Bird Brain Utility Vehicle 4391A User Manual

INSTRUCTION BOOK  
OPERATING INSTRUCTIONS  
MULTI-PURPOSE  
THRULINE® WATTMETER  
RF POWER ANALYST®  
MODEL 4391A  
©Copyright 2008 by Bird Electronic Corporation  
Instruction Book Part Number 920-4391A Rev. H  
Thruline® and Power Analyst® are Registered Trademark of  
Bird Electronic Corporation  
 
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.  
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 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. Observe general  
safety precautions for handling high voltage equipment. Always  
disconnect power before attempting any repairs.  
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.  
Chemical Hazard  
Dry cleaning solvents for cleaning parts may be potentially dangerous.  
Avoid inhalation of fumes or prolonged contact with skin.  
Safety Earth Ground  
An uninterruptible 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.  
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.  
i
 
 
Bird Model 4391M Power Analyst  
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 information in the  
instruction manual regarding that particular area.  
NOTE: Calls attention to supplemental information  
Fuse Replacement  
Always use the same type and rating of fuse when replacing the fuse.  
Fuse information can be found in the parts list on page 30.  
Warning Statements  
The following safety warnings appear in the text where there is danger to  
operating and maintenance personnel, and are repeated here for emphasis.  
WARNING  
Use only NIckel Metal Hydride (NiMH) batteries that have a minimum  
capacity of 4600 milliamper hours (mAh). Do not install batteries that are  
not Nickel Metal Hydride. Do not install NiMH batteries that have less  
than 4600 mAh capacity. Failure to comply may result in damage to the  
batteries, damage to the instrument, and injury to personnel from battery  
chemicals.  
WARNING  
Use dry cleaning solvents in a well ventilated area. Avoid excessive  
inhalation of solvent fumes, since they can be toxic in heavy concentrations.  
Always wear eye protection and avoid skin contact with the solvent.  
WARNING  
Be sure that the power cable is unplugged before opening the wattmeter  
case. The power supply capacitor, C1, can retain a dangerous charge that  
must be removed before touching. Always have another person standing by  
who is trained in electric shock first aid.  
ii  
 
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  
Long-term storage of this instrument can affect battery performance and  
reduce battery life. Do not store the instrument for long periods of time  
without recharging the batteries (refer to page 19). Failure to comply may  
result in reduced battery charge and shortened battery life.  
CAUTION  
If the element cannot be fully inserted into the socket, do not force  
it. You might damage the element.  
CAUTION  
Internal batteries are connected. Remove one of the battery tubes before  
unsoldering wires connected to the Main PCB. Failure to comply may result  
in permanent equipment damage and severe shock to individuals.  
CAUTION  
Never apply RF power to the Model 4391A Wattmeter unless both line  
section sockets are filled with either an element or a dust plug. If an  
element is used it is advisable to place the element with the arrow at a 90°  
angle to the coaxial line.  
CAUTION  
Always be certain the 115/230 voltage selector is set to the proper voltage  
before ac power is applied.  
CAUTION  
Always disconnect AC power before opening the Model 4391 enclosure.  
Removal of at least one battery cell is also recommended when servicing the  
instrument.  
CAUTION  
This instrument contains static sensitive electronic components. Before  
opening or servicing the unit, make sure that you understand and practice  
electrostatic discharge component handling. Failure to comply may result  
in permanent damage to sensitive components.  
iii  
 
Bird Model 4391M Power Analyst  
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.  
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  
iv  
 
PRÉVENIR UN CHOC ÉLECTRIQUE DANGEREUX, NE PAS EFFECTUER  
D’ENTRETIEN SI L’ON N’A PAS ÉTÉ QUALIFIÉ POUR CE FAIRE.  
UNITS ARE EQUIPPED WITH RECHAREABLE BATTERIES.  
THESE ARE TO BE REPLACED BY AUTHORIZED SERVICE  
PERSONNEL ONLY!!!  
LAS UNIDADES VIENEN EQUIPADAS CON BATERIAS  
RECARGABLES. ¡¡¡Y SOLAMENTE EL PERSONAL DE SERVICIO  
AUTORIZADO PUEDE REEMPLAZARLAS!!!  
GERÄTE SIND MIT WIEDER AUFLADBAREN BATTERIEN BESTÜCKT.  
BATTERIEN SIND NUR VON QUALIFIZIERTEM SERICE PERSONAL  
AUSZUWECHSELN!!!  
CES DISPOSITIFS SONT ÉQUIPÉS DE BATTERIES RECHARGEABLES.  
SEUL LE PERSONNEL D’ENTRETIEN AUTORISÉ EST HABILITÉ À LES  
REMPLACER!  
LE UNITÀ SONO DOTATE DI BATTERIE RICARICABILI, CHE DEVONO  
DA COME SPECIFICATO DAL PRODUTTORE LA PROTEZIONE DI  
SICUREZZA POTREBBE VENIRNE COMPROMESSA.  
USE CORRECT VOLTAGE SETTING AND FUSE - SEE  
MANUAL.  
UTILISER UNE TENSION ET UN FUSIBLE CORRECTS -  
CONSULTER LE MODE D’EMPLOI.  
USE LA INSTALACION Y FUSIBLE DE VOLTAJE CORRECTO - VEA EL  
MANUAL.  
AUSSCHLIESSLICH VORSCHRIFTSMÄSSIGE WECHSELSPANNUNGS-  
EINSTELLUNG UND SICHERUNG BENUTZEN - SIEHE DAZU  
HANDBUCH.  
UTILLIZZARE TENSIONE E FUSIBLE ADATTI - FARE RIFERIMENTO AL  
MANUALE.  
BE SURE THE 115/230V AC VOLTAGE SELECTOR IS SET TO  
THE PROPER LINE VOLTAGE, AND THE CORRECT AC LINE  
FUSE IS INSTALLED BEFORE AC POWER IS APPLIED.  
S’ASSURER QUE LE SÉLECTEUR DE TENSION 115/230V C.A.  
EST BIEN RÉGLÉ POUR LA TENSION DU RÉSEAU ET QUE LE FUSIBLE  
DE LIGNE C.A. CORRECT EST EN PLACE AVANT DE METTRE SOUS  
TENSION C.A.  
CERCIORESE QUE EL SELECTOR DE VOLTAJE DE 115/230V CA ESTE  
COLOCADO A LA LINEA DE VOLTAJE APROPIADA Y QUE EL FUSIBLE  
ESTE INSTALADO A LA LINEA CA ANTES DE APLICAR LA CORRIENTE  
ALTERNA.  
VOR EINSCHALTEN DER WECHSELSTROMZUFUHR SICHERSTELLEN,  
DASS DER 115/230V WECHSELSPANNUNGS-SELEKTOR AUF DIE  
VORSCHRIFTSMÄSSIGE LEITUNGSSPANNUNG EINGESTELLT UND  
DIE RICHTIGE WECHSELSTROM-HAUPTSICHERUNG EINGESETZT  
IST.  
v
 
