INSTRUCTION BOOK
A
OPERATING INSTRUCTIONS
TENULINE®ATTENUATOR
MODEL 8327-300
Electronic Corporation
Cleveland (Solon) Ohio US
©Copyright 1998 by Bird Electronic Corporation
Instruction Book Part Number 920-8327-300 Revision A
Tenuline
®
is a Registered Trademark of
Bird Electronic Corporation
Bird Model 8327-300 Attenuator
Safety Precautions
The following are general safety precautions that are not necessarily related to any specific part or procedure,
and do not necessarily appear elsewhere in this publication. These precautions must be thoroughly
understood and applied to all phases of operation and maintenance.
Keep Away From Live Circuits
Operating personnel must at all times observe general safety precautions. Do not replace components or
make adjustments to the inside of the test equipment with the high voltage turned on. To avoid casualties,
always remove power.
Shock Hazard
Do not attempt to remove the RF transmission line while RF power is present. Radiated RF power is a
potential health hazard.
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 or rendering aid.
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.
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 information.
Model 8327-300 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.
i
Bird Model 8327-300 Attenuator
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 disconnect the equipment from the transmission line while RF power is being applied. Leaking RF
energy is a potential health hazard.
Model 8327-300 Caution Statements
The following caution appears in the text whenever a procedure, if not properly followed, could put the
equipment in danger of damage and is 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.
Model 8327-300 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.
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.
ii
SERVICIO
LAS INSTRUCCIONES DE SERVICIO SON PARA USO EXCLUSIVO DEL PERSONAL DE SERVICIO CAPACITADO. PARA EVITAR EL PELIGRO DE DESCARGAS ELÉCTRICAS, NO REALICE NINGÚN SERVICIO A MENOS QUE ESTÉ
CAPACITADO PARA HACERIO.
WARTUNG
ANWEISUNGEN FÜR DIE WARTUNG DES GERÄTES GELTEN NUR FÜR
GESCHULTES FACHPERSONAL.
ZUR VERMEIDUNG GEFÄHRLICHE, ELEKTRISCHE SCHOCKS, SIND WARTUNGSARBEITEN AUSSCHLIEßLICH VON QUALIFIZIERTEM SERVICEPERSONAL DURCHZUFÜHREN.
ENTRENTIEN
L’EMPLOI DES INSTRUCTIONS D’ENTRETIEN DOIT ÊTRE RÉSERVÉ AU PERSONNEL FORMÉ AUX OPÉRATIONS D’ENTRETIEN. POUR PRÉVENIR UN
CHOC ÉLECTRIQUE DANGEREUX, NE PAS EFFECTUER D’ENTRETIEN SI
L’ON N’A PAS ÉTÉ QUALIFIÉ POUR CE FAIRE.
ASSISTENZA TECNICA
LE ISTRUZIONI RELATIVE ALL’ASSISTENZA SONO PREVISTE ESCLUSIVAMENTE PER IL PERSONALE OPPORTUNAMENTE ADDESTRATO. PER EVITARE PERICOLOSE SCOSSE ELETTRICHE NON EFFETTUARRE ALCUNA
RIPARAZIONE A MENO CHE QUALIFICATI A FARLA.
CONNECT INTERLOCK TO TRANSMITTER BEFORE OPERATING.
BRANCHER LE VERROUILLAGE À L’ÉMETTEUR AVANT EMPLOI.
CONECTE EL INTERBLOQUEO AL TRANSMISOR ANTES DE LA OPERACION.
VOR INBETRIEBNAHME VERRIEGELUNG AM SENDER ANSCHLIESSEN.
PRIMA DI METTERE IN FUNZIONE L’APPARECCHIO, COLLEGARE IL DISPOSITIVO DI BLOCCO AL TRASMETTITORE.
iii
Bird Model 8327-300 Attenuator
iv
About This Manual
This instruction manual covers the Model 8327-300 Tenuline Attenuator. This instruction book is arranged
so 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 the location of major assemblies or parts, refer to the parts lists and associated drawings in Chapter
5 - Maintenance.
