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Larcan MX Series Manual

1 watt uhf amplifier
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ection
NOTICES, ETC. .................................................................................................................. 2
SAFETY AND HEALTH WARNINGS..............................................................................3&4
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
Section
LIST OF FIGURES: see PUB99-92, page 92-1 for the drawing listing.
TSM 20-312 rev 0: June 14, 2000
MX Series - 1 Watt UHF AMPLIFIER
Title
Page
1) Parts Lists Explained ......................................................................................... 4
2) Interpreting LARCAN Drawing Numbers ........................................................... 4
3) The LARCAN Assembly Prefix Numbering System........................................... 5
4) List of Prefix Numbers for the 1W Amplifier ....................................................... 6
5) Production Changes .......................................................................................... 6
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 Maintenance/Replacement Parts ............................................... 92-5
8.
Parts List ............................................................................................ 92-12
1
Page
1
W UHF Amplifier

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  • Page 1: Table Of Contents

    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 Amplifier Chassis Description .............. 92-1 Pre-Amp Module ..................

  • Page 2: Notices, Etc

    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.
  • Page 3 MX Series - 1 Watt UHF AMPLIFIER TRANSMITTER SAFETY PRECAUTIONS: AC VOLTAGES USED FOR THE OPERATION OF THIS EQUIPMENT ARE DANGEROUS TO HUMAN LIFE! This instruction manual has been written for the general guidance and information of operation, maintenance and service personnel who are aware of, and are familiar with, the hazards of working with high powered electronic circuits.
  • Page 4 MX Series - 1 Watt UHF AMPLIFIER TSM 20-312 rev 0: June 14, 2000 W UHF Amplifier...

  • Page 5: General Service Information

    Interpreting LARCAN Drawing Numbers Engineering drawings at LARCAN are based on the concept that an assembly or subassembly is simply a GROUP of component parts, thus when a G appears on a list, it means an "assembly". Thus a circuit board loaded with parts may be referenced in this manual as "21B1389G1".

  • Page 6: The Larcan Assembly Prefix Numbering System

    "which C1 or R1 are we talking about?" The LARCAN prefixing system and its "undocumented features" represent a beginning and evolving solution to some of these problems. It begins by assigning a distinct assembly prefix number to each subassembly.

  • Page 7: Production Changes

    MX Series - 1 Watt UHF AMPLIFIER GENERAL SERVICE INFORMATION List of Assembly Prefixes Prefix 1 Main Amplifier Chassis Assembly Sub-assembly Prefix 2 Line Filter “ “ 3 Power Supply “ “ 4 Pre-Amplifier “ “ 5 Metering Board “...

  • Page 8: General Description

    GENERAL DESCRIPTION INTRODUCTION This manual describes the LARCAN 1Watt UHF amplifier which is designed to operate on channels 14 through 69. This solid state 1W UHF amplifier was designed to operate conservatively at 1W peak sync visual RF power, and 0.1W average aural carrier RF power, with superb performance, reliability and operating economy.

  • Page 9: Specifications

    MX Series - 1 Watt UHF AMPLIFIER GENERAL DESCRIPTION ELECTRICAL AND MECHANICAL SPECIFICATIONS NTSC Power Output: ....................Visual 1 W peak, Aural 0.1W Diplexing: ......................internally diplexed, 10:1 V to A Frequency Range: ..................470-806 MHz (channels 14 thru 69) Amplifier Output Impedance: ........................50 Ω...

  • Page 10: About This Manual

    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.
  • Page 11 MX Series - 1 Watt UHF AMPLIFIER GENERAL DESCRIPTION FIRST-TIME, ON-SITE TRANSMITTER START-UP PROCEDURE: Please take the time to read and understand the technical Sections of this manual, which contain information that you might want or need when you first start your newly installed transmitter.
  • Page 12 MX Series - 1 Watt UHF AMPLIFIER GENERAL DESCRIPTION Notes: TSM 20-312 rev 0: June 14, 2000 W UHF Amplifier...
  • Page 13 1W UHF AMPLIFIER ASSEMBLY Contents: Part Topic Page Amplifier Chassis Description ..................92-1 Pre-Amplifier Module...................... 92-2 PA Module........................92-2 Directional Coupler......................92-3 Metering Board ......................92-3 Power Supply ......................... 92-4 Basic Maintenance/Replacement Parts ................. 92-5 Parts List ........................92-12 List of Figures: Figure Title Drawing Reference...

