BIRD TERMLINE 8141 User manual

INSTRUCTION BOOK
OPERATING INSTRUCTIONS
TERMLINE®LOAD RESISTOR
MODELS 8141 & 8141-010
©Copyright 1998 by Bird Electronic Corporation
Instruction Book Part Number 920-8141 Rev. D
Termaline®is a Registered Trademark
of Bird Electronic Corporation
Electronic Corporation
Cleveland (Solon) Ohio US
A

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.
Keep Away From Live Circuits
Operating personnel must at all times observe general safety precautions. Do
not replace components inside equipment with the high voltage supply
turned on. To avoid casualties, always remove power.
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 who
is capable of rendering aid.
Safety Earth Gound
An uninterruptible earth 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.
Shock Hazard
Do not attempt to disconnect an RF transmission line while RF power is pres-
ent. Radiated RF power is a potential health hazard.
Resuscitation
Personnel working with or near high voltages should be familiar with modern
methods of resuscitation.
i

Safety Symbols
WARNING
Warning notes call attention to a procedure, which if not performed
correctly, could result in personal injury.
CAUTION
Caution notes call attention to procedure, which if not performed
correctly, could result in damage to the equipment.
This symbol appears on the equipment indicating there is important informa-
tion in the instruction manual regarding that particular area.
+NOTE: Calls attention to supplemental information.
Warning Statements
The following safety warnings appear in the text where there is danger to op-
erating and maintenance personnel, and are repeated here for emphasis.
WARNING
Never attempt to disconnect RF equipment from the transmission line
while RF power is being applied. Leaking RF energy is a potential
health hazard.
WARNING
This product contains a resistor substrate made of beryllium oxide.
This is a potentially toxic ceramic and may be harmful to your health.
Beryllia oxide must be disposed of in accordance with the legal statutes
dealing with hazardous material.
Do not attempt to repair this unit, but return to BIRD ELECTRONIC
CORPORATION.
ii

Caution Statements
The following equipment cautions appear in the text whenever the equipment
is in danger of damage and are repeated here for emphasis.
CAUTION
Do not operate this equipment over the rated 250 watts continuously.
Damage to the resistive element will result.
Safety Statements
USAGE
ANY USE OF THIS INSTRUMENT IN A MANNER NOT
SPECIFIED BY THE MANUFACTURER MAY IMPAIR
THE INSTRUMENT’S SAFETY PROTECTION.
iii

SERVICE
SERVICING INSTRUCTIONS ARE FOR USE BY SERV-
ICE - TRAINED PERSONNEL ONLY. TO AVOID DAN-
GEROUS ELECTRIC SHOCK, DO NOT PERFORM ANY
SERVICING UNLESS QUALIFIED TO DO SO.
iv

About This Manual
This instruction book covers the models 8141 and 8141-010 Termaline Load
Resistor.
This instruction book is arranged so that essential information on safety is
contained in the front of the book. Reading the Safety Precautions Section be-
fore operating the equipment is strongly advised.
The remainder of this Instruction Book is divided into Chapters and Sections.
At the beginning of each chapter, a general overview describes the contents of
that chapter.
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
section.
Maintenance
All personnel should be familiar with preventative maintenance found in
Chapter 5 - Maintenance. If a failure should occur, the troubleshooting sec-
tion will aid in isolating and repairing the failures.
Parts
For location of major assemblies or parts, refer to the parts lists and associ-
ated drawings in Chapter 5.
Changes To This Manual
We have made every effort to ensure this manual is accurate at the time of
publication. If you should discover any errors or if you have suggestions for
improving this manual, please send your comments to our factory. This man-
ual may be periodically updated, when inquiring about updates to this man-
ual refer to the part number and revision level on the title page.
v

Table Of Contents
Safety Precautions ......................i
Safety Symbols ......................ii
Warning Statements ....................ii
Caution Statements ....................iii
Safety Statements.....................iii
About This Manual ....................v
Introduction .........................1
General .........................1
Purpose And Function ...................1
Performance Characteristics and Capabilities .........1
Dimensions and Weight ..................1
Power and Utility Requirements ...............2
Environmental Requirements ................2
Items Supplied ......................2
Items Required ......................2
Tools and Test Equipment .................2
Theory Of Operation .....................3
General .........................3
Installation .........................5
General .........................5
Operating Instructions ....................7
Start-up .........................7
Normal Operation .....................7
vi

