BIRD Termaline 8920 Series User manual

INSTRUCTION BOOK
TERMALINE®LOAD RESISTOR
SERIES 8920
COVERING MODELS:
8921 8922 8926 8927 8928
8922D 8926D 8927D
©Copyright 2008 by Bird Electronic Corporation
Instruction Book Part Number 920-8920S Rev. H
Termaline® and Thruline® are Registered Trademarks
of Bird Electronic Corporation

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.
Chemical Hazard
Dry cleaning solvents for cleaning parts may be potentially dangerous.
Avoid inhalation of fumes or prolonged contact with skin.
Resuscitation
Personnel working with or near high voltages should be familiar with
modern methods of resuscitation.

Bird 8920 Series Termaline Coaxial Load Resistor
ii
Safety Symbols
NOTE: Calls attention to supplemental information.
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
Warning notes call attention to a procedure, which if not correctly
performed, could result in personal injury.
CAUTION
Caution notes call attention to a procedure, which if not correctly
performed, could result in damage to the instrument.
This symbol indicates that a shock hazard exists if the
precautions in the instruction manual are not follwed.
The caution symbol appears on the equipment indicating
there is important information in the instruction manual
regarding that particular area.
This symbol indicates that the unit radiates heat and
should not be touched while hot.
WARNING
The vent plug must be used at all times when the unit is operating or
cooling. Failure to do so could result in an explosion or severe burns.
WARNING
Disconnect the unit from all power sources before servicing.
The unit may be energized from multiple sources.
The potential for electric shock exists.
WARNING
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.

iii
Caution Statements
The following equipment cautions appear in the text whenever the
equipment is in danger of damage and are repeated here for emphasis.
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.
WARNING
Oil is slippery. If a leak occurs, be careful not to fall.
CAUTION
This load is designed for operation in a horizontal position only, with
the vent plug up. Do not use in any other manner.
CAUTION
If installed, connect optional interlock before applying RF power.
CAUTION
Use only Bird coolant, P/N 5-1070, to prevent damage to the load.

Bird 8920 Series Termaline Coaxial Load Resistor
iv
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.
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.

v
About This Manual
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.
Operation
First time operators should read Chapter 1 - Introduction and Chapter 3 -
Installation to get an overview of equipment capabilities and how to
install it. An experienced operator can refer to Chapter 4 - Operating
Instructions. All instructions necessary to operate the equipment are
contained in this chapter.
Maintenance
All personnel should be familiar with preventative maintenance found in
Chapter 5 - Maintenance. If a failure should occur, the trouble-shooting
section will aid in isolating and repairing the failure. Parts lists and
repair instructions are also in this chapter.
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.

vi
Table of Contents
Safety Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . i
About This Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Items Supplied . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Items Required but not Supplied. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Optional Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Theory of Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Load Resistor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Coolant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Thermal Interlock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Unpacking and Inspection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Setup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Installing Thermoswitch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Interlock Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Connecting RF Power. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Operating Instructions . . . . . . . . . . . . . . . . . . . . . . . . . 11
Normal Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Operation Under Abnormal Conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Emergency Shutdown. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
DC Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Coolant Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

vii
Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
RF Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Load Resistor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Storage and Shipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Customer Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Replacement Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Available “QC” Type Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

viii

1
Chapter 1 Introduction
Bird 8920 Series Loads are portable, 50 ohm, coaxial RF transmission
line terminations, designed for frequency ranges of dc – 1 GHz. Bird
8920D Series Loads are identical, except that they are designed for
the UHF (470 – 860 MHz) band. They provide accurate, dependable,
and low reflection line terminations. Up to 5000 watts of RF power
can be dissipated.
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. The load’s simple and rugged design minimizes
maintenance requirements.
Items Supplied yLoad Resistor: Pre-filled with coolant at the factory
yOne Shipping Plug
yOne Vent Plug
yInstruction Manual
Items Required but
not Supplied
yCoupling Kit: Connects the load to the RF line
Optional
Accessories
yInterlock Thermoswitch: Automatically shuts off the transmitter
to prevent overheating of the load

Bird 8920 Series Termaline Coaxial Load Resistor
2
Figure 1
Bird 8920 Series
Outline Drawing
VENT PLUG
INTERLOCK
THERMOSWITCH
(OPTIONAL)
26-7/8”
(681mm)
28-1/4”
(718mm)
8-3/8”
(212mm)
DEPENDS ON
CONNECTOR
7”
(178mm)
9-1/8”
(241mm)
(4) MTG. HOLES
3/8” (10 mm)

3
Chapter 2 Theory of Operation
Load Resistor Bird 8920 series loads consist of a thin-film-on-ceramic resistor
immersed in a dielectric coolant. The resistor, individually selected
for its accuracy, is enclosed in a special housing. When surrounded by
the coolant, this produces a uniform, practically reflectionless line
termination over the specified frequencies.
Coolant The load is cooled by natural fluid and air 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 surrounding the tank transfer the heat to the air.
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.
Thermal Interlock Loads can be supplied with an optional passive overtemperature
thermoswitch. Normally closed, it opens at the maximum safe load
temperature of 236 °C (457 °F), turning off transmitter power. The
interlock system will not permit use of the transmitter until the load
has reached a safe temperature.

