OPERATOR MANUAL
SERIES 8320
TENULINE® ATTENUATOR
Electronic Corporation
Cleveland (Solon) Ohio USA
©Copyright 1996 by Bird Electronic Corporation
Instruction Book Part Number 920-8320s Rev. A
Tenuline® is a Registered Trademark
of Bird Electronic Corporation
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 spec
ified, from date of shipment and to conform to applicable specifications, draw
ings, 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 (transporta
tion-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 manufac
turer’s warranty to Seller.
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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, IN
CLUDING WARRANTIES OF MERCHANTABILITY AND FITNESS, AND
NO PERSON IS AUTHORIZED TO ASSUME FOR SELLER ANY OBLIGA
TION OR LIABILITY NOT STRICTLY IN ACCORDANCE WITH THE
FOREGOING.
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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 inside test 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 someone who is capable of rendering aid.
Safety Earth Ground
An earth uninterruptible 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.
Shock Hazard
Do not attempt to remove RF transmission line while RF power is present.
Chemical Hazard
Dry cleaning solvents used to clean parts may be potentially dangerous.
Avoid inhalation of fumes and also prolonged contact with skin.
Resuscitation
Personnel working with or near high voltages should be familiar with modern
methods of resuscitation.
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Bird Model 8320S Tenuline Attenuator
Safety Symbols
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.
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 connect or disconnect RF cables while RF power is
on. Radiated RF is a potential health hazard.
WARNING
HIGH VOLTAGE
Electrical shock hazard. Be careful when working near high voltage
cables. Always have someone near capable of rendering aid.
WARNING
Use dry cleaning solvents only in a well ventilated area away from
open flames or sparks. Do not breathe the fumes.Avoid direct skin
contact with solvent.
WARNING
Do not place compressed air near or directly against skin. Do not used
compressed air in excess of 30 psig (207 kPA) when cleaning or drying
parts. Improper use of compressed air can cause serious injury or
death.
WARNING
Coolant contains ethylene glycol a potential health hazard. Avoid
ingestion, inhaling of vapors and eye and skin contact.
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The following equipment cautions appear in the text whenever the equipment
is in danger of damage and are shown here for emphasis.
CAUTION
The Calorimeter can overheat if operated without sufficient coolant.
Failure to keep coolant reservoir adequately filled can result in serious
damage to the equipment.
CAUTION
Use only premixed coolant, Bird part number 6091-120. Use of other
solutions will damage the instrument and void all warranties.
CAUTION
Do not tighten the jack screws with a screwdriver. The screwdriver
slots in the screws are provided for removal purposes only.
CAUTION
During remote operation, periodically monitor the bus service request
line. Failure to detect the service request can result in major equipment
damage.
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About This Manual
This instruction book covers the Tenuline Attenuator Models 8321, 8322,
8323 & 8325, which collectively are refered to as the 8320 Series.
This instruction book is arranged so that essential information on safety ap
pears 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 devided into Chapters and Sec
tions. At the beginning of each chapter, a general overview describes the con
tents of that chapter.
Operation
First time users should read Chapter 1 - Introduction, and Chapter 2 - Installation, to get an overview of equipment capabilities and installation. An experienced operator can refer to Chapter 3 - Operating Instructions. All
instructions necessary to operate equipment appears in this chapter.
Maintenance
All personnel should be familiar with preventative maintenance found in
Chapter 4 - 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 Chapter 4.
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 comment to our factory. This manual may be periodically
updated. When inquiring about updates to this manual refer to the part num
ber and revision level on the title page.
