Bird 4304A User Manual

INSTRUCTION BOOK

RF DIRECTIONAL

THRULINE® WATTMETER

MODEL 4304 A

©Copyright 2002 by Bird Electronic Corporation

Instruction Book Part Number 920-4304A Rev. E

Thruline® and Termaline® are registered trademarks

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 normal safety
regulations. Do not replace components or make adjustments inside
the equipment with high voltage turned on. To avoid casualties,
always rem o ve p ow e r.

Shock Hazard

Do not attempt to remove the RF transmission line while RF power is
present.

Do Not Service or Adjust Alone

Under no ci r cumstan ce s should any perso n re ach into an e nclosure to
service or adjust 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 sou rc e to test instrume nts. Gr ou nd in g on e cond uc to r o f a
two conductor power cable is not sufficient protection. Serious injury
or death can occu r if t his gr ound ing is not prope rly installed.

i

Bird 4304A Thruline Wattmeter

Resuscitation

Personnel working with or near high voltages should be familiar with
modern methods of resuscitation.

Safety Symbols

WARNING

Warning no tes call attention to a proce dure, which if not cor rec tly

performed, co uld re s ult in pers o nal injury.

CAUTION

Caution notes call attention to a procedure, which if not correctly

performed, could result in damage to the instrument.

The caution symbol appears on the equipment indicating
there is important informatio n in the ins tru ction manual
regarding that pa rt icular are a.

NOTE: Calls attention to supplemental information

☞

Warning Statements

The following safety warnings appear in the text where there is
danger to operating and maintenanc e personnel , a nd are rep eate d
here for em ph asis.

WARNING

Never attempt to co nn ect or di sconnect equip m ent R F equipment

from the transmis sio n lin e wh ile RF p owe r is being applied.

Leaking RF ene rg y is a poten tial he alth hazar d .

ii

WARNING

When working with RF powers of 200 watts or more, the potential of

the center condu cto r of the line se cti on will exce ed 100 vo lts.

Do not touch the center condu ctor while RF power is o n.

Caution Statements

The following equipmen t cautions app ear in the text whenev er the
equipment is in dange r of dama ge, and a re re peated here for emph asis.

CAUTION

Do not drop. Calibration could be disturbed or the meter could be

damaged as a result.

CAUTION

Above 800 MHz, do not exceed 150 W RF power.

CAUTION

RF power must not exceed range switch setting.

CAUTION

Do not attempt to re m ove the RF cent er cond u cto r . This will

damage the lin e sec tio n.

CAUTION

When handling the circuit board, use caution:

Do not bend the dc contact finger that ext end s into the line section.

Do not lose the contact finger insulator or the

spacers on the mounting screws.

Do not disturb the potentiometer settings.

iii

Bird 4304A Thruline Wattmeter

Safety Statements

USAGE
ANY USE OF THIS INSTRUMENT IN A MANNER NOT

SPECIFIED BY THE MANUFACTURER MAY IMPAIR

THE INSTRUMENT’S SAFETY PR OT ECTION.
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 QU I N’EST PAS

EXPLICITEMENT PRÉVUE PAR LE FABRICANT PEUT
ENDOMMAGE R LE DISPOSITIF DE PROTECT ION DE
L’INSTRUMENT.

IMPIEGO
QUALORA QUESTO STRUMENTO VENISSE UTILIZZATO IN

MODO DIVERSO DA COME SPECIFICATO DAL PRODUTTORE
LA PROZIONE DI SICUREZZA POTREBBE VENIRNE
COMPROMESSA.

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

iv

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.

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.

v

Bird 4304A Thruline Wattmeter

About This Manual

This instruction book cove r s the Bird 4304A RF Th ru line W attm ete r.
The manual 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 genera l overview
describes the contents of that chapter.

Operation

First time users should read Chapter 1 – Intr odu cti on, and Chapte r 3
– Installation, to get an overview of equipment capabilities and
installation. An experienced operator can refer to Chapter 4 –
Operating Instruction s . All ins t ruct i ons neces sary to operate the
equipment appears in this chapte r.

Maintenance

All personnel should be fa m iliar with the preventive ma in te nan ce
found in Chapte r 5 – Mainte nance. If a failure should o ccur , th e
troubleshooti ng se ct ion will aid in iso lat ing and correcting the cau se.
Specifications and replacement part lists are also in this chapter.

Chang es 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 up da ted . Whe n in quir ing about updates to this
manual refer to the part number and revision level on the title page.

vi

Table of Contents

Safety Precautions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i

About This Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Theory of Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Travelling Wave Viewpoint. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

Coupling Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Load Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

Standing Wave vs. Travelling Wave Viewpoint . . . . . . . . . . . . . . . . .6

ρ vs. φ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Component Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Impedance Mismatch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Load Matching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Operating Ins tructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

Normal Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

Low Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

VSWR Measuremen ts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

Cleaning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

Zero Adjust. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

Connector Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Element Removal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

Back Cover Removal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Line Section Replacement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25

Meter Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

Calibration Checks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28

Customer Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28

Specifica tions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

Replacement Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30

Available “QC” Type Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . .31

Chapter 1 Introduction

The Bird 4304A Wattmeter is an in-line sensor that measures RF
power and load match in 50
used with CW, AM, FM, and TV modulation, but not p uls e
modulation. It is supp lied with a special broa dband elemen t with a
frequency range of 25 to 1000 MHz. It can measure up to 500 W,
depending on the frequency, an d has a max imum VSW R of 1.07 with
the standard “N” connectors. A range switch allows the full scale
power to be reduced for greater accuracy.

The wattmeter is portable, with an included carryi ng 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 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.

The RF line sectio n is pre cis io n ma ch ined to prov ide the best poss ible
impedance ma tc h to the transmission line un d er te st. A form ed
phosphor-bronze sprin g finger protrudes into the element socket to
make contact with the element . At each end of the line secti on 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.

Ω coaxial transmission lines. It can be

Combining th e Thr ulin e Watt m eter with a Bird Termaline Load
Resistor creates an accurate absorption wattmeter. With this
combination , readin gs o nly need to be tak en in the forward direc tion
because the reflecte d p owe r will be ne gligible.

1

Bird 4304A Thruline Wattmeter

(

)

Figure 1 Bird 4304A Thruline Wattmeter Outlin e Dr awi ng

POWER RANGE

SWITCH

150

500

4”

(100 m m )

5

15

50

“QC” CONNECTORS

FEMA LE N NORMALLY

SUPPLIED

1-3/4”

(44 mm)

ELEMENT

6-7/8”

(175 m m )

2-3/8”

(59 mm)

4”

100 mm

2

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 sectio n re sult from the interaction o f
two travelling wave s :

! The forward wave (and its power) travels from the so urce t o the

load. It has RF voltage E

! The reflected wave (and its power) originates by reflection at the

load and travels from the load bac k to the so urce. It has an RF
voltage E

and curr ent Ir in phase, with Er / Ir = Zo.

r

Each wave is math ematically simple and has a constant power:

and curr ent 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
43 is a length of uniform air line wit h Z

Ω. The RF circuit of the Bird

= 50Ω.

o

3