Tait TB7100 User manual

TB7100 base station
Service Manual
MBB-00005-01
Issue 1
October 2005

2TB7100 Service Manual
© Tait Electronics Limited October 2005
Tait Contact Information
Tait Radio Communications
Corporate Head Office
Tait Electronics Ltd
P.O. Box 1645
Christchurch
New Zealand
For the address and telephone number of
regional offices, refer to the TaitWorld
website:
Website: http://www.taitworld.com
Technical Support
For assistance with specific technical issues,
contact Technical Support:
E-mail: [e-mail]
Website: http://support.taitworld.com
To our European customers:
Tait Electronics Limited is an environmentally responsible company which
supports waste minimization and material recovery. The European Union’s
Waste Electrical and Electronic Equipment Directive requires that this
product be disposed of separately from the general waste stream when its
service life is over. Please be environmentally responsible and dispose
through the original supplier, your local municipal waste “separate
collection” service, or contact Tait Electronics Limited.

TB7100 Service Manual 3
© Tait Electronics Limited October 2005
Contents
Tait Contact Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Scope of Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Hardware and Software Versions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Enquiries and Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Updates of Manual and Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Copyright . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Disclaimer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Associated Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Publication Record . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Alert Notices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Abbreviations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.1 Frequency Bands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.2 RF Output Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.3 Product Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2 Mechanical Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.1 Tray. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.2 UI Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.3 Receiver Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.4 Transmitter Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.5 SI Board. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3 Functional Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.1 Receiver Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.1.1 RF Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
3.1.2 Digital Baseband Processing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.1.3 Audio Processing and Signalling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.2 Transmitter Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.2.1 Audio Processing and Signalling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.2.2 Frequency Synthesizer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
3.2.3 RF Power Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
3.3 User Interface Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.4 System Interface Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
3.4.1 Internal Power Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
3.4.2 Serial Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
3.4.3 General Purpose IO. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
3.4.4 Receiver Audio Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

TB7100 Service Manual 4
© Tait Electronics Limited October 2005
3.4.5 Tone On Idle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
3.4.6 Transmitter Audio Processing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3.4.7 Opto Isolated Keying. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3.4.8 Relay Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3.4.9 Fan Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3.4.10 RSSI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3.4.11 Receiver Gate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3.4.12 Receiver Inhibit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3.5 Fan Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4 Circuit Descriptions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
4.1 Transmitter Circuitry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
4.2 Receiver Circuitry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
4.3 Frequency Synthesizer Circuitry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
4.4 Frequency Control Loop. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
4.5 CODEC and Audio Circuitry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52
4.6 Power Supply Circuitry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
4.7 Interface Circuitry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
4.8 Digital Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
5 Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
5.1 External Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
5.2 Internal Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
5.2.1 Transmitter and Receiver Connectors . . . . . . . . . . . . . . . . . . . . . . . . 68
5.2.2 SI Board Connectors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
5.2.3 UI Board Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73
6 General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
6.1 Repair Levels and Website Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
6.2 Tools, Equipment and Spares . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
6.3 Servicing Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
6.4 Test Equipment Setup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .82
6.5 Replacing Board Components. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
6.6 Shielding Cans and Connectors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
6.7 SMT Repair Techniques. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
6.8 Computer-Controlled Test Mode (CCTM). . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
6.9 Visual Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
7 Disassembly and Reassembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
7.1 Removing the Base Station and Opening the Tray. . . . . . . . . . . . . . . . . . . . . . 100
7.2 Replacing the UI Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
7.3 Replacing the Receiver Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

