BIRD 8931A400-115 User manual

TERMALINE® DUAL LOAD RESISTOR
SEMICONDUCTOR
MODEL 8931A400
Operation Manual

This unit requires the supplied vent plug be installed prior to use.
Operating the unit without the vent plug installed WILL result in equipment damage and may
cause personal injury.
©Copyright 2023 by Bird Technologies Inc.
Instruction Book P/N 920-8931A400 Rev. B
Termaline® and Thruline® are Registered Trademarks
of Bird Electronic Corporation

Safety Precautions
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 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 remove power.

Shock Hazard
Do not attempt to remove the RF transmission line while RF power is present.

Do Not Service Or Adjust Alone
Under no circumstances should any personnel 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.

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 of this grounding is not properly supplied.

Resuscitation
Personnel working with or near high voltages should be familiar with modern methods of
resuscitation.

Remove Power
Observe general safety precautions. Do not open the instrument with the power applied.

Semiconductor Termaline Dual Coaxial Load Resistor
ii
Safety Symbols

Warnings call attention to a procedure, which if not correctly performed, could result in
personal injury.

Cautions call attention to a procedure, which if not correctly performed, could result in damage
to the instrument.

Notes call attention to supplemental information.
This symbol indicates that a shock hazard exists if the precautions in the
instruction manual are not followed.
The caution symbol appears on the equipment indicating there is
important information in the instruction manual regarding that particular
area. Refer to page 11 for specific instructions.
This symbol indicates that the unit radiates heat and should not be
touched while hot.

Safety Precautions
iii
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.

The load weighs 150 lbs (68 kg), do not attempt to lift alone. Two or more people, or mechanical
assistance, are required to lift the load. Injury may result from lifting alone.
See page 4 and 14

The vent plug must be used at all times when the unit is in operation or cooling.
Always check to ensure vent plug is installed prior to operation.
Failure to do so WILL result in damage to the equipment and endanger the operator’s safety.
See pages 5 and 15

Never attempt to connect or disconnect RF equipment from the transmission line while RF
power is being applied. Leaking RF energy is a potential health hazard.
See pages 6, 7, 9, and 13

Turn off AC power and RF power when attaching the power cable.
See page 5

Do not touch the load during operation. During operation, load surfaces are extremely hot.
Touching the load during or after operation may cause burns.
See page 7

Disconnect the unit from all power sources before servicing. The unit may be energized from
multiple sources. The potential for electric shock exists.
See pages 9, 11, 12, 14, 15, 17

Do not operate with side panel removed. Doing so could result in personal injury.
See page 11

Semiconductor Termaline Dual Coaxial Load Resistor
iv
Caution Statements
The following equipment cautions appear in the text whenever the equipment is in danger of damage and are
repeated here for emphasis.

Only one resistor can be energized at a time. Applying RF power to both resistors simultaneously
will overheat the load.
See Pages 1, 3, 7

Maximum power is 2,500 W when the blower is not running.
If the indicator light turns off, immediately reduce RF power to less than 2,500 W.
See Pages 3, 7

Do not block airflow. The air intake vent on the bottom of the load must not be obstructed.
See Page 4.

This load is designed for operation in a horizontal position only, with the vent plug up.
Do not use in any other manner.
See Page 5.

Check the local electrical code for proper AC hookup prior to operation of the unit. Make sure
the neutral or return hookup is only used for that purpose.
See Page 5

If installed, connect optional interlock before applying RF power.
See Page 7

Use only Bird coolant, P/N 5-1070, to prevent damage to the load.
See Page 12

Safety Precautions
v
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.

Semiconductor Termaline Dual Coaxial Load Resistor
vi
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.

