Page 1
INSTRUCTION BOOK
A
OPERATING INSTRUCTIONS
TERMALINE
COAXIAL LOAD RESISTOR
MODELS
8251, 8252 & 8255
Electronic Corporation
Cleveland (Solon) Ohio US
ÓCopyright 1997 by Bird Electronic Corporation
Instruction Book Part Number 920-8251/52/55 Rev. C
Termaline
is a Registered Trademark of
Bird Electronic Corporation
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Bird Model 8251/52/55 Termaline Coaxial Load Resistor
Page 3
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.
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 uniterruptible 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
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Bird Model 8251/52/55 Termaline Coaxial Load Resistor
CAUTION
Caution notes call attention to a procedure which if not correctly
performed, could result in damage to the instrument.
This symbol appears on the equipment indicating there is
important information in the instruction manual regarding that particular area.
Note: Calls attention to supplemental informa-
+
tion.
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
The vent plug must be used at all times when the unit is in operation
or cooling. Failure to do this could result in damage to the equipment
and endanger the operator’s safety. Be sure to check this plug.
WARNING
Using this load in the upper end of its power dissipation range will
cause the housing to become hot! Care should be exercised in touching
it.
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.
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
This equipment is designed for operation in a horizontal position only,
with mounting brackets down. Do not operate in any other manner.
CAUTION
Do not operate this equipment over the rated 1000 watts continuously.
Damage to the resistive element will result.
ii
Page 5
CAUTION
The unit is factory filled to the proper level with 0.8 gallons (3.03 liter)
of Bird P/N 5-1070. No other coolant should be used
CAUTION
Do not leave out the O-Ring seal, P/N 5-504 when interchanging the
vent and shipping plugs.
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.
iii
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Bird Model 8251/52/55 Termaline Coaxial Load Resistor
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
DESCARGÉAS ELCTRICAS, 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.
iv
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About This Manual
This instruction book covers models 8251, 8252, and 8255 Termaline Coaxial
Resistors.
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 instruction book is divided into Chapters and Sections.
Operation
First time operators should read Chapter 1 - Introduction, Chapter 2 - Theory
of Operation, 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 preventive maintenance 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 parts lists and associated drawings in Chapter - Maintenance.
Changes To This Manual
We have made every effort to ensure this manual is accurate. If you should
discover any errors, or if you have suggestions for improving this manual,
please send your 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.
v
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Bird Model 8251/52/55 Termaline Coaxial Load Resistor
vi
Page 9
Table Of Contents
Safety Precautions. ......................i
Warning Statements. .....................ii
Caution Statements. .....................ii
Safety Statements. .....................iii
About This Manual. .....................v
Introduction. ........................1
Purpose and Function. ...................1
Applications. .......................1
Performance Characteristics and Capabilities. .........1
Power and Utility Requirements................2
Environmental Requirements. ................2
Items Supplied. ......................2
Items Required. ......................2
Tools and Test Equipment . .................2
Specifications. .........................3
Theory of Operation. .....................5
Cooling. .........................5
Installation. .........................7
Location. .........................7
Shipping and Vent Plugs. ..................7
Connecting to Transmitter. ....................8
Models 8251 & 8255.....................8
Model 8252.........................8
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Bird Model 8251/52/55 Termaline Coaxial Load Resistor
Operating Instructions. ....................9
Normal Operation. .....................9
Operation Under Abnormal Conditions. ............9
Shutdown. ........................9
Emergency Shutdown. ...................10
Maintenance. ........................11
Troubleshooting. ........................11
Cleaning. ...........................11
Inspection. ..........................12
Preventive Maintenance. ....................12
Checking Coolant Level. ..................12
DC Resistance Measurement. ..................13
Preparation and Tools Required. ..............13
Checking the DC Resistance . ...............13
Disassembly. .........................14
Tools Required.......................14
RF Connector. ......................14
Rear Seal and Coolant. ..................15
RF Load Resistor Assembly. ................15
Radiator Handle. .....................16
Assembly............................16
RF Connector. ......................16
Diaphragm and Coolant Oil. ................16
RF Load Resistor Assembly. ................16
Radiator Handle. .....................16
Storage. ...........................17
viii
Page 11
Customer Service. .......................17
Sales/Repair Facilities. ..................17
Sales Facilities. .....................17
Preparation for Shipment. ....................17
Replacement Parts List......................18
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Bird Model 8251/52/55 Termaline Coaxial Load Resistor
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Page 13
Chapter 1
Introduction
This publication refers to the Termaline Coaxial Load Resistor Models 8251, 8252, and 8255. The differences between models are listed in the specifications. All models
will generally be referred to as a load thoughout this
manual.
