Johnson DM3474 User manual

HIGH SPECIFICATION DATA TRANSCEIVER
PART NO. 242-3474-XX0
Second Printing
August 1998
Part No. 001-3474-002 8-98 Printed in U.S.A.

HIGH SPECIFICATION DATA TRANSCEIVER
PART NO. 242-3474-XX0
Copyright1998 by the Johnson Data Telemetry Corporation.
The Johnson Data Telemetry Corporation designs and manufactures radios and radio modems to serve a wide variety of data
communication needs. The Johnson Data Telemetry Corporation produces equipment for the fixed data market including
SCADA systems for utilities, petrochemical, waste and fresh water management markets and RF boards for OEM applications
in the Radio Frequency Data Capture market.
DATA TELEMETRY PRODUCT WARRANTY
The manufacturer's warranty statement for this product is available from your product supplier or from the Johnson Data
Telemetry Corporation, 299 Johnson Avenue, Box 1733, Waseca, MN 56093-0833. Phone [phone].
WARNING
This device complies with Part 15 of the FCC rules. Operation is subject to the condition that this device does not cause
harmful interference. In addition, changes or modification to this equipment not expressly approved by Johnson Data
Telemetry Corporation could void the user's authority to operate this equipment (FCC rules, 47CFR Part 15.19).
DO NOT allow the antenna to come close to or touch, the eyes, face, or any exposed body parts while the radio is transmitting.
DO NOT operate the radio near electrical blasting caps or in an explosive atmosphere.
DO NOT operate the radio unless all the radio frequency connectors are secure and any open connectors are properly
terminated.
DO NOT allow children to operate transmitter equipped radio equipment.
SAFETY INFORMATION
Proper operation of this radio will result in user exposure below the Occupational Safety and Health Act and Federal
Communication Commission limits.
The information in this document is subject to change without notice.
is a trademark of the Johnson Data Telemetry Corporation.

i
TABLE OF CONTENTS
1GENERAL INFORMATION
1.1 SCOPE OF MANUAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-1
1.2 EQUIPMENT DESCRIPTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-1
GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
DM3474 SYNTHESIZER PROGRAMMING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.3 TRANSCEIVER IDENTIFICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-1
1.4 PART NUMBER BREAKDOWN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-2
1.5 ACCESSORIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-2
1.6 FACTORY CUSTOMER SERVICE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-2
1.7 PRODUCT WARRANTY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-3
1.8 REPLACEMENT PARTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-3
1.9 IF A PROBLEM ARISES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4
FACTORY REPAIR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4
GENERAL SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-5
2INSTALLATION
2.1 PRE-INSTALLATION CHECKS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-1
2.2 INTERFACING WITH DATA EQUIPMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-1
DM3474 ONLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-1
3PROGRAMMING
3.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1
3.2 DM3474 SYNTHESIZER DATA PROTOCOL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1
D-WORD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1
B-WORD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-2
A-WORD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-2
3.3 RECEIVE TO TRANSMIT SEQUENCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-6
3.4 TRANSMIT TO RECEIVE SEQUENCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-7
4CIRCUIT DESCRIPTION
4.1 GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1
SYNTHESIZER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1
RECEIVER. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1
TRANSMITTER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-2
4.2 SYNTHESIZER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-2
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-2
VOLTAGE-CONTROLLED OSCILLATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-5
VCO AND REFERENCE OSCILLATOR MODULATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-6
CASCODE AMPLIFIERS (Q851/Q852). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-6
AMPLIFIER (Q853) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-6
VOLTAGE FILTER (Q832) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-6
VCO FREQUENCY SHIFT (Q831) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-6
SYNTHESIZER INTEGRATED CIRCUIT (U801) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-7
LOCK DETECT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-7