Safety Precautions
vii
About This Manual
This instruction book covers the models listed below:
This instruction book is arranged so that essential information on safety is in the front of the book. Reading the
Safety Precautions before operating the equipment is strongly advised. The remainder of this instruction book is
divided into Chapters and Sections.
Changes To The 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 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.
Chapter Layout
Introduction — Describes the features of the Bird Termaline RF Load Resistor lists equipment supplied and
optional equipment, and provides power-up instructions.
Theory of Operation — Describes how the Termaline RF Load Resistor works and its functions.
Installation — Describes the how to install the Termaline RF Load Resistor.
Operation with Blower — Describes procedures require for operating the load resistor equipped with a blower
unit.
Maintenance — Lists routine maintenance tasks as well as troubleshooting for common problems. Specifications
and parts information are also included.
8931A400-115 8931A400-230

viii
Table of Contents
Safety Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .i
Safety Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii
Warning Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii
Caution Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .iv
Safety Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
About This Manual. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
Changes To The Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
Chapter Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
Chapter 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Items Supplied . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Items Required but not Supplied . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Chapter 2 Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Load Resistor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Coolant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Fans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Power Rating Reduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Chapter 3 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Unpacking and Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Site and Shelter Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Tools Required . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Vent Plug . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
AC Power Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Connecting RF Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Chapter 4 Operating Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Blower Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Normal Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Operation Under Abnormal Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Emergency Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Chapter 5 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Routine Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Inspect the Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Clean the Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Clean the Blower Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Inspect the Coolant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
RF Assembly Resistance Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
DC Resistance Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
RF Connector Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Load Resistor Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Indicator Light Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Table of Contents
ix
Fuse Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Fan Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Storage and Shipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Storing the Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Shipping the Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Customer Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Replacement Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Limited Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

1
Chapter 1 Introduction
Bird 8931A400 Dual Resistor Semiconductor Loads are portable, 50 ohm, coaxial RF transmission line terminations.
They are designed for frequency ranges of DC – 30 MHz. They provide accurate, dependable, and low reflection line
terminations. The load has two resistors and two connectors allowing easy dual-frequency high precision
measurements. Up to 10,000 watts of RF power can be dissipated in each resistor.

Only one resistor can be energized at a time. Applying RF power to both resistors simultaneously
will overheat the load.
The load has a coolant chamber surrounded by radiator fins. The front and rear fins form mounting flanges which
can be used as supports for freestanding use or as brackets for fixed mounting. A vent plug at the top of the unit
relieves internal pressure from coolant expansion. A blower with three axial fans is on the bottom of the load. The
load’s simple and rugged design minimizes maintenance requirements.
Items Supplied

The load is pre-filled with coolant at the factory
Load Resistor:
Detachable 3-wire power cable (without male plug for 230 VAC power cable)
One Shipping Plug
One Vent Plug
Instruction Manual
Items Required but not Supplied
Coupling Kit: Connects the load to the RF line
Male plug for the power cable (230 VAC only)

Introduction
2
Figure 1 8931A400 Outline Drawing
07*+2/(6
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7ZR5)
&RQQHFWRUV

PP
02817,1*+2/(6

PP

PP

PP

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02817,1*+2/(6
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9HQW
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2ULQJ

3
Chapter 2 Theory of Operation
Load Resistor
Bird 8931A400 loads consist of dual thin-film-on-ceramic resistors immersed in the same dielectric coolant. The
resistors, individually selected for accuracy, are enclosed in a special housing. When surrounded by the coolant, this
produces a uniform, practically reflectionless line termination over the specified frequencies.
Coolant

Only one resistor can be energized at a time. Applying RF power to both resistors simultaneously
will overheat the load.
The load is cooled by forced air and natural fluid convection currents. The coolant, chosen for its dielectric and
thermal characteristics, carries heat from the resistor to the walls of the cooling tank, where radiator fins around the
tank transfer the heat to the forced air flow.
When the coolant is heated, thermal expansion causes an increase in the internal pressure. The vent plug relieves
this pressure while protecting the opening from dirt or other contaminants.
Fans
Forced airflow is provided by three axial fans beneath the heat exchanger. Baffles direct the air over the radiator fins
for more efficient cooling. The fans are on whenever AC power is supplied.
Power Rating Reduction

Maximum power is 2,500 W when the blower is not running.
If the indicator light turns off, immediately reduce RF power to less than 2,500 W.
The baffles interfere with the free flow of normal air currents, causing a 75% reduction in heat transfer efficiency if
the forced airflow is stopped. The maximum power dissipation when the fans are not functioning is 2.5 kW.