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Table Of Contents
Safety Precautions..................i
Safety Precautions .....................i
Warning Statements ....................ii
Caution Statements ....................iii
About This Manual ....................iv
Introduction ....................1
Purpose and Function ...................1
Performance Characteristics and Capabilities .........1
Dimensions and Weight ..................1
Power and Utility Requirements ...............1
Environmental Requirements ................1
Items Furnished ......................1
Items Required ......................1
Tools and Test Equipment .................2
Installation .....................5
Location .........................5
Mounting .........................5
Theory of Operation .................7
General .........................7
Operating Instructions ................9
Use And Function Of Controls................9
Initial Adjustments ....................9
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Bird Model 8320S Tenuline Attenuator
Start-up .........................9
Normal Operation .....................9
Operation Under Abnormal Conditions............10
Shutdown ........................10
Emergency Shutdown ...................10
Maintenance....................11
Troublshooting ......................11
Cleaning ...........................11
Outside Surfaces .....................11
Inspection ...........................11
Preventive Maintenance .....................12
RF Assembly Tests .......................12
Disassembly ..........................12
RF Connector ......................12
Coolant and Seals ....................13
Coolant Level .........................14
Models 8321, 8322 and 8323 ................14
Add Coolant .......................14
Replace Coolant .....................14
Model 8325 .......................15
Add Coolant .......................15
Replace Coolant .....................15
Assembly ...........................15
RF Load Resistor Assembly (All Models) ...........15
RF Connector ......................16
Coolant and Seal .....................16
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Reassembly .......................16
Repairs .........................16
Shipment ........................16
Storage .........................17
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viii
Chapter 1
Introduction
Purpose and
Function
Performance
Characteristic
Requirements
Environmenta
Requirements
s and
Capabilities
Dimensions
and Weight
Power and
Utility
The Series 8320 Tenuline Attenuator are low reflection re
sistance networks for use in reducing RF power in 50 ohm
transmission lines by known and controlled amounts. They
are self-contained instruments that require no external
source of power or utility service. The radiators having cool
ing fins spaced evenly along their lengths for efficient cool
ing. These attenuators are useful for lowering a high input
RF power to a level suitable for feeding into a scope, fre
quency counter or similar device.
Relying only on ambient air currents, these attenuators will
safely absorb, and dissipate harmlessly as heat, up to their
maximum rated input power. Over the frequency range of
dc to 500 MHz, the power output will be reduced by 30 dB
(99.9 percent) ± 0.5 dB. Up to 500 MHz, the input VSWR
will not exceed 1.1 and the out put VSWR 1.15.
The dimensions and weight of these attenuators are given
in the Specifications. The weights given are net weights.
Therefore, the shipping weights will be approximately 20
percent higher.
These attenuators are passive devices that are self-contained; therefore, do not need any external source of power
or utilities to function.
Operate these attenuators in a dust and vibration free envi
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ronment. The ambient temperature range should remain be
tween -40°C and +45°C (-40°F and 113°F) for proper
operation. Allow at least 6 inch (150 mm) of clearance
around the unit to permit an unimpeded access of convec
tion air currents for adequate heat dissipation.
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Items
Furnished
Items
Required
The Series 8320 Attenuators are equipped with a Bird
Quick-Change “QC” design connectors. Female N type con
nectors are normally supplied for the input and output but
may be conveniently and easily interchanged with other AN
type “QC” connectors. This instruction book is the only other
item furnished as standard equipment.
The only other items required are two matching connectors
on the coaxial transmission line to which the load will be
connected.
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Bird Model 8320S Tenuline Attenuator
Tools and
Test
Equipment
Only simple tools such as screwdrivers will be necessary for
disassembly of this equipment. A resistance bridge or ohm
meter with an accuracy of one percent or better at 50 ohms
is useful for checking the resistance of the RF Section as
sembly.