Bird Model 4391M Power Analyst  
PRIMA DI EROGARE CORRENTE, ASSICURARSI CHE IL SELETTORE DI  
VOLTAGGIO 115/230 V.C.A. SIA REGOLATO CORRETTAMENTE E CHE  
IL FUSIBLE ADATTO ALLA LINEA DI ALIMENTAZIONE C.A. SIA  
INSTALLATO.  
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.  
vi  
 
About This Manual  
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 manual is divided into Chapters and Sections.  
Figures and tables are numbered sequentially within each chapter.  
Chapter Layout  
Introduction  
Introduces the external features and and functions of the unit, equipment  
provided, and optons available.  
Theory of Operation  
Describes the overall operation of the circuitry and the instrument  
functions.  
Installation  
Provides information about connecting the instrument to your equipment.  
Operation  
equipment capabilities and how to install it. Experienced operators can  
operate the equipment, are contained in this section.  
Maintenance  
All personnel should be familiar with calibration and repair information  
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 drawings.  
Changes to this Manual  
We have made every effort to ensure this manual is accurate at the time of  
publication. If you should discover any errors or if you have suggestions for  
improving this manual, please send your comments 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.  
vii  
 
 
Bird Model 4391M Power Analyst  
viii  
 
Table of Contents  
ix  
 
Chapter 1  
Introduction  
The Model 4391A is a multi-purpose Radio Frequency  
wattmeter designed around a microcomputer. A program  
stored in permanent memory controls the operation of the  
instrument at all times, permitting the detection and  
correction of various error sources and the refinement of the  
raw data produced by the directional detectors. The  
instrument can compute VSWR, amplitude modulation, and  
various decibel variables reducing the odds of error and  
making such measurements consistent or repeatable  
regardless of who makes the measurement.  
Other benefits include extended range using standard  
elements in some modes of operation, continuous monitoring  
of maximum and minimum readings, a peaking aid, and  
error messages.  
Because of its complexity, the proper use of the 4391A is not  
always obvious. For this reason it is strongly advised that  
this manual be read in its entirety before using the device.  
Purpose and  
Function  
The 4391A RF Power Analyst is an insertion type digital RF  
Directional Thruline® Wattmeter designed to measure peak  
or average power flow, load match, and amplitude  
modulation in 50 ohm coaxial transmission lines. It is  
intended for use with CW, AM, FM, SSB, TV, and Pulse  
modulation envelopes. The instrument directly reads PEP or  
CW power in watts, milliwatts, or kilowatts in 9 ranges from  
2.5 to 1000 full scale forward power and 0.25 to 100 full scale  
reflected power depending on the Plug-in Element. In  
addition it reads SWR directly over the range of 1.00 to  
99.99, percent modulation directly over the range of 0.0 to  
99.9, and return loss over the range of 0 to 36.1 dB. For  
convenience, forward and reflected CW power can be  
displayed in dBm (dB above 1 milliwatt) from 6 dB above to  
24 dB below nominal element range.  
Power range and frequency band are determined by the  
Plug-in Elements used. Two switches on the front panel of  
the instrument are set by the user to correspond to the  
nominal power range of the forward element. The reflected  
element is assumed to have a nominal range one tenth that  
of the forward element.  
In any mode of operation, the instrument can recall from  
memory the lowest or highest reading taken or tell the  
operator whether the newest reading is less than, equal to,  
or greater than the previous reading.  
1
 
     
Bird Model 4391A Power Analyst  
Description  
The instrument is housed in an aluminum case  
approximately 4-3/8 inches high by 9-5/8 inches deep by 6-1/  
4 inches wide (111 mm x 244 mm x 159 mm) including  
connections, see Figure 1. At each end of the line section are  
Bird Quick-Change type RF connectors which may be easily  
interchanged with any other Bird QC connector. See Bird  
Catalog for types available.  
Operating power is derived from rechargeable nickel metal  
hydride batteries inside the unit or from a 115/230 VAC  
power source connected to the unit through the power cord  
supplied with the unit.  
Figure 1  
Outline  
Drawing  
2
 
   
Chapter 2  
Theory of Operation  
Description of  
Operation  
Figure 2 is a block diagram of the major functional parts of  
the Model 4391A RF Wattmeter. The Microcomputer  
integrated circuit shown, controls all the other portions of  
the instrument, which fall into two major groups.  
Figure 2  
Circuit Block  
Diagram  
Keyboard,  
Range  
Switches, and  
Display  
The keyboard and range switches serve only to pass  
information to the computer. The display, of course, returns  
information from the computer to the operator. The display,  
which is comprised of four seven-segment LED digits, is  
strobed digit by digit left to right at a rate of approximately  
one digit per millisecond. This serves to conserve battery  
power and drive circuitry while providing scanning for the  
columns of the keyboard. Each time a digit is strobed, the  
corresponding column of the keyboard is read and if a key is  
pressed, the computer puts the code for that key into a  
memory cell. The nine mode keys select which parameter is  
to be measured. The three modifier keys simply modify the  
way in which the result is displayed. The range selector  
switches identify to the computer the nominal full scale  
values of the elements used. They have no effect on input  
sensitivity, which is determined by the elements.  
Group  
Elements,  
Analog  
Circuitry, and  
A/D Converter  
These components are controlled by the computer. The Plug-  
in Elements in the line section provide low level positive  
voltages related to the instantaneous value of power (see  
Figure 3). The first group of solid state switches selects the  
forward element, the reflected element, or ground as the  
input to the preamplifier which boosts these signals to 0.1 to  
2.0 volt range. The remaining switches shown as two groups  
direct the output of the preamp to the analog-to-digital  
converter either directly or through a peak or negative peak  
detector. The analog-to-digital converter converts the voltage  
to a 15 digit binary number.  
3
 