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 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
Bird Model 8327-300 Attenuator
vi
Table Of Contents
Safety Precautions. . . . . . . . . . . . . . . . . . . . . . . . . . . . i
Warning Statements. ..................................i
Caution Statements. ..................................ii
Safety Statements. ...................................ii
About This Manual. ................................. v
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Purpose and Function. ................................ 1
Description. ...................................... 1
Items Supplied. .................................... 1
Items Required. ................................... 1
Optional Items. .................................... 1
Specifications. ...................................... 2
Theory Of Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Site and Shelter Requirements. ........................... 5
Unpacking and Inspection. .............................. 5
Tools Required. ................................... 5
Mounting. ....................................... 5
Vent Plug. ...................................... 6
Thermoswitch. .................................... 6
Operating Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . 9
Initial Adjustments. .................................. 9
Connection. ...................................... 9
Normal Operation. .................................. 9
Operation Under Abnormal Conditions. .......................10
Shutdown. ......................................10
Emergency Shutdown. ................................10
vii
Bird Model 8327-300 Attenuator
Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Troubleshooting. .................................... 11
Cleaning. ........................................ 11
Preventive Maintenance. ................................ 11
RF Connector. ..................................... 12
Coolant. ......................................... 13
RF Load Resistor. ................................... 14
Thermoswitch. ..................................... 14
Repairs. ......................................... 14
Measure dc Resistance. .............................. 11
Adding Coolant. ................................... 13
Replacing Coolant. ................................. 13
Customer Service. ................................... 14
Sales / Repair Facilities. .............................. 14
Sales Facilities. ................................... 15
Shipment. ........................................ 15
RF Section Assembly. ............................... 15
Complete Unit. ................................... 15
Storage. ......................................... 15
Replacement Parts List. ................................ 16
viii
Chapter 1
Introduction
This publication refers to the Tenuline Attenuator Model 8327-300. This chapter
contains introductory information including product specifications; items supplied;
and accessory items available.
Purpose and
Function
Description A system of resistive film-on-ceramic cylindrical resistors immersed in a dielectric
Items Supplied The following items are supplied with the Model 8327-300
The Model 8727-300 Attenuator is a low-refection resistance network for application
in reducing RF power by known and controlled amounts. The radiator has rhombic
shaped cooling fins spaced evenly along its length for the most efficient cooling. This
attenuator is useful for lowering a high input RF power to a level suitable for feeding
into an oscilloscope, frequency counter or similar device. The attenuator is designed
to match the most commonly used 50 ohm transmission line systems.
coolant constitutes the RF section assembly. By convection, the coolant carries the
heat generated in the various resistor elements to the walls of the coolant housing.
The housing is encased in a set of radiating fins which are attached to its outer
surface. The radiating fin surfaces dissipate the heat of the coolant into the surrounding air.
The unit may be used for isolation of power sources up to 1000 W and for low level
monitoring. The low power value obtained at the output of the attenuator can easily
be read on an oscilloscope or terminated in a small RF load resistor.
This attenuator does not require any external source of power or utilities for cooling
purposes. It is a self-contained instrument intended to be fully cooled by natural
convection in normal ambient air with a power input of 1000 W. The front and rear
panels of the unit have mounting flanges. These flanges act as supports for optional
fixed mount. Mounting holes are provided for this purpose. Mounting of this unit is
described in Chapter 3 - Installation.
s LC Female connector - input end
s N Female connector - output end
s Instruction Manual
Items Required The following items are required to put the Model 8327-300 into service.
s Multimeter
s Screwdrivers
s Matching connectors on the coaxial transmission line
Optional Items The following items are available as optional equipment.
s Overload thermoswitch, P/N 2450-056 for protection against burnout.
s Quick-Change connectors for convenient and easy interchange with other “AN”
type “QC” connectors. Refer to the list in the Maintenance Chapter.
