Larcan MXD1U User Manual

MX Series - 1 Watt UHF AMPLIFIER

S

ection Title Page

NOTICES, ETC. .................................................................................................................. 2

SAFETY AND HEALTH WARNINGS..............................................................................3&4

GENERAL SERVICE INFORMATION

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

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 Maintenance/Replacement Parts ............................................... 92-5

8. Parts List ............................................................................................ 92-12

LIST OF FIGURES: see PUB99-92, page 92-1 for the drawing listing.

TSM 20-312 rev 0: June 14, 2000 1 1W UHF Amplifier

MX Series - 1 Watt UHF AMPLIFIER

NOTICES, ETC.:

THIS EQUIPMENT USES STATIC-SENSITIVE CMOS INTEGRATED CIRCUITS. Observe proper

handling precautions (indicated in Maintenance Sections) at all times when working with this equipment.

TOXIC MATERIALS NOTICE... IMPORTANT...

Effective thermal management in certain semiconductor devices in this equipment is possible only through
the use of Beryllium Oxide ceramic materials. This equipment contains devices made with Beryllium
Oxide!

Beryllium and its compounds is a POISON if taken into the body in any manner.

To reduce your risk, remember: In case of accidental breakage of any kind of semiconductor
device, DO NOT INHALE THE DUST, and AVOID GETTING DUST IN YOUR MOUTH; it could contain
Beryllium. DO NOT LET BERYLLIUM DUST INTO YOUR BLOODSTREAM THROUGH CUTS OR
OPEN WOUNDS!

Seek and obtain IMMEDIATE medical attention if the dust enters your body in any manner.
Avoid cuts by wearing gloves while picking up the pieces. Wash your hands thoroughly after

replacing devices. Dispose of defective devices only through approved toxic waste disposal
facilities.

Remember too, after cleaning up an accidental breakage, avoid inhaling the dust while replacing or
emptying vacuum cleaner filter bags, and wash your hands well after servicing 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 necessarily an endorsement of the trademark or its owner. Parts lists
may also contain trademarked vendor names as an aid in procurement of spare parts. We apologize for
any inadvertent omission of trademark acknowledgement; any such omission was completely accidental.

Although the following pages contain as much information about the 1W UHF Amplifier as it is reasonably
possible to provide, nevertheless we must state that these instructions do not purport to cover all details or
variations in equipment nor to provide for every possible contingency to be met in connection with its
installation, operation, or maintenance. It is assumed that fully competent technical personnel will be
responsible for the maintenance and repair of the equipment that is described in this manual. Should
further information be desired, or should particular problems arise which are not covered sufficiently herein
for the purchaser's purposes, or should replacement parts be required, the matter should be referred to us.

LARCAN INC.
228 Ambassador Drive,
Mississauga, Ontario, Canada L5T-2J2.
Telephone [phone], FAX [phone]

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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.

This manual does not purport to detail all of the safety precautions that should be observed when servicing
this or any other electronic equipment. Servicing by inadequately trained or inexperienced personnel may
expose such personnel to serious risks that could result in personal injury or death, and/or damage to this
equipment. All personnel concerned with the servicing of this equipment should be thoroughly familiar
with standard first aid procedures for the treatment of electrical burns and shock.

The equipment has been designed to protect operating personnel from accidental contact with voltages
dangerous to human life, either by means of distance (where it is necessary to deliberately reach to make
contact with live terminals) or with shielding. It is therefore of prime importance that any protective
covering devices are kept in place at all times.

While all practical safety precautions have been adopted to safeguard personnel from possible injury, in
times of off-air emergency there is often a strong tendency to act without due regard for normal caution;

for this reason, both supervisory and operating personnel are urged to ENSURE THAT THE SAFETY

RULES DETAILED BELOW ARE FOLLOWED AS AN ESTABLISHED ROUTINE 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 SHIELDS

Under normal circumstances no safety shield should be removed.

3. REMOVE PERSONAL JEWELRY WHEN WORKING ON THE EQUIPMENT

The 48 volt power supply in this transmitter, although overload protected, is able to deliver currents
capable of heating metallic tools or personal jewellery such as a watchband, bracelet, or ring. Accidental
short circuits from such metallic objects can cause them to heat sufficiently to result in serious personal
injury.

4. KNOW FIRST AID, AND KEEP FIRST AID SUPPLIES AVAILABLE

Illustrated first aid instructions for the treatment of electrical shock and burns should be displayed in a
prominent location adjacent to the equipment. In rendering first aid, the timeliness and effectiveness of
the treatment are vitally important to the recovery of the injured person.

Without exception, all personnel should thoroughly familiarize themselves with the procedures involved.
One person, whose regular duties place him or her at the transmitter site often, should be delegated and
given the complete responsibility and authority to ensure that first aid supplies are kept on site and
maintained fresh and up to date.

Prominently display a list of emergency telephone numbers. This list should include the telephone
numbers of the nearest ambulance, hospital, doctor, and fire department paramedics; and the public
works (highways or county roads) department in case the former persons need access to the site during
inclement weather.

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MX Series - 1 Watt UHF AMPLIFIER

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MX Series - 1 Watt UHF AMPLIFIER

HEALTH WARNINGS:

1. Non-metallic coverings of some coaxial cables used in this equipment are FLAMMABLE and may

transmit fire when ignited. Other wire coverings are not capable of supporting combustion, but
any non-metallic covering when heated sufficiently may emit dense smoke and acid gases which

can be highly TOXIC and often CORROSIVE.

2. Be careful when replacing RF power transistors. Thermal transfer properties in these devices are
achievable only by the use of Beryllium Oxide ceramics. We stated it earlier but we will

emphatically repeat it again and again, Beryllium Oxide is a TOXIC substance. If the ceramic

or other encapsulation is opened, crushed, broken or abraded, the Beryllium Oxide dust can be
hazardous if taken into the body in any manner. Use caution in replacing these devices.