4
Chapter 3 Installation
This chapter provides information for on-site requirements, unpacking, inspection, and preparing the load for use.
Unpacking and Inspection

The load weighs 150 lbs (68 kg), do not attempt to lift alone. Two or more people, or mechanical
assistance, are required to lift the load. Injury may result from lifting alone.
1. Carefully inspect shipping container for signs of damage.
If the shipping container is damaged, do not unpack the unit. Immediately notify the shipping carrier and
Bird Technologies.
If the shipping container is not damaged, unpack the unit. Save shipping materials for repackaging.
2. Inspect unit for visual signs of damage.

If there is damage, immediately notify the shipping carrier and Bird Technologies.
Site and Shelter Requirements
The unit should be operated in a dry, dust and vibration free environment.
Do not use outdoors or in areas of condensing humidity.
The ambient temperature range should remain between -40 to +45 °C (-40 to +113 °F)@ 60 Hz or – 40 to +40 °C
(– 40 to +104 °F) @ 50 Hz for proper operation.

Do not block airflow. The air intake vent on the bottom of the load must not be obstructed.
Allow at least 15" (40 cm) of clearance on all sides of the load, or mount it over a suitably reinforced opening
measuring 26"L x 7"W x 5"D (660 x 178 x 127 mm).
Place the unit as close as possible to the transmitting equipment, to permit the shortest possible cable length.
Tools Required
The following tools and supplies will be required to prepare the unit for use:
Wrenches
Screwdrivers
Bolt and nut sets or lag screws for mounting) (38“(9.53 mm) max. diameter)

Semiconductor Termaline Dual Coaxial Load Resistor
5
Mounting

This load is designed for operation in a horizontal position only, with the vent plug up. Do not
use in any other manner.
The load is intended for stationary or fixed use. The mounting brackets on the front and rear faces have four
mounting holes arranged in a 7” x 2738” (114.3 x 526.3 mm) rectangle. Use a screw with a 38” (9.53 mm) diameter
max.
The following instructions are for mounting the unit to a suitable surface.
1. Place the unit on a flat surface.
2. Insert the bolts through the surface and the mounting slots.
3. Secure the bolts with nuts and lock washers.
Vent Plug

The vent plug must be installed at all times when the unit is in operation or cooling.
Always check to ensure vent plug is installed prior to operation.
Failure to do so WILL result in damage to the equipment and endanger the operator’s safety.
Before placing the unit into service, the solid shipping plug, P/N 2450-049, must be removed and replaced by the
spring loaded vent plug, P/N 2450-094. The plugs are linked together by a short length of bead chain.
1. Locate the vent hole for the plug, located at the top near the front.
See
Figure 1 on page 2 .
2. Remove the shipping plug.
3. Verify the O-Ring is installed on the vent plug.
4. Install the vent plug.
AC Power Connection

Turn off AC power and RF power when attaching the power cable.

Check the local electrical code for proper AC hookup prior to operation of the unit. Make sure
the neutral or return hookup is only used for that purpose.
The AC power supply required for this unit is 115/230 V, depending on the model, @ 50/60 Hz, 1. The blower is
equipped with an IEC 320 “cold” (65C) AC inlet.
Connecting RF Power
Before first using the load, perform the following steps.
1. Wipe all connectors and insulator surfaces on the transmission line face with a clean soft cloth.
2. Check the RF input connector for signs of wear, damage, or dirt.

Installation
6
3. Clean the connector if necessary. Use a self-drying, non-residue forming contact cleaner on the interior portions
of the connector.
4. Check the input resistance of the load. Refer to
"RF Assembly Resistance Test" on page 13 for details.
5. The RF transmission line can be attached using standard coaxial line coupling kits.

