BIRD Thruline 43 User manual

INSTRUCTION BOOK
RF DIRECTIONAL
THRULINE® WATTMETER
MODEL 43
Also Covers Models 4431, 43P
And Series 4300 and 4520
©Copyright 2009 by Bird Electronic Corporation
Instruction Book Part Number 920-43 Rev. J
Thruline® and Termaline® are registered trademarks
of Bird Electronic Corporation

THIS PAGE INTENTIONALLY LEFT BLANK

Bird Model 43 Wattmeter
i
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 apply to all phases of operation and maintenance.
WARNING
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.
WARNING
Shock Hazard
Do not attempt to remove the RF transmission line while RF power
is present.
WARNING
Do Not Service Or Adjust Alone
Under no circumstances should any person reach into an enclosure
for the purpose of service or adjustment of equipment except in the
presence of someone who is capable of rendering aid.
WARNING
Safety Earth Ground
An uniterruptible earth safety 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 supplied.

Bird Model 43 Wattmeter
ii
Safety Symbols
The caution 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 safety warnings appear in the text where there is dan-
ger to operating and maintenance personnel, and are repeated here
for emphasis.
WARNING
Resuscitation
Personnel working with or near high voltages should be familiar
with modern methods of resuscitation.
WARNING
Remove Power
Observe general safety precautions. Do not open the instrument
with the power on.
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.

Bird Model 43 Wattmeter
iii
On page 17.
On page 21.
Caution Statements
The following equipment cautions appear in the text and are repeated
here for emphasis.
On page 11.
On page 17.
On page 29.
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
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.

Bird Model 43 Wattmeter
iv
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.

Bird Model 43 Wattmeter
v
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 NINGÚN
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.
ASSISTENZA TECNICA
LE ISTRUZIONI RELATIVE ALL’ASSISTENZA SONO PREVISTE
ESCLUSIVAMENTE PER IL PERSONALE OPPORTUNAMENTE
ADDESTRATO. PER EVITARE PERICOLOSE SCOSSE
ELETTRICHE NON EFFETTUARRE ALCUNA RIPARAZIONE A
MENO CHE QUALIFICATI A FARLA.

Bird Model 43 Wattmeter
vi
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.

Bird Model 43 Wattmeter
vii
About This Manual
This manual covers the operating and maintenance instructions for
the following models:
Changes to this Manual
We have made every effort to ensure this manual is accurate. If you
discover any errors, or if you have suggestions for improving this man-
ual, please send your comments to our Solon, Ohio factory. This man-
ual may be periodically updated. When inquiring about updates to
this manual refer to the part number and revision on the title page.
Literature Contents
Chapter Layout
Introduction —Describes the features of the 43 Wattmeter, lists
equipment supplied and optional equipment, and provides power-up
instructions.
Theory of Operation —Describes how the 43 Wattmeter works and
Installation —Describes how to set up and prepare the 43 Wattmeter
for use.
Operation - All instructions necessary to operate the equipment
appears in this chapter.
43 43P 4301 4305A 4431 4527
4521 4522 4526

Bird Model 43 Wattmeter
viii
Maintenance —Lists routine maintenance tasks as well as trouble-
shooting for common problems.
Model Differences —Describes how each indivdual models vary from
each other.
Specifcations —Specifications and parts information are included in
this chapter.

Table of Contents
Safety Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i
Safety Symbols. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ii
Warning Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ii
Caution Statements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii
Safety Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv
About This Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
Changes to this Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
Chapter Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .vii
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Purpose and Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Performance Characteristics and Capabilities . . . . . . . . . . . . . . . . 1
Chapter 1 Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Travelling Wave Viewpoint. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Formulas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Coupling Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Load Power. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Standing Wave vs. Travelling Wave Viewpoint (ρvs. φ). . . . . . . . . . 7
Low Reflection Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Transmitter Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Component Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Measuring Insertion Loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Frequency Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Impedance Mismatch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Chapter 2 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Replacing Quick-Change Connectors . . . . . . . . . . . . . . . . . . . . 18
Remote Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Chapter 3 Operating Instructions . . . . . . . . . . . . . . . . . . . . . . . 21
Normal Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Load Matching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Chapter 4 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Troublehshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Contact Adjustment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Zero Adjust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Customer Service. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Bird 43 Replacement Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Bird 43 Replacement Parts List . . . . . . . . . . . . . . . . . . . . . . . . 33
Available “QC” Type Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Chapter 5 Model Differences . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Bird 43P Peak Wattmeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Peak Detector Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Rectangular Pulses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Peak Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Bird 4301 Thruline Wattmeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Bird 4305A Thruline Wattmeter. . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Bird 4305A Replacement Parts List . . . . . . . . . . . . . . . . . . . . . 39
Bird 4431 Thruline Wattmeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Bird 4431 Replacement Parts List . . . . . . . . . . . . . . . . . . . . . . 42

Bird 4520 Series Thruline Wattmeters . . . . . . . . . . . . . . . . . . . . .43
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Bird 4520 Series Replacement Parts List . . . . . . . . . . . . . . . . 44
Chapter 6 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

1
Chapter 1 Introduction
Purpose and Function
The 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. When used in 50 ohm applications, the 43 has a maxi-
mum VSWR of 1.05 for frequencies up to 1000 MHz. The meter pro-
vides 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).
This manual 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 comes ready
for panel mounting. Differences are discussed in Chapter 6, on
page 35. Except where indicated, instructions and specifications for
the 43 apply to other models also.
Performance Characteristics and Capabilities
The Bird 43 is portable, with an attached 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.

Bird Model 43 Wattmeter
2
A shielded cable connects the RF line section to the rest of the wattme-
ter. This lets you remove the line section from the wattmeter housing
for custom installation and still make measurements. The RF line sec-
tion is precision machined to provide the best possible impedance
match to the 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 1).
Contacts on opposite sides of the element connect with the spring fin-
ger 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.
Figure 1
Securing an
element

Bird Model 43 Wattmeter
3
Figure 2
Bird 43
Thruline
Wattmeter
Outline
Drawing

Bird Model 43 Wattmeter
4

5
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:
• Forward Wave (and its power) travels from the source to the load.
It has RF voltage Efand current Ifin phase, with Ef/ If= Zo.
• 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
Erand current Irin phase, with Er/ Ir= Zo.
Formulas
Each wave is mathematically simple and has a constant power:
Forward
Reflected
Note: Zois 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 Zo= 50 ohms.
WfWattsForward Ef
2Zo
⁄If
2ZoEfLf
====
WrWattsReflected Er
2Zo
⁄Ir
2ZoErLr
====

Bird Model 43 Wattmeter
6
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.
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 capac-
itive current, while that produced by the wave travelling in the oppo-
site direction will subtract. The additive or “arrow” direction is
assigned to the forward wave.
The electrical characteristics of the element are carefully adjusted so
that, for the reverse travelling wave, the inductive current will com-
pletely cancel the capacitive current. The result is directivity greater
than 25 dB. Thus, the element is sensitive at either of its settings, but to
only one of the two travelling waves. Thruline Wattmeter measure-
ments are also independent of position along the transmission line.
Like similar diode devices, the Bird 43 indicates the carrier component
of amplitude modulation, with very little response to side band compo-
nents added by modulation.
Figure 3
Thruline Wattmeter
Schematic