  • Page 14: Pa Module

    1W UHF AMPLIFIER ASSEMBLY Pre-amplifier 10A1453G7 : Figures 92-3 The Pre-amplifier module is a conservatively designed broadband amplifier which can operate on frequencies between 470MHz to 860MHz with a excellent gain of about 18dB. It also has a very good return loss and DC current stability with temperature.

  • Page 15: Uhf Amplifier Assembly

    1W UHF AMPLIFIER ASSEMBLY Another (final) check is made before applying RF: gate voltages at C102 and C112 are measured. With good FETs, both voltages should be approximately equal and in the range +3.5 to +5.5VDC. Current limiting is checked by increasing the setting of RV3; the current will increase to a threshold of, and must not exceed, 1.6 amperes.

  • Page 16: Power Supply

    1W UHF AMPLIFIER ASSEMBLY RF Metering Board Test and Calibration: Forward Power Meter Calibration - Zero Adjust With no RF input connected, measure the DC voltage at U1-7 (or TP1) and adjust R18 until the output voltage at U1-7 (TP1) drops to a minimum, approximately 10 to 50 mVDC. A DC coupled scope will make the adjustment easier to see;...

  • Page 17: Basic Maintenance/Replacement Parts

    1W UHF AMPLIFIER ASSEMBLY BASIC MAINTENANCE Please note that the following are basic maintenance guidelines and general information and not all may be applicable to your particular equipment. GENERAL When the transmitter was installed and commissioned it was in proper operating condition. During final tests, all circuits were checked for optimum adjustment to ensure both peak performance and conservative operation of components, and test results were recorded for future reference.
  • Page 18 1W UHF AMPLIFIER ASSEMBLY MONTHLY In addition to the normal operational tests, thorough physical inspection of every piece of equipment should be made, with all power turned off. All surfaces should be dusted off or wiped down, terminal boards checked for loose connections, and all components examined for any evidence of overheating. Air filter media should be inspected and replaced if necessary.
  • Page 19 1W UHF AMPLIFIER ASSEMBLY The average person wearing rubber-soled shoes and walking across a woollen or synthetic carpet or untreated vinyl tiled floor is able to generate voltages in excess of 15 to 20 kV. Most MOS devices will suffer puncture of the oxide insulating their gates, at 20 to 40 V. Many CMOS devices are fabricated with built-in zeners which will clamp foreign voltages, but the amount of energy that must be dissipated may easily exceed the rating of this protection.
  • Page 20 1W UHF AMPLIFIER ASSEMBLY It is recommended for better accuracy that meter faces be given an anti-static treatment, either by cleaning with an antistatic cleaning agent, or sprayed with an antistatic coating, or both. Suitable antistatic chemicals should be available through your nearest electronics parts distributor, and typically carry such names as "Zero Charge"...
  • Page 21 Use eutectic tin-lead 63/37 solder (preferred, but if 63/37 is not available, 60/40 is acceptable). Current manufacturing process at LARCAN uses AIM™ (American Iron & Metal Company Inc.) 63/37 solder containing a "no clean" flux which becomes inert during soldering, therefore does not require subsequent board cleaning.
  • Page 22 1W UHF AMPLIFIER ASSEMBLY Inexpensive cotton swabs (available in drug stores or supermarkets) can be used for wiping the solvent over the area to be cleaned, then a stiff bristle brush (an old toothbrush) can be used to scrub if necessary.

  • Page 23: Basic Maintenance/Replacement Parts

    Although LARCAN can supply any part when required, in many instances it may be more conveniently obtained from a local source. Part numbers of replaceable components used in LARCAN equipment are almost always the catalog numbers of the various parts manufacturers, with the rare exception of proprietary items such as tightly specified RF power FETs, crystals, or analog 50 μA meters.
  • Page 24 1 of each when less than 20) for each value and size of resistor, is usually sufficient. Incidentally, when a molded carbon composition resistor (as specified on LARCAN drawings 3R152, 3R77, 3R78, or 3R79) such as those made by Ohmite™ or Allen-Bradley™, is used in an RF circuit, it is not necessarily good practice to make substitution without knowing exactly what the replacement resistor is;...

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