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Specifications
Impedance 50 ohms nominal
VSWR
Input
Output
Connectors
Input
Output
Power Rating
Model 8321
Model 8322
Model 8323
Model 8325
Frequency Range DC-500 MHz
Attenuation 30 db ± ½ db, dc-500 MHz
Calibration Frequencies
(to ± 0.2 dB)
Dimensions
Model 8321
Model 8322
Model 8323
Model 8325
Ambient Temperature -40°C to +45°C (-40°F to +113°F)
Cooling Method Dielectric and air convection currents
Weight
Model 8321
Model 8322
Model 8323
Model 8325
Operating Position Horizontal only
Finish Light navy gray baked enamel
Mounting Rectangle
Model 8321
Model 8322
Model 8323
Model 8325
1.1:1.0 maximum dc-500 MHz
1.15:1.0 maximum dc-500 MHz
Bird “QC”, Female N normally supplied
Bird “QC”, Female N normally supplied
50 W
200 W
100 W
500 W
30, 100, 200, 300, 400, and 500 MHz
10-7/32"L x 3-15/16"W x 6-11/32"H
(260 x 100 x 161 mm)
17-½"L x 5-15/16"W x 8-½"H
(445 x 151 x 216 mm)
10-11/32"L x 5-15/16"W x 8-½"H
(263 x 151 x 216 mm)
17-½"L x 5-15/16"W x 8-½"H
(445 x 151 x 216 mm)
6-½ lb (3 kg)
19 lb (9 kg)
11 lb (5 kg)
25 lb (11 kg)
7" x 3" (178 x 76 mm)
14-3/8" x 5-1/8" (365 x 130 mm)
7-15/32" x 5-1/8" (190 x 130 mm)
15" x 5-1/8" (381 x 130 mm)
Introduction
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Bird Model 8320S Tenuline Attenuator
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Chapter 2
Installation
Location
CAUTION
This equipment is designed for operation in a
horizontal position only, with the mounting
brackets down. Do not operate in any other
manner.
Allow at least six inches (150 mm) of clearance around the
unit, to permit an unimpeded access of convection air cur
rents for adequate heat dissipation. Place the attenuator to
permit the shortest possible cable length between the unit
and the transmitting equipment. Operate the attenuator in
a horizontal position only, with the handles on top.
Mounting The attenuator may be used for portable operation or for
fixed installation, that is, it may stand free or be secured to
a bench or any convenient flat surface. For Models 8322,
8323 and 8325, the front and rear fins are made of heavier
gauge material bent outward 90• to form mounting flanges.
At each corner of these flanges is a _ inch hole. The holes
are arranged in a rectangle, see Specifications, Page 1-3,
and the fasteners must be placed throughout the bench and
the holes. Secure the screws in place with nuts and lock
washers. Model 8321 is equipped with rubber bumper feet
which can be removed for permanent mounting. The holes
are tapped for 8-32 screws. All models have a convenient
carrying handle nested among the cooling fins on the top
side.
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Bird Model 8320S Tenuline Attenuator
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.
Before placing the Model 8325 Attenuator into service, the
solid shipping plug, P/N 2450-049 must be removed and re
placed by the spring loaded vent plug, P/N 2450-094. The
vent hole for this plug is located on the top near the rear.
The two plugs are linked together by a piece of bead chain.
The shipping plug should be placed back in the vent hole
whenever the attenuator is to be shipped. Take care not to
lose the O-Ring seal.
WARNING
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Chapter 3
Theory of Operation
General The Series 8320 Attenuators are symmetrical “T” pads, with
the power distribution on the legs being different. The value
of the resistance on each leg varies; therefore, according to
the power it is to absorb. On the input resistance element, a
proportionately larger resistor is of course required for its
much greater power dissipation. A “T” configuration is used
to provide equal input and output impedances for the 50
ohm transmission line attenuation.
The input resistor is joined to the “T” leg joint in an expo
nentially tapered housing to provide a linear reduction in
surge impedance directly proportional to the distance along
the resistor. The output resistor is enclosed in a housing designed to return the attenuator to the characteristic impedance of 50 ohms. This arrangement produces a uniform and
practically reflectionless attenuation characteristic over the
stated frequencies of the attenuator.
This system of film-on-ceramic cylindrical resistors immersed in a dielectric coolant constitutes the RF section assembly. The dielectric constant of the cooling fluid and the
tapered input and output resistor housings provide the
proper electrical characteristics for the coaxial line attenuation throughout the internal circuitry.
