Bird 43, 43P, 4305, 4431, 4521 User Manual
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INSTRUCTION BOOK
RF DIRECTIONAL
THRULINE® WATTMETER
MODEL 43
Also Covers Models
4305, 4431, 4521-27, and 43P
©Copyright 1998, 2001
Instruction Book Part Number 920-43 Rev. D
Thruline® and Termaline® are registered trademarks
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by Bird Electronic Corporation
of Bird Electronic Corporation
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Safety Precautions
The following are general safety precautions that are not necessarily
related to any specific part or procedure, and do not necessarily
appear elsewhere in this publication. These precautions must be
thoroughly understood and applied to all phases of operation and
maintenance.
Keep Away From Live Circuits
Operating personnel must at all times observe general safety
precautions. Do not replace components or make adjustments to the
inside of the test equipment with the high voltage supply turned on.
To avoid casualties, always remove power.
Shock Hazard
Do not attempt to remove the RF transmission line while RF power is
present. Radiated RF power is a potential health hazard.
Do Not Service or Adjust Alone
Under no circumstances should any person reach into an enclosure to
service or adjust the equipment except in the presence of someone who
is capable of rendering aid.
Safety Earth Ground
An uninterruptible safety earth ground must be supplied from the
main power source to test instruments. Grounding one conductor of a
two conductor power cable is not sufficient protection. Serious injury
or death can occur if this grounding is not properly installed.
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Bird Model 43 Wattmeter
Resuscitation
Personnel working with or near high voltages should be familiar with
modern methods of resuscitation.
Safety Symbols
WARNING
Warning notes call attention to a procedure, which if not correctly
performed, could result in personal injury.
CAUTION
Caution notes call attention to a procedure, which if not correctly
performed, could result in damage to the instrument.
This symbol appears on the equipment indicating there is
important information in the instruction manual regarding
that particular area.
☞
Note: Calls attention to supplemental information
Warning Statements
The following warnings appear in the text where there is danger to
operating and maintenance personnel, and are repeated here for
emphasis.
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WARNING
Leaking RF energy is a potential health hazard. Never attempt to
connect or disconnect equipment from the transmission line while
RF power is being applied. Severe burns, electrical shock, or death
can occur.
WARNING
When working with RF powers of 200 watts or more, the potential of
the center conductor of the line section will be over 100 volts. Do not
touch the center conductor while RF power is on.
Caution Statements
The following equipment cautions appear in the text whenever the
equipment is in danger of damage, and are repeated here for emphasis.
CAUTION
For low reflection measurements, do not rotate the reflected power
element to read forward power. Damage to the element or
wattmeter could result.
CAUTION
Handle elements with care. Calibration could be disturbed if they
are dropped.
CAUTION
Do not attempt to remove the RF center conductor. This will
damage the line section.
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Bird Model 43 Wattmeter
Safety Statements
USAGE
ANY USE OF THIS INSTRUMENT IN A MANNER NOT
SPECIFIED BY THE MANUFACTURER MAY IMPAIR
THE INSTRUMENT’S SAFETY PROTECTION.
USO
EL USO DE ESTE INSTRUMENTO DE MANERA NO
ESPECIFICADA POR EL FABRICANTE, PUEDE ANULAR LA
PROTECCIÓN DE SEGURIDAD DEL INSTRUMENTO.
BENUTZUNG
WIRD DAS GERÄT AUF ANDERE WEISE VERWENDET ALS VOM
HERSTELLER BESCHRIEBEN, KANN DIE GERÄTESICHERHEIT
BEEINTRÄCHTIGT WERDEN.
UTILISATION
TOUTE UTILISATION DE CET INSTRUMENT QUI N’EST PAS
EXPLICITEMENT PRÉVUE PAR LE FABRICANT PEUT
ENDOMMAGER LE DISPOSITIF DE PROTECTION DE
L’INSTRUMENT.
IMPIEGO
QUALORA QUESTO STRUMENTO VENISSE UTILIZZATO IN
MODO DIVERSO DA COME SPECIFICATO DAL PRODUTTORE
LA PROZIONE DI SICUREZZA POTREBBE VENIRNE
COMPROMESSA.
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SERVICE
SERVICING INSTRUCTIONS ARE FOR USE BY
SERVICE - TRAINED PERSONNEL ONLY. TO AVOID
DANGEROUS ELECTRIC SHOCK, DO NOT PERFORM ANY
SERVICING UNLESS QUALIFIED TO DO SO.