TABLE OF CONTENTS
ii
4.3 RECEIVER CIRCUIT DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8
HELICAL FILTER (Z201), RF AMPLIFIER (Q201) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8
MIXER (U221), FIRST LO AMPLIFIER (Q301) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8
AMPLIFIER (Q222), CRYSTAL FILTER (Z221/Z222), IF AMP (Q221). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8
SECOND LO AMP/TRIPLER (Q401), SECOND IF FILTER (Q901). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9
SECOND MIXER/DETECTOR (U241) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9
4.4 TRANSMITTER CIRCUIT DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-10
BUFFER (Q851). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-10
PRE-DRIVER (Q501), DRIVER (Q521). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11
-5V POWER CONTROL SUPPLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11
FINAL (Q541), POWER CONTROL (U542) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11
ANTENNA SWITCH (CR561, CR562). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11
5SERVICING
5.1 GENERAL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
PERIODIC CHECKS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
SURFACE-MOUNTED COMPONENTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
SCHEMATIC DIAGRAMS AND COMPONENT LAYOUTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
REPLACEMENT PARTS LIST. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
TCXO MODULE NOT SERVICEABLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
5.2 SYNTHESIZER SERVICING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
REFERENCE OSCILLATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2
VCO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2
SYNTHESIZER (U801). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2
5.3 RECEIVER SERVICING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3
SUPPLY VOLTAGES AND CURRENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3
MIXER/DETECTOR (U201). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3
RF AMPLIFIER (Q201) AND FIRST MIXER (Q221). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4
RF AND IF AMPLIFIERS, FIRST MIXER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4
5.4 TRANSMITTER SERVICING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4
SUPPLY VOLTAGES AND CURRENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4
6ALIGNMENT PROCEDURE AND PERFORMANCE TESTS
6.1 GENERAL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
6.2 DL3474 TRANSCEIVER ONLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
FREQUENCY AND CONTROL LINE VOLTAGE CHECK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
2W TRANSMITTER POWER ALIGNMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
LOW POWER ALIGNMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2
MODULATION FLATNESS ALIGNMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3
RECEIVER ALIGNMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4
IF AND AUDIO ADJUSTMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4
7PARTS LIST

TABLE OF CONTENTS
iii
8SCHEMATICS AND COMPONENT LAYOUTS
VCO COMPONENT LAYOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-2
TRANSCEIVER COMPONENT LAYOUT-COMPONENT SIDE VIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3
TRANSCEIVER COMPONENT LAYOUT-OPPOSITE SIDE VIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-4
TRANSCEIVER SCHEMATIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-5
LIST OF FIGURES
3-1 D-WORD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
3-2 B-WORD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
3-3 A-WORD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
3-4 SERIAL INPUT WORD FORMAT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5
3-5 RX TO TX TIMING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6
3-6 TX TO RX TIMING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7
4-1 DATA TRANSCEIVER BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
4-2 U801 SYNTHESIZER BLOCK DIAGRAM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4
4-3 U241 BLOCK DIAGRAM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9
5-1 RECEIVER SERVICING FLOWCHART . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4
5-2 TRANSMITTER SERVICING FLOWCHART . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5
6-1 TRANSMITTER TEST SETUP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2
6-2 RECEIVER TEST SETUP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4
6-3 ALIGNMENT POINTS DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-6
8-1 VCO COMPONENT LAYOUT (COMPONENT SIDE VIEW). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-2
8-2 TRANSCEIVER COMPONENT LAYOUT (COMPONENT SIDE VIEW) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3
8-3 TRANSCEIVER COMPONENT LAYOUT (OPPOSITE COMPONENT SIDE VIEW) . . . . . . . . . . . . . . . . . . . . 8-4
8-4 TRANSCEIVER SCHEMATIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-5
LIST OF TABLES
1-1 ACCESSORIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