The dielectric coolant is carefully chosen for its desirable di
electric properties, to which the diameters of the resistors
and housings are matched, and for its high thermal stability
characteristics. The coolant used is 10C Transformer Oil,
P/N 5-030. Model 8321 requires approximately 1 pint (0.47
liter); Model 8322, 0.7 gallons (2.65 liter); Model 8323, 0.35
gallons (1.3 liter) and Model 8325, 0.9 gallons (3.4 liter). For
Model 8325 expansion of the coolant when power is applied
to the attenuator, is accomplished by allowing the air, which
is compressed by the expanding coolant, to escape through
the vent plug located on the top and near the rear face of
the unit. Models 8321, 8322 and 8323 allow for expansion of
the coolant by using underfilled radiator tanks and a derat
ing of their load carrying capacities.
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By convection, the cooling fluid carries the heat generated
in the various resistor elements to the walls of the coolant
housing. This housing is encased in a set of radiating fins
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Bird Model 8320S Tenuline Attenuator
which are attached to its outer surface. These radiating sur
faces dissipate the heat of the coolant into the surrounding
air.
The Series 8320 may be used for the isolation of power
sources up to their maximum power rating and for low level
monitoring. The low power value obtained at the output of
the attenuator can easily be fed into an oscilloscope or ter
minated in a small RF load resistor.
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Chapter 4
Operating Instructions
Use And
Function Of
Controls
Initial
Adjustments
Start-up
These attenuators, being passive devices, have no indicators
or operating controls.
No initial adjustments are necessary other than to connect
the attenuator to the RF source and load by means of coax
ial cables equipped with suitable matching connector plugs.
CAUTION
The input and output ends of these attenuators
are clearly labeled. Do not couple an
attenuator backwards to the direction of power
flow. Destruction of the output resistor will
result.
Models 8322, 8323 and 8325 are labeled INPUT and OUTPUT on the respective ends. Model 8321 is labeled on the
output end only. The proper ends of these attenuators may
also be identified by the input connector being mounted on
the flat gold colored disc whereas the output connector is
mounted on the rounded silver colored dome. Connect the
attenuator to the transmitting equipment under test and to
a suitable load with 50 ohm coaxial cabling (RG-8A/U,
RG-9/U, RG-213/U or equal) equipped with plugs which
mate with the RF input and output connectors of the at
tenuator. After the transmitter has been connected to the
attenuator, proceed according to the transmitter manufac
turer’s instructions. When reconnecting the antenna, it may
become necessary to slightly readjust the transmitter due to
possible differences in VSWR between the attenuator and
the antenna system.
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Normal
Operation
WARNING
Using these attenuators in the upper end of its power
dissipation range will cause the housing to become hot!
Care should be exercised in touching them.
Because the Series 8320 Attenuators are passive devices
and have no indicators or controls, they require no operat
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Bird Model 8320S Tenuline Attenuator
ing procedures or surveillance when the stated performance
limits are not exceeded. They should function faultlessly,
absorbing and converting the excess RF energy into heat in
definitely, if they are properly maintained and not subjected
to an overload.
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Operation
Under
Abnormal
Conditions
The Series 8320 TENULINE® Attenuators are not intended
or recommended for outdoor use where they will be unpro
tected and exposed to the elements. They may be subjected
to very moderate overloads for limited periods of time with
out overheating. However, this should be done very cau
tiously to guard the attenuator against the dangers of
overheating.
Shutdown These attenuators, being passive devices, cannot be shut off.
The source of RF energy must be cut off instead.
Emergency
Shutdown
WARNING
Never attempt to disconnect any 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 its source.
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Chapter 5
Troubleshooting
PROBLEM POSSIBLE CAUSE REMEDY
Leakage of coolant oil
around clamping
bands or radiator
housing.
Excessive overheating
of the radiator.
High or low DC resistance.
Clamping band not
tight.
Faulty input or output
O-Ring.
Transmitter power too
high.
Faulty RF section as
sembly.
Coolant oil level too
low.
Faulty RF input connector.
Loose RF input connector.
Faulty RF section assembly.
Maintenance
Tighten slightly with a
screwdriver.
Replace
Reduce transmitter
power.
