BIRD THRULINE 4450 Datasheet

INSTRUCTION BOOK
OPERATING INSTRUCTIONS
WITH PARTS LIST
MODEL 4450
THRULINE®WATTMETER

LIMITED WARRANTY
All products manufactured by Seller are warranted to be free from defects in material and w orkmanship for a period of one
(1) year, unless otherwise specified, from date of shipment and to conform to applicable specifications, drawings, blueprints
and/or samples. Seller’s sole obligation under these warranties shall be to issue credit, repair or replace any item or part
thereof which is proved to be other than as warranted; no allowance shall be made for any laborcharges of Buyer for replace-
ment of parts, adjustment or repairs, or any other work, unless such charges are authorized i n advance by Seller.
If Seller’s products are claimed to be defective in material or workmanship or not to conform to specifications, drawings,
blueprints and/or samples, Seller shall, upon prompt notice thereof, either examine the products where they are located or is-
sue shipping instructions for return to Seller (transportation-charges prepaid by Buyer). In the event any of our products are
proved to be other than as warranted, transportation costs (best way) to and from Seller’s plant, will be borne by Seller and
reimbursement or credit will be made for amounts so expended by Buyer. Every such claim for breach of these warranties
shall be deemed to be waived by Buyer unless made in writing within ten (10) days from the date o f discovery of the defect.
The above warranties shall not extend to any products or parts thereof which have been subject ed to any misuse or neglect,
damaged by accident, rendered defective by reason of improper installation or by the performance of repairs or alterations
outside of our plant, and shall not apply to any goods or parts thereof furnished by Buyer or ac quired from others at Buyer’s
request and/or to Buyer’s specifications. In addition, Seller’s warranties do not extend to the failure of tubes, transistors, fuses
and batteries, or to other equipment and parts manufactured by others except to the extentof the original manufacturer’s war-
ranty to Seller.
The obligations under the foregoing warranties are limited to the precise terms thereof. These warranties provide exclusive
remedies, expressly in lieu of all other remedies including claims for special or consequential damages. SELLER NEITHER
MAKES NOR ASSUMES ANY OTHER WARRANTY WHATSOEVER, WHETHER EXPRESS, STATUTORY,
OR IMPLIED, INCLUDING WARRANTIES OF MERCHANTABILITY AND FITNESS, AND NO PERSON IS
AUTHORIZED TO ASSUME FOR SELLER ANY OBLIGATION OR LIABILITY NOT STRICTLY IN AC COR-
DANCE WITH THE FOREGOING.

INSTRUCTION BOOK
OPERATING INSTRUCTIONS
WITH PARTS LIST
MODEL 4450
THRULINE®WATTMETER
© Copyright 1994 by Bird Electronic Corporation
Instruction Book Part Number 920-4450-1 Rev.B
THRULINE® is a registered trademark of Bird Electronic Corporation

Safety Precautions
Safety Precautions
The following are general safety precautions that are not necessarily related to any spec ific part or procedure and do not nec-
essarily appear elsewhere in this publication. These precautions must be thoroughly unde rstood and apply to all phases of op-
eration and maintenance.
KEEP AWAY FROM LIVE CIRCUITS
Operating personnel must at all times observe general safety precautions. Do not replace c omponents or make adjustments in-
side equipment with the high voltage supply turned on. To avoid casualties, always remove p ower.
DO NOT SERVICE OR ADJUST ALONE
Under no circumstances should any person reach into an enclosure for the purpose of serviceor adjustment of equipment ex-
cept in the presence of someone who is capable of rendering aid.
CHEMICAL HAZARD
Dry cleaning solvents used to clean parts may be potentially dangerous. Avoid inhalation o f fumes and also prolonged con-
tact with skin.
RESUSCITATION
Personnel working with or near high voltages should be familiar with modern methods of res uscitation.
SAFETY SYMBOLS
WARNING
Warning notes call attention to a procedure, which if not correctly performed, could resultin personal injury.
CAUTION
Caution notes call attention to a procedure, which if not correctly performed, could resul t in damage to the instru-
ment.
MODEL 4450 THRULINE WATTMETER WARNING STATEMENTS
The following safety warnings appear in the text and are repeated here for emphasis.
WARNING
Exposure to RF power radiation and the possibility of RF shock or burns exists with some o perating conditions. Al-
ways be sure to turn off transmitter when connecting or disconnecting wattmeter. Be sure tra nsmission line is termi-
nated into a load or antenna.
WARNING
Provide adequate ventilation and observe normal precautions when using dry cleaning sol vents. Many dry cleaning
agents emit toxic fumes that be harmful to your health if inhaled. Avoid excessive skin contact or inhalation of the
fumes when using any dry cleaning solvents.