1
Bird Model 8327-300 Attenuator
Specifications
Impedance 50 ohms nominal
VSWR
Input, dc-500 MHz
Output, dc-500 MHz
Nominal Attenuation: 30 dB
Input Power Rating 1000 Watts
Maximum Frequency Deviation
Calibration Accuracy ±0.2 dB
Calibration Frequencies 30, 100, 200, 300, 400, 500 MHz
Power Sensitivity Correction
Input Connector Female “LC”, Bird “QC”
Output Connector Female “N”, Bird “QC”
Operating Position Horizontal
Dimensions 23-15/32"L* x 7-1/8"W x 17-3/16"H
Mounting Dimensions 20-23/32" x 4-1/2" rectangle
Ambient Temperature -40°C to +45°C
Weight 57 lb (26 kg)
Finish Grey Powder Coat
Safety Meets European Safety Standard EN 61010-1, Which is in accordance with
1.10:1.0 maximum
1.15:1.0 maximum
dc-500 MHz 1/2 dB
-1 x 10 -6 dB/Watt/MHz ±0.2 dB
(596 x 181 x 437 mm)
(526.3 x 114.3 mm)
(-40°F to +113°F)
Council directives 73/23/EEC and 93/68/EEC.
*Using respective LC & N connectors normally supplied.
2
Chapter 2
Theory Of Operation
The Model 8327-300 Attenuator is a symmetrical “T” pad, with the power distribution
on the legs being different. Therefore, the value of the resistance on each leg is
different according to the power it is to absorb. On the input resistor element, a
propotionately larger resistor is of course required for its much greater power
dissipation. A “T” configuration is used to provide equal input and output impedance’s
for the 50 ohm transmission line attenuation.
The input resistor is joined by the “T” leg joint in an exponentially tapered housing
to provide a linear reduction in surge impedance of 50 ohms. This arrangement
produces a uniform and practically reflectionless attenuation characteristic over the
stated frequencies of the attenuator.
This system of carbon-film-on-ceramic cylindrical resistors immersed in a dielectric
coolant constitutes the RF section assembly. The cooling liquid and the tapered input
resistor housing provide the proper electrical characteristics of the coaxial line
termination.
The dielectric coolant is carefully chosen for its desirable dielectric properties, to
which the diameters of the resistors and housings are matched, and for its high
thermal stability characteristics. 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 near the top and front
face of the unit.
By convection, the coolant 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
which are attached to its outer surface. These radiating fin surfaces dissipate the
heat of the coolant into the surrounding air.
The Model 8327-300 may be used for isolation of power sources up to 1000 W and
for low level monitoring. The low power value obtained at the output of the attenuator
can easily be read on an oscilloscope or terminated in a small RF load resistor.
3
Bird Model 8327-300 Attenuator
FILLER AND VENT VALVE
INTERLOCK THERMOSWITCH
(OPTIONAL)
INPUT CONNECTOR
FEMALE "LC" AND
FEMALE "N"
NORMALLYSUPPLIED
2-61/64
(75mm)
Model 8327-300 Outline Drawing
21-45/64
(551mm)
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
20-23/32
(526mm)
MTG. HOLE CENTERS
Figure 1
17-3/16
(437mm)
20-15/16
(532mm)
21-5/8
(549mm)
<<<<<<<<<<<<<<<<<<
SOCKET PLUG
4-1/2
(114mm)
MTG. HOLE
CENTERS
7-1/8
(181mm)
4
Chapter 3
Installation
This chapter provides information for on site requirements, unpacking, inspection,
and preparing the equipment for use.
Site and Shelter
Requirements
Unpacking and
Inspection
Tools Required The following tools and supplies will be required to prepare the unit for use.
Mounting
The Model 8327-300 Attenuator should be operated in a dry, dust and vibration free
environment. The ambient temperature range should remain between -40°C and
+45°C (-40°F and +113°F) for proper operation. Allow at least 12" (305 mm) of
clearance around the unit to permit an unimpeded access of convection air currents
for adequate heat dissipation. To permit the shortest possible cable length, place the
attenuator as close as possible to the transmitting equipment.
Follow the steps below when unpacking the equipment.
1. Inspect the shipping container for signs of damage. If damage is
noticed, do not unpack the equipment. Immediately notify the shipping carrier and Bird Electronic Corporation of the damage.