           
Bird Model 4391A Power Analyst  
Each reading output by the display is derived from up to  
three voltage readings using the circuitry described above.  
Once these voltages are measured, all remaining operations  
are performed within the computer chip as follows:  
The voltages are corrected for error due to dc drift in the  
analog circuitry. Each voltage is converted to square root of  
power using stored data tables. These values are then  
combined mathematically to arrive at the final result in  
binary. This is used to update the registers containing the  
last value, the maximum value, or the minimum value as  
required. Finally, the result is converted to a decimal  
number and placed into a register from which the display  
driving routine operates.  
Figure 3  
Plug-In  
Element  
Schematic  
Diagram  
The coupling circuit that samples the travelling waves is in  
the Plug-in Element. The circuitry of the element and its  
relationship to the other components of the Thruline Watt-  
meter are illustrated in the schematic diagram. Energy will  
be produced in the coupling circuit of the element by both  
mutual inductance and capacitance from the travelling RF  
waves of the line section. The inductive currents will flow  
according to the direction of the travelling waves producing  
them. The capacitive portion of these currents is  
independent of the direction of the travelling waves.  
Therefore, assuming that the Plug-in Element remains  
stationary, the coupling currents produced from the waves of  
one direction will add in phase, and those produced from  
waves of the opposite direction will accordingly subtract in  
phase. The additive or “arrow” direction is assigned to the  
forward wave.  
4
 
 
Theory of Operation  
The electrical values of the element circuits are carefully  
balanced and designed so that current from the reverse wave  
will cancel the other almost completely. The result is  
directivity always higher than 25 dB, which means that the  
element is highly insensitive (nulled) to the REVERSE  
direction wave. Being highly directional, the Thruline  
element is sensitive (at one setting) only to one of the  
travelling waves that produce standing waves by  
interference. Thruline Wattmeter measurements are,  
therefore, independent of position along standing waves.  
Figure 4  
Readings with  
Various  
Envelopes  
5
 
 
Bird Model 4391A Power Analyst  
6
 
Chapter 3  
Installation  
The Model 4391A RF Power Analyst is completely portable  
and very suitable for field or laboratory use. Its power is  
derived from rechargeable nickel metal hydride batteries  
inside the unit or from an AC outlet via the power cord  
supplied with the device.  
The batteries are shipped in a low charge state. It is,  
therefore, recommended that you charge the instrument for  
16 hours before using it for continuous operation.  
CAUTION  
Long-term storage of this instrument can affect battery  
performance and reduce battery life. Do not store the  
instrument for long periods of time without recharging the  
batteries (refer to page 19). Failure to comply may result  
in reduced battery charge and shortened battery life.  
Operating on  
AC Power  
For ac power operation, the Model 4391A is simply  
connected to an AC receptacle using the line cord provided.  
The correct AC voltage is selected via a rear panel switch  
(Figure 5). The meter may be operated in this manner with  
the batteries removed if desired.  
CAUTION  
Always be certain the 115/230 voltage selector is set to the  
proper voltage before ac power is applied.  
Figure 5  
Rear Panel  
Item No.  
Description  
1
2
3
AC input voltage selector switch  
Fuse holder  
AC power cable connector  
7
 
       
Bird Model 4391A Power Analyst  
Connections  
The Model 4391A contains a short section of rigid 50 ohm  
coaxial air dielectric transmission line. To make  
measurements relating to the travelling waves in a coaxial  
line, that line must be disconnected at some convenient point  
to permit the Model 4391A air line to be inserted.  
Although the Model 4391A is normally supplied with two  
Female N-type connectors, a variety of easily  
interchangeable connectors are available to facilitate  
connecting to the user’s system.  
Once the Model 4391A is installed in the coaxial line, a Plug-  
in Element or a pair of Plug-in Elements must be selected  
which correspond to the frequency and power levels to be  
measured.  
NOTE: The instrument is shipped with dust plugs  
installed in the element sockets. Remove the dust plugs  
to insert elements.  
In order to take full advantage of the Model 4391A’s  
capabilities, two elements in a 10:1 ratio of power range  
should be used. If only one element is used, the other socket  
should be filled with a dust plug or a higher power element.  
Also, for greatest accuracy, the element(s) should be chosen  
having the lowest possible power range that will not result  
in over-ranging. Table 1 lists elements required for each  
mode of operation.  
Table 1  
Plug-In  
Elements  
Required  
Mode  
Forward  
Reflected  
FWD CW  
RFL CW  
SWR  
*  
FWD PEP  
RFL PEP  
% MOD  
FWD dBm  
RFL dBm  
RTN Loss  
*  
*
The reflected element must have a nominal power range  
one tenth that of the forward element.  
The higher power element is placed in the socket marked  
“FORWARD” and its arrow pointed in the direction of  
forward power flow (toward antenna or load). The lower  
power element is placed in the socket marked  
“REFLECTED” and is normally pointed in the direction  
opposite to forward power flow. The elements are clamped in  
place by the hold-down catches on the face of the line section.  
These catches must be used to avoid error due to the element  
not contacting the bottom or seating plate of the socket. With  
the element(s) in place, set the range switches to correspond  
8
 
   
Installation  
with the nominal power range of the elements. For example,  
if the forward element is a 5 watt element, the switches are  
set at 5 and x1. For a 250 watt element they are set at 2.5  
and x100. Sometimes it is necessary to use milliwatts or  
kilowatts as the unit of measure. In other words, 1 watt  
becomes 10 x 100 milliwatts and 2500 watts becomes 2.5 x 1  
kilowatts.  
9
 