Replace
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Add more coolant oil
to the radiator.
Replace
Tighten with a screwdriver.
Replace
Outside
Surfaces
Cleaning
The outside surface of the attenuator should be wiped free
of dust and dirt when necessary. The principle maintenance
required by the operator will be to periodically wipe the ac
cumulated dust and lint off of 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 connectors should become
dirty or grimy, wipe them off with a soft cloth. Use a contact
cleaner that is self-drying and nonresidue forming to clean
the inaccessible internal parts.
Inspection
Periodically inspect the clamping bands around the connec
tors, for signs of possible coolant leakage, see Preventive
Maintenance for proper action. Check the connector assem
bly for tightness. Inspect the cooling fins for accumulation of
dust and lint and the painted metal parts for signs of corro
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Bird Model 8320S Tenuline Attenuator
sion. Also, occasionally check the coolant level in the radia
tor tank.
Preventive Maintenance
If there are signs of coolant leakage around the clamping
bands, try tightening them. If the leakage persists, it is
likely that the O-Ring seal is damaged or deteriorated. Re
place it; see the sections for “coolant and seals” under Dis
assembly. Wipe the cooling fins clean of accumulated dust
and lint in order to preserve their efficiency in the transfer
ring heat to the environment. If any portions of the radiator
have become corroded or rusted, clean the areas with a fine
flint sandpaper, and then touch them up with grey enamel.
RF Assembly Tests
Accurate measurement of the dc resistance between the in
put to ground, output to ground, and input to output will
provide a good check of the condition of the attenuator. For
these measurements, a resistance bridge, or ohmmeter with
an accuracy of one percent or better at 50 ohms should be
used. Use low resistance leads, preferably a short piece of 50
ohm cable (RG-8A/U or RG-9B/U) with attached Male plugs
which mate with the Female connectors on the attenuator.
When the resistance of the equipment is check at room temperature, the measured readings should be with ± 2 ohms of
their nominal resistance values, commonly 93.7 ohms input
to output and 50 ohms from either end to ground. It is recommended that for reference purposes, these resistance val
ues should be measured and recorded upon receipt of the
attenuator and then checked periodically thereafter.
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Disassembly
There are no special techniques required for the repair or
replacement of components in these Tenuline Attenuators.
A screwdriver and possibly an adjustable wrench are the
only tools needed. The paragraphs below outline the compo
nent removal procedures.
RF Connector The connectors are a “Quick-Change” design which permits
easy interchange with the use of only a screwdriver. This
process does not interfere with the essential coaxial continu
ity of the attenuator RF input, output or the coolant oil
seals. For replacement, proceed as follows:
1. Remove the four 8-32 x 5/16 round head machine
screws from the corners of the RF connector.
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Maintenance
2. Pull the connector straight out of its socket.
Coolant and
Seals
To replace or examine the coolant oil, proceed as follows:
Models 8321, 8322 and 8323
1. Carefully raise up the back (output connector)
end of the attenuator until the unit is resting on
its front (input connector) end.
2. Brace the attenuator into a vertical position to
avoid tipping it over. Take care not to exert ex
cessive downward pressure on the attenuator
while it is in this position and thereby damage
the input connector.
3. Remove the V Band Clamp by loosening the
10-32 screw on its clamping blocks.
4. The Models 8322/23 have a special end cover. Remove this output end cover assembly which has a
specially designed bushing, P/N 2430-089, sealing
the attenuator output housing. Be careful when
disassembling to avoid damaging either the sealing ring, P/N 2430-089, on the output housing or
the O-Ring, P/N 5-243, on the RF output section.
the interior of the radiator tank and the RF section assembly are now exposed to view.
5. Check the coolant level.
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Model 8325
1. Carefully raise up the back (output connector)
end of the attenuator until the unit is resting on
its front (input connector) end.
2. Brace the attenuator into a vertical position to
avoid tipping it over. Take care not to exert ex
cessive downward pressure on the attenuator,
while it is in this position, and thereby damage
the input connector.
