DESCRIPTION INTRODUCTION 7 SPECIFICATIONS 8 ABOUT THIS MANUAL 9 ON SITE First Time Start up 10 PUBLICATION LIST for MX series 1W UHF Amplifier PUB99 92 1W UHF Amplifier Assembly Section Page 1 Amplifier Chassis Description 92 1 2 Pre Amp Module 92 2 3 PA Module 92 2 4 Directional Coupler 92 3 5 RF Metering Board 92 3 6 Power Supply 92 4 7 Basic M...

Page 2: ...vicing the vacuum cleaner All material in this manual is copyright LARCAN INC and reproduction in whole or in part in any form for any purpose other than exclusive use of the equipment owner without prior written authorization from LARCAN INC is prohibited Trademarks are the property of their respective owners and are mentioned in the text for discussion purposes any such mention is not necessaril...

Page 3: ...UTINE at all times 1 KILL THE AC POWER BEFORE IT KILLS YOU Under no circumstance should any person reach within the cabinets for the purpose of servicing or adjusting the equipment without first disconnecting the AC power or without the immediate presence of another person capable of rendering aid Use of the buddy system is encouraged for transmitter work 2 DO NOT TAMPER WITH INTERLOCKS OR SAFETY ...

Page 4: ...MX Series 1 Watt UHF AMPLIFIER TSM 20 312 rev 0 June 14 2000 4 1W UHF Amplifier ...

Page 5: ... case the amplifier model 40D2180G3 which it designates as level 0 The computer first checks the parent list for major subassemblies then each subassembly list for more subassemblies etc and arranges these lists in order of hierarchy beginning with level 0 then 1 then 2 etc then prints each in the order in which they were found In these booklets which together describe the PARTS of the amplifier w...

Page 6: ...rican tech schools and therefore learned about component values that are specified with the use of decimal notation but schematics drawn this way are common in other parts of the world In a parts list moreover an R followed by a dash and a number indicates a revision but you will be able to recognize the difference from the layout framework of the list 3 The LARCAN Assembly Prefix Numbering System...

Page 7: ...e to time it may become necessary that changes be made in the equipment described in this manual Such changes are usually made either to provide improved performance or to accommodate component substitutions necessitated by vendor product availability A revision letter or number may follow the model or group number marked on the nameplate chassis or circuit board or on the parts list where it is a...

Page 8: ...lected power are displayed on an analog percent power meter located on the front panel of the amplifier unit AMPLIFIER CHAIN The amplifier chain consists of two stages of amplification These are the Pre amplifier and PA stages Both stages operate in class A The system has a minimum gain of 30dB The internally diplexed composite RF output of the channel processor or exciter is fed to a conservative...

Page 9: ...Visual Carrier 0 5 1 0 dB Harmonic Radiation 60 dB Spurious Emission fv 4 5MHz fv 9 0 MHz 40 dB Intermodulation Distortion 50 dB ELECTRICAL AC Line Input 117VAC Power Consumption 40VA typical ENVIRONMENTAL Ambient Temperature 0 C to 45 C Humidity 0 to 90 Altitude 7500 ft COOLING Convection DIMENSIONS The amplifier and standard channel processor chassis are standard 19 rack wide units Amplifier hei...

Page 10: ...nted Finally the Figures illustration drawings in 11 x 17 size complete the booklet The Parts Lists in all booklets have been compiled by and then extracted from the LARCAN materials management computer system and are current as of the date of issue of the booklet We have attempted to present our circuit descriptions in such a way that they would be meaningful to the competent technician whose mai...

Page 11: ...itters only Apply 117VAC to the exciter Connect a 1 V peak to peak video signal to the exciter video input jack Connect an audio signal to the exciter audio input Connect the RF output of the exciter to the RF input of the amplifier Be sure to adjust the RF output level control at minimum for the time being Translator only Apply 117VAC to the channel processor Apply the input channel signal to the...

Page 12: ...MX Series 1 Watt UHF AMPLIFIER TSM 20 312 rev 0 June 14 2000 12 1W UHF Amplifier GENERAL DESCRIPTION Notes ...