Bird Model 4391A Power Analyst  
10  
 
Chapter 4  
Operating Instructions  
Operating  
Modes  
The Model 4391A has nine modes of operation which are  
selected by pressing the mode keys momentarily. In  
addition, each mode has three output options selected by  
pressing the modifier keys. Detailed descriptions of the  
modes and output options follow.  
Reading  
Forward CW  
Power  
For this measurement only a forward element is needed.  
Install the meter and element according to the preceding  
paragraphs and move the power switch to LINE or BAT  
depending on the power source desired. When powered up,  
the Model 4391A always goes into the forward CW power  
mode. If the unit is already operating, the forward CW power  
mode is selected by pressing the FWD CW key momentarily.  
If the applied power exceeds 120 percent of the range, two  
right-facing arrow heads (i.e., “greater-than” symbols) will  
be displayed. The operation of this error message does not  
depend on the correct setting of the range switches by the  
operator, nor will the meter or its elements be damaged if  
the switches are incorrectly set.  
CAUTION  
Never apply RF power to the Model 4391A Wattmeter  
unless both line section sockets are filled with either an  
element or a dust plug. If an element is used it is  
advisable to place the element with the arrow at a 90°  
angle to the coaxial line.  
CAUTION  
Always disconnect ac power before opening the Model  
4391A enclosure. Removal of at least one battery cell is  
also recommended when servicing the instrument.  
Figure 6  
Forward  
Power (CW)  
The Model 4391A arrives at values of CW power by a method  
quite different from analog meters such as the Model 43, also  
manufactured by Bird Electronic. While the two instruments  
will agree when the measured wave is of constant amplitude,  
AM or SSB waves will result in different indications (in the  
CW mode). This is because the analog instrument uses the  
inertia of the microammeter to “time-average” the varying  
11  
 
       
Bird Model 4391A Power Analyst  
signal coming from the element, whereas the Model 4391A  
uses peak and negative peak detector circuits to measure  
peak and minimum square root of power and combines them  
using the equation:  
2
Peak Power + Minimum Power  
-----------------------------------------------------------------------------------  
CW POWER =  
2
With this technique, operation of CW mode is predictable  
regardless of envelope shape (see Figure 4).  
Reading  
Reflected CW  
Power  
Operation of the reflected CW power mode is identical to  
that for forward CW power described above with two  
exceptions: the readings are taken from the element in the  
socket marked “REFLECTED” and the range of the element  
is assumed to be 1/10 the range indicated by the range  
switches.  
Figure 7  
Reflected  
Power (CW)  
Reading SWR  
Two elements with a 10 to 1 power range ratio are required  
for this mode. Press the SWR key momentarily. If average  
forward power is between 10% and 120% of the scale and the  
average reflected power is less than 120% of the reflected  
element range, SWR will be displayed. If any of the above  
conditions are not met, an error message will be displayed.  
Two arrows pointing to the right — or “greater-than”  
symbols — indicate over-range, while two left-pointing  
arrows — or “less-than” symbols — indicate under-range or  
too little power. Refer to Table 2.  
Figure 8  
Standing  
Wave Ratio  
(SWR)  
12  
 
   
Operating Instructions  
Table 2  
Voltage  
Standing  
Wave Ratio  
(VSWR)  
VSWR Return  
Loss  
Reflected VSWR Return Reflected  
Power %  
Loss  
(dB)  
Power %  
(dB)  
1.01  
1.02  
1.03  
1.04  
1.05  
1.06  
1.07  
1.08  
1.09  
1.10  
1.15  
1.20  
1.25  
1.30  
1.35  
1.40  
46.1  
40.1  
36.6  
34.2  
32.3  
30.7  
29.4  
28.3  
27.3  
26.4  
23.1  
20.8  
19.1  
17.7  
16.5  
15.6  
0.00  
0.01  
0.02  
0.04  
0.06  
0.08  
0.11  
0.15  
0.19  
0.23  
0.49  
0.83  
1.23  
1.70  
2.22  
2.78  
1.45  
1.50  
1.75  
2.00  
2.25  
2.50  
2.75  
3.00  
3.25  
3.50  
3.75  
4.00  
4.25  
4.50  
4.75  
5.00  
14.7  
3.37  
4.00  
14.0  
11.3  
9.50  
8.30  
7.40  
6.60  
6.00  
5.50  
5.10  
4.70  
4.40  
4.20  
3.90  
3.70  
3.50  
7.44  
11.11  
14.79  
18.37  
21.78  
25.00  
28.03  
30.86  
33.52  
36.00  
38.32  
40.50  
42.53  
44.44  
Measuring  
Peak  
Envelope  
Power  
PEP power measurements are made in the same manner as  
CW power readings described above, except that the FWD  
PEP and RFL PEP buttons are pressed and the readings are  
displayed directly as peak power.  
NOTE: The accuracy of measurements made with  
modulation having a frequency, duty cycle, pulse width,  
or repetition rate outside the instrument range cannot  
be assured in any mode of operation.  
Figure 9  
Peak  
Envelope  
Power (PEP)  
13  
 
   
Bird Model 4391A Power Analyst  
Measuring  
Amplitude  
Modulation  
Only a forward element is required for this mode. Point the  
element in the direction of forward power and press % MOD.  
Modulation is displayed directly in percent, provided the  
average signal is above 10% and the PEP of the signal is  
below 400% of the element’s nominal full scale. For specified  
accuracy, the average CW power levels must be greater than  
one-third of full scale. Modulation is calculated as follows:  
Peak Power – Minimum Power  
------------------------------------------------------------------------------------  
Peak Power + Minumum Power  
MODULATION =  
× 100  
and is therefore limited to the range of 0 to 99.9 percent.  
Over-modulation will be indicated as 99.9 percent. Refer to  
Table 3  
Amplitude  
Modulation  
Peak /  
% Modulation Peak /  
CW Power  
% Modulation  
CW Power  
1.00  
1.10  
1.21  
1.32  
1.44  
1.56  
1.69  
1.82  
1.96  
2.10  
2.25  
0
2.40  
2.56  
2.72  
2.89  
3.06  
3.24  
3.42  
3.61  
3.80  
4.00  
55  
60  
65  
70  
75  
80  
85  
90  
95  
100  
5
10  
15  
20  
25  
30  
35  
40  
45  
50  
Because of the threshold of the RF diode, a modulated signal  
which has a minimum power level below 0.3 percent of full  
scale will result in high modulation reading with uncertain  
accuracy.  
Figure 10  
Amplitude  
Modulation  
(%)  
14  
 