The information in this instruction book pertains to all
models except noted differences referred to in the text.
Purpose and
Function
Applications Use these loads:
Performance
Character-
istics and
Capabilities
The Bird Termaline Coaxial Load Resistors are portable,
general purpose 50 ohm coaxial transmission line terminations. These loads provide accurate, dependable, and
practically nonreflective line terminations.
These models are rectangular in shape with transverse
fins encasing a dielectric coolant cylinder. A retractable
handle is recessed in the radiator fins. The front and rear
fins are made of heavier gauge material and are bent 90°
to form bottom mounting flanges. These flanges are supports for free standing use, or brackets for fixed mounting. Holes are provided in the flanges for fixed mounting.
s
As a substitute antenna for tuning transmitters under nonradiation conditions or making
routine test and adjustments.
s
As a substitute for any circuit loading element.
s
To measure, with a suitable indication device,
the power output of any coaxially transmitted
signal within their range.
Models 8251 and 8252 loads can absorb up to 1000 watts
continuously and dissipate it harmlessly as heat over a
frequency range of dc to 2400 MHz. They will show a
maximum VSWR of 1.10 from dc to 1000 MHz, 1.25 from
1000 to 2000 MHz and , for Model 8251 only, 1.30 from
2000 to 2400 MHz.
1
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Bird Model 8251/52/55 Termaline Coaxial Load Resistor
Power and
Utility Re-
quirements
Environ-
mental Re-
quirements
Items
Supplied
Items
Required
Tools and
Test
Equipment
These loads are passive devices that are self-contained
and require only RF input to function.
These loads should be operated in a dust and vibration
free environment. Allow at least 6 inches (153 mm) of
clearance around the units to permit adequate heat dissipation.
Load Resistor
s
Instruction Book
s
Input Connector (refer to the specifications for
s
type of connectors supplied).
Matching connector on the coaxial transmission line to
which the load will be attached.
A screwdriver and an adjustable wrench will be necessary
for disassembly of this equipment. A resistance bridge or
ohmmeter with an accuracy of one percent or better at 50
ohms is useful for checking the resistance value of the
RF section assembly.
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Specifications
Impedance, Nominal 50 ohms
VSWR:
Models 8251/52
1.10 max. dc to 1000 MHz
1.25 max. 1000-2000 MHz
Introduction
Model 8251
Model 8255
Connectors:
Model 8251
Model 8252
Model 8255
Power Range:
Models 8251/52
Model 8255
Frequency Range:
Model 8251
Model 8252
Model 8255
Ambient Temperature:
Models 8251/52
Model 8255
Cooling Method Oil dielectric and convection currents
Dimensions:
Model 8251
Model 8252
Model 8255
Weight:
Net
Shipping
Operating Position: Horizontal only - vent plug up
Finish:
Models 8251/52
Model 8255
European Safety: Meets European Standard EN 61010-1:1993 -
1.30 max. 2000-2400 MHz
1.25 to 1.0 max.
Female LC “QC” type normally supplied
3-1/8" EIA swivel flange
7/8" EIA flanged “QC” type
1000 watts continuous
0-825 watts continuous
dc-2400 MHz
dc-2000 MHz
1250-1350 MHz
-40°C to +45°C (-40°F to +133°F)
-40°C to +50°C (-40°F to +122°F)
17-29/32"L x 5-15/16"W x 8-1/2"H
(455 x 151 x 216 mm)
19-33/64"L x 5-15/16"W x 8-1/2"H
(496 x 151 x 216 mm)
18-5/8"L x 5-15/16"W x 8-1/2"H
(473 x 151 x 216 mm)
25 lb. 8 oz. (11.6 kg)
30 lb. (13.6 kg)
Grey Powder Coat
Black Powder Coat
Safety, Group II. In accordance with Council Directive 73/23/EEC and 93/68/EEC.
3
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Bird Model 8251/52/55 Termaline Coaxial Load Resistor
4
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Chapter 2
Theory of Operation
These loads consist essentially of a carbon film resistor
on a ceramic substrate immersed in a dielectric coolant.