TABLE OF CONTENTS
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SECTION 1
1-1
Part No. 001-3474-002
GENERAL INFORMATION
1.1 SCOPE OF MANUAL
This service manual contains alignment and service information for the Johnson Data Telemetry (JDT)
DM3474 UHF High Specification Data Module Transceiver.
1.2 EQUIPMENT DESCRIPTION
1.2.1 GENERAL
The JDT DM3474 is a synthesized data transceiver (transmitter and receiver) which operates in the 403-512
MHz UHF frequency range. Transmitter power output is 2 watts nominal, and operation is simplex or half duplex.
Versions of the 3474 covered in this manual are indicated in Section 1.4. The 3474 has a frequency stability of
±1.5 PPM (see Section ).
The number of channels that can be selected with the DM3474 model is determined by the customer supplied
synthesizer loading circuitry.
1.2.2 DM3474 SYNTHESIZER PROGRAMMING
The DM3474 requires customer supplied circuitry to load the synthesizer with channel information. The
protocol that this circuitry must follow is described in Section .
1.3 TRANSCEIVER IDENTIFICATION
The transceiver identification number is printed on a label that is affixed to the PC board. The following
information is contained in that number:
3474 2A1 4 3 A12345
Model Revision
Letter Manufacture Date
Week No.
of Year Year
Plant Warranty Number
Eighth Digit
of PN
Range

GENERAL INFORMATION
1-2
Part No. 001-3474-002
1.4 PART NUMBER BREAKDOWN
The following is a breakdown of the part number used to identify this transceiver:
1.5 ACCESSORIES
Accessories available for the 3474 data transceiver are listed in Table 1-1.
1.6 FACTORY CUSTOMER SERVICE
The Customer Service Department at JDT provides customer assistance on technical problems and the
availability of local and factory repair facilities. Customer Service hours are 7:30 a.m. - 4:30 p.m. Central Time,
Monday - Friday. From within the continental United States, the Customer Service Department can be reached at
this toll-free number
1-800-992-7774
Table 1-1 ACCESSORIES
Accessory Part No.
MCX to SMA RF cable 023-3472-009
242-3474 - X Y Z 0 = Base
2 = Portable
1 = 12.5 kHz BW
2 = 20 kHz BW
3 = 25 kHz BW
9 = 25 kHz BW *
8 = 12.5 kHz BW *
* This number applies to 450-470 MHz transceivers.
8 = 496-512 MHz
7 = 480-496 MHz
6 = 464-480 MHz
5 = 450-466 MHz, 450-470 MHz
4 = 435-451 MHz
3 = 419-435 MHz
2 = 403-419 MHz
1 = 380-403 MHz

GENERAL INFORMATION
1-3
Part No. 001-3474-002
When your call is answered at JDT, you will hear a brief message that contains the options: “1” for Sales, “2”
for Order Entry, “3” for Customer Service, “4” for Marketing, “7” for other issues, or “9” to repeat the message.
When you enter a first number of “3”, you may enter “1” for Technical Assistance, “2” for Product Repair or
“3” for Warranty. This number may be entered during or after the message using a tone-type telephone. If you have
a pulse-type telephone wait until the message is finished and an operator will come on the line to assist you. You
can enter the four digit extension number of the person that you want to reach at any time. If you are calling from
outside the continental United States, the Customer Service numbers are:
Customer Service Department - [phone]
FAX Machine - Cust Serv(507) 835-6969
You can contact the Customer Service Department by mail or email. Please include any information that may
help solve your problem. The mailing or email addresses are:
Johnson Data Telemetry Corporation
Customer Service Department
299 Johnson Avenue
P.O. Box 1733
Waseca, MN 56093-0514
[email protected]
1.7 PRODUCT WARRANTY
The warranty statement for this transceiver is available from the Warranty Department at JDT (see address or
telephone number in Section 1.6). The Warranty Department may also be contacted for Warranty Service Reports,
claim forms, or any questions concerning warranties or warranty service.
1.8 REPLACEMENT PARTS
Replacement parts can be ordered directly from the Service Parts Department. To order parts by phone, dial
the toll-free number and then enter “3” as described in Section 1.6. When ordering, please supply the part number
and quantity of each part ordered. JDT customers should give their account number.If there is uncertainty about
the part number, include the model number of the equipment the part is from (refer to Section 1.3).
You can send your order by mail or FAX (see Section 1.6 for mailing address). Mail orders should be sent to
the Service Parts Department.
FAX Machine - Sales [phone]