   
Operating Instructions  
Measuring  
Power in dBm  
Operation of the forward and reflected dBm modes is  
identical to the forward and reflected CW power modes,  
except that the resulting reading is converted to dB above 1  
milliwatt before it is displayed. It should be noted that in  
doing this conversion, the range set on the slide switches is  
assumed to be watts rather than kilowatts or milliwatts. If it  
is not, 30.0 must be added to all dBm readings when the  
range is in kilowatts, or subtracted from all readings when it  
is in milliwatts. An error message is displayed if CW power  
is more than 24 dB below, or peak power is more than 6 dB  
above the nominal element range. Refer to Table 4.  
Figure 11  
CW Power in  
dBm  
Table 4  
Watts/dBm  
Equivalents  
Power  
1 milliwatt  
dBm  
Power  
4 watts  
dBm  
36  
0
10 milliwatts  
100 milliwatts  
1 watt  
10  
20  
30  
33  
10 watts  
20 watts  
40 watts  
100 watts  
40  
43  
46  
50  
2 watts  
Measuring  
Return Loss  
The measurement of return loss is the same as that of SWR  
except that the result is displayed in dB. In other words a  
reading of 21.65 indicates that reflected power is 21.6 dB  
down from forward power.  
Figure 12  
Return Loss,  
Insertion  
Loss, or  
Attenuation  
15  
 
     
Bird Model 4391A Power Analyst  
Insertion  
Loss or  
Attenuation  
Attenuation or insertion loss can be measured directly using  
an external single port line section (P/N 4230-006-1), a dc  
feed-in adapter (P/N 4381-050), and a dc cable (P/N 3170-  
058-6). The Model 4391A is inserted at the source end of the  
device being measured. The second line section is inserted at  
the load end and its dc output is routed by the dc cable to the  
adapter inserted in the REFLECTED socket of the Model  
4391A. Both elements are in this case pointed in the  
direction of forward power flow. If the two elements do not  
have a ten to one ratio, a correction factor must be added to  
or subtracted from the “return loss” reading see Table 6,  
depending on the ratio of the elements.  
Table 5  
Correction  
Factors  
Table 6 Correction Factors  
Ratio of  
Elements  
Added dB Ratio of  
Elements  
Added dB  
1:1  
–10  
–7  
–6  
–4  
–3  
0
3
4
6
7
100:1  
200:1  
250:1  
400:1  
500:1  
1000:1  
2000:1  
2500:1  
4000:1  
5000:1  
10  
13  
14  
16  
17  
20  
23  
24  
26  
27  
2:1  
2.5:1  
4:1  
5:1  
10:1  
20:1  
25:1  
40:1  
50:1  
Monitoring  
Maximum and  
Minimum  
While operating in any of the modes described, the Model  
4391A will continuously keep track of the highest and lowest  
reading obtained. This action begins after ten reading cycles  
to allow time for the peak detectors to settle from the  
previous mode. To recall the maximum or minimum reading,  
depress and hold the MAX or MIN key. When these keys are  
released, the meter goes back to displaying the current value  
of the parameter being measured. Recalling max or min does  
not stop the meter from continuing to monitor the current  
value and updating the minimum and maximum registers.  
To clear the minimum and maximum register, the mode key  
must be pressed again or a new mode selected. For example,  
if CW power deviations are monitored, the Model 4391A is  
installed as described at the beginning of this section and  
turned on, then the power source is turned on and allowed to  
stabilize. Once the system has stabilized, press FWD CW to  
clear the MAX and MIN registers. At any time during test  
the MAX and MIN keys can be used to recall the maximum  
and minimum values without affecting the test. However,  
pressing the FWD CW key or changing modes will clear the  
registers.  
Readings  
16  
 
     
Operating Instructions  
Figure 13  
Maximum or  
Minimum  
Readings  
Using the  
Peaking Aid  
The peaking aid is useful for making adjustments to  
optimize any of the parameters which the Model 4391A  
measures. After the mode is selected, press the delta () key  
momentarily. This blanks the least significant digit of the  
display, and replaces it with a right-facing arrow head if the  
measured quantity is increasing or a left-facing arrow head  
if it is decreasing. If there is no change, the digit is left  
blank. To find a peak, begin making the adjustment in  
whichever direction produces a right-facing arrow and  
continue slowly in that direction until the arrow head turns  
around. At this point the peak has been reached. To check to  
make sure the peak has not been passed, press the MAX key  
to read the highest value read and release it to read the  
current value. The two should be the same. Desired  
minimum levels (e.g. of reflected power or of SWR) are found  
in a similar manner.  
Figure 14  
Peaking Aid  
()  
17  
 
 
Bird Model 4391A Power Analyst  
Battery Care  
With average use, the nickel metal hydride batteries in the  
4391A will power the unit for 12 hours before needing  
recharged. The 4391A will maintain rated accuracy until all  
the decimal points light, indicating that recharging is  
required. To recharge, connect AC power to the unit. To fully  
charge the batteries requires approximately 16 hours. To  
prolong the life of the batteries, it is recommended that you  
periodically allow the batteries to discharge until the  
decimal points light before recharging. If the batteries lose  
the ability to hold a charge they should be replaced. See  
Chapter 5 - Maintenance for important precautions  
regarding static electricity when opening the housing.  
WARNING  
Use only NIckel Metal Hydride (NiMH) batteries that  
have a minimum capacity of 4600 milliamper hours  
(mAh). Do not install batteries that are not Nickel Metal  
Hydride. Do not install NiMH batteries that have less  
than 4600 mAh capacity. Failure to comply may result in  
damage to the batteries, damage to the instrument, and  
injury to personnel from battery chemicals.  
CAUTION  
Long-term storage of this instrument can affect battery  
performance and reduce battery life. Do not store the  
instrument for long periods of time without recharging the  
batteries (refer to page 19). Failure to comply may result  
in reduced battery charge and shortened battery life.  
18  
 