The resistor, individually selected for its accuracy, is enclosed in a special exponentially tapered housing. This
provides a linear reduction in surge impedance directly
proportional to the distance along the resistor. When surrounded by the dielectric coolant, the characteristic impedance is therefore: 50 ohms at the front (connector
end), 25 ohms at the mid-point (to compensate for the resistance already passed over), and zero ohms at the rear
where the resistor joins the housing, forming the return
conductor of the coaxial circuit. This produces a uniform,
practically reflectionless line termination over the stated
frequencies of the load resistor.
Cooling The dielectric coolant was chosen for its desirable dielec-
tric and thermal characteristics. Cooling of the load is accomplished by natural fluid and air convection currents.
The 0.8 gallons (3.03 liters) of dielectric coolant carries
the electrically generated heat from the resistor to the
walls of the cylindrical cooling tank. This tank is encased
in a set of radiating fins, constructed from heavy gauge
aluminum alloy, and firmly pressed into the cylinder. the
heat from the dielectric oil is transferred to the surrounding air by the fins.
Expansion of the coolant, caused by the rise in its temperature, is allowed for by the use of an expansion tank
located on the upper rear of the load. The expansion tank
is equipped with a spring loaded vent for relief of the internal pressure.
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Bird Model 8251/52/55 Termaline Coaxial Load Resistor
Figure 1
Shipping Plug
O-ring seal
Figure 2
Vent Plug
O-Ring Seal
6
Page 19
Chapter 3
Installation
CAUTION
This equipment is designed for operation in a
horizontal position only, with mounting brackets down.
Do not operate in any other manner.
The Models 8251, 8252, and 8255 are to be installed, and
operated, in a horizontal position. The unit is shipped
horizontal, and normally stands on its base brackets.
The load may be used for portable operation and stand
free, or it may be secured to a bench top or other flat
surface for a fixed installation. Mount the load with four
screws of up to 1/4 inch diameter. Fasten the screws
through the four 9/32 inch holes in the mounting brackets
that arranged in a 5-1/8 inch x 15 inch (130.2 x 381 mm)
rectangle.
Location For operation above 300 watts, allow at least six inches
(153 mm) of clearance on each side. Operate the load in a
horizontal position only, with the handle on top.
Shipping and
Vent Plugs
WARNING
The vent plug must be used at all times when the unit
is in operation or cooling. Failure to do this could
result in damage to the equipment and endanger the
operator’s safety. Be sure to check this plug.
CAUTION
Do not leave out the O-Ring seal, P/N 5-504 when
interchanging the vent and shipping plugs.
Before placing the unit into operation, remove the shipping plug on the top of the radiator and replace with the
vent plug supplied. Refer to figures 1 and 2 for identification of the plugs. Don’t forget to use the O-Ring seal, P/N
5-504. The shipping and vent plugs are connected with a
short length of bead chain to prevent the mislaying or
loss of the unused plug.
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Bird Model 8251/52/55 Termaline Coaxial Load Resistor
Connecting to Transmitter
Models 8251
& 8255
Model 8252 The 3-1/8 inch EIA flange connector is fastened to the
Connect the load to the transmitting equipment under
test with 50 ohm coaxial cable (RG-8A/U, RG-9/U,
RG-213/U or equivalent) and a Male LC type plug. The
Male LC plug will mate with the RF input connector of
the load. After the transmitter has been connected to the
load, proceed according to the transmitter manufacturer’s
instructions. When reconnecting the antenna, it may be
necessary to slightly readjust the transmitter due to possible differences in VSWR between the load and the antenna system.
transmission line by six 3/8-16 by 1-1/2 inch stainless
steel screw and nut assemblies. The center conductors
must be joined with a bullet for 50 ohm 3-1/8 inch coaxial
lines. Bird P/N 4600-020 Bullet Kit includes six screw
and nut sets, O-Ring and center conductor bullet.
Note: Avoid the use of adapters and elbows
+
whenever possible.
Follow the instructions below for line installation.
1. Seat the bullet so that half of the thickness of
the insulator is nested in the counterbore of each
connector flange.
2. Place the load resistor so that it will be aligned
with the coaxial input line.
3. Push in on the center contact.
4. Tighten the flange nuts evenly all around (finger
tight).