3. Use a 7/16 wrench to loosen the captive compres
sion nut that connects the access tube to the res
ervoir expansion tank. The reservoir is located on
the top rear side of the attenuator.
4. The nut must be completely unscrewed from the
threaded fitting on the reservoir tank.
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Bird Model 8320S Tenuline Attenuator
5. Now release and remove the clamping band by
loosening the 10-32 screw on its clamping block.
6. Remove the domed end cover assembly, P/N
8325-015, which has a special seal busing ring,
P/N 2430-089, sealing the attenuator output
housing. Be careful when disassembling not to
damage either this sealing ring which is fitted on
the coolant cylinder housing or the O-Ring, P/N
5-243, on the RF output section. The interior of
the radiator and the RF section assembly are
now exposed to view.
Coolant Level
Do not overfill the radiator tank with coolant. Room
must be allowed for expansion of the heated coolant.
CAUTION
Models 8321,
8322 and
8323
The level of the dielectric coolant, P/N 5-030, should remain
constant in the unit even after prolonged usage under normal operating conditions. As shipped, the coolant is at a factory determined level, and should be about 7/8 inch (22.2
mm) below the face of the output end, with the unit in a vertical position. The coolant should just cover the upper surface of the cubical center block of the RF section assembly.
However, loss of up to 10 percent of the full tank capacity
should not impair the operating efficiency of the attenuator.
The coolant should be a clear light yellow color. If not, it is
contaminated and should be replaced. Inspect occasionally
around the clamping bands at the input and output ends for
possible coolant leakage. If necessary, tighten the clamping
screw and make certain the diaphragm and output housing
seals are in good condition; i.e., soft, pliable and free from
surface cracks.
Add Coolant Add coolant directly into the radiator tank unit it reaches
the proper level.
Replace
Coolant
To replace all of the coolant, use the following procedure:
1. Pick up the attenuator and carefully pour out the
coolant into a suitable container. Allow as much
to drip out as possible.
2. Replace the coolant with fresh coolant, filling the
radiator tank to the proper level.
Model 8325 The level of the dielectric coolant oil, P/N 5-030, should re
main constant in the unit, even after prolonged usage under
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Maintenance
normal operating conditions. As shipped the coolant is at a
factory determined level which should approximately fill the
entire cylindrical radiator tank. Expansion of the heated
coolant is provided for by the expansion reservoir tank. The
vent plug allows the release of excess internal pressure.
However, the loss of up to 10 percent of the full radiator
tank capacity should not impair the operating efficiently of
the attenuator. The coolant should be a clear light yellow
color, if not, it is contaminated and should be replaced. In
spect occasionally around the clamping bands at the input
and output ends for possible coolant leakage. Tighten the
clamping screw if necessary, and make certain the dia
phragm and output housing seals are in good condition; i.e.,
soft, pliable and free from surface cracks.
Add Coolant Remove vent plug and add coolant directly into the reservoir
tank. Fill to a depth of only about 1/8 inch in reservoir.
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Replace
Coolant
RF Load
Resistor
Assembly
(All Models)
To replace all of the coolant, follow the procedure of paragraph Coolant and Seals, Disassembly, pertaining to coolant
and seals for Model 8325.
1. Pick up the attenuator and carefully pour out the
coolant into a suitable container. Allow as much
to drip out as possible.
2. Replace the coolant with fresh coolant, filling the
radiator tank to the proper level.
Assembly
To replace the load resistor assembly, use the same proce
dure as in paragraph Coolant and Seals, Disassembly and
then continue as follows:
1. Carefully pour the coolant into a clean container.
If the coolant is uncontaminated it can be reused,
otherwise discard it.
2. Release the clamping band from the input end as
in paragraph Coolant and Seals, Disassembly.
Disassemble and remove it.
3. The RF section assembly can now be removed
through the input end. Grasp the “QC” connector
and carefully work the assembly free and then
pull it out of the radiator tank. Inspect the input
O-Ring seals, P/N 5-229, for Model 8321 and, P/N
8110-039, for Models 8322, 8323, and 8325, or
signs of deterioration.