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MODEL 4450 THRULINE WATTMETER CAUTION STATEMENTS
The following equipment cautions appear in the text and are repeated here for emphasis.
CAUTION
Do not drop the Thruline Wattmeter equipment or submit it to hard blows. The voltmeter circuitry or microammeter,
even though it is shock mounted, may be damaged by severe impact.
CAUTION
Clean the meter glass only when necessary and be careful not to use an excessive amount of water/detergent solution
that might drip inside the housing and damage the electrical components.
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About This Manual
About This Manual
This instruction book covers the model 4450 Thruline Wattmeter
This instruction book is arranged so that essential information on safety is contained in the front of the book. Reading the
Safety Precautions Section before operating the equipment is strongly advised.
The remainder of this Instruction Book is divided into Chapters and Sections. Figures and t ables are numbered sequentially
within each chapter. At the beginning of each chapter a general overview will be given, desc ribing the contents of that chap-
ter.
OPERATION
First time operators should read Chapter 1 - Introduction, and Chapter 3 - Preparation f or Use, to get an overview of equip-
ment capabilities and how to install it. An experienced operator can refer to Chapter 4 - Operating Instructions. All instruc-
tions necessary to operate the equipment, are contained in this section.
MAINTENANCE
All personnel should be familiar with preventive maintenance found in Chapter 5 - Maintenance. If a failure should occur, the
troubleshooting section will aid in isolating and repairing the failure.
PARTS
For location of major assemblies or parts refer to the part lists and associated drawingsin the maintenance chapter.
CHANGES
Changes to this publication will be made available in supplements. To keep your instructionbook accurate and up to date, it
is recommended that a periodic request of the latest supplement be made. It will be supplied at no cost. When requesting up-
dates, reference your instruction book part number and its revision level listed on the tit le page.
REPORTING ERRORS
It is our goal to provide our users with the information needed to operate and maintain theThruline Wattmeter. If you should
discover any errors in this publication, or if you have suggestions for improving this instruction book, please send your com-
ments to our factory.
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Table of Contents
Safety Precautions............................i
Model 4450 Thruline Wattmeter Warning Statements.............i
Model 4450 Thruline Wattmeter Caution Statements..............ii
About This Manual...........................iii
IntroductionChapter 1
Purpose and function..........................1-1
Description..............................1-1
Performance Characteristics and Capabilities................1-1
Power Requirements..........................1-1
Specifications..............................1-2
Outline Drawing.............................1-2
Schematic Diagram...........................1-3
Theory Of OperationChapter 2
Traveling Wave Concept........................2-1
Traveling Wave vs Standing Wave....................2-1
Coupling Circuit............................2-1
Reflected Power Reading........................2-1
InstallationChapter 3
Portability..............................3-1
Connections.............................3-1
Operating InstructionsChapter 4
Preliminary Set-up...........................4-1
Reverse Power Operation........................4-1
Load Power.............................4-1
VSWR Calculations..........................4-2
MaintenanceChapter 5
General................................5-1
Sales / Repair Facilities.........................5-1
Sales Facilities............................5-1
Preventive Maintenance..........................5-2
Troubleshooting.............................5-2
Repair.................................5-3
Remove Back Cover..........................5-3
Circuit Board Repair or Replacement ...................5-3
Calibration Board and Meter Removal...................5-3
Range and Mode Switch Replacement ..................5-4
Replacement Parts List..........................5-5
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List of Figures
Outline Drawing.............................1-2
Schematic Diagram...........................1-3
Zero Adjustment Screw..........................4-1
VSWR Conversion Monograph.......................4-2
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Chapter 1 Introduction
Purpose and functionThe Model 4450 Thruline Wattmeter is an insertion-type RF wattmeter designed to measure RF
power flow and load match in 50 ohm RF coaxial transmission lines. Its primary intended use is
for the test and evaluation of power line carrier equipment, although it is well suited low fre-
quency low power RF application. When used in a 50 ohm application, with N type connectors,it
has an insertion VSWR of less than 1.10 for frequencies from 25W and 0 to 100W to correspond
with the range switch (S-2) settings.
This unit will not only give forward power indications with a high degree of accuracy, but a lso
will indicate reflected power with a turn of mode switch S-1.
DescriptionThe Model 4450 Thruline Wattmeter is a portable unit contained in a formed aluminum housing,
with formed sheet aluminum back closure which is easily removed. The unit is equipped with a
leather strap for carrying, four rubber shock feet on the base, and four rubber bumpers on theback,
which allow the unit to be used standing vertically or horizontally. The meter is specially shock
mounted for additional protection and has a slotted adjustment screw on the front face of the meter
bezel for mechanical zeroing adjustment. Just below the meter on the front face is a modeswitch
for selecting power range or OFF position. On the sides of the unit are the RF connectors which
are labeled for input and output.