Page 13: ...consists of a standard 19 rack mounted 3 5 2RU enclosure containing a line filter power supply two amplifier module assemblies a directional coupler metering board and a metering panel Its basic part number is 40D2180 The amplifier modules are broadband thus covering the entire UHF television spectrum ranging from 470MHz to 860MHz 117VAC to the amplifier chassis comes in via a fused line filter 2L...

Page 14: ...ce of the FET is higher than its input impedance The output match consists of the equivalent of a Tee followed by an L the input of the L is adjustable with variable capacitor C103 or C113 This capacitor is adjusted to provide flat response over the range An output coupling capacitor C104 or C114 completes the match to 50 ohms two outputs are combined in a quadrature hybrid HY2 Bias to the gates o...

Page 15: ...ow signal levels The opposing connection of CR1 diode junction and Q1 emitter base junction provides temperature compensation Q1 buffer amplifier provides a low impedance source to drive the trap C3 C4 and L1 through R9 This trap is broadly resonant to 4 3 MHz and significantly attenuates 3 58 MHz NTSC colour subcarrier as well as any 4 5 MHz intercarrier that may be generated in CR1 or CR2 due to...

Page 16: ... switched ON set at 10dB below visual would normally read about 0 59W on an AVERAGE power meter or 1W sync peak Black video signal no setup with no aural carrier present would also read 0 59W on the average power meter according to the formula Pav Psp 1 685 Measuring power using the spectrum analyzer method Connect the output of the amplifier to the spectrum analyzer using a short low loss cable T...

Page 17: ...e influenced by site location and the station s market parameters consequently its hours of operation equipment configuration and technical personnel deployment For example is the station on the air for 24 hours a day are there main standby transmitters and are they attended or unattended In general the following routines should form the basis of any maintenance program 7 2 DAILY At an attended si...

Page 18: ...ion light bulbs of the tower antenna and grounding system should be conducted annually 7 6 TRANSMITTER COOLING SYSTEM Air filter material supplied with some transmitter cabinets has been impregnated with a polyester coating which is designed to attract and hold very fine particles that may be in the air flow This air filter material should be inspected every month or oftener and replaced when dirt...

Page 19: ...ductive bags or boxes when not in place in the equipment and that spare CMOS ICs are in conductive chip carriers or plugged into conductive foam Be careful about this point many plastic foams can be coloured black but may still be an insulator Use your ohmmeter to be sure Don t accept any devices whose pins are punched through aluminum foil into foam plastic People who don t know better have used ...

Page 20: ...T INHALE THE RESULTING BERYLLIUM DUST and AVOID GETTING BERYLLIUM DUST IN YOUR MOUTH DO NOT LET BERYLLIUM DUST INTO YOUR BLOOD STREAM THROUGH CUTS OR OPEN WOUNDS Seek and get IMMEDIATE medical attention if the dust enters your body in any manner Avoid cuts by wearing gloves while picking up the broken pieces Be careful do not inhale dust while replacing or emptying vacuum cleaner filter bags and w...

Page 21: ...he heat must travel from the FET to the heatsink too much compound effectively adds more distance which could result in overheating e Lightly pre tin and gently bend the FET tabs upward slightly so that the tabs and the circuit board do not prevent the FET from making proper thermal contact with the heatsink f Torque the screws evenly to 4 5 inch pounds This amount is recommended by the FET manufa...

Page 22: ...e mount Components Hints and Advice Failures of small surface mounted resistors on boards where they were companion to other components having leads were traced to mechanical overstress of their end caps as a result of the soldering procedure to the component Our manufacturing procedure has since been altered to fix this problem and despite our embarrassment we think it is important that you shoul...

Page 23: ...l dealer therefore we have listed very few such commodity items here but we believe the following information might be useful to you during your spares requirements planning Capacitors Generally most ceramic or film capacitors are reliable and 5 spares 1 spare for each 20 identical parts and 1 each if less than 20 will be found to be a satisfactory inventory level This includes ceramic polystyrene...

Page 24: ...d or capacitance associated with your replacement resistors Spare Parts The list on the following pages began as computer output listings STS10B STS50B etc from our database used to compile the parts list data for each Section of the manual and the computer has classified recommended spare parts and suggested their quantities by part number Because the manual is written to apply to the entire low ...