-
15
Bird Model 8320S Tenuline Attenuator
4. The RF section assembly is not subject to further
disassembly in the field. A defective unit must be
returned to the factory for repair.
RF Connector To install a new connector, reverse the procedures found in
RF Connector, Disassembly. Be sure that the projecting cen
ter pin on the connector is carefully engaged and properly
seated in the mating socket of the load resistors and then
push it firmly home.
-
Coolant and
Seal
Models 8321, 8322 and 8323 - proceed as follows:
1. Inspect the output cover sealing ring (Model
8321, P/N 8321-025; Models 8322 and 8323, P/N
2430-089) on the output ring diaphragm and the
output end O-Ring (Model 8321, P/N 5-176,
Models 8322 and 8323, P/N 5-243). They should
both be soft, pliable and free of surface cracks. If
not, replace them.
2. After adding to or replacing the coolant, if required, reverse the disassembly procedure.
Model 8325
Inspect the output cover sealing ring, P/N 2430-089, on the
coolant cylinder and the output O-Ring, P/N 5-243. They
should both be soft, pliable and free of surface cracks. If not,
replace them.
Reassembly a. If the input O-Ring is not soft, pliable and free of
surface cracks, replace it.
b. After replacing the RF load resistor assembly, if
necessary, reverse the procedure of Coolant and
Seals, Disassembly.
Repairs Repairs, beyond what is covered in this instruction book,
will require return of the equipment to Bird Electronic Cor
poration for service. Please consult the factory.
-
Shipment Pack and brace the attenuator in a suitable shipping con
tainer, a sturdy corrugated paper box is satisfactory. It is
not necessary to remove the dielectric coolant before ship
ping, but do not forget to replace the vent plug with the
shipping plug on Model 8325.
Storage No special preparations for storage are necessary other than
to cover the equipment to keep out dust and dirt. Store this
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 equipment.
16
-
-
Maintenance
Replacement Parts List
Item Qty. Description Part Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
1
1
1
2
2
1
1 pint
(0.31 liter)
0.7 gallon
(2.65 liter)
0.35 gallon
(1.3 liter)
0.9 gallon
(3.4 liter)
1
1
1
4
1
1
2
1
RF section assembly
Model 8321
Models 8322/25
Models 8323
Radiator assembly
Model 8321
Model 8322
Model 8323
Model 8325
Radiator handle
Models 8321/23
Model 8322
Model 8325
RF connectors
Clamping band assembly
Model 8321
Models 8322/23/25
End cover assembly 8322/23
8325
Dielectric coolant
Model 8321
Model 8322
Model 8323
Model 8325
Input end O-Ring
Model 8321
Models 8322/23/25
Output end O-Ring
Output cover seal
Model 8321
Model 8322 & 8325
Bumper feet (8321 only)
Vent plug (8325 only)
Shipping plug (8325 only)
O-Ring, vent and shipping
plugs (8325 only)
Chain assembly (8325 only)
8321-002
8322-002-1
8323-002
2400-025
2440-020
2400-015
2430-028
2400-017
2440-009
2430-028
*See Below
7500-254
2430-055
8322-005
8325-015
5-030-1
(1 pint container)
5-030-3
(1 gallon container)
5-030-2
(½ gallon container)
5-030-3
(1 gallon container)
5-229
8110-039
5-243
8321-025
2430-089
5-049
2450-094
2450-049
5-504
8180-094
17
Bird Model 8320S Tenuline Attenuator
* Available QC Type Connectors
N-Female 4240-062 LT-Female
M-Male 4240-063 LT-Male
HN-Female 4240-268 C-Female
HN-Male 4240-278 C-Male
LC-Female 4240-031 UHF-Female (SO-239)
LC-Male 4240-025 UHF-Male (PL-259)
BNC-Female 4250-125 7/8" EIA Air Line
BNC-Male 4240-132
4240-018
4240-012
4240-100
4240-110
4240-050
4240-179
4240-002
18
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