BIRD Termaline 8940SC Series User manual

Termaline® Semiconductor
Load Resistor
Series 8940SC
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 Part Number 920-8940-SEMICON Rev. B
Termaline® is a Registered Trademark
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
apply to all phases of operation and maintenance.

Keep Away From Live Circuits
Operating Personnel must at all times observe general safety precautions. Do not replace
components or make adjustments to the inside of the test equipment with the high voltage
supply turned on. To avoid casualties, always remove power.

Shock Hazard
Do not attempt to remove the RF transmission line while RF power is present.
Capacitors can store a dangerous electrical charge. Avoid contact with all system capacitors. If it
is necessary to perform work near a system capacitor, be sure to discharge the capacitor through
a low resistance.

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.

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.

Remove Power
Observe general safety precautions. Do not open the instrument with the power on.

Termaline® Semiconductor 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.
The caution symbol appears on the equipment indicating there is
important information in the instruction manual regarding that
particular area.

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 236 lbs (107 kg), do not attempt to lift alone. Two or more people, or
mechanical assistance, are required to lift the load. Injury may result from attempting to lift
alone.
See pages 3, 5, and 15.

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.
See pages 4, 6, and 16.

Turn off AC power and RF power when attaching the power cable.
See page 7.

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 8.

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 7, 8, and 10.

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 10, 12, 13, 13, 15, 16, 16, and 18.

Do not operate with side panel removed. Doing so could result in personal injury.
See page 12.

Termaline® Semiconductor 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.

Maximum power is 3,700 W when the blower is not running. If the indicator light should turn
off, immediately reduce RF pwer to less than 3,700 W.
See page 2.

Do not block airflow. The air intake vent on the bottom of the load must not be obstructed.
See page 3.

This load is designed for operation in a horizontal position only, with the vent plugs up. Do not
use in any other manner.
See page 4.

Blocking should be used to support the load to avoid damage to the RF connector.
The RF connector extends from the front of the load.
See page 5.

Blocking should be used to support the load to avoid damage to the thermoswitch.
The thermoswitch extends from the back of the load.
See page 5 and 15

If installed, connect optional interlock before applying RF power.
See page 6 and 8.

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 7.

Do not use a cleaning solution that will damage the plastic parts of the fan.
See page 12.

Use only Bird coolant, P/N 5-1070, to prevent damage to the load.
See page 13.

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.

Termaline® Semiconductor 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
CONNECT INTERLOCK TO TRANSMITTER/GENERATOR/AMPLIFIER BEFORE OPERATING.
BRANCHER LE VERROUILLAGE À L’ÉMETTEUR/GÉNÉRATEUR/AMPLIFICATEUR AVANT EMPLOI.
CONECTE EL INTERBLOQUEO AL TRANSMISOR/GENERADOR/AMPLIFICADOR ANTES DE LA
OPERACION.
VOR INBETRIEBNAHME VERRIEGELUNG AM SENDER/GENERATOR/VERSTÄRKER
ANSCHLIESSEN.
PRIMA DI METTERE IN FUNZIONE L’APPARECCHIO, COLLEGARE IL DISPOSITIVO DI BLOCCO AL
TRASMETTITORE/GENERATORE/AMPLIFICATORE.

Termaline® Semiconductor Load Resistor
viii
About This Manual
This instruction book covers the models listed below:
Changes to this Manual
We have made every effort to ensure this manual is accurate. If you discover any errors, or if you have suggestions
for improving this manual, please send your comments to our Solon, Ohio factory. This manual may be periodically
updated. When inquiring about updates to this manual refer to the part number and revision 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.
Operating Instructions — 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.
115 VAC 230 VAC
8941-115SC13 8941-230SC13

ix
Table of Contents
Safety Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .i
Safety Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii
Warning Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii
Caution Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .iv
Safety Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
About This Manual. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii
Changes to this Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .viii
Chapter Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .viii
Chapter 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Items Supplied . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Items Required but not Supplied . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Optional Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Chapter 2 Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Load Resistor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Coolant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Fans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Power Rating Reduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Thermal Interlock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Chapter 3 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Unpacking and Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Site and Shelter Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Tools Required . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Vent Plug . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Thermoswitch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Interlock Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
AC Power Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Connecting RF Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Chapter 4 Operating Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Blower Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Normal Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Operation Under Abnormal Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Emergency Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Chapter 5 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Routine Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Inspect the Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Clean the Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Clean the Blower Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Radiator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Fans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Inspect the Coolant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Termaline® Semiconductor Load Resistor
x
RF Assembly Resistance Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
DC Resistance Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
RF Connector Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Load Resistor Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Indicator Light Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Fuse Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Fan Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Storage and Shipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Storing the Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Shipping the Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Customer Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Replacement Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Available QC Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Limited Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