5. Tighten the nuts evenly with wrenches.
The swivel flange on the Model 8252 makes the load resistor connector independent of the orientation of a fixed
mating flange on the input line.
Due to the difference in the VSWR between the dummy
load and the transmitter’s antenna, the transmitter may
require readjustment when reconnected to the original
antenna.
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Page 21
Normal
Operation
Operation
Under
Abnormal
Conditions
Chapter 4
Operating Instructions
CAUTION
Do not operate this equipment over the rated 1000
watts continuously. Damage to the resistive element
will result.
These loads have no indicators or operating controls,
therefore require no special operating procedures or surveillance when the stated performance limits are not exceeded. Follow the instructions pertaining to the specific
transmitting equipment.
WARNING
Using this load in the upper end of its power
dissipation range will cause the housing to become hot!
Care should be exercised in touching it.
These units will sustain an input moderately greater
than 1000 watts for short periods of time. Such loading
must be spaced at reasonable intervals to allow sufficient
time for cooling to a safe temperature. They can, for instance, sustain an input of 1200 watts for a maximum of
five minutes with an interval of at least 30 minutes between each power application.
Shutdown These loads, being passive devices, have no way of being
turned off. Their source of RF power must be turned off
instead.
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Bird Model 8251/52/55 Termaline Coaxial Load Resistor
Emergency
Shutdown
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.
Turn off RF power at the source.
10
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Table 1
Troubleshooting
Chapter 5
Maintenance
Troubleshooting
For corrections requiring repair or replacement or components, refer to the appropriate section for your specific
model.
Problem Possible Cause Remedy
Coolant oil leak
around clamping
band or radiator
housing
Overheating of
the radiator
Clamping bands not
tight
Faulty O-Ring
(front)
Faulty O-Ring (rear) Replace O-Ring
Transmitter power
too high
Coolant oil level too
low
Accumulation of dirt
on cooling fins
Faulty RF section
assembly, check dc
resistance
Tighten slightly
with a screwdriver
Replace O-Ring
Reduce transmitter power
Add more coolant oil to the radiator
Clean cooling
fins
Replace if
needed
Cleaning
The outside surface of the load should be wiped free of
dust and dirt when necessary. The principal maintenance
required by the operator will be to periodically wipe off
the accumulated dust and lint from the radiator fins. Excessive collection of dust and lint on the cooling fins will
interfere with the efficient dissipation of heat. If the teflon insulator or metallic contact surfaces of the connector
should become dirty, wipe them off with a soft cloth. Use
a contact cleaner that is self-drying and leaves no residue
on the inaccessible internal parts.
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Bird Model 8251/52/55 Termaline Coaxial Load Resistor
Inspection
With the rugged and simple construction of the loads, periodic inspection will be necessary at only about six
month intervals. Inspection should include the items
listed below:
Oil Leakage - check for coolant oil leaking
s
around the radiator tank, particularly at the
front and back around the underside of the
clamping band. If leakage is observed, refer to
the troubleshooting section and, check tightness of the front and rear clamping bands.
Inspect the load for completeness and general
s
condition of the equipment.
Preventive Maintenance
Due to the basic simplicity of construction, the major requirement for preventive maintenance is to keep the
equipment clean, particularly the radiator fins. It is important to maintain the heat transfer efficiency of the
cooling fins.. Also, occasionally check the coolant level in
the radiator tank.
Checking
Coolant Level
12
CAUTION
The unit is factory filled to the proper level with 0.8
gallons (3.03 liter) of Bird P/N 5-1070. No other coolant
should be used
To check the coolant level:
1. Remove the vent plug from the socket on the top
surface of the expansion tank. Unscrew the vent
plug using a 3/4 wrench.
+
Note: The coolant level, at room temperature,
should not be more than 1/8 inch above the bottom surface of the expansion tank.
2. Check the coolant level by carefully lifting the
front end of the load and noting presence of coolant on the bottom surface. The coolant quantity
should be sufficient to fill the radiator cylinder.
The inner housing, for the resistor element, is
specially shaped to match the dielectric properties of the recommended coolant.
Page 25
DC Resistance Measurement
Maintenance
Preparation
and Tools
Required
Be sure that the vent plug is installed.
Preparation:
Tools: Common hand tools
s
Ohmmeter with an accuracy of ± 1% at 50
s
ohms.