 
Chapter 5  
Maintenance  
The 4391A RF Power Analyst was designed and built to  
provide many years of trouble free service. This section  
provides the information needed to prevent and correct  
equipment failure.  
Preventive Maintenance  
To avoid unnecessary damage, always observe the following  
cautions:  
1. The RF Power Analyst is a rugged and portable instru-  
ment intended for field use. However, it should not be  
unnecessarily exposed to extreme environmental condi-  
tions.  
2. When not in use, store the RF Power Analyst with the  
LINE/OFF/BATT switch is in the off position.  
3. Charge the batteries for 16 hours prior to extended use  
of the RF Power Analyst. Refer to “Battery Care” on  
Cleaning and  
Inspection  
Perform a periodic inspection to ensure that the RF power  
analyst is always operational. Any damage noticed during  
inspection should be listed and repaired before use.  
1. Visually inspect the equipment for loose or damaged  
parts.  
2. Wipe dust and dirt from the front panel and lower hous-  
ing. Remove stubborn dirt with mild detergent and a  
soft cloth.  
WARNING  
Use dry cleaning solvents in a well ventilated area.  
Avoid excessive inhalation of solvent fumes, since they  
can be toxic in heavy concentrations. Always wear eye  
protection and avoid skin contact with the solvent.  
3. Clean the inside of the line section bores using cotton  
swab stick dampened with alcohol.  
4. Visually inspect the RF connectors for any sign of wear  
or damage and replace if necessary. Clean the connec-  
tors with alcohol or any acceptable dry cleaning fluid.  
Long-term  
Storage  
Do not store the instrument for long periods of time without  
recharging the batteries. When the instrument is stored for  
long periods of time without use, the batteries will loose  
their charge and also loose the ability to reach full charge  
when put into service. To restore the battery charge, perform  
a full charge for 16 hours. If the batteries are not fully  
charged after 16 hours, completely discharge the batteries  
19  
 
           
Bird Model 4391A Power Analyst  
then perform a full charge again. If necessary, repeat this  
discharge and charge cycle up to three times. If the batteries  
do not remain charged after three discharge-charge cycles,  
replace the batteries.  
WARNING  
Use only NIckel Metal Hydride (NiMH) batteries that  
have a minimum capacity of 4600 milliamper hours  
(mAh). Do not install batteries that are not Nickel Metal  
Hydride. Do not install NiMH batteries that have less  
than 4600 mAh capacity. Failure to comply may result in  
damage to the batteries, damage to the instrument, and  
injury to personnel from battery chemicals.  
Calibration  
The RF Power Analyst should be calibrated once each year  
or after any repair.  
Required  
Equipment  
Refer to Table 7 for test equipment needed to calibrate the  
RF Power Analyst.  
Table 7  
Required  
Equipment  
Recommended Model  
Calibrator/Source  
Keithly Model 263 or  
equivalent  
Calibration  
Equipment  
Cable Assembly (1 Required)  
BNC to BNC (1 meter long)  
DC Feed-in Element (1 required) Bird Electronic 4381-050  
Initial Setup  
On a clean flat workspace perform the following setup  
procedure:  
1. Remove the front panel. Refer to “Front Panel Removal”  
2. Insert a DC feed-in adapter into the FWD element of the  
socket. Insert a metal dust plug (supplied with the  
instrument) into the RFL element socket.  
3. Connect a BNC to BNC cable assembly from the output  
of calibrator/source to the DC feed-in adapter.  
4. Set the RF Power Analyst range switches to the 10 and  
x100 positions. Connect AC power and place the LINE/  
OFF/BATT switch to the LINE setting.  
20  
 
     
Maintenance  
5. Switch on the Calibrator/Source and let it warm up for  
at least one hour.  
6. Set the Calibrator/Source to output 30 ±0.05 microamps.  
7. Adjust potentiometer, R25 (Figure 15, page 21), until  
the RF Power Analyst Displays 1000 ±5.  
Figure 15  
Calibration  
Potentiometer  
Element Wiper Contact Adjustment  
CAUTION  
If the element cannot be fully inserted into the  
socket, do not force it. You might damage the  
element.  
Continuous insertion or rotation of the element might  
cause a slight change in the position of the contact  
spring in the element socket. If the contact spring  
changes position, you might experience erratic power  
readings.  
You can use a small screwdriver to adjust the position  
of the contact spring. Be careful not to bend the spring  
out so far that it interferes with insertion of the  
elements.  
21  
 
   
Bird Model 4391A Power Analyst  
Perform the following steps to adjust the contact  
spring.  
1. Using a small flat head screwdriver, place the  
flat side of the screwdriver behind the contact  
bar as indicated and bend the contact bar so  
that the contact rests in the center of the slot  
adjacent to the element socket (Figure 16).  
Figure 16  
Adjust Element  
Contact Up  
and Down  
2. After centering the contact, bend it slightly  
toward the center of the element socket bore,  
so that the profile of the element contact is  
visible when viewing the element socket from  
Figure 17  
Adjust Element  
Contact In and  
Out  
3. If the contact is accidently moved too far into  
the element bore, the element will not slide  
into the socket. Move the contact back into the  
recessed area and repeat the process.  
22  
 
   
Maintenance  
Troubleshooting  
General  
The troubleshooting instructions are intended to aid in fault  
isolation. This is accomplished through the use of a  
troubleshooting table.  
First, locate the symptom(s) in the problem column of  
Table 8. In some cases the same fault can have more than  
one symptom and more than one possible remedy. Compare  
the possible causes until you arrive at a suspected fault.  
Once a fault has been isolated, repair or replace the defective  
components.  
NOTE: Always recalibrate the RF Power Analyst after  
repairing the fault.  
Table 8  
Trouble-  
shooting  
PROBLEM  
POSSIBLE CAUSE  
REMEDY  
Inaccurate  
RF Power Analyst  
Recalibrate.  
power readings uncalibrated  
Defective Plug-in  
Elements  
Replace defective elements.  
Intermittent connection  
at the element wiper  
Adjust the element wiper  
contact. Refer to page 21.  
Loose hold down catch  
Readjust catch to hold element  
securely in place.  
Worn line section  
Replace line section. Refer to  
Defect on Data  
Acquisition PC board  
assembly  
Replace the PC board  
assembly (attached to line  
High standing  
waves  
Dirty Connectors  
Worn or damaged  
connectors  
Clean the connectors.  
Replace the connectors Refer  
Foreign objects in line  
section  
Remove object from the line  
section.  
Short battery  
life  
115/230V switch in  
wrong position  
Set 115/230V switch to correct  
position.  
Damaged/worn batteries Replace the batteries.  
Will not operate 115/230V switch in  
Set 115/230V switch to correct  
position.  
from AC line  
wrong position  
Blown fuse  
Defective line cord  
Repair or replace.  
23  
 