1
Chapter 1 Introduction
Bird 8940 Series Semiconductor Loads are general purpose, 50 ohm, coaxial RF transmission line terminations,
useful as standby reject loads. They provide accurate, dependable, and low reflection line terminations over a
frequency range of DC – 20 MHz, specially calibrated for great stability at 13.56 MHz. Up to 15,000 watts can be
dissipated.
The loads have 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 five 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
Shipping Plug
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)
Optional Accessories
Interlock Thermoswitch: Automatically shuts off the generator to prevent overheating of the load
Figure 1 Bird 8940 Series Outline Drawing
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2
Chapter 2 Theory of Operation
Load Resistor
Bird 8940 Loads consist of two thin-film-on-ceramic resistors immersed in a dielectric coolant. The resistors,
individually selected for accuracy, are enclosed in special housings. When surrounded by the coolant, this produces
a uniform, practically reflectionless line termination over the specified frequencies.
Coolant
The load is cooled by forced air and natural fluid convection currents. The coolant, chosen for its desirable dielectric
and thermal characteristics, carries heat from the resistor to the walls of the cooling tank, where radiator fins
surrounding the tank transfer the heat to the forced air flow.
When the coolant is heated, thermal expansion causes an increase in the internal pressure. A vent plug relieves this
pressure while protecting the opening from dirt or other contaminants.
Fans
Forced airflow is provided by five axial fans beneath the heat exchanger. Baffles direct the air over the radiator fins
for more efficient cooling. A passive, normally open control thermoswitch closes when the coolant reaches 60 °C
(140 °F), turning the fans on.
Power Rating Reduction

Maximum power is 3,700 W when the blower is not running. If the indicator light should turn
off, immediately reduce RF pwer to less than 3,700 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 3.75 kW.
Thermal Interlock
When installed, a passive, normally closed over-temperature thermoswitch opens above the maximum safe load
temperature of 226 °C (439 °F), turning off generator power. The interlock will not permit use of the generator until
the load has reached a safe temperature.

3
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 236 lbs (107 kg), do not attempt to lift alone. Two or more people, or
mechanical assistance, are required to lift the load. Injury may result from attempting to lift
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

Do not block airflow. The air intake vent on the bottom of the load must not be obstructed.
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 +5 to +40 °C (+41 to +104 °F) for proper operation.
Allow at least 15" (40 cm) of clearance on all sides of the load, or mount it over a suitably reinforced opening
measuring 42"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)
These tools and supplies are required for the optional thermoswitch installation:
9/16 Hex wrench
Pipe sealing compound (Loctite 567, or equivalent)
Soldering Iron and solder
Torque Wrench

Termaline® Semiconductor Load Resistor
4
Mounting

This load is designed for operation in a horizontal position only, with the vent plug up. Do not
use in any other manner.
Bird 8940 Loads are intended for stationary or fixed use. The mounting brackets on front and rear faces have four
mounting holes arranged in a 7" x 40-23/32" (177.8 x 1031.3 mm) rectangle. Use a screw with a 3/8" (9.5 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 1 .
2. Remove the shipping plug.
3. Verify the O-Ring is installed on the vent plug.
4. Install the vent plug.

Installation
5
Thermoswitch
Bird 8940 Loads can be equipped with an optional interlock thermoswitch, P/N 8890-017. It is normally closed,
opening at 226 °C (439 °F), with a rating of 10 A @ 120 VAC and 5 A @ 230 VAC.
A control thermoswitch, P/N 8892-333, is used to control the blower assembly. It is normally open, closing at 60 °C
(140 °F), with a rating of 10 A @ 120 VAC and 5 A @ 230 VAC.
To install or replace a thermoswitch, follow these instructions:
1. Remove the vent plug.
2. Verify the O-Ring is installed on the shipping plug.
3. Install the shipping plug.