Performance
Characteristics and
Capabilities
The Model 4450 Thruline Wattmeter is capable of measuring RF power up to 100 Watts in three
ranges: 5, 25, and 100 Watts. These power levels are selected by adjusting the range switch and
can be used for either forward or reflected power by adjusting the mode switch to RFLor FWD
position. When checking reflected power greater resolution can be obtained by selecting a lower
power setting on the range switch.
If necessary, the input and output connections may be reversed without loss of accuracy; however,
the mode switch will be just the opposite of normal settings, i.e. RFLposition will indicate for-
ward power and FWD position will indicate reflected power.
The RF connectors are the Quick-Change (QC) type and may changed to other available QC types
if necessary.
Power RequirementsThe Model 4450 Thruline Wattmeter has no batteries and requires no outside utility power sourc e
for operation other than the RF power to be measured. This makes the unit especially suited for
mobile, marine, and field use.
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Specifications
Impedance50 ohms nominal
Power range5/25/100 Watts
Insertion VSWR1.10 maximum
ConnectorsBird QC type, Female N normally Sup-
plied
Temperature Range
Operating
Storage+5°C to +45°C (41°F to 113°F) -10°C to +45°C (14°F to 113°F)
Accuracy* (From 5°C to 45°C)
30 to 535 kHz
20 kHz to 1 MH z
(Into a 50 ohm load)
5% of full scale
10% of full scale
Dimensions3"D x 3 53 64“W x 6 78”H
(76 x 97.2 x 175mm)
Insertion Loss0.2 dB maximum
Directivity25 db minimum
Weight2lb (0.91 kg)
* On the 5 Watt range only the lower frequency is 30 kHz for 10% accuracy and the
ambient temperature is limited to 15°C to 25°C for this accuracy.
Outline Drawing
Bird Model 4450 Thruline Wattmeter
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Schematic Diagram
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Bird Model 4450 Thruline Wattmeter
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Chapter 2 Theory Of Operation
Traveling Wave
ConceptThe operation of the Model 4450 Wattmeter is based on the traveling wave concept of RF trans-
mission. As RF power is applied to a transmission line, there is a forward wave traveling fr om the
transmitter to the load, and a reflected wave traveling from the load to the transmitter. Th e closer
the load is matched to the line, the smaller the reflected wave will be. To determine the watts dis-
sipated in the load it is necessary to determine the power of the forward wave and the power of the
reflected wave. The difference between the two will indicate effective power dissipation .
Traveling Wave vs
Standing WaveThe interference between forward and reflected waves produces a standing wave in the coaxial
system. In the standing wave concept, VSWR (voltage standing wave ratio) is a widely used im-
plement. There is a simple relationship between forward power, reflected power, and VSWR.
Where: Wf = forward power and Wr = reflected power.
Since there is a definite relationship between standing wave ratio and the forward-reflected power
ratio, the forward and reflected powers may be read as indicated by the Thruline meter, and conve-
niently converted to VSWR. The charts furnished in this instruction book may be used for this
purpose.
Coupling CircuitWhen the wattmeter is connected into a coaxial system, the RF power is directed through the me -
tered line section, which is a short section of 50 ohm air line. This line section will not imp air the
impedance of the RF coaxial line into which it is inserted.
The main line or center conductor of this line section passes through a toroid coil, which actsas a
current transformer having a one turn primary. The secondary turns of this toroid coil vary and are
determined by the power range involved.
The current induced in the secondary windings of the toroid coil are fed to a resistive network
which produces voltages proportional to the line current.
There is also a capacitive divider network in the line that senses the line voltage. This net work
produces a voltage nearly equal to voltage produced by the resistive network.
When the mode switch is in the forward position, these voltages will add in phase. This voltage is
rectified and is calibrated to give an indication on the microammeter equal to forward powe r in the
line section.
Reflected Power
ReadingA coupling circuit, identical to the forward power coupling circuit, is used for the reflec ted power
reading. This circuit is positioned so that it will sense the power in the direction opposite to the
forward direction. The meter will indicate this power when the mode switch is placed in the R FL
position. The energy resulting from the inductively coupled component of the forward wave will
bring about cancellation as described above.
When the mode switch is in the reflected (RFL) position these voltages will oppose and almost
completely cancel each other when a good 50 ohm load termination is used. This resultant voltage
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will be indicated on the microammeter as the power opposite to the forward power, or reflecte d
power.
Bird Model 4450 Thruline Wattmeter
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Chapter 3 Installation
PortabilityThe Model 4450 THRULINE Wattmeter is a portable unit and the housing is not designed for
fixed mounting. A leather strap handle is provided on the unit for carrying purposes. When trans-
porting the Model 4450 turn the range switch to the OFF position. This will shunt the meter move-
ment and effectively dampen the pointer action to protect it during handling or shipping.
