Bird Technologies 8329-300 User Manual

INSTRUCTION BOOK

A

OPERATING INSTRUCTIONS

TENULINE®ATTENUATOR

MODEL 8329-300

Electronic Corporation

Cleveland (Solon) Ohio US

©Copyright 1998 by Bird Electronic Corporation

Instruction Book Part Number 920-8329-300 Revision A

Tenuline®is a Registered Trademark of

Bird Electronic Corporation

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 supply turned on. To avoid casualties, always re­move power.

Shock Hazard

Do not attempt to remove the RF transmission line while RF power is pres­ent.

Do Not Service Or Adjust Alone

Under no circumstances should any person reach into an enclosure for the
purpose of service or adjustment of equipment except in the presence of some­one who is capable of rendering aid.

Safety Earth Ground

An uninterruptible earth safety ground must be supplied from the main
power source to test instruments. Grounding one conductor of a two conduc­tor power cable is not sufficient protection. Serious injury or death can occur
if this grounding is not properly supplied.

Resuscitation

Personnel working with or near high voltages should be familiar with modern
methods of resuscitation.

Safety Symbols

WARNING

Warning notes call attention to a procedure, which if not correctly

performed, could result in personal injury.

i

CAUTION

Caution notes call attention to a procedure which if not correctly

performed, could result in damage to the instrument.

This symbol appears on the equipment indicating there is
important information in the instruction manual regarding
that particular area.

Note: Calls attention to supplemental informa-

+

tion.

Warning Statements

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 the plug.

WARNING

Using this attenuator 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.

Caution Statements

CAUTION

This equipment is designed for operation in a horizontal position only,

with mounting brackets down. Do not operate in any other manner.

CAUTION
RF power rating must always be cut in half when the blower assembly
is installed but is not running. Under this conditiona2kWattenuator

will be limited to approximately 1 kW.

ii

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.

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.

iii

Bird Model 8329-300 Tenuline Attenuator

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.

iv

About This Manual

This instruction manual covers the Model 8329-300 Tenuline Attenuator.
This instruction book is arranged so that essential information on safety is
contained in the front of the book. Reading the Safety Precautions section be­fore operating the equipment is strongly advised.

The remainder of this instruction book is divided into chapters and sections.

Operation

First time operators should read Chapter 1 - Introduction, Chapter 2 - Theory
of Operation, and Chapter 3 - Installation to get an overview of equipment ca­pabilities and how to install it. An experienced operator can refer to Chapter
4 - Operating Instructions. All instructions necessary to operate the equip­ment are contained in this chapter.

Maintenance

All personnel should be familiar with preventive maintenance found in Chap­ter 5 - Maintenance. If a failure should occur, the troubleshooting section will
aid in isolating and repairing the failure.

Parts

For 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 8329-300 Tenuline Attenuator

vi

Table of Contents

Safety Precautions. ......................i

Warning Statements. ......................ii

Caution Statements........................ii

Introduction. ........................1

Purpose and Function. ...................1

Description.........................1

Dimensions and Weight. ..................1

Items Supplied. ......................1

Items Required. ......................2

Optional Items. ......................2

Specifications. .........................3

Theory of Operation. .....................5

Operating Instructions. ....................7

Site and Shelter Requirements. ...............7

Unpacking and Inspection. .................7

Tools Required. ......................7

Mounting. ........................8

Vent Plug. ........................8

Thermoswitch. ......................9

Blower Assembly......................11

Operating Instructions. ...................13

Initial Adjustments.....................13

Connection. .......................13

vii

Bird Model 8329-300 Tenuline Attenuator

Normal Operation. ....................14

Operation Under Abnormal Conditions. ...........15

Shutdown. ........................15

Emergency Shutdown. ...................15

Maintenance. ........................17

Troubleshooting. ........................17

Cleaning. ...........................17

Preventive Maintenance. ....................18

Measure dc Resistance. ..................18

RF Connector. .........................19

Coolant. ...........................20

Adding Coolant. .....................20

Replacing Coolant. ....................20

RF Load Resistor. .......................22

Thermoswitch. .........................22

Repairs. ...........................22

Customer Service. .......................23

Sales / Repair Facilities. ..................23

Sales Facilities. .....................23

Shipment............................23

RF Section Assembly. ...................23

Complete Unit. ......................23

Storage. ...........................24

Replacement Parts List......................24

viii

Chapter 1

Introduction

This publication refers to the Tenuline Attenuator Model
8329-300. This chapter contains introductory information
including product specifications, items supplied, and acces­sory items available.