TB7100 Service Manual 5
© Tait Electronics Limited October 2005
7.4 Replacing the Transmitter Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
7.5 Disassembling the Transmitter Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
7.6 Reassembling the Transmitter Module. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
7.7 Replacing the SI Board. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
7.8 Replacing the Fans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
7.9 Replacing the Fan Power Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
7.10 Replacing the Temperature Sensor Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
7.11 Replacing the Speaker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
7.12 Final Reassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
8 Servicing Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .111
8.1 Initial Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
8.2 Final Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
9 Power Supply Fault Finding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .127
10 Interface Fault Finding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137
11 Frequency Synthesizer Fault Finding . . . . . . . . . . . . . . . . . . . . . . . . . . . . .143
11.1 Initial Checks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
11.2 Power Supplies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
11.3 Phase-locked Loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
11.4 Loop Filter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
11.5 Receive VCO and Related Circuitry (UHF Radios) . . . . . . . . . . . . . . . . . . . . 166
11.6 Transmit VCO and Related Circuitry (UHF Radios). . . . . . . . . . . . . . . . . . . . 175
11.7 VCO and Related Circuitry (VHF Radios) . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
11.8 Power Supply for FCL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
11.9 VCXO and TCXO Outputs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
11.10Signals at TP501 and TP502. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
11.11VCXO and CODEC Circuitry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
12 Receiver Fault Finding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .201
12.1 Faulty Receiver Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
12.2 Excessive Loss of Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204
12.3 Moderate or Slight Loss of Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208
12.4 Incorrect RSSI Readings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
12.5 Faulty Radio Mute. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
12.6 High Receiver Distortion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216

TB7100 Service Manual 6
© Tait Electronics Limited October 2005
13 Transmitter Fault Finding (25W). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .219
13.1 Power Supplies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
13.2 Transmitter RF Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228
13.3 Biasing of PA Driver and PAs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
13.4 RF Signal Path. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258
14 Transmitter Fault Finding (50W/40W). . . . . . . . . . . . . . . . . . . . . . . . . . . .273
14.1 Power Supplies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276
14.2 Transmitter RF Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285
14.3 Biasing of PA Driver and PAs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297
14.4 RF Signal Path. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320
15 CODEC and Audio Fault Finding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .343
15.1 Power Supplies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 344
15.2 Faulty Speaker Audio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 347
15.3 No Speaker Audio at Auxiliary Connector. . . . . . . . . . . . . . . . . . . . . . . . . . . . 354
15.4 Faulty Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 359
15.5 Faulty Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 362
15.6 Faulty Modulation Using Auxiliary Connector. . . . . . . . . . . . . . . . . . . . . . . . . 366
16 Spare Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .369
Tait General Software Licence Agreement . . . . . . . . . . . . . . . . . . . . . . . . . . . .371

TB7100 Service Manual 7
© Tait Electronics Limited October 2005
Preface
Scope of Manual
This manual contains information to service technicians for carrying out
level-1 and level-2 repairs of the TB7100 base station.
Level-1 repairs entail the replacement of faulty parts and circuit boards;
level-2 repairs entail the repair of the transmitter and receiver modules, with
the exception of certain special items on the boards. The manual does not
cover level-3 repairs, which entail the repair of the special items.
For more information on repair levels and serviceable parts, refer to
“General Information” on page 75.
Hardware and Software Versions
This manual describes the following hardware and software versions.
The IPNs (internal part numbers) of the transmitter and receiver boards are
listed below; the last two digits in the IPN represent the issue of the board.
■B1 band, 25W : 220-01700-10
■H5 and H6 bands, 25W : 220-01697-10
■B1 band, 50W : 220-01723-02
■H5 and H7 bands, 50W/40W : 220-01722-02
■Programming application : version 1.06
■Calibration application : version 1.03
Enquiries and Comments
If you have any enquiries regarding this manual, or any comments,
suggestions and notifications of errors, please contact Technical Support
(refer to “Tait Contact Information” on page 2).
Updates of Manual and Equipment
In the interests of improving the performance, reliability or servicing of the
equipment, Tait Electronics Ltd reserves the right to update the equipment
or this manual or both without prior notice.

8TB7100 Service Manual
© Tait Electronics Limited October 2005
Copyright
All information contained in this manual is the property of
Tait Electronics Ltd. All rights are reserved. This manual may not, in whole
or in part, be copied, photocopied, reproduced, translated, stored, or
reduced to anyelectronicmediumormachine-readable form,withoutprior
written permission from Tait Electronics Ltd.
All trade names referenced are the service mark, trademark or registered
trademark of the respective manufacturers.
Disclaimer
There are no warranties extended or granted by this manual.
Tait Electronics Ltd accepts no responsibility for damage arising from use of
the information contained in the manual or of the equipment and software
it describes. It is the responsibility of the user to ensure that use of such
information, equipment and software complies with the laws, rules and
regulations of the applicable jurisdictions.
Associated Documentation
The following associated documentation is available for this product:
■MBB-00001-xx TB7100 Installation and Operation Manual
■MBB-00002-xx TB7100 Specifications Manual
■MBB-00003-xx TB7100 Installation Guide
The characters xx represent the issue number of the documentation.
All available documentation is provided on the CD (406-00047-xx)
supplied with the base station. Updates may also be published on the Tait
support website.
Publication Record
Issue Publication Date Description
01 October 2005 first release