C A U T I O N
Do not drop the THRULINE Wattmeter equipment or submit it to hard blows. The voltmeter
circuitry or microammeter, even though it is shock mounted, may be damaged by severe im-
pact.
ConnectionsW A R N I N G
Exposure to RF power radiation and the possibility of RF shock or burns exists with some
operating conditions Always be sure to turn off transmitter when connecting or
disconnecting wattmeter. Be sure transmission line is terminated into a load or antenna.
Insert the Model 4450 THRULINE Wattmeter in transmission lines of 50 ohms nominal imped-
ance. Attachment is made through the connectors on either side of the wattmeter housing. A short
length of 50 ohm coaxial transmission cable fitted with appropriate mating connectors s hould be
used when installing the wattmeter. The input side of the wattmeter, labeled “INPUT”, must be
connected to the transmitter output cable and the OUTPUT side of the wattmeter to a suitable
dummy load or antenna.
The Model 4450 is normally supplied with two Female N connectors which are of the Bird
Quick-Change design. These connectors may be readily and easily changed to other “QC” type
connectors listed in the Replacement Parts List. These connectors are available from Bird El ec-
tronic Corporation and may be requested at time of order to facilitate connection to the user’s sys-
tem.
These “QC” connectors are easily changed by removing the four 6-32 pan head machine screws
from the corners of the connector flange and pulling the connector straight off. To install connec-
tors, reverse the removal procedure making sure the center contact pin aligns properly withits
mating socket.
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Bird Model 4450 Thruline Wattmeter
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Chapter 4 Operating Instructions
The apparent features of the Thruline equipment have been discussed in the preceding sectio ns. As
previously mentioned, no batteries or external power source is required to operate the wattmeter.
A sufficient amount of power is taken from the RF transmission line to operate the unit. This
power is negligible and does not affect the power output to a noticeable degree.
Preliminary Set-upBefore applying any RF power, make sure the meter pointer is exactly set on the ZERO mark of
the scale. If adjustment is required, the pointer must be set on the ZERO mark under no-power
conditions with the range switch set on one of the lower power ranges. Using a small screwdriver,
turn the zero adjust screw on the bezel of the meter clockwise or counterclockwise as necessary
until the pointer exactly aligns with the ZERO mark on the meter scale.
The range switch should be in the OFF position or at least on the 100 watt range, when power is
applied. This is especially true when the amount of power being applied is unknown. After RF
power is applied, the range switch may be turned to a position where a power indication is given
in the upper one-third of the scale.
The mode switch should normally be in the FWD position and switched to the RFL position after
a forward reading has been taken. In the RFL position a more accurate reflected power readi ng can
be obtained by turning the range switch to a lower setting. However, with this condition caremust
be taken not to turn the mode switch back the the FWD position until the range switch has been re-
turned to its original setting. Failure to do this will cause overranging of the meter and pos sible
damage. This practice, of course, is not possible when power less than five watts is being mea -
sured.
Reverse Power
OperationThe Model 4450 may be installed backward in the transmission line if necessary, i.e. transmi tter
output to wattmeter output and wattmeter input to load; however, the forward and reflected po wer
indications will be reversed. Therefore when the mode switch is in the FWD position, revers e
power will be indicated and the RFL position will indicate forward power. Since the line cou plers
and circuitry are similar, acceptable power indications are given with little, if any, change in accu-
racy. Reversing the unit in the transmission line should only be done when absolutely necess ary
since there is the potential danger of overranging the meter movement.
Load PowerWhere an appreciable amount of power is reflected from a load, as with some antennas, it is n eces-
sary to subtract the reflected power reading from the forward power to obtain actual load pow er.
RF power delivered to and dissipated in a load is given by the formula:
WL = watts into load = Wf - Wr
This correction is negligible (less than 1 percent) if the load is such as to have a VSWR of 1.2 to
1.0 or less. Good load resistors such as Bird TERMALINE Loads will give this negligible or un-
readable reflected power.
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Figure 4-1
Zero Adjustment Screw

VSWR CalculationsAfter obtaining the forward and reflected power readings described above, the VSWR may be
found by calculation as described on page 2-1 Traveling wave vs. Standing wave. Conversion
nomographs to simplify determining VSWR are provided below. Simply find the numbers on the
horizontal and vertical axis of the nomograph which correspond to the actual forward and reverse
power readings respectively. Follow the cross lines until they intersect, and read the VSWR from
the nearest slanted line.
Bird Model 4450 Thruline Wattmeter
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Figure 4-2
VSWR Conversion
Monograph
Power Values vs.
VSWR