SERVICIO
LAS INSTRUCCIONES DE SERVICIO SON PARA USO
EXCLUSIVO DEL PERSONAL DE SERVICIO CAPACITADO. PARA
EVITAR EL PELIGRO DE DESCARGAS ELÉCTRICAS, NO
REALICE NING¤N SERVICIO A MENOS QUE ESTÉ CAPACITADO
PARA HACERIO.
WARTUNG
ANWEISUNGEN FÜR DIE WARTUNG DES GERÄTES GELTEN
NUR FÜR GESCHULTES FACHPERSONAL.
ZUR VERMEIDUNG GEFÄHRLICHE, ELEKTRISCHE SCHOCKS,
SIND WARTUNGSARBEITEN AUSSCHLIEßLICH VON
QUALIFIZIERTEM SERVICEPERSONAL DURCHZUFÜHREN.
ENTRENTIEN
L’EMPLOI DES INSTRUCTIONS D’ENTRETIEN DOIT ÊTRE
RÉSERVÉ AU PERSONNEL FORMÉ AUX OPÉRATIONS
D’ENTRETIEN. POUR PRÉVENIR UN CHOC ÉLECTRIQUE
DANGEREUX, NE PAS EFFECTUER D’ENTRETIEN SI L’ON N’A
PAS ÉTÉ QUALIFIÉ POUR CE FAIRE.
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Bird Model 43 Wattmeter
RF VOLTAGE MAY BE PRESENT IN RF ELEMENT
SOCKET - KEEP ELEMENT IN SOCKET DURING
OPERATION.
DE LA TENSION H.F. PEAT ÊTRE PRÉSENTE DANS LA PRISE
DE L’ÉLÉMENT H.F. - CONSERVER L’ÉLÉMENT DANS LA PRISE
LORS DE L’EMPLOI.
HF-SPANNUNG KANN IN DER HF-ELEMENT-BUCHSE
ANSTEHEN - ELEMENT WÄHREND DES BETRIEBS
EINGESTÖPSELT LASSEN.
PUEDE HABER VOLTAJE RF EN EL ENCHUFE DEL ELEMENTO
RF - MANTENGA EL ELEMENTO EN EL ENCHUFE DURANTE
LA OPERACION.
IL PORTAELEMENTO RF PUÒ PRESENTARE VOLTAGGIO RF TENERE L’ELEMENTO NELLA PRESA DURANTE IL
FUNZIONAMENTO.
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About This Manual
This instruction book covers RF Directional Thruline Wattmeters
Models:
43 43P 4305A 4431 4521
4522 4523 4525 4526 4527
This instruction book is arranged so that essential safety information
appears 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. At the beginning of each chapter, a general overview
describes the contents of that chapter.
Operation
First time users should read Chapter 1 - Introduction, Chapter 3 Installation, and Chapter 2 - Theory of Operation, to get an overview
of equipment capabilities and installation. Specifications are provided
in Chapter 7 - Specifications. An experienced operator can refer to
Chapter 4 - Operating Instructions. All instructions necessary to
operate the equipment appears in this chapter. If you are not using
the Model 43, refer to Chapter 6 - Model Differences for instructions
specific to your unit.
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Bird Model 43 Wattmeter
Maintenance
All personnel should be familiar with the preventive maintenance
found in Chapter 5 - Maintenance. If a failure should occur, the
troubleshooting section will aid in isolating and correcting the cause.
Changes to This Manual
We have made every effort to ensure this manual is accurate. If you
should discover any errors or if you have suggestions for improving
this manual, please send your comment to our factory. This manual
may be periodically updated. When inquiring about updates to this
manual refer to the part number and revision level on the title page.
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Table of Contents
Safety Precautions .................................................................................. i
About This Manual ............................................................................... vii
Introduction............................................................................................. 1
Purpose and Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Performance Characteristics and Capabilities . . . . . . . . . . . . . . . . . . 2
Theory of Operation ............................................................................... 5
Travelling Wave Viewpoint. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Coupling Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Load Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Standing Wave vs. Travelling Wave Viewpoint . . . . . . . . . . . . . . . . . 8
ρ vs. φ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Low Reflection Measurements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Transmitter Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Component Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Frequency Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Impedance Mismatch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Installation............................................................................................. 17
Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Remote Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Operating Instructions ......................................................................... 21
Normal Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Load Matching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Maintenance.......................................................................................... 29
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Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Contact Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Zero Adjust. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Customer Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Bird 43 Replacement Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Available “QC” Type Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Model Differences................................................................................. 37
Bird 43P Peak Wattmeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Peak Detector Response. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Rectangular Pulses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Peak Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Bird 4305A Thruline Wattmeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Bird 4305A Replacement Parts List. . . . . . . . . . . . . . . . . . . . . . 40
Bird 4431 Thruline Wattmeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Bird 4431 Replacement Parts List . . . . . . . . . . . . . . . . . . . . . . . 44
Bird 4520 Series Thruline Wattmeters . . . . . . . . . . . . . . . . . . . . . . . 45
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Bird 4520 Series Replacement Parts List . . . . . . . . . . . . . . . . . 45
Specifications ....................................................................................... 47
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Figure 1
Bird 43 Thruline Wattmeter
Outline Drawing
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Chapter 1 Introduction
Purpose and Function
This instruction book covers the operation of the Bird 43 Thruline
Wattmeter and its descendants. Two models have RF sampler
ports, while the Bird 43P can measure peak power. The Bird 4520
series of models come ready for panel mounting. Similarities and
differences are discussed in Chapter 6, on page 37. Except where
indicated, instructions and specifications for the Bird 43 apply to
these instruments as well.