TB7100 Service Manual 9
© Tait Electronics Limited October 2005
Alert Notices
Within this manual, four types of alerts are given to the reader: warning,
caution, important and note. The following paragraphs illustrate each type
of alert and its associated symbol.
Warning!! This alert is used when there is a potential risk
of death or serious injury.
Caution This alert is used when there is the risk of minor or
moderate injury to people.
Important This alert is used to warn about the risk of equipment dam-
age or malfunction.
Note This alert is used to highlight information that is required to
ensure that procedures are performed correctly.
Abbreviations
Abbreviation Description
ACP Adjacent Channel Power
ADC Analog-to-Digital Converter
AGC Automatic Gain Control
ALC Automatic Level Control
ASC Accredited Service Centre
BOM Bill of Materials
CCTM Computer-Controlled Test Mode
CODEC Coder-Decoder
CSO Customer Service Organisation
DAC Digital-to-Analog Converter
DC Direct Current
DSP Digital Signal Processor
ESD Electrostatic Discharge
FCL Frequency Control Loop
FE Front-End

10 TB7100 Service Manual
© Tait Electronics Limited October 2005
FPGA Field-Programmable Gate Array
IC Integrated Circuit
IPN Internal Part Number
IF Intermediate Frequency
IQ In-Phase and Quadrature
ISC International Service Centre
LCD Liquid-Crystal Display
LED Light-Emitting Diode
LNA Low-Noise Amplifier
LO Local Oscillator
LPF Low-Pass Filter
PA Power Amplifier
PCB Printed Circuit Board
PLL Phase-Locked Loop
PTT Press-To-Talk
RISC Reduced Instruction Set Computing
RSSI Received Signal Strength Indication
SMD Surface-Mount Device
SMT Surface-Mount Technology
SMPS Switch-Mode Power Supply
SPI Serial Peripheral Interface
TCXO Temperature-Compensated Crystal Oscillator
TEL Tait Electronics Limited
VCO Voltage-Controlled Oscillator
VCXO Voltage-Controlled Crystal Oscillator
Abbreviation Description

TB7100 Service Manual Introduction 11
© Tait Electronics Limited October 2005
1Introduction
The TB7100 is a software and hardware link-configured base station which
is designed for operation in large variety of standard frequency ranges.
It makes extensive use of digital and DSP technology. Many operating
parameters such as channel spacing, audio bandwidth and signalling are
controlled by software.
This manual includesthe information required forservicing the base station.
This section describes the different options available for:
■frequency bands
■RF output power
■product codes
For specifications, refer to the specifications manual or the area on the
TaitWorld website reserved for TB7100 products.
1.1 Frequency Bands
The base station is available in the following frequency bands:
■136 to 174MHz (B1)
■400 to 470MHz (H5)
■450 to 530MHz (H6)
■450 to 520MHz (H7)
The RF band of the base station is implemented by the frequency band of
the transmitter and receiver modules.
Figure 1.1 TB7100 base station

12 Introduction TB7100 Service Manual
© Tait Electronics Limited October 2005
1.2 RF Output Power
The base station is available with 25W and 50W/40W RF output power.
The RF outputpower options are implemented by different transmitter and
receiver modules.
The 25W base station is available in the following frequency bands:
■B1
■H5
■H6
The 50W/40W base station is available in the following frequency bands:
■B1 (50W)
■H5 (40W)
■H7 (40W)
1.3 Product Codes
This section describes the product codes used to identify products of the
TB7100 base station product line.
The product codes of the TB7100 base station product line has the format:
TBBaabb-cdd-ee
where:
■aa identifies the frequency band of the transmitter:
B1=136 to 174MHz, H5=400 to 470MHz, H6=450 to 530MHz,
H7=450 to 520MHz
■bb identifies the frequency band of the receiver:
B1=136 to 174MHz, H5=400 to 470MHz, H6=450 to 530MHz,
H7=450 to 520MHz
■cidentifies the RF output power:
A=25W, B=50W/40W
■dd identifies the power supply option:
00=DC power supply
■ee identifies base station options:
00=no options