Temperature of the load between 20°C to 25°C
s
(68°F to 77°F)
VSWR and RF Impedance are the true benchmark of a
quality dummy load. Accurate measurement of the dc resistance between the inner and outer conductors of the
RF input connector will provide a good check of the condition of the load resistor. Checking the dc resistance is
simply used to measure a change in the condition of the
resistor over time. The tracking of the dc resistance must
start before the resistor is first put into service. Perform
the following steps and record the value for future comparison. Check and record the resistance of the load periodically according to use.
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.
Checking the
Resistance
DC
Measure the dc resistance. Follow the instructions below.
1. Turn off RF power and interlock circuitry before
any electrical disconnection’s are made.
2. Disconnect RF coaxial line.
3. Connect the multimeter test leads across the center and outer conductor of the load resistor. Refer
to figure 3.
4. Record the value of the resistance before the load
is put into service. Compare subsequent values
with the latest reading. If the values vary more
than two ohms this could be an indication of a
failing resistive element.
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Bird Model 8251/52/55 Termaline Coaxial Load Resistor
These tests are by no means a necessity to the operation
of the load but merely guidelines for the users information and advisement.
Disassembly
Figure 3
Measuring DC
Resistance
There are no special techniques required for the repair or
replacement of components in these Termaline Load Resistors.
50.0
Tools
Required
Models 8251 and 8255 - A screwdriver and a small
wrench are they only tools needed for these models.
Model 8252 - A screwdriver, a small wrench, and an adjustable wrench (for the connector bolts) will be needed.
RF Connector This section applies to the Models 8251 and 8255. (The
Model 8252 has a 3-1/8 inch EIA flanged connector and
must be returned to the factory for connector replacement). The connector on the Models 8251 and 8255 are
“Quick-Change” design that permits easy interchange
with the use of only a screwdriver. This process does not
interfere with the essential coaxial continuity of the load
resistor RF input or the coolant oil seal. For replacement,
proceed as follows:
1. Remove the four 8-32 x 5/16 screws from the corners of the RF connector flanges.
2. Pull the connector straight out of its socket.
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Page 27
Maintenance
Rear Seal
and Coolant
Before any disassembly of the rear of the load, if the coolant has not already been drained from the tank, stand
the radiator on end with the connector pointed down.
1. Unscrew the four 10-32 screws at the corners of
the guard cover.
2. Unscrew the tube nut from the tank nozzle, using a small wrench if necessary, and pull the
nozzle free.
3. Loosen the clamp screw with a screwdriver from
the bottom of the V-band, same type as at the
front, and remove the V-band clamp.
4. Remove the rear cover which includes the attached escape tube with captive nut, P/N
2430-088, and the diaphragm seal, P/N 2430-089.
5. Inspect the diaphragm seal and replace it if it is
not soft and pliable, or shows signs of surface
cracks.
6. Replace the coolant if it appears contaminated,
i.e., if it is not clear
The expansion tank is vented through the vent plug, P/N
2450-094. The unit unscrews from a socket on top of the
tank, but is not itself subject to disassembly.
RF Load
Resistor
Assembly
The shipping plug is sealed by compression of an O-Ring,
P/N 5-504, which should be included when replacing the
vent plug.
CAUTION
Do not leave out the O-Ring seal, P/N 5-504 when
interchanging the vent and shipping plugs.
1. Replace the vent plug with the shipping plug in
the fill hole of the expansion tank to prevent
coolant loss. Refer to figures 1 and 2 for plug
identification.
2. Stand the unit on its back end, i.e., vertically
with the RF connector up. Brace the unit in this
position to prevent it from tipping over.
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Bird Model 8251/52/55 Termaline Coaxial Load Resistor
3. Loosen the 10-32 x 1-1/2 inch screw on the
clamping band until the band is free. Remove the
band.
4. Grasp the RF connector and slowly lift the load
resistor assembly out of the radiator tank to allow the excess coolant to drip back in.
5. Before replacing the load assembly (Model 8251,
P/N 8890-050; Model 8252, P/N 8891-050) check
the O-Ring seal to be sure it is properly placed
and is in good condition. It should be free of
twists and positioned evenly around the beveled
flange of the resistor housing. Furthermore, it
should still be soft and pliable and not hard or
showing signs of surface cracks.