2. If the shipping container is not damaged, unpack the unit. Save all
shipping materials for repackaging.
3. Inspect all components for visual signs of damage. Immediately notify
the shipping carrier and Bird Electronic Corporation of equipment
damage or missing parts.
s Wrenches
s Screwdrivers
s 9/16 Hex wrench (for thermoswitch installation)
s Pipe sealing compound (for thermoswitch installation)
s Soldering Iron and solder (for thermoswitch installation)
s Bolt and nut sets or lag screws (for mounting)
CAUTION
This equipment is designed for operation in a horizontal position only, with mounting
brackets down. Do not operate in any other manner.
The attenuator may stand free or may be secured to a bench or any convenient flat
surface. The front and rear face plates are made of heavier gauge material bent
outward 90° at the bottom to form mounting flanges. At each corner if these flanges
is a 3/8 inch x 15/32 inch elongated hole for use with suitable fasteners up to 3/8
inch. The holes are arranged in a 20-23/32 inch x 4-1/2 inch rectangle (526.3 x 114.3
mm). The front and rear face plates of the attenuator are also bent over on the top
to form convenient carrying handles. The following instructions are for mounting the
unit to a suitable surface.
1. Place the unit on a flat surface.
2. Insert the fasteners, up to 3/8 inch, through the bench and the holes.
3. Secure the bolts with nuts and lock washers.
5
Bird Model 8327-300 Attenuator
Vent Plug
Before placing the attenuator into service, the solid shipping plug, P/N 2450-049,
must be removed and replaced by the spring loaded vent plug, P/N 2450-094. The
vent hole for these plugs is located at the top left hand side near the front. The two
plugs are linked together by a short length of bead chain. The shipping plug should
be placed back in the vent hole whenever the attenuator is to be shipped. Be careful
not to lose the O-Ring seal. Refer to figures 2 and 3.
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.
Figure 2
Shipping Plug
O-ring seal
Thermoswitch As an optional item, the attenuator can be provided with a thermoswitch assembly,
Figure 3
Vent Plug
O-Ring Seal
P/N 2450-056. When the thermoswitch is installed, it prevents possible damage from
accidental power overloading from the transmitter or equipment malfunction. The
thermoswitch is normally closed and opens at a maximum safe temperature. Since
the thermoswitch is connected in series with the transmitter interlock, it cuts off
transmitter power if the coolant temperature exceeds this value. The assembly
consists of:
s Thermoswitch body - P/N 2450-040
s Coupling Jack - P/N 2450-018
If the thermoswitch is to be field installed, proceed as follows:
1. Replace the vent plug with the shipping plug.
2. Stand the unit on its back end with the input connector end up.
+ Note: In this position there is no danger of the coolant pouring out through the
socket plug hole.
3. Remove the socket plug located just above the connector on the front
face of the radiator. Use a 9/16 hex wrench. Refer to figure 1.
4. Replace the plug with the thermoswitch. Use an acceptable pipe
sealing compound sparingly on only the external threads of the
thermoswitch.
+ Note: Do not contaminate the coolant with pipe sealing compound.
5. Check the unit for coolant leaks.
6
Installation
While following the instructions below for connecting the thermoswitch, refer to figure
4.
1. Unscrew the larger knurled ring-nut (A) at the lower end of the
coupling jack assembly. Pull it off from the thermoswitch jack (B).
Unscrew the small knurled cover fitting (C) from the base plug (D)
of the connector to release the base.
2. Thread the interlock wires through the clamp (E) with the washers
(F) inside and with its threaded fitting in place.
3. Service the interlock wire with short tips, use spaghetti sleeves over
the wire ends if needed.
4. Securely solder the interlock leads to the lugs (G) of the connector
base.
+ Note: Be sure that the larger captive clamping nut (A) is in place over the base
plug (D) with the knurled end outward towards face.
5. Screw on the cover ring (C) first, then fasten the cable clamp (E) in
place, and tighten the two yoke screws (H) on the cable. Push the
plug back onto the thermoswitch, and tighten the captive knurled
connecting ring. Do not attempt to operate the equipment without the
interlock attached.