Shutdown ........................7
Emergency Shutdown ...................8
Maintenance .........................9
Troubleshooting.........................9
Cleaning............................9
Outside Surface ......................9
Inspection...........................10
Preventive Maintenance.....................10
RF Assembly Test .......................10
DC Resistance ......................10
Disassembly..........................11
RF Input Connector....................11
Coolant Oil & Diaphragm .................11
RF Load Resistor Assembly ................12
Reassembly ..........................12
RF Input Connector....................12
Coolant Oil & Diaphragm .................12
RF Load Resistor Assembly ................13
Repairs ............................13
Customer Service .....................13
Storage .........................14
Shipment ........................14
Replacement Parts List ..................14
vii

Chapter 1
Introduction
General This instruction book is intended for use by operators of the
Models 8141 and 8141-010 Termaline Load Resistor.
This chapter contains introductory information including
product specifications; items supplied; and accessory items.
Purpose And
Function
The Models 8141 and 8141-010 Termaline Load Resistor are
portable, general purpose 50 ohm coaxial transmission line
terminations. They are self-contained units requiring no
outside power source or additional equipment. They provide
accurate, dependable, and practically nonreflective termina-
tions for testing and adjusting transmitters under nonradi-
ating conditions from dc to 2500 MHz.
The models are rectangular in shape with transverse cool-
ing fins spaced evenly along its entire length. Their short
length makes it particularly useful in locations. Also, the
ten pounds total weight is a convenience in portable use.
Mounting holes are provided, see Chapter 3, Installation.
The RF connector, on the front face of the unit, is a Female
N similar to UG-58A/U, but is a “Quick-Change” design per-
mitting rapid and easy interchange with other AN type con-
nectors.
Performance
Characteristics
and Capabilities
The loads will absorb and dissipate as heat up to 250W of
RF power in continuous duty. It can handle up to 20 percent
overload for a maximum of ten minutes overload without
damage, provided a half-hour interval is maintained for
cooling between power applications. The design of the resis-
tor and its impedance matching shell keeps the VSWR be-
low 1.1 to 1.0 from dc to 1000 MHz, 1.2 to 1.0 from 1000 to
1800 MHz and 1.3 to 1.0 from 1800 to 2500 MHz. With its
“QC” type of connector Model 8141 can be adapted to coaxial
cables equipped with any of a variety of standard connec-
tors.
Dimensions and
Weight
Consult the Specification Sheet for the size and weight of
each load
1

Power and
Utility
Requirements
Other than the RF power input the Models 8141 and 8141-
010 has no need for an external source of power or utility
services.
Environmental
Requirements
The loads should be operated in as clean and vibration free
an environment as possible. The ambient temperature
range should remain within -40°C to +45°C (-40°F to
+113°F) for proper operation.
Items Supplied The models are a self-contained unit, there are no addi-
tional parts other than this instruction book supplied. The
load is prefilled at the factory with the proper amount of
coolant.
Items Required No additional items are required other than a coaxial cable
for connecting the RF source to the load. The load is fur-
nished with a Female N type connector. The cable should be
equipped with a Male N type plug. If the cable has any
other type of standard connector, then the load should be or-
dered with the appropriate type of mating connector.
Tools and Test
Equipment
Only a screwdriver is needed for disassembling for service.
An ohmmeter or resistance bridge with an accuracy of one
percent or better at 50 ohms, is useful for checking resistor
condition.
Specifications
Impedance 50 ohms nominal
VSWR
dc-1000 MHz
1000-18000 MHz
1800-2500 MHz
1.1:1 maximum
1.2:1 maximum
1.3:1 maximum
Connectors Bird Quick Change “QC” Female N Normally
supplied.
Power Range 250 W continuous, 300 W intermittent (10
Minutes maximum).
Frequency Range dc to 2500 MHz
Dimensions 9-9/16”L x 5-15/16”W x 8-1/2”H
(243 x 151 x 216 mm)
Ambient Temperature 40°C to +45°C (-40°F to +113°F)
Weight 10 lb (4.5 kg)
Operating Position Horizontal only
Finish Light grey powder coat
2
Bird Model 8141 Termaline Load Resistor