TB7100 Service Manual Mechanical Design 13
© Tait Electronics Limited October 2005
2 Mechanical Design
Overview The base station consists of the following main modules:
■tray b
■UI board (user interface) d
■receiver module h
■transmitter module i
■SI board (system interface) 1)
■duplexer (optional) 1!.
All modules and boards are mounted from above into the 1U tray b.
The modules are secured byscrews or clips into standoffs on the tray chassis,
and are easily removed for replacement.
The base station also includes two cooling fans fand a fan duct ein front
of the receiver and transmitter modules, a speaker cmounted behind the
front panel, a fan power board gmounted on the fan duct, and a
temperature sensor board jmounted on the heatsink of the transmitter
module i.
The modules and components are interconnected by looms and cables.
Figure 2.1 Parts of the base station
1!
g
i
1)
b
c
d
f
e
h
j

14 Mechanical Design TB7100 Service Manual
© Tait Electronics Limited October 2005
2.1 Tray
The 1U tray consists of a mild steel folded chassis and a flat cover (not
shown) which is fastened to the chassis with 15 Torx T10 screws. The tray
can be fitted into a standard 19 inch rack or cabinet using the two rack
mounting brackets.
The front panel has holes to accommodate the controls and the
microphone/programming connector of the UI board.
Therearpanelhasholestoaccommodatetheconnectors and thefuseholder
of the SI board, the antenna connectors, and a ground terminal.
For more information on the connections, refer to “Connections” on
page 63.
2.2 UI Board
The UI board is mounted behind the front panel with three Torx T10
screws cand two spring clips D. The UI board is connected to the
transmitter and receiver modules via the two Micro-MaTch connectors e
and the two UI cables (not shown). The UI board also has a speaker
connector b.
A volume knob is fitted to the shaft of the volume-control potentiometer.
Figure 2.2 UI board
e
d
c
b
Cables not shown.

TB7100 Service Manual Mechanical Design 15
© Tait Electronics Limited October 2005
2.3 Receiver Module
The receiver module is mounted in the front left of the tray with five Torx
T10 screws g.
The receiver module is a printed circuit board in SMT design with
components on the top and bottom sides.A digital board is reflow-soldered
to the receiver. Most components are shielded by metal cans.
There are different boards for each frequency band and each RF output
power configuration.
The RF b, DC power c, auxiliary d, and user interface f connectors are
located on the bottom side of the board. The internal options connector e
and a factory connector (not shown) for factory use are located on the top
side of the board.
For compliance reasons, there are different variants of the receiver module
for use in the 25W and 50W/40W base stations. The 25W version has a
white DC power connector Cand the 50W/40W version has a black DC
power connector.
For more information on the connectors, refer to “Connections” on
page 63.
Figure 2.3 Receiver module
g
g
f
bcd
g
e

16 Mechanical Design TB7100 Service Manual
© Tait Electronics Limited October 2005
2.4 Transmitter Module
The transmitter module consisting of a transmitter board fmounted on a
purpose-designed heatsink 1) is mounted in the left rear of the tray with
four Torx T10 screws (not shown).
The transmitter board is a printed circuit board in SMT design with
components on the top and bottom sides. A digital board is reflow-soldered
to the board. Most components are shielded by metal cans. There are
different boards for each frequency band and each RF output power
configuration.
The RF b, DC power c, auxiliary d, and user interface f connectors are
located on the bottom side of the board. The internal options connector e
and a factory connector (not shown) for factory use are located on the top
side of the board.
The 50W/40W version has a black DC power connector Cand the 25W
version has a white DC power connector. For more information on the
connectors, refer to “Connections” on page 63.
The board fis mounted to the heatsink 1) with seven Torx T10 screws
fand g.
AnL-shapedgappadiand(withthe 50W/40W version)arectangulargap
pad jare fitted between the board fand the heatsink 1) to improve heat
transfer.
Figure 2.4 Transmitter module
g
h
g
c
f
1)
D
b
e
j
i