Bird 8920 Series Termaline Coaxial Load Resistor
4
Figure 2
Shipping Plug
O-ring seal
Figure 3
Vent Plug
O-ring seal

5
Chapter 3 Installation
This chapter provides information for on-site requirements,
unpacking, inspection, and preparing the load for use.
Unpacking and
Inspection 1. Carefully inspect the shipping container for signs of damage. If
damage is noticed, do not unpack the unit. Immediately notify the
shipping carrier and Bird Electronic Corporation.
2. If the container is not damaged, unpack the unit. Save the packing
materials in case the unit should need to be shipped again.
3. Inspect all of the components for visible signs of damage.
Immediately notify the shipping carrier and Bird Electronic
Corporation of equipment damage or missing parts.
Mounting Place the load in a dry, dust and vibration free environment. Do not
use outdoors or in areas of condensing humidity. Allow at least 12"
(30 cm) of clearance on all sides of the load.
The load is equipped for either portable use or fixed installation. The
mounting brackets on the front and rear faces have four mounting
slots arranged in a 41⁄2" x 147⁄32" rectangle (114.3 x 361.2 mm). Use a
screw with a 3⁄8" (9.53 mm) diameter max.
Setup yBefore first using the load, get a resistance baseline for future
maintenance. Refer to “DC Resistance” on page 14 for details.
yRemove the shipping plug from the load and replace it
with the vent plug. Refer to Figure 2 and Figure 3 for pictures
of the plug.
CAUTION
This load is designed for operation in a horizontal position only,
with the vent plug up. Do not use in any other manner.
WARNING
The vent plug must be used at all times when the unit is operating
or cooling. Failure to do so could result in an
explosion or severe burns.

Bird 8920 Series Termaline Coaxial Load Resistor
6
Installing
Thermoswitch Bird 8920 series loads can be equipped with an optional interlock
thermoswitch, P/N 8890-008. It is normally closed, opening at 236 °C
(457 °F), with a rating of 10A @ 120 Vac and 5A @ 230 Vac.
To install or replace the thermoswitch:
1. Remove the vent plug. Install the shipping plug.
2. Stand the unit on its front, supporting it so that the connector is
not damaged. In this position there is no danger of the coolant
pouring out through the socket plug hole.
3. Remove the socket plug just above the connector assembly, using
a 9⁄16" hex wrench.
4. Replace the plug with the thermoswitch. Sparingly apply pipe
sealing compound to the external threads, only, of the
thermoswitch. Do not contaminate the coolant with pipe sealant.
5. Check for coolant leaks upon completion.
6. Remove the shipping plug. Install the vent plug.
WARNING
The vent plug must be used at all times when the unit is operating
or cooling. Failure to do so could result in an
explosion or severe burns.

Installation
7
Interlock
Connection Connect the thermoswitch to the interlock as follows (see Figure 4):
1. Unscrew the large knurled ring-nut (A) at the lower end of the
coupling jack assembly. Pull it off the thermoswitch jack (B).
Unscrew the small knurled cover fitting from the base plug (D) of
the connector to release the base.
2. Thread the control switch wires through the clamp (E) with the
washers (F) inside and with its threaded fitting in place. Service
the control switch wire with short tips and put spaghetti sleeves
over the wire ends if necessary.
3. Securely solder the control switch leads to the lugs (G) of the
connector base.
NOTE: The ring-nut (A) must be in place over the base plug (D)
with the knurled end facing out.
4. Screw on the cover ring, then fasten the cable clamp (E) in place
and tighten both yoke screws (H).
5. Put the plug back on the thermoswitch and tighten the nut (A).
CAUTION
If installed, connect optional interlock before applying RF power.
Figure 4
Thermoswitch
Assembly

Bird 8920 Series Termaline Coaxial Load Resistor
8
Connecting RF
Power After installing the load, the RF transmission line can be attached
using standard coaxial line coupling kits.
“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.
Swivel Flanged Coupling: To couple the swivel flange with a flanged
RF transmission line, use an appropriate coupling kit. Refer to
Figure 5 while following the instructions below:
yInsert the center bullet and push it in until it is fully seated.
yConnect the coaxial input in a straight line and push carefully on
the center conductor to close.
NOTE: The swivel flange on the load makes connection
independent of the orientation of the fixed flange on the coaxial
input outer conductor.
yInsert the bolt sets and tighten evenly all around to transmission
line manufacturer’s recommended torque. Use all of the bolts.
WARNING
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.
Figure 5
Swivel Flanged
Coupling
BOLT BULLET LOADRF COAXIAL LINE

Installation
9
Unflanged Coupling: To couple the unflanged connector with an
unflanged RF line, use an appropriate coupling kit. Refer to Figure 6
while following the instructions below:
yInsert the center bullet and bottom it on the midpoint nibs.
yPosition the outer sleeve, with clamping bands, over the input
connector.
ySet the transmission line snugly against the coupling stops.
yPosition the clamping bands evenly about 3/4” from the ends of
the sleeve.
yTighten the clamping bands.
Figure 6
Unflanged
Coupling
RF COAXIAL
LINE CLAMPING BANDS CONNECTOR SLEEVE BULLET LOAD

Bird 8920 Series Termaline Coaxial Load Resistor
10

11
Chapter 4 Operating Instructions
Normal Operation Bird 8920 series loads have no indicators or operating controls. They
require no special operating procedures or surveillance when their
performance limits are not exceeded. Follow the instructions for the
specific transmitter equipment.
Operation Under
Abnormal
Conditions
The load can be subjected to moderate overloads for short periods. If
this is likely, make sure the interlock is properly connected to prevent
damage to the load.
Shutdown These loads are passive devices, so have no way of being turned off.
Turn off RF power at the source.
Emergency
Shutdown Turn off RF power at the source.
If the interlock thermoswitch is properly connected, RF power will be
automatically turned off when the coolant temperature reaches an
unsafe level.
WARNING
The vent plug must be used at all times when the unit is operating
or cooling. Failure to do so could result in an
explosion or severe burns.
WARNING
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.