Chapter 2
Theory Of Operation
General The Models 8141 and 8141-010 Termaline Load Resistor
consists essentially of a cylindrical film type resistor im-
mersed in a dielectric coolant. The resistor, individually se-
lected for its accuracy, is enclosed in a special tapered
housing which provides a linear reduction in surge imped-
ance directly proportional to the distance along the resistor.
This produces the uniform, practically reflectionless line ter-
mination over the stated frequencies of the load.
The dielectric coolant is chosen for its desirable electrical
properties and thermal characteristics. Cooling of the load is
accomplished by natural fluid and air convection. The 0.35
gallon (1.3 liter) of dielectric coolant carries the electrically
generated heat from the resistor to the walls of the cylindri-
cal cooling tank. The tank is encased in a set of heavy gauge
aluminum radiator fins, which are firmly pressed on the cyl-
inder. The heat from the dielectric oil is transferred to the
surrounding air through the fins by natural convection.
A synthetic rubber diaphragm located in the rear dome of
the load allows for the expansion of the coolant as the tem-
perature rises.
3

Chapter 3
Installation
General Position the Model 8141 and 8141-010 Termaline Load Re-
sistor to provide at least six inches of unobstructed space
around and above the unit. Place the load to permit the
shortest possible cable length between the unit and the
transmitting equipment.
Operate the load in a horizontal position only, with the han-
dle on top. The load may be free-standing or fastened to any
convenient flat surface. The front and rear fins are made ex-
tra thick and bent outward 90° to form mounting flanges.
Fasten the Model 8141 by its mounting brackets with 1/4
machine screws and nuts or No. 12 wood screws if desired.
The four 9/32 inch holes in the mounting brackets form a
base rectangle of 7-15/32" x 5-1/8" (189.7 x 130.2 mm)for the
Model 8141 and 7/13/32” x 5/1/8” (180 x 130.2 mm) for the
Model 8141-010.
5

Chapter 4
Operating Instructions
Start-up Connect the Models 8141 and 8141-010 Termaline Load Re-
sistor to the transmitting equipment under test with 50
ohm coaxial cable such as RG-213/U or equal, equipped with
a Male N type plug (UG-21E/U or equal) which mates with
the RF input connector of the load. After the transmitter
has been connected to the load, proceed according to the
transmitter manufacturer’s instruction.
Due to the difference in VSWR between the dummy load
and the transmitter’s antenna, readjustment of the trans-
mitter may be required when returning to the original an-
tenna.
CAUTION
Do not operate this equipment over the rated 250 watts
continuously. Damage to the resistive element will
result.
The unit will sustain an intermittent input of 300 W maxi-
mum for up to ten minutes with half-hour off intervals be-
tween power applications.
Normal
Operation
The loads will dissipate 250W of RF power safely and con-
tinuously without an operator in attendance.
As stated previously, the load can be overloaded to 300W of
RF power for a maximum of ten minutes at a time with an
interval of at least a half-hour in between to permit the load
to cool off. Because of the additional heat that must be given
off by the cooling fins under these conditions, touch the load
with caution to avoid the possibility of painful burns.
Shutdown The only way to turn off the equipment is to cut off power
from the RF generator. Allow sufficient time for the load to
cool down after removing RF power before handling it.
7

Emergency
Shutdown
WARNING
Never attempt to disconnect RF equipment from the
transmission line while RF power is being applied.
Leaking RF energy is a potential health hazard.
Turn off the equipment by removing power from the RF gen-
erator.
8
Bird Model 8141 Termaline Load Resistor