The Bird 43 is an insertion-type RF wattmeter, designed to measure
RF power and load match in 50 ohm coaxial transmission lines. It is
intended for use with CW, AM, FM, and TV modulation, but not
pulse modulation. The Bird 43, when used in 50 ohm applications,
has a maximum VSWR of 1.05 for frequencies up to 1000 MHz. The
meter provides direct readings in watts with an expanded scale for
easy reading. The scale is graduated for 25, 50, and 100 full scale.
Elements are available in a variety of power and frequency ranges
(see the Bird Electronic Corporation Catalog for details).
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Bird Model 43 Wattmeter
Performance Characteristics and Capabilities
The Bird 43 is portable, with an included carrying strap. It has an
aluminum housing and an easily removed back cover, with bumpers
on the base and back that allow the meter to stand or lie flat. For
additional protection, the microammeter is specially shock mounted.
A slotted screw on the lower front face of the meter is used to zero the
pointer. Below the meter face, the RF line section protrudes slightly
from the wattmeter housing with the element socket in the center.
A shielded cable connects the RF line section to the rest of the
wattmeter. This lets you remove the line section from the wattmeter
housing for custom installation and still use it to make measurements.
The RF line section is precision machined to provide the best possible
impedance match to the RF transmission line under test. A formed
phosphor-bronze spring finger protrudes into the element socket to
make contact with the element.
At each end of the line section are Bird Quick-Change RF connectors
that may be interchanged with any other Bird “QC” connector. The
wattmeter housing does not interfere with connector changes.
To make measurements, a Bird Plug-In Element is inserted into the
line section socket and rotated against one of the stops. A small catch
in the corner of the socket face presses on the shoulder of the element
to keep it in proper alignment. This assures good contact between the
spring finger and the element contact and between the lower edge of
the element and the line section body (see Figure 2).
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Introduction
Figure 2
Securing an
element
Contacts on opposite sides of the element connect with the spring
finger when the element is in the forward or reverse position. This
occurs when the stop pin on the element is against either stop and the
catch is in place.
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Bird Model 43 Wattmeter
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Chapter 2 Theory of Operation
Travelling Wave Viewpoint
The easiest way to visualize Thruline operation is from a travelling
wave viewpoint. In transmission lines the voltages, currents, standing
waves, etc., on any uniform line section result from the interaction of
two travelling waves:
y The forward wave (and its power) travels from the source to the
load. It has RF voltage E
y The reflected wave (and its power) originates by reflection at the
load and travels from the load back to the source. It has an RF
voltage E
and current Ir in phase, with Er / Ir = Zo.
r
Each wave is mathematically simple and has a constant power:
and current If in phase, with Ef / If = Zo.
f
Wf = Watts Forward = E
Wr = Watts Reflected = E
2
/ Zo = I
f
2
/ Zo = I
r
2
Zo = Ef I
f
2
Zo = Er I
r
f
r
Zo is the characteristic impedance of a uniform line section. For useful
lines it is usually a pure resistance of 50 ohms. The RF circuit of the
Bird 43 is a length of uniform air line with Z
= 50 ohms.
o
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Bird Model 43 Wattmeter
Coupling Circuit
The coupling circuit that samples the travelling waves is in the Bird
Plug-In Element. The element circuitry and its relationship to the rest
of the Bird 43 are illustrated in Figure 3.
Figure 3
Thruline Wattmeter Schematic
Current is produced in the coupling circuit by the travelling waves in
the line section. Both inductive and capacitive coupling contribute to
this. The inductive current flows in the direction of the travelling
wave. The capacitive current is independent of the direction of the
travelling wave. Therefore, the inductive current produced by one of
the travelling waves will add in phase with the corresponding
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