GENERAL INFORMATION
1-4
Part No. 001-3474-002
1.9 IF A PROBLEM ARISES...
JDT products are designed for long life and failure-free operation. If a problem arises, factory service is
available. Contact the Customer Service Department before returning equipment. A service representative may
suggest a solution eliminating the need to return equipment.
1.9.1 FACTORY REPAIR
Component level repair is not recommended on the DM3474 Transceiver. Surface mount technology is used
to install many components that require specialized training and equipment to service board level components.
JDT’s factory is best equipped to diagnose problems and make component level repairs.
When returning equipment for repair, fill out a Factory Request Form for each unit to be repaired regardless of
warranty status. These forms are available free of charge by calling Customer Service (see Section 1.6). Describe
the problem in the space provided and note any prior physical damage to the equipment. Include a form in the
shipping container with each unit. Your phone number and contact name are important. There are times when
technicians have specific questions that need to be answered in order to identify the problem and repair the
equipment.
When returning equipment for repair, use a reference number on your paperwork in case you need to call
Customer Service about your unit. That number is referenced on the repair order to make it easier to locate your
unit in the lab.
Return authorization (RA) numbers are not necessary unless you have been given one by the Customer
Service Department. They require RA numbers for exchange units or if they want to be aware of a specific
problem. If you have been given an RA number, reference this number of the Factory Repair Request Form sent
with the unit. The repair lab will contact the Customer Service Department when the unit arrives.

GENERAL INFORMATION
1-5
Part No. 001-3474-002
The following are general specifications intended for use in testing and servicing this transceiver. For current
advertised specifications, refer to the specification sheet available from the Marketing Department. Specifications
are subject to change without notice.
GENERAL
Frequency Range 403-512 MHz
Frequency Control Synthesized
Channel Spacing 12.5/20/25 kHz
Mode of Operation Simplex or Half Duplex
Operating Voltage +7.5V DC ±10%
Regulated Supply Voltages +5V DC ±5%
RF Input/Output MCX Jack
Power and Data Interface 14-pin in-line socket, 100 mil center
Operating Temperature -30°to +60°C (-22°to +140°F)
Maximum Dimensions 2.83" L (7.19 cm), 2.19" W (5.56 cm), 0.64" H (1.70 cm)
Weight (w/o Loader Bd) 2.3 oz (65 g)
FCC Compliance DM3474 customer must apply
RECEIVER
Bandwidth 16 MHz
Frequency Stability ±1.5 PPM
Sensitivity - 12 dB SINAD 0.45 µV
RF Input Impedance 50 ohms
Spurious and Image Rejection -70 dB
Selectivity -60 dB (12.5 kHz), -70 dB (20/25 kHz)
Intermodulation -70 dB
FM Hum and Noise -40 dB (12.5 kHz), -45 dB (20/25 kHz)
Conducted Spurious -57 dBm
Receive Current Drain < 70 mA nominal
Receive Attack Time < 7 ms (dependent on synthesizer loading implementation)
Audio
Distortion < 3%
Output Level DM3474 600-1200 mV P-P or 200-400 mV RMS (1 kHz at ±3 kHz)
Response
DM3474 ±2 dB from DC to 5 kHz (reference to 1 kHz)
Minimum Load Impedance 1k ohms
TRANSMITTER
Bandwidth 16 MHz
Frequency Stability ±1.5 PPM
TCXO Coupling DC
RF Power Output 2W nominal adjustable to 500 mW (-XX0)
500 mW nominal
RF Output Impedance 50 ohms
Modulation Distortion < 3%