Chapter 5
Maintenance
Troubleshooting
For corrections requiring repair or replacement of compo-
nents, refer to the appropriate section for your specific
model.
Cleaning
Outside Surface The outside surface of the instrument, especially the cooling
fins, should be wiped free of dust and dirt when necessary.
Clean the RF input connector with a clean dry cloth. Use an
aerosol type non residue forming contact cleaner on the in-
accessible portions. Take special care to clean the metallic
contact surfaces and exposed face of the teflon insulator.
9
Problem Possible Cause Correction
Coolant oil leak
around clamping
band or radiator
Clamping bands not
tight
Tighten slightly with
screwdriver
Faulty O-ring (front) Replace O-ring
Faulty diaphragm Replace diaphragm
Overheating of
the radiator
Transmitter power
too high
Reduce transmitter
power
Coolant oil level too
low
Add more coolant oil
to the radiator
Accumulation of dirt
on cooling fins
Clean cooling fins
Faulty RF section
assembly, check
Rdc
Replace if needed
High or low dc
resistance values
Loose or faulty RF
connector
Tighten or replace as
needed
Faulty RF section
assembly
Replace if needed
Table 1
Troubleshooting

Inspection
With the rugged and simple construction of loads, periodic
inspection will be necessary at only about six month inter-
vals. Inspection should include the items listed below:
a. Cleanliness - Keep the housing and
connector free of grime.
b. Oil Leakage - Check for coolant oil
seepage from the radiator tank, and
particularly at the front and rear near
the under side of the clamping band.
See Troubleshooting Chart if leakage
is observed. Check tightness of the
clamping screw.
c. Inspect the load for completeness and
general condition of the equipment.
Preventive Maintenance
The load requires only nominal routine care. It is designed
to operate for long periods of time, if care is taken not to ex-
ceed its power handling capabilities.
The principal item of preventive maintenance is cleanliness.
Keep the cooling fins clear of accumulated dust and grime.
They interfere with the efficient and rapid transfer of heat
from the fins to the surrounding air and therefore could
cause the unit to overheat. Keep the coolant level up.
RF Assembly Test
DC Resistance The electrical condition of the load resistor itself may be as-
certained generally from its dc resistance at room tempera-
ture.
It must be remembered that VSWR and RF impedance are
the prime requisites of a good dummy load, however, occa-
sionally checking the dc resistance will offer an indication of
a failing load.
Normally the dc resistance of the load will be a nominal 50
ohms. Stabilization of the resistive film or temperature can
cause a change in the dc resistance. Always check the load
when its temperature is between 20 and 25 degrees Celsius.
Check and record the dc resistance value of the load before
it is put into service. Use a resistance bridge or ohmmeter
10
Bird Model 8141 Termaline Load Resistor

with an accuracy of one percent or better at 50 ohms for this
purpose.
If the load is used frequently, daily to weekly, it would be
wise to check the resistance on a monthly schedule. If how-
ever, the load is used more infrequently you may want to set
up a six month to yearly schedule accordingly. If there is no
change or even a slight change in dc resistance there is no
cause for alarm, however, if there is a drastic change
greater than two ohms, this could be an indication of a fail-
ing load.
These tests are by no means a dire necessity to the opera-
tion of the load but merely guidelines for the users informa-
tion and advisement.
Disassembly
There are no special techniques required for the repair or
replacement of components. A screwdriver is the only tool
needed. The following paragraphs outline component re-
moval.
RF Input
Connector
The input connector is a “Quick-Change” design which per-
mits easy interchange with the use of only a screwdriver.
This process does not interfere with the essential coaxial
continuity of the load resistor’s RF input or the coolant oil
seal. For replacement, proceed as follows:
a. Remove the four 8-32 x 5/16 inch pan
head machine screws from the corners
of the RF connector.
b. Pull the connector straight out of its
socket.
Coolant Oil
& Diaphragm
To examine the coolant oil and diaphragm, remove the dia-
phragm cover. Proceed as follows:
a. Stand the load vertically, with the
back end up.
b. Loosen the clamp screw to release the
clamping band.
11
Maintenance