Figure 4
Thermoswitch
Assembly
A
D
F
C
E
H
B
G
7
Bird Model 8327-300 Attenuator
8
Chapter 4
Operating Instructions
There are no operating controls for the Model 8327-300 Attenuator. Read and become
familiar with the following instructions before operating the unit. If your attenuator
is equipped with a thermoswitch, refer to the instructions for connection to the
interlock.
Initial Adjustments Before connection of the attenuator, perform the following steps.
1. Wipe all connectors and insulator surfaces on the transmission line
face with a clean soft cloth.
2. Check the RF input connector. Clean the connector if necessary. Use
a self-drying, non-residue forming contact cleaner on the inaccessible
portions of the connector.
3. Check the input resistance of the attenuator. Refer to the Maintenance chapter.
WARNING
Never attempt to disconnect the equipment from the transmission line while RF power is
being applied. Leaking RF energy is a potential health hazard.
Connection The front or input end of the attenuator is identified by the four inch (102 mm)
diameter die-cast aluminum disc on which the connector is mounted. The rear face
of the unit has OUTPUT stenciled above the connector. Do not couple the attenuator
backwards to the direction of power flow. Destruction of the output resistor will
result.
1. Connect the attenuator input to the transmitter’s power output. Use
50 ohm coaxial cable.
2. Connect the attenuator output to a suitable load with 50 ohm coaxial
cable (RG-8A/U, RG-9/U, RG-213/U or equivalent) equipped with
connectors which mate with the RF output connector of the attenuator.
3. Follow the transmitter manufacturer’s instructions.
+ Note: If the attenuator is to be operated at both maximum power and frequency
values, use a Male LC connector with a suitable cable (RG-218/U or RG-220/U)
on the input and Male N connector with appropriate cable or load on the output.
These connect to the RF fittings normally supplied.
Before applying any RF power to the attenuator, be certain to check that the vent
plug is in place in the vent hole. Refer to Installation.
Normal Operation
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
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.
9
Bird Model 8327-300 Attenuator
Because the Model 8327-300 Attenuator is a passive device and has no indicators or
controls, it requires no operating procedures or surveillance when the performance
limits are not exceeded. It should function faultlessly, absorbing and converting the
excess RF energy into heat indefinitely, if it is properly maintained and not subjected
to an overload.
CAUTION
This equipment is designed for operation in a horizontal position only, with mounting
brackets down. Do not operate in any other manner.
Operation Under
Abnormal
Conditions
The Model 8327-300 Attenuator is not intended or recommended for outdoor use.
The Attenuator may be subjected to moderate overloads for limited periods of time
without overheating. However, this should be done cautiously, and it is strongly
recommended that if such a use is contemplated, the attenuator should be equipped
with a thermoswitch, P/N 2450-056. When interlocked with the power line to the
source of RF energy, the thermoswitch becomes a fail safe device to guard the
attenuator against the dangers of overheating.
WARNING
Never attempt to disconnect the equipment from the transmission line while RF power is
being applied. Leaking RF energy is a potential health hazard.
Shutdown This attenuator, being a passive device, cannot be shut off. The source of RF energy
must be cut off instead.
Emergency
Shutdown
Turn off RF power at its source.
10
Chapter 5
Maintenance
This chapter contains operator maintenance instructions, troubleshooting, and parts
information.
Troubleshooting
Problem Possible Cause Remedy
Leaking of coolant oil around clamping
band or radiator housing.
Excessive overheating of the radiator. Transmitter power too high Reduce transmitter power
High or low dc resistance values per the
Measure dc Resistance paragraph.
Clamping band not tight. Tighten slightly with a
screwdriver.
Faulty O-Ring (Input) Replace, refer to the
Coolant paragraph
Faulty O-Ring (Output) Replace, refer to the
Coolant paragraph
Faulty RF section assembly Replace, refer to Coolant
paragraph
Coolant oil level too low Add more coolant oil to
the radiator.
Faulty RF input connector Replace the input
connector per the RF
Connector paragraph.
Loose RF input connector Tighten the input
connector with a
screwdriver.