   
Bird Model 4391A Power Analyst  
PROBLEM  
POSSIBLE CAUSE  
REMEDY  
Display  
indicates “0”  
Power  
Element wiper not  
Readjust the element wiper to  
make good contact (page 21).  
Replace Plug-In Element.  
contacting the element  
Defective Plug-in  
Element  
Defect on Data  
Acquisition PC board  
assembly  
Replace the PC board  
assembly (attached to line  
One segment of Defective Display  
a display doesn’t  
light  
Replace the display.  
All decimal  
points stay lit  
Low charge on the  
batteries  
Recharge the batteries.  
Defective circuit  
component  
Replace the Main circuit board  
assembly. Refer to page 25.  
Same segment  
on all displays  
doesn’t light  
Defective circuit  
component  
Replace the Main circuit board  
assembly. Refer to page 25.  
One or more  
keys do not  
function  
Defect on Main PC board Replace the Main circuit board  
assembly.  
Disassembly  
WARNING  
Be sure that the power cable is unplugged before opening  
the wattmeter case. The power supply capacitor, C1, can  
retain a dangerous charge that must be removed before  
touching. Always have another person standing by who is  
trained in electric shock first aid.  
CAUTION  
This instrument contains static sensitive electronic  
components. Before opening or servicing the unit, make  
sure that you understand and practice electrostatic  
discharge component handling. Failure to comply may  
result in permanent damage to sensitive components.  
Front Panel  
Removal  
1. Disconnect AC power from the instrument.  
2. Remove the six screws that secure the front panel to the  
Main PCB supports (Figure 18, page 25, item 1).  
3. Remove the two screws and lock washers that secure the  
front panel at the bottom of the housing (item 2).  
4. Remove the two screws and lock washers that secure the  
front panel at the back of the housing (item 3).  
24  
 
   
Maintenance  
5. Lift the front panel from the housing. Be careful to clear  
the line section blocks.  
6. Remove pads from the three toggle switches.  
Figure 18  
Removing  
Front Panel  
Main Printed  
Circuit (PC)  
Board  
1. Remove the front panel (Refer to “Front Panel Removal”  
2. Disconnect cable assembly at header (P1) (Figure 19,  
page 26, item 1).  
Removal  
3. Remove the six screws and washers that secure the cir-  
cuit board supports to the housing (item 2).  
CAUTION  
Internal batteries are connected. Remove one of the battery  
tubes before unsoldering wires connected to the Main PCB.  
Failure to comply may result in permanent equipment  
damage and severe shock to individuals.  
4. Lift the Main PC board and remove one battery tube.  
Refer to figure on page 29.  
5. On the Main PC board, unsolder and remove the red and  
orange wires that come from the power supply circuit  
board.  
25  
 
   
Bird Model 4391A Power Analyst  
Figure 19  
Removing  
Main PCB  
QC  
Connectors  
Removal  
1. Remove the eight screws (four on each connector) that  
secure the connectors to the housing (Figure 20, item 1).  
2. Remove the two “QC” connectors (item 2) by pulling  
them away from the line section assembly.  
26  
 
   
Maintenance  
Line Section  
Removal  
1. Remove the QC connectors (page 26).  
2. Remove the four screws and lock washers that secure  
line section assembly to the housing (item 3).  
3. Using minimum pressure, spread apart the sides of the  
lower housing assembly just far enough to allow the line  
section assembly to be removed.  
Figure 20  
Removing QC  
Connectors  
and Line  
Section  
To remove the line section PCB, continue with the next  
steps.  
CAUTION  
This instrument contains static sensitive electronic  
components. Before opening or servicing the unit, make  
sure that you understand and practice electrostatic  
discharge component handling. Failure to comply may  
result in permanent damage to sensitive components.  
4. Remove the two screws (units with serial numbers 1723  
and below) or the two hex nuts (units with serial  
numbers 1724 and above) (Figure 21, item 5) that secure  
the PCB cover then remove the cover (item 6) and  
spacers (item 7).  
5. Disconnect the ribbon cable assembly from the PC board  
header (J1).  
27  
 
   
Bird Model 4391A Power Analyst  
6. Remove the two screws (item 4) that secure the PCB to  
the line section then pull the PC board assembly (item 3)  
away from the line section subassembly. Remove the  
spacers (item 2).  
7. Remove keying beads (item 1) from the element wiper  
contacts on the PC board assembly.  
Figure 21  
Removing Line  
Section PCB  
Battery  
Replacement  
1. Remove the front panel (refer to “Front Panel Removal”  
2. Remove the four screws and lock washers (Figure 22,  
item 1) that secure the Main PCB.  
3. Loosen, but do not remove the remaining two screws  
that secure the Main PCB (item 2).  
4. Tilt the Main PC board assembly up to expose the bat-  
teries then tighten the two screws to secure the PCB.  
5. Unfasten the velcro strap and remove it from the D-ring.  
6. Note the polarity orientation of the batteries. Remove  
the three battery tubes from the battery clips then  
remove two batteries from each tube.  
7. Install new batteries into the tubes then secure the  
tubes in the battery clips. Be sure to observe proper  
polarity.  
28  
 
   
Maintenance  
8. Lower and secure the Main PC board assembly  
9. Replace and secure the front cover.  
10. Charge the batteries for 16 hours before using the  
instrument.  
Figure 22  
Tilt Main  
PCB to  
Expose  
Batteries  
Figure 23  
Battery  
Replacement  
29  
 