Radiator
Handle
The radiator handle slides on and is held in place by the
two retaining studs that are riveted to the fins. It may be
removed or replaced as follows:
1. Gently pry apart the fins next to each stud just
enough to clear the handle thickness. Use a
large screwdriver, the blade covered with a rag,
or a suitable wooden stick.
2. With the fins pried apart sufficiently, slide each
leg of the handle off its respective stud.
Assembly
RF Connector To install a new connector, reverse the disassembly proce-
dure. Be sure that the projecting center pin on the connector is carefully engaged and properly seated with the
mating socket of the load resistor input.
Diaphragm
and Coolant
RF Load
Resistor
Assembly
Radiator
Handle
To assemble, reverse the disassembly procedure.
Oil
To assemble, reverse the disassembly procedure.
To assembly, reverse the disassembly procedure.
16
Page 29
Maintenance
Storage
No special preparations for storage are necessary other
than to cover the equipment to keep out dust and dirt.
Store the unit in a dry and dust-free environment where
the ambient temperature will remain within the -40°C to
+45°C (-40°F to +113°F) working range of the load.
Customer Service
Any maintenance or service beyond the scope of those
provided in this section should be referred to a qualified
service center. Bird Electronic Corporation maintains
complete repair and calibration facilities at the following
address:
Sales/Repair
Facilities
Sales
Facilities
U.S.A. Sales and Manufacturing
Service Group
Bird Electronic Corporation
30303 Aurora Road
Cleveland (Solon), Ohio 44139-2794
Phone: (440) 248-1200
Fax: (440) 248-5426
For the location of the sales office nearest you, give us a
call or visit our Web site at:
http://www.bird-electronic.com
Preparation for Shipment
Should you need to return the load, use the original shipping package if possible. Wrap the RF connector with
padding and tape securely in place. It is not necessary to
remove the coolant to ship the load. Simply replace the
vent plug with the shipping plug attached to the bead
chain. Be sure the O-Ring seal is mounted on the plug to
avoid leakage.
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Bird Model 8251/52/55 Termaline Coaxial Load Resistor
Replacement Parts List
Qty. Description Part Number
1 RF Section Assembly
Model 82514/8255
Model 8252
1 Radiator Assembly
Model 8251
Model 8252
Model 8255
1 Diaphragm Cover Guard
Model 8251
Model 8252
Model 8255
0.8 gals
(3.03 liter)
1 “QC” connector for Models 8251/8255 *See below
1 Diaphragm Seal 2430-089
1 Diaphragm Cover 2430-088
2 Clamp Band Assembly (2430-043 & screw) 2430-055
1 RF Section O-Ring Seal 5-230
1 Vent Plug 2450-094
1 Shipping Plug 2450-049
1 Radiator Handle 2430-028
1 Chain Assembly 8180-094
2 Vent and Shipping Plug O-Ring 5-504
1 Expansion Tank, part of Radiator 2430-080
Coolant Oil - Dielectric
1 pint container
1 gallon container
5 gallon container
8890-050
8891-050
2430-123
2430-146
2430-153
2430-078
2430-078-1
2430-078-2
5-1070-1
5-1070-2
5-1070-3
*Available QC Type Connectors
N-Female 4240-062 LT-Female 4240-018
N-Male 4340-063 LT-Male 4240-012
HN-Female 4240-268 C-Female 4240-100
HN-Male 4240-278 C-Male 4240-110
LC-Female 4240-031 7/8" EIA Air Line 4240-002
LC-Male 4240-025
UHF-Female (SO-239) 4240-050
UHF-Male (PL-259) 4240-179
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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. 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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DECLARATION OF CONFORMITY
Manufacturer: Bird Electronic Corporation
Product: TERMALINE RF COAXIAL LOAD RESISTOR
The undersigned hereby declares, on behalf of Bird Electronic Corporation of
Cleveland, Ohio, that the above-referenced product, to which this declaration relates, is
in conformity with the provisions of the following standards;
1. European Standard EN 61010-1:1993 - Safety, Group II.
This standard is in accordance with Council Directive 73/23/EEC and 93/68/EEC.
The technical documentation file required by this directive is maintained at the corporate
headquarters of Bird Electronic Corporation, 30303 Aurora Road, Cleveland, Ohio.
30303 Aurora Road
Cleveland, Ohio 44139-2794
Models: 8251 8252 8255
Ken DeVore
QA/Metrology Manager
Bird Electronic Corporation
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