Purpose and

Function

Description Relying only on ambient air currents, this Tenuline

The Model 8329-300 Attenuator is a low-reflection resis­tance network for application in reducing RF power by
known and controlled amounts. It is a self-contained instru­ment that requires no external source of power (except if
blower equipped) or utility service. 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.

Attenuator will safely absorb, and dissipate harmlessly as
heat, up to 2000 watts of input power. When equipped with
an optional blower, Model BA-300, the increased air flow
will allow a doubling of the rated load capacity to 4000
watts. Over the frequency range of dc to 500 MHz, the
power output will be reduced by 30dB (99.9%) ±0.5dB. Up to
500 MHz, the input VSWR will not exceed 1.1 and the out­put VSWR 1.15.

This attenuator is a passive device that is self-contained
and does not need any external source of power or utilities
to function. The exception would be the use of the optional
BA-300 blower for a higher cooling rate. The BA-300-115 re­quires 115V at 50/60 Hz and the BA-300-230 requires 230V
at 50/60 Hz.

Dimensions

and Weight

Items

Supplied

This attenuator is 23-1/4"L x 7-1/8"W x 17-3/16"H (591 x 181
x 437mm). It has a net weight of 57 lbs. (26kg) and a ship­ping weight of approximately 68 lbs. (31 kg). Equipped with
a blower assembly the net weight is 70.5 lbs. (32kg) and the
shipping weight is 85 lbs. (39kg).

The following items are supplied with the Model 8329-300.

s

LC Female connector - input end

s

N Female connector - output end

1

Bird Model 8329-300 Tenuline Attenuator

Instruction Manual

s

Items

Required

Optional

Items

The following items are required to put the Model 8329-300
into service.

Multimeter

s

Screwdrivers

s

Matching connectors on the coaxial transmis-

s

sion line.

The following items are available as optional equipment.

Overload thermoswitch, P/N 8329-028, for pro-

s

tection against burnout.
Quick-Change connectors for convenient and

s

easy interchange with other “AN” type “QC”
connectors. Refer to the list in the Mainte­nance Chapter.

2

Specifications

Impedance: 50 ohms nominal
VSWR:

Input (dc-500MHz)
Output (dc-500MHz)

Connectors:

Input

1.1:1.0 maximum

1.15:1.0 maximum

Bird “QC” Type, Female LC nor­mally supplied

Introduction

Output

Power Range:

Without blower assembly:
With blower assembly:
With blower, but not running:

Frequency Range: dc-500MHz
Attenuation: 30dB ±0.5dB, dc-500MHz*
Calibration Frequencies (to ±0.2dB) 30, 100, 200, 300, 400 and

Dimensions: 23-1/4"L x 7-1/8"W x 17-3/16"H

Ambient Temperature: -40°C to +45°C (-40°F to +113°F)
Cooling Method:

Without blower assembly
With blower assembly

Weight:

Without blower assembly
With blower assembly

Operating Position: Horizontal only
Finish: Grey Powder Coat

*Special Attenuation Data to 1000MHz is available at time of order.

Bird “QC” Type, Female N normally
supplied.

2000W
4000W
1000W maximum

500MHz

(591 x 181 x 437mm)

Convection currents
Forced draft

57 lbs. (26kg)

70.5 lbs. (32kg)

3

Bird Model 8329-300 Tenuline Attenuator

FILLER AND VENT VALVE

Interlock Thermoswitch
(Optional)

Input Connector
Per Customer Order
Female "LC"
Normally Supplied

Model 8329-300 Outline Drawing

Figure 1

<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

2-61/64
(75mm)

<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

20-23/32 ±1/32

(526 ±.8mm)

MTG. HOLE CENTERS

THIS DIMENSION DEPENDENT UPON
Q.C. CONNECTOR USED.
(1-5/8 (41mm) FOR FEMALE "LC")

21-45/64
(551mm)

20-15/16
(532mm)

21-5/8

(549mm)

<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

17-3/16

(437mm)

<<<<<<<<<<<<<<<<<<

4-1/2 ±1/64

(114 ±.4mm)

MTG. HOLE

CENTERS

7-1/8

(181mm)

4

Chapter 2

Theory of Operation

The Model 8329-300 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 proportionately 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 8329-300 may be used for isolation of power
sources up to 2000 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.