   
Bird Model 4391A Power Analyst  
Parts List  
This section contains an illustrated list of all authorized  
replacement parts for the 4391A RF power Analyst. Parts  
are grouped into major assemblies and subassemblies.  
Figure 24  
Parts  
Drawing  
Item No. Description  
Part No.  
Qty  
1
Connector, QC F-N  
4240-062  
5-1337  
2
4
1
1
1
1
1
6
2
1
2
LED display, (DS1 - DS4)  
Keyboard legend  
3
4386-012  
4391B007  
5-1958  
4
PC board, Main, assembly  
Velcro strap  
5
6
PC board assy (includes rectifier circuit)  
Fuse, Slo-Blo, IEC 1/8 amp  
Battery (rechargeable) “C” cell  
Dust plug  
4391A041  
5A2257-7  
5A1230  
7
N/S  
N/S  
N/S  
3610-031  
4421-055  
Cable, power cord, 115V / 230V  
N/S = not shown in figure  
30  
 
     
Maintenance  
Figure 25  
Line Section  
Assembly  
(S/N 1723  
and below)  
Item No.  
Description  
Part No.  
Qty  
1
2
3
4
5
Line Section, Subassembly  
PC Board, Data Acquisition Assy  
Bead, Keying  
4381-005  
4391A006  
4391-026  
4391-027  
COML  
1
1
2
2
2
Spacer  
Screw, Machine, filister head,  
No. 4-40, 1/4 in. lg, sst  
6
7
Support  
4381-029  
COML  
2
4
Screw, Machine, filister head,  
No. 8-32, 1/2 in. lg, sst  
8
Screw, Machine, filister head,  
No. 4-40, 7/8 in. lg, sst  
COML  
2
9
Spacer  
4391-035-1  
4391-034  
COML  
2
1
2
1
10  
11  
N/A  
Cover, PC Board  
Lock Washer, No. 4 internal sst  
Line Section Complete  
4391-014  
31  
 
 
Bird Model 4391A Power Analyst  
Figure 26  
Line Section  
Assembly  
(S/N 1724  
and above)  
Part No.  
Description  
Part No.  
Qty  
1
2
3
4
5
Line Section, Subassembly  
PC Board, Data Acquisition Assy  
Bead, Keying  
4381-005  
4391A006  
4391-026  
4391-027  
COML  
1
1
2
2
2
Spacer  
Screw, Machine, filister head,  
No. 4-40, 1/4 in. lg, sst  
6
7
Support  
4381-029  
COML  
2
4
Screw, Machine, filister head,  
No. 8-32, 1/2 in. lg, sst  
8
Hex Nut, with nylon insert, No. 4-40  
Spacer  
1131-1013-00  
4391-035-1  
4391-034  
COML  
2
2
1
2
2
9
10  
11  
12  
Cover, PC Board  
Lock Washer, No. 4 internal sst  
Standoff, Threaded  
4391-038  
32  
 
 
Maintenance  
Customer Service  
Any maintenance or service procedure beyond the scope of  
those in this chapter should be referred to a qualified service  
center.  
If you need to return the unit for any reason, contact the  
Bird Service Center for a return authorization. All  
instruments returned must be shipped prepaid and to the  
attention of Bird Service Center.  
Bird Service Center  
30303 Aurora Road  
Cleveland (Solon), Ohio 44139-2794  
Phone: (440) 519-2298  
Fax: (440) 519-2326  
For the location of the Sales Office nearest you, give us a call  
or visit our Web site at:  
33  
 
 
Bird Model 4391A Power Analyst  
Specifications  
Measuring Medium  
RF Power Range*  
RF Transmission in 50 ohm lines  
100 mW to 10 kW full scale using Bird Plug-in Elements.  
Accuracy not guaranteed with components not supplied by  
Bird  
Usable Over-Range*  
To 120% of scale on CW, PEP, SWR, and Return loss functions.  
To 400% of scale (PEP) on dBm and 0% modulation.  
450 kHz to 2.7 GHz  
Frequency Range*  
Sampling Range  
Settling Time  
2-3 readings per second  
10 seconds (worst case)†  
Accuracy  
Power Readings  
CW  
PEP  
SWR  
% Modulation  
Return Loss  
±5% of full scale  
±8% of full scale  
±10% of reading  
±5%‡  
±0.3 dB to corresponding SWR value  
Impedance  
50 ohms  
Insertion SWR  
1.05 max to 1000 MHz  
Pulse Parameters (square pulses)  
0.8 µsec. min.**  
25 pps min.  
0.01% min.  
Pulse Width  
Repetition Rate  
Duty Cycle  
RF Line Connections  
Standard  
Optional  
Bird Quick Change “QC” Female N  
Any Standard AN “QC” type  
Temperature Range  
Operating  
Storage  
10ºC to 45ºC (50ºF to 113º F)  
-20ºC to 45ºC (-4ºF to 113º F)  
Input Power Requirements  
Voltage  
100-130 or 200-230 VAC (Switch Selectable) or 7.2 Vdc  
(internal battery)  
50-60 Hz  
6 Watts  
Frequency  
Power  
Batteries  
Battery Life  
Weight  
6-1.2 V NiMH C size (Rechargeable)  
12 hours approx.  
5-3/4 lb (2.6 kg)  
*
Frequency band and power range is determined by the Plug-in Elements select-  
ed. See Bird Catalog for availability. Some modes require two elements in a 10:1  
power ratio.  
VSWR and return loss functions settle in less than 1 second.  
For CW power levels greater than one-third of full scale, accuracy of the percent  
modulation mode is 5% from 0 to 90% and +10% from 90 to 100%. Modulation fre-  
quency is 25 to 100,000 Hz; except for “A” and “B” elements: 25 to 20,000 Hz; and  
“H” elements: 25-10,000 Hz.  
** For “A” and “B” elements the minimum pulse width is 1.5 microseconds. For “H”  
elements the minimum pulse width is 15 microseconds.  
34  
 
 
Limited Warranty  
All products manufactured by Seller are warranted to be free from  
defects in material and workmanship 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 labor charges  
of Buyer for replacement of parts, adjustment or repairs, or any other  
work, unless such charges are authorized in 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 issue 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 (cheapest 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 of  
discovery of the defect.  
The above warranties shall not extend to any products or parts  
thereof which have been subjected 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  
acquired from others at Buyer’s request and/or to Buyer’s  
specifications. Routine (regularly required) calibration is not covered  
under this limited warranty. 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  
extent of the original manufacturer’s warranty 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 ACCORDANCE  
WITH THE FOREGOING.  
 

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