GENERAL INFORMATION
1-6
Part No. 001-3474-002
Duty Cycle 50%, 60 seconds maximum transmit
Transmitter Attack Time < 7 ms (dependent on synthesizer implementation)
Spurious and Harmonic FM -37 dBm
FM Hum and Noise -40 dB 12.5 kHz, -45 dB 25 kHz
Audio Response ±1.5 dB from DC to 5 kHz (reference to 1 kHz)
Programmable to ±1 dB at the RF band edges via J201, pin 14.
Data Input Impedance 100k ohm
Modulation Response ±1 dB from DC to 5 kHz (reference to 1 kHz)
Current Drain < 800 mA at 2W, +7.5V DC

SECTION 2
2-1
Part No. 001-3474-002
INSTALLATION
2.1 PRE-INSTALLATION CHECKS
Field alignment should not be required before the 3474 is installed. However, it is a good practice to check
the performance to ensure that no damage occurred during shipment. Performance tests are located in Section 6.2.
2.2 INTERFACING WITH DATA EQUIPMENT
2.2.1 DM3474 ONLY
Connector J201 on the data transceiver PC board provides the interface with the data equipment. This is a 14-
pin female connector with .025" square pins on 0.1" centers (Dupont 76308-114).
The following is a general description of the various J201 input and output signals.
Pin 1 (Ground) - Chassis ground.
Pin 2 (+7.5V DC Continuous) - This voltage should be stabilized near +7.5V DC. Variations from +6V to +9V can
change power output as much as 6 dB.
Pin 3 (+7.5V DC Transmit) - This input should be +7.5V DC in transmit mode only.
Pin 4 (+5V DC Receive Control Line) - This input should be +5V DC in the receive mode only, ≤0.3 V DC in Tx,
input impedance ≥10k ohms.
Pin 5 (+5V DC Continuous) - This voltage should be stabilized near +5V DC.
Pin 6 (Tx Input) - Provides a response of ±1.5 dB from DC to 5 kHz. The sensitivity is approximately 7 kHz
deviation per volt RMS. When this input is used, a temperature compensated 2.5V DC bias is required because
variations in voltage cause the frequency to change. In addition, the transceiver regulatory compliance must be
applied for with the customer supplied modulation limiting/filter circuit and chassis.
Pin 7 (Synthesizer Lock) - Output from synthesizer lock detect circuit. Low = unlocked, high = locked.
Pin 8 (Synthesizer Enable) - Latch enable signal. A rising edge on this input latches the data loaded into synthesizer
IC U801.
Pin 9 (Synthesizer Data) - Serial data line used for programming synthesizer IC U801.
Pin 10 (Synthesizer Clock) - Software generated serial clock. Data is valid on the rising edge of this signal.

INSTALLATION
2-2
Part No. 001-3474-002
Pin 11 (Carrier Detect) - This output is not used at this time.
Pin 12 (RSSI Output) - The RSSI (Receive Signal Strength Indicator) output provides a voltage that increases in
proportion to the strength of the RF input signal.
Pin 13 (Rx Output) - The data output level is 600-1200 millivolts P-P (200-400 mV RMS) with a modulation signal
of 1 kHz at 60% of maximum deviation. The output is DC coupled and referenced to +2.5V DC. Load impedance
should be 10k-100k ohms.