3. Solvents such as alcohol, ketones, aliphatic or aromatic hydrocarbons, halogenated
hydrocarbons, etc. as found in glues, paints, paint thinners, paint removers, and/or cleaning fluids,

may emit TOXIC VAPOURS and some may be FLAMMABLE. Read and understand the

directions on their containers, and ensure that they are used only in well-ventilated locations.

GENERAL SERVICE INFORMATION

1. Parts List Layout - EXPLAINED

Parts lists for manuals are computer-generated out of the LARCAN materials management database.
They are presented in hierarchical or family tree order.

The computer is input with the parent parts list number, in this 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, we have used the computer's electronic data output
to allow us to more easily integrate the relevant parts list with the text.

The line of text immediately above the horizontal line on the first page of each list provides the number
and name of the relevant assembly that the list represents.

An "R" followed by a dash and a number indicates revision status. This information is meaningful to our
Renewal Parts and/or Customer Service people, and in order that these people can be most helpful, they
should be advised of this revision number especially if renewal parts are needed.

2. 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". In this example, G1 is the
amplifier used in the IPA2 stage while G2 is the amplifier used in the PA stage. Furthermore, the `P’ in
21B1389P1 indicates that this is a part in itself (a printed circuit board) with no parts in it. In this case this
part is called up in 21B1389G1 parts list. The `S’ in 21B1389S indicates that this is a schematic diagram.
In some cases the schematic diagram may be a completely different number.

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GENERAL SERVICE INFORMATION

2. Interpreting LARCAN Drawing Numbers (continued).

Other assemblies may be shown as a number of separate assemblies (Parts 1, 2, 3, 4, or 5), on several
sheets of a single drawing. The drawing "parts" all are assembled the same way, but vary in quantity and
type of components.

For vendor components such as resistors and capacitors, often a generic drawing describing basic
specifications, but having many "parts", will be used.

As an example, Drawing 3R152: Resistor, composition, ¼ watt. Drawing 3R152 describes a ¼ W resistor,
but the drawing PART number calls for the value and tolerance of the resistor wanted. The first two digits
after the "P" are the first two significant figures of the resistance, the third digit is the number of following
zeroes in the resistance value, and a J is 5% tolerance, or K is 10% tolerance. Some example part
numbers are: 47 Ω, ±10%, ¼W, is "3R152P470K"; and "3R152P243J" specifies 24 kΩ, ±5%, ¼W. For
resistance values between 1 Ω and 10 Ω, a letter "R" will appear in the part number to indicate the decimal
place; for instance a 5.6 Ω, ±5%, ¼W resistor will be designated as "3R152P5R6J".

Often the letter "R" appears on schematics or in parts lists where it specifies the decimal place when
referring to resistances, such as "51R" or "75R" or "5R6", and sometimes the letter "k" will appear in the
same context, such as "3k3". This practice is deplored by old-timers in our midst who attended North
American 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

Because a transmitter is a complex device, a referencing system for unique identification of component
parts reduces the chaotic situation that would otherwise result from the natural numbering system found in
every parts list, in which the first capacitor is designated C1 and the first resistor is likewise designated R1,
but when several assemblies using capacitors or resistors appear together, the entire question then

becomes "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.

Prefix 1, the amplifier chassis assembly, has other subassemblies, which are uniquely prefixed such as
the metering board, which is prefixed 5. This sub assembly could have a C1, an R1, etc. Identification of
each component in full is done by simply adding the prefix number to the component designator, thus 5C1,
5R1, etc.

Prefix designation is great for written communications such as letter or FAX, but when talking about it
during a phone conversation, it is probably more natural to simply say "C1 in the preamp board" or "R7 in
the output amplifier" than to go through the routine of looking up the prefix number.

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GENERAL SERVICE INFORMATION

4. 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
“ “ 6 Not Used
“ “ 7 Directional Coupler
Sub-assembly Prefix 8 Power Amplifier (PA)

5. Production Changes

From time 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 an "R" followed by a dash and a number). Whenever a revision letter or number appears, it
should be quoted in any correspondence or communication regarding the equipment.

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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. This amplifier accepts an on-channel internally diplexed (in a 10:1 ratio Vis to Aur)
composite driving signal of about 1mW peak visual RF as input to its RF chain.

The 1W amplifier and channel processor chassis’ are designed to fit in a single 19" customer-provided
cabinet rack, and require 5.25" (3RU) of vertical panel space for a complete transmitter or translator
system. Alternatively, a 19" customer-provided tabletop cabinet could be substituted if the site requires it.

The RF amplifier and other sub-assemblies are all convection cooled. The simplicity of design, the
deployment of all modular and other subassemblies, and the use of standard readily available
components, also enhances serviceability.

Peak forward and reflected 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 conservatively
designed broadband solid-state Pre-amplifier. This amplifier requires no tuning or adjustment. Simplicity of
operation, reduced maintenance costs and increased reliability are a few of the major benefits derived
from this module.

This first stage is a broadband pre-amplifier module which delivers about 40mW to the PA stage to
achieved overall 1W sync peak at the output. The gain of the pre-amplifier is about 18 dB.

The 1W PA module also operates in class A mode, and has a gain of about 15dB. This amplifier is also
wideband and does not require retuning even if it has to operate on another channel.

TRANSMITTER CONTROL

Because of its simple and rugged design, this amplifier does not require any special control, interlocking,
nor protection circuitry. The amplifier can operate safely over ambient temperature of over 45°C, and will
tolerate extremely high VSWR.

The control is simply a front panel switch which applies 117VAC to the power supply.

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