Faulty RF section assembly. Replace per the Coolant
paragraph.
Measure dc
Resistance
Cleaning
The most important cleaning task is to remove accumulations of dust and lint from
the radiator fins. An extensive collection of dust and lint on the cooling fins will
interfere with the efficient dissipation of heat.
When dirt and dust have accumulated in the radiator fin spaces it should be cleaned.
Preparation:
s Material: Lint-free cleaning cloth
s Mild detergent
To clean the unit follow the instructions below.
1. Gently remove loose dirt and grime using a soft clean cloth dampened with a mild
warm solution of detergent and water.
2. Check the condition of the RF coaxial connector. If it needs cleaning, clean the
connector with a self-drying contact cleaner, that leaves no residue on the inaccessible
portions.
Preventive Maintenance
Preparation:
s Tools: Common hand tools
11
Bird Model 8327-300 Attenuator
s Ohmmeter with an accuracy of ±1% at 50 Ohms.
s Temperature of the load between 20°C to 25°C (68°F to 77°F)
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 disconnect the equipment from the transmission line while RF power is
being applied. Leaking RF energy is a potential health hazard.
1. Turn off RF power and interlock circuitry before any electrical disconnection’s are made.
2. Disconnect the RF coaxial line.
3. Connect the multimeter test leads across the center and outer conductor of the load resistor. Refer to figure 5.
Figure 5
Meter Lead
Placement
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 2 ohms, this could be an indication of a failing
resistive element.
+ Note: It is recommended that this resistance check be performed each time the
load is to be used.
RF Connector
Tool required:
s Screwdriver
12
The following paragraphs outline the component removal and replacement procedure.
The connector is a “Quick-Change” design which permits easy interchange with the
use of only a screwdriver. This process does not interfere with the essential coaxial
continuity of the attenuator RF input, out put, or the coolant oil seals. For replacement, proceed as follows:
1. Remove and retain the four screws from the corners of the RF
connector.
Maintenance
2. Pull the connector straight out of its socket.
3. Insert the new connector into the mating connector. Be sure the
projecting center pin on the connector is properly engaged and seated
in the mating socket, then push it in firmly.
4. Install the four screws that were previously removed.
Coolant
The level of the dielectric coolant should remain constant in the unit after prolonged
usage under normal operating conditions. As shipped, the coolant is at a factory
determined level, and should be about 3-1/4 inches (82.5 mm) below the surface of
the thermoswitch hole, with the unit in a vertical position. However, loss of up to
10% of the full tank capacity should not impair the operating efficiency of the
attenuator. The coolant should be a light yellow color. If it is dark and not a light
yellow, it may be contaminated and should be replaced. Occasionally inspect around
the clamping band at the input end for possible coolant leakage. Tighten the clamping
screw if necessary, and make certain the O-Ring seal is in good condition; i.e., soft
and pliable and free from surface cracks.
Adding Coolant Add coolant through the pipe plug hole (thermoswitch hole) until it reaches the
proper level, about 3-1/4 inches below the surface of the hole. Do not overfill the
unit beyond the recommended level.
Replacing Coolant To replace all of the coolant use the following procedure:
1. Remove the rear (output) connector per the Disassembly paragraph.
2. Replace the vent plug with the shipping plug.
3. Carefully raise the unit by its front handle and foot until it is tipped
up on its back.
4. Position the load on the bench top so that the entire rear connector
assembly, minus the connector, projects over the edge of the bench.
Brace it vertically in this position so that it will not topple over.
5. Place a clean container for liquid just under the rear connector
assembly to receive the oil. The volume of the oil is 2.9 gallons (11
liters), so the container must be at least a three gallon size, and
preferably five gallons.
6. Remove the V-band clamp from around the front (input) connector
assembly by loosening the 10-32 holding screw sufficiently to slip the
band off.
7. Carefully work the RF section assembly loose and lift it straight out
of the resistor tank.
+ Note: There will be some initial resistance as the O-Ring seal around the rear
connector assembly comes loose from the housing.