c. Remove the diaphragm cover and lift
the diaphragm from the back end of
the radiator tank. The diaphragm
should be soft and pliable. If it is hard
or shows signs of surface cracks, re-
place it. (Bird P/N 2430-015).
d. The coolant level should be about one
inch below top of the cylinder. If oil
appears contaminated, replace. Use
only the specified coolant, Bird P/N 5-
1070.
RF Load
Resistor
Assembly
To replace the load resistor assembly proceed as follows:
a. Stand the radiator vertically with RF
input connector up.
b. With a screwdriver, loosen the 10-32
clamping screw on the clamp band
that holds the RF section in place. Re-
move the clamping band.
c. Lift the RF section straight up and out
of the radiator tank. Hold for a short
time over tank to allow oil to drain
back in.
d. Inspect the O-Ring seal just inside the
sloped flange of the mounting ring. Re-
place this seal, Bird P/N 5-230, if it
shows any evidence of cuts or deterio-
ration such as hardening or surface
cracks.
Reassembly
RF Input
Connector
To install a new connector, reverse the procedures in para-
graph RF Input Connector, Disassembly. Be sure that the
projecting center contact pin on the connector is carefully
engaged and properly seated with the mating socket of the
load resistor input.
Coolant Oil &
Diaphragm
Inspect the diaphragm and coolant oil as indicated in disas-
sembly.
a. Put the diaphragm back in place on
the radiator tank.
12
Bird Model 8141 Termaline Load Resistor

b. Press the cup-like swelling in the cen-
ter of the diaphragm down into the
tank to remove the trapped air bubble.
To allow the air to escape, pry the dia-
phragm away from the edge of the
tank. Through the same opening add
more oil, if necessary, until the oil
level is flush with the top of the tank.
c. Replace the diaphragm cover and the
clamping band. Tighten the clamping
screw.
RF Load
Resistor
Assembly
To install assembly, reverse the disassembly procedures in
paragraph RF Load Resistor Assembly, Disassembly.
Repairs
WARNING
This product contains substrate made of beryllium
oxide. This is a potentially toxic ceramic and may be
harmful to your health. Beryllia oxide must be
disposed of in accordance with the legal statutes
dealing with hazardous material.
Do not attempt to repair this unit, but return to BIRD
ELECTRONIC CORPORATION.
Repairs beyond what is covered in this instruction book will
require return of the equipment to Bird Electronic Corpora-
tion for service. Please consult the factory.
Customer
Service
Any maintenance or service procedure beyond scope of those
provided in this section should be referred to a qualified
service center. Bird Electronic Corporation maintains a
complete repair and calibration facility at the following ad-
dress:
13
Maintenance

Storage No special preparation for storage is required other than to
cover the equipment to keep it free of dust and dirt accumu-
lations. Storage in a dry, dust and vibration free environ-
ment is recommended. The storage temperature should
preferably remain within the working temperature range of
-40°C to +45°C (-40°F to +113°F).
Shipment Wrap and secure the RF connector with tape to keep out for-
eign material during shipment. Pack and brace the load in a
shipping container, a corrugated paper container should suf-
fice.
Replacement
Parts List
Models 8141 and 8141-010
ITEM QTY DESCRIPTION PART NUMBER
1 1 Radiator assembly 2440-015
2 1 RF section assembly 8141-002
3 1 Coolant .35 gallons
(1.3 liter)(1 gallon container)
5-1070-2
4 1 “QC” connector See below*
5 2 Clamp band assembly 2430-055
6 1 O-Ring seal 5-230
7 1 Diaphragm 2430-015
8 1 Diaphragm cover 2430-148
*Available QC Type Connectors
N-Female 4240-062 LT-Male 4240-012
N-Male 4240-063 C-Female 4240-100
HN-Female 4240-268 C-Male 4240-110
HN-Male 4240-278 UHF-Female(SO-230 4240-050
LC-Female 4240-031 UHF-Male (PL-259) 4240-179
LC-Male 4240-025 7/8" EIA Air Line 4240-002
LT-Female 4240-018
14
Bird Model 8141 Termaline Load Resistor