Never attempt to connect or disconnect RF equipment from the transmission line while RF
power is being applied. Leaking RF energy is a potential health hazard.
“QC” Connector Coupling — Use 50 ohm coaxial cable such as RG-218/U or -220/U (-17A or -19A), appropriate
for the frequency and power level of operation. Use a cable connector which will mate with the one on the load.

7
Chapter 4 Operating Instructions

Never attempt to connect or disconnect RF equipment from the transmission line while RF
power is being applied.
Leaking RF energy is a potential health hazard.

Do not touch the load during operation. During operation, load surfaces are extremely hot.
Touching the load during or after operation may cause burns.

Only one resistor can be energized at a time. Applying RF power to both resistors simultaneously
will overheat the load.

If installed, connect optional interlock before applying RF power.
Blower Controls
Bird 8931A400 Loads are equipped with an indicator light on the front of the blower, underneath the RF connector.
The blower will turn on whenever the unit is connected to AC power. The indicator light, labeled “AC ON”, will also
turn on.
Normal Operation
Check that the blower and the indicator light are on.
Apply RF power.
Operation Under Abnormal Conditions
The load can be subjected to moderate overloads for short periods

Maximum power is 2,500 W when the blower is not running. If the indicator light should turn
off, immediately reduce RF power to less than 2,500 W.
If the indicator light turns off or the fans stop unexpectedly, immediately turn off RF power or reduce it to less than
2,500 W. Refer to
"Troubleshooting" on page 9 to correct the problem.
Shutdown
Turn off RF power at the source.
Wait approximately 15 minutes. This will allow the load to cool without causing heat stress.
Turn off the blower.

Operating Instructions
8
Emergency Shutdown
Turn off RF power at the source.

9
Chapter 5 Maintenance
This chapter covers cleaning, inspection, trouble-shooting, and specifications for Bird 8931A400 Loads.

Disconnect the unit from all power sources before servicing. The unit may be energized from
multiple sources. The potential for electric shock exists.

Never attempt to connect or disconnect RF equipment from the transmission line while RF
power is being applied. Leaking RF energy is a potential health hazard.
Troubleshooting
The table below provides troubleshooting information for problems which may occur during normal operation. This
manual cannot list all malfunctions that may occur, or their corrective actions. If a problem is not listed or is not
corrected by the listed actions, notify a qualified service center.
PROBLEM POSSIBLE CAUSE CORRECTION
No air flow from blower;
“BLOWER ON” light off
Unplugged power cable Connect the power cable
No AC power Make sure AC power is properly connected and on
Fuse burnout Replace fuse after correcting the burnout cause
(See
"Fuse Replacement" on page 16 )
No air flow from blower;
“BLOWER ON” light on
Fan obstructed by bent grill Straighten the grill
Fan motors overheated Clean the grill and fan blades
(See
"Clean the Load" on page 10 )
Fan motors burnt out Replace fan (See
"Fan Replacement" on page 17 )
Air flow from blowers;
“BLOWER ON” light off Lamp burnout Replace lamp (See
"Indicator Light Replacement" on page 15 )
Leaking coolant
Loose clamping band Tighten the clamping band
Defective or improperly
installed O-ring
Replace the O-ring
(See
"Load Resistor Replacement" on page 14 )
High or low DC
resistance
Loose RF input connector Tighten connector
Faulty RF input connector Replace connector
(See
"RF Connector Replacement" on page 14 )
Faulty resistor Replace the resistor
(See
"Load Resistor Replacement" on page 14 )
Overheating radiator
RF power too high Lower RF power (See
"Specifications" on page 19 for
maximum RF power)
Coolant level too low Check the coolant level. Add coolant if necessary
(See
"Inspect the Coolant" on page 12 )
Coolant degraded Replace the coolant
(See
"Inspect the Coolant" on page 12 )
Faulty resistor Replace the resistor
(See
"Load Resistor Replacement" on page 14 )