5

Bird Model 8329-300 Tenuline Attenuator

Note: At the full power and frequency capabil-

+

ity of this model, refer to the Specifications,
only type LC, LT (Female or Male) or 7/8" EIA
(air line) connectors will be adequate on the in­put line.

6

Chapter 3

Operating Instructions

This chapter provides information for on-site requirements,
unpacking, inspection, and preparing the equipment for use.

Site and

Shelter

Requirements

Unpacking

and

Inspection

The Model 8329-300 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"
(300mm) of clearance around the unit, 6" (150mm) if it is
equipped with a blower, to permit 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.

Tools

Required

The following tools and supplies will be required to prepare
the unit for use.

s

Wrenches

s

Standard screwdrivers

s

9/16 Hex wrench (for thermoswitch installa­tion)

s

Pipe sealing compound (for thermoswitch in­stallation)

s

Soldering Iron and solder (for thermoswitch in­stallation)

7

Bird Model 8329-300 Tenuline Attenuator

Bolt and nut sets or lag screws (for mounting)

s

Mounting

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, 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 of
these flanges is a 3/8 inch 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 114.3mm). 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.

CAUTION

8

Vent Plug

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 the plug.

Before placing the attenuator into service, the solid shipping
plug must be removed and replaced by the spring loaded
vent plug. 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 O­Ring seal. Refer to figures 2 and 3 for plug identification.

Figure 2

Shipping Plug

Figure 3

Vent Plug

Operating Instructions

O-ring seal

O-Ring Seal

Thermo-

switch

As an optional item, the attenuator can be provided with a
thermoswitch assembly (P/N 8329-028). 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 of +200°C

(+392°F). Since the thermoswitch is connected in series with
the transmitter interlock, it cuts off the transmitter power if

the coolant temperature exceeds this value. The assembly
consists of:

s

Thermoswitch body - P/N 8329-027

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.

9

Bird Model 8329-300 Tenuline Attenuator

Note: Be very careful removing the iron pipe

+

plug, the threads in the socket hole are alumi­num, and can be easily damaged.

4. Replace the plug with the ther­moswitch. Use an acceptable pipe seal­ing compound sparingly only on the
external threads of the thermoswitch.

Note: Do not contaminate the coolant with pipe

+

sealing compound.

5. Check the unit for coolant leaks.

While following the instructions 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.

Figure 4

Thermoswitch

Assembly

10

A

D

F

C

E

H

B

G

Operating Instructions

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 wires 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.

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.

Blower

Assembly

For field installation of the blower assembly refer to the
blower instruction manual.

11

Bird Model 8329-300 Tenuline Attenuator

12

Chapter 4

Operating Instructions

There are no operating controls for the Model 8329-300
Attenuator. However, if it is equipped with a blower assem­bly, BA-300, there will be an ON/OFF switch and a
BLOWER ON indicator lamp on the assembly. Read and be­come familiar with the following instructions before operat­ing the unit.

Initial

Adjustments

Connection

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 self­drying, 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.

The front or input end of the attenuator is identified by the
four inch (102mm) 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.

13

Bird Model 8329-300 Tenuline Attenuator

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 (RG­218/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 the Installation Chapter.

Normal

Operation

14

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 the plug.

WARNING

Using this attenuator in the upper end of its power

dissipation range will cause the housing to become hot.

Care should be exercised in touching it.

CAUTION

This equipment is designed for operation in a

horizontal position only, with mounting brackets down.

Do not operate in any other manner.

CAUTION

RF power rating must always be cut in half when the

blower assembly is installed but is not running. Under

this conditiona2kWattenuator will be limited to

approximately 1 kW.