As the RF section comes out of the rear connector assembly, the
coolant will start to pour into the container. Work the RF section
loose slowly, so that the coolant doesn’t splash coming out.
8. Let the coolant drip for a few minutes to get as much as possible out
of the radiator tank. As the RF section is raised out of the radiator
tank some coolant will be trapped in the rear end cylinder. Turn the
section over carefully to empty it out.
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Bird Model 8327-300 Attenuator
+ Note: An alternate, but much slower, method of draining the radiator would be
to siphon the coolant out of the thermoswitch hole.
9. Discard the contaminated coolant collected in the container.
10. Replace the RF section assembly making sure that it is smoothly and firmly
seated in the rear connector assembly.
11.Replace the V-band on the front connector plate assembly and tighten the
the screw.
12.Add clean coolant to the unit. Fill the unit until the level is about
3-1/4 inches below the thermoswitch hole.
13.Coat the pipe plug or thermoswitch threads sparingly with pipe
sealant. Do not contaminate the coolant.
14.Screw the pipe plug or thermoswitch back in place carefully to avoid
stripping the aluminum threads of the plug hole.
15.Lower the attenuator back onto its feet.
16.Check all seals for signs of leaks.
Sales / Repair
Facilities
RF Load Resistor
To replace the load resistor follow the same procedure as in the Replacing Coolant
section. However, inspect the O-Ring seals. Do not reuse the O-Rings if they are no
longer soft and pliable or shows signs of cracks. If the coolant removed is not
contaminated, it may be reused in the radiator tank with additional new coolant as
required. The RF section is not field repairable and further disassembly should not
be attempted. Return the entire RF assembly to the factory for repair or replacement.
Thermoswitch
To remove or replace the thermoswitch use the procedures in the Thermoswitch
paragraph in Chapter 3 - Installation.
Repairs
Any maintenance or service procedure beyond the scope of those provided in this
section should be referred to a qualified service center.
Customer Service
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
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Maintenance
Sales Facilities For the location of the sales office nearest you, give us a call or visit our Web site
at:
http://www.bird-electronic.com
Shipment
RF Section
Assembly
Wrap the RF section assembly with sufficient padding to avoid damage in shipping
and tape securely. Place the wrapped RF section in a cardboard carton and pad or
brace it to prevent shifting.
Complete Unit Should you need to return the Attenuator, first remove the vent plug and replace it
with the shipping plug. The unit may be shipped with its dielectric coolant; however,
do not ship the unit with its dielectric coolant if the unit has developed a leak. Drain
the coolant first. Place the attenuator in a wooden crate or other substantial shipping
container, and pack or brace it securely to prevent damage in shipping.
All instruments returned for service must be shipped prepaid and to the attention
of the Customer Service Group.
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)
operational range of the load.
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Bird Model 8327-300 Attenuator
Replacement Parts List
Item Qty. Description Part Number
1 1 RF section assembly 8327-302
2 1 Radiator assembly 8329-307
3 2.9 gal.
(11 liters)
4 3 “QC” connector *See Below
5 1 Clamp band assembly (includes screws) 2430-055
6 1 Input O-Ring seal 8110-039
7 1 Output O-Ring seal 5-176
8 1 Vent relief valve 2450-094
9 1 Shipping plug 2450-049
10 2 Vent and shipping plug O-Ring 5-504
11 1 Chain assembly 8180-094
12 1 Thermoswitch plug 5020-103
13 1 Thermoswitch & connector assembly accessory kit
Dielectric coolant 5-030-3
(1 gallon container)
2450-056
consisting of:
Connector assembly
Thermoswitch assembly
2450-018
2450-040
*Available “QC” Type Connectors
† N-Female(input/output) 4240-062 LT-Female 4240-018
N-Male 4240-063 LT-Male 4240-012
HN-Female 4240-268 C-Female 4240-100
HN-Male 4240-278 C-Male 4240-110
†LC-Female(input) 4240-031 UHF-Female (SO-239) 4240-050
LC-Male 4240-025 UHF-Male (PL-259) 4240-179
7/8" EIA Air Line 4240-002
†Normally supplied
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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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