The load weighs 236 lbs (107 kg), do not attempt to lift alone. Two or more people, or
mechanical assistance, are required to lift the load. Injury may result from attempting to lift
alone.
4. For Interlock Thermoswitch:

Blocking should be used to support the load to avoid damage to the RF connector.
The RF connector extends from the front of the load.
a. Stand the unit on its front with the RF connector down.

In this position there is no danger of the coolant pouring out through the socket plug hole.
b. Remove the socket plug with a 916" hex wrench.
5. For Control Thermoswitch:

Blocking should be used to support the load to avoid damage to the thermoswitch.
The thermoswitch extends from the back of the load.
a. Stand the unit on its back with the RF connector up.

In this position there is no danger of the coolant pouring out through the socket plug hole.
b. Remove the top socket plug with a 916" hex wrench.

Do not contaminate the coolant with pipe sealing compound.
6. Sparingly apply pipe sealing compound to the external threads, only.
7. Install the thermoswitch in place of the plug. Torque to 40 +/-2 ft-lbs.
8. Lower the unit back onto its feet.
9. Check for coolant leaks upon completion.

Termaline® Semiconductor Load Resistor
6

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.
10. Remove the shipping plug.
11. Verify the O-Ring is installed on the vent plug.
12. Install the vent plug.
Interlock Connection
If installed, connect the optional interlock thermoswitch to the interlock as follows (see Figure 2 ):

If installed, connect optional interlock before applying RF power.
1. Unscrew the larger knurled ring-nut (A) at the lower end of the coupling jack assembly.
2. Pull it off the thermoswitch jack (B).
3. Unscrew the small knurled cover fitting (C) from the base plug (D) of the connector to release the base.
4. Thread the interlock wires through the clamp (E) with the washers (F) inside and with its threaded fitting in
place.
5. Service the interlock wires with short tips and put spaghetti sleeves over the wire ends if necessary.
6. Securely solder the interlock leads to the lugs (G) of the connector base.

The ring-nut (A) must be in place over the base plug (D) with the knurled end facing out.
7. Screw on the cover fitting (C).
8. Fasten the cable clamp (E) in place.
9. Tighten both yoke screws (H).
10. Push the plug back on the thermoswitch
11. Tighten the nut (A).

Do not attempt to operate the equipment without the interlock attached.
12. Connect the Thermoswitch wiring to the transmitter’s interlock.
Figure 2 Thermoswitch Assembly

Installation
7
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.
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.

8
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.

If installed, connect optional interlock before applying RF power.
Blower Controls
Bird 8940 Loads are equipped with a control switch and indicator light on the front of the blower, underneath the RF
connector. The switch is labeled “MANUAL/AUTOMATIC”. When the switch is set to MANUAL, the fans will run
continuously. When set to AUTOMATIC, the fans will be turned on when the coolant reaches a preset temperature.
The indicator light, labeled “AC ON”, will turn on whenever the unit is connected to AC power.
Normal Operation
1. Check that the indicator light is on.
2. Set the switch to MANUAL momentarily to check that the fans are working properly, then set the switch back to
AUTOMATIC.
3. Apply RF power.
Operation Under Abnormal Conditions

Maximum power is 3,750 W when the blower is not running. If the indicator light should turn
off, immediately reduce RF power to less than 3,750 W.
If the indicator light turns off or the fans stop unexpectedly, immediately turn off RF power or reduce it to less than
3,750 W. Refer to
"Troubleshooting" on page 10 to correct the problem. A properly connected interlock will
prevent overload.
The load can be subjected to higher power levels for short intervals. If this is likely, make sure the interlock is
properly connected to prevent damage to the load.
Shutdown
1. Turn off RF power at the source.
2. Wait approximately 15 minutes, or for the fans to stop running. This will allow the load to cool without causing
heat stress.
3. Turn off the blower.