Operating Instructions

Because the Model 8329-300 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.

Operation

Under

Abnormal

Conditions

Shutdown

The Model 8329-300 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.
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.

This attenuator, being a passive device, cannot be shut off.
Only the optional blower can be shut off. The source of RF
energy must be turned off instead.

1. Turn off the source of RF power.

2. Let the blower run of at least five min­utes to adequately cool the radiator.

3. Turn off the blower.

Emergency

Shutdown

Turn off the RF power at the source.

15

Bird Model 8329-300 Tenuline Attenuator

16

Chapter 5

This chapter contains operator maintenance instructions,
troubleshooting, and parts information.

Troubleshooting

Problem Possible Cause Remedy

Leakage of Coolant Oil
around clamping band
or radiator housing.

Excessive overheating
of the radiator

High or low dc resis­tance values.

Maintenance

Clamping band not tight Tighten slightly with a

screwdriver.

Faulty O-Ring (input) Replace per the instruc-

tions in this Chapter.

Faulty O-Ring (output) Replace per the instruc-

tions in this Chapter.

Transmitter power too
high

Blower off or malfunc­tioning (if equipped).

Faulty RF section as­sembly

Coolant Oil level too
low

Faulty RF input connec­tor

Loose RF input connec­tor

Faulty RF section as­sembly

Reduce transmitter
power

Turn on blowers; con­sult troubleshooting in
the blower manual.

Replace per the instruc­tions in this chapter.

Add more coolant oil to
the radiator per the in­structions in this
chapter

Replace per the instruc­tions in this chapter

Tighten with a screw­driver

Replace per the instruc­tions in this chapter

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 on the radiator fin
spaces it should be cleaned.

17

Bird Model 8329-300 Tenuline Attenuator

Preparation:

Material: Lint-free cleaning cloth

s

Mild detergent

s

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

Measure dc

Resistance

Preparation:

s Tools: Common hand tools
s Multimeter 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 disconnec­tions are made.

18

2. Disconnect the RF coaxial line.

Figure 5

Meter Lead

Placement

Maintenance

3. Connect the multimeter test leads
across the center and outer conductor
of the load resistor. Refer to figure 5.

4. Record the value of the resistance be­fore the load is put into service. Com­pare the 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

Tools Required: Screwdriver

The connector is a “Quick-Change” design which permits
easy interchange with the use of only a screwdriver. For re­placement, proceed as follows:

1. Remove and retain the four screws
from the corners of the RF connector.

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.

19

Bird Model 8329-300 Tenuline Attenuator

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" (82.5mm) 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

Replacing

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.

To replace all of the coolant use the following procedure:

1. Remove the rear (output) connector.

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 coolant. The volume of the
coolant is 2.9 gallons (11 liters), so the
container must be at least a three gal­lon size, and preferably five gallons.

20

Maintenance

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.

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.

+ 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
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.

21

Bird Model 8329-300 Tenuline Attenuator

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.

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.

22

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

Maintenance

Sales /

Repair

Facilities

Sales

Facilities

RF Section

Assembly

Complete

Unit

U.S.A. Sales and Manufacturing

Service Group
Bird Electronic Corporation
30303 Aurora Road
Cleveland (Solon), Ohio 44139-2794
Phone: [phone]
Fax: [phone]

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

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.

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.

23

Bird Model 8329-300 Tenuline Attenuator

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.

Replacement Parts List

Qty. Description Part Number

1 RF Section Assembly 8329-302
1 Radiator Assembly 8329-307

Coolant - 2.9 gallons (11 liters) 5-1070-2 (1

1 “QC” Connector *See Below
1 Clamp Band Assembly 2430-043
1 O-Ring Seal, Input 5-230
1 O-Ring Seal, Output 5-243
1 Vent Plug 2450-094
1 Shipping Plug 2450-049
1 O-Ring, Vent and Shipping Plug 5-504
1 Chain Assembly 8180-094

gallon)

24

*Available “QC” Type Connectors

N-Female
(output)

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)
7/8” EIA Air

Line

Normally Supplied

4240-062 LT-Female 4240-018

4240-031 UHF-Female

(SO-239)

4240-002

4240-050

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.