SECTION 3
3-1
Part No. 001-3474-002
PROGRAMMING
3.1 INTRODUCTION
The information in Section 3.2 describes synthesizer programming protocol. This information can be used as
a basis for designing the synthesizer programming hardware and software required.
3.2 DM3474 SYNTHESIZER DATA PROTOCOL
Programming of the dividers and the charge pumps are performed on a 3-line bus; SYNTH ENABLE,
SYNTH DATA, AND SYNTH CLK. On initial power up three 34-bit words are required to load the 3474 Data
Transceiver. After the initial load, one 32-bit word can be used to change channels.
The SA7025 Synthesizer IC uses four address words; D, C, B and A (see Figure 3-4). The C word is not used
in the 3474. The 24- and 32-bit words contain one or four address bits, depending on the address bits, the data is
latched into registers. When the A-word is loaded, the data of these temporary registers is loaded together with the
A-word into the work
registers.
3.2.1 D-WORD
Refer to Figure 3-1.
TCXO Reference Frequency is 17.5 MHz.
Loop Reference Frequency is 50 kHz.
Reference Divide (NR) = 17.5 MHz ÷50 kHz =350 Decimal or 000101011110 Binary.
The 3474 has frequency resolution of 6.25 kHz and 10 kHz. When programming 6.25 kHz frequency
resolution use FMOD=8. When programming 10 kHz frequency resolution use FMOD=5.
Example:
(FCM) ÷FMOD = 50 kHz ÷8 = 6.25 kHz
(FCM) ÷FMOD = 50 kHz ÷5 = 10 kHz
Where:
FCM = Loop Reference Frequency
FMOD = Fractional N Modulus
Since FMC is the same for both 6.25 kHz and 10 kHz the loop dynamics are very similar and the same loop
filter values can be used.

PROGRAMMING
3-2
Part No. 001-3474-002
3.2.2 B-WORD
The B-Word is 24-bits long (see Figure 3-2). It contains the Address, Charge Pump setting factor (CN),
Binary Acceleration factors (CK, CL), and Prescaler Type (PR).
The Charge Pump Current setting (CN) could be changed on a channel-by-channel basis for ultimate rejection
of the Fraction N spurious responses close into the carrier frequency. The 3474 synthesizer has an adjust (R855)
for the fractional compensation current. The factory preset value will allow CN to be set to the following ranges:
Frequency in a Band CN
Lowest TX 86
Highest TX 90
Lowest RX 96
Highest RX 100
The value of CN should be interpolated for frequencies between the band edges. With these recommended
values of CN, the transceiver should have the fractional spurs minimized far below the levels needed to make ETSI
70 dB adjacent channel RX or TX
specifications.
Example:
Model 3474-530 is a 450-466 MHz transceiver.
458 MHz TX CN = 88 01011000 Binary
458 MHz RX CN = 98 01100010 Binary
3.2.3 A-WORD
The A-Word must be sent last (see Figure 3-3). The A-Word contains new data for the loop dividers and is
programmed for every channel. The A-Word can be a 24-bit or 32-bit word depending on the state of the flag
LONG in the D-Word. The 24-bit word (A0) is sent if LONG=0 and the 32-bit word (A1) is sent if LONG=1. The
extra 8-bits in A1 are the CN charge pump settings. Upon power up the D-, B- and A-Words must be sent, but after
that only the A1 word needs to be sent.
The Fractional-N increment (NF) is a 3-bit word that is channel dependent. NF is used to program the sub-
channels below the 50 kHz Loop Reference frequency. FCM = 50 kHz and if FMOD = 8, then the Fractional-N
increment is: 50 kHz ÷8 = 6.25 kHz
To program an 18.75 kHz channel:
NF = 18.75 kHz ÷6.25 kHz
NF = 3

PROGRAMMING
3-3
Part No. 001-3474-002
NM1 and NM2 are calculated as follows:
N = (NM1 + 2) x 64 + NM2 x 65 Where: N = total division ratio
NM1 = Number of main divider cycles when prescaler modulus equals 64
NM2 = Number of main divider cycles when prescaler modulus equals 65
Example:
Calculate NM1 and NM2 to Receive 454.500 MHz.
LO = 454.5 + 52.95 = 507.45 MHz
(52.95 MHz IF with High Side Injection)
N = RX LO ÷FCM = 507.45 ÷0.05 = 10149
(FMC = Loop Reference Frequency)
NM2 = 64 x FRAC [N ÷64]
= 64 x FRAC [10149 ÷64]
= 64 x 0.57813
= 37
NM1 = INTEGER [N ÷64] - 2 - NM2
= 158 - 2 - 37
= 119
Figure 3-1 D-WORD

PROGRAMMING
3-4
Part No. 001-3474-002
Figure 3-2 B-WORD
Figure 3-3 A-WORD