TB7100 Service Manual Mechanical Design 17
© Tait Electronics Limited October 2005
2.5 SI Board
The SI board is mounted in the rear right of the tray with two Torx T10
screws j, one Pozidriv screw i, and two spring clips 1).
The SI board has the following external connectors:
■13.8V DC power connector (labelled 12V DC) b
■system connector (labelled SYSTEM) c
■serial data connector (labelled IOIOI) D.
The SI board has the following internal connectors:
■two system interface connectors e(to transmitter and receiver)
■two DC power output connectors h(to transmitter and receiver)
■fan control connector f(to fan power board on fan duct)
■temperature control connector g(to temperature sensor on transmitter
heatsink).
For more information on the connectors, refer to “Connections” on
page 63.
Figure 2.5 SI board
g
h
bc d
jj
i
1)
1) ef

18 Mechanical Design TB7100 Service Manual
© Tait Electronics Limited October 2005

TB7100 Service Manual Functional Description 19
© Tait Electronics Limited October 2005
3 Functional Description
This section describes some principles of the base station operation.
The descriptions are based on a 25W base station.
Figure 3.1 below shows the high-level block diagram of the base station.
It illustrates the main inputs and outputs for power, RF and control signals,
as well as the interconnection between modules.
■programdataandaudiofromthePROG/MIC socketon the UI boardtoand
from the transmitter and receiver modules
■audio and signalling from the SYSTEM connector to and from the
transmitter and receiver modules
■RS-232 data from the serial data connector (IOIOI) to and from the
transmitter and receiver modules
■fan power and control from the SI board
■power distribution from the DC power input connector to the
transmitter and receiver modules, and from the receiver module to the
UI board.
The circuitry of the individual modules that make up the base station is
described in more detail in the following sections.
Figure 3.1 Base station high-level block diagram
Receiver
Module
Transmitter
Module
Front
Panel/
UI Board
SI Board
Fans
DC Power connector
System Interface connector
Serial Data connector
Rx (RF Port)
Tx/ANT (RF Port)
Internal Power
UI/Rx
UI/Tx
Rx/SI
TX/SI
PROG/MIC
connector
Fan Control
Temp.
Sensor
Fused
Internal
Power

20 Functional Description TB7100 Service Manual
© Tait Electronics Limited October 2005
Frequency Bands
and Sub-bands The circuitry in the base station modules is common to all frequency bands,
and is therefore covered by a single description in this manual. Where the
circuitry differs between bands, separate descriptions are provided for each
frequency band. For more information refer to “Frequency Bands” on
page 11.
RS-232 Signals External data communications all occur directly between the connected
computer (or other electrical equipment) and the transmitter and receiver
modules over the RS-232 serial lines.
Fan Signals The power and ground signals for the fans are routed from the SI board to
the fans behind the front panel. These signals are electrically isolated from
allothersystemsignalstoensurefannoise isnottransferredtoothersensitive
system components.
Ifthereisafaultinthefancircuitry,the transmittermoduleisprotected from
overheating by its internal foldback circuitry.
Speaker Signal Received audio is sent from the receiver module to the UI board.
The volume is controlled by the volume potentiometer on the UI board.
The audio signal is then passed to the speaker for monitoring purposes.
Power and Ground The SI board provides power to the transmitter and receiver modules.
The receiver modules provides power to the UI board.
3.1 Receiver Operation
Parts of Receiver
Board The main circuit parts of the receiver modules are:
■receiver
■frequency synthesizer
■CODEC (coder-decoder) and audio circuitry
■power supply
■interface circuitry
Software plays a prominent role in the functioning of the radio.
When describing the operation of the radio the software must be included
with the above. This is considered further below.
These functional parts are described in detail below.