Hitachi ATT-20 Operating instructions

SM 6299
1000 Technology Drive, Pittsburgh, PA 15219
645 Russell Street, Batesburg, SC 29006
ATT-20 Audio Track Transceiver
STS USA Part Numbers
N454052-3901
through
N454052-3906
Installation
Operation
Troubleshooting

ATT-20 Audio Track Transceiver
Copyright 2019 SM 6299 Rev. 3, March 2019

ATT-20 Audio Track Transceiver
Copyright 2019 SM 6299 Rev. 3, March 2019 i
Proprietary Notice
This document and the information contained therein are
confidential – the disclosure or other communication, copying,
reproduction and any use whatsoever is forbidden without the
written authorization of Hitachi Rail STS USA, Inc.
Important Notice
STS USA constantly strives to improve our products and keep our customers apprised
of changes in technology. Following the recommendations contained in the attached
service manual will provide our customers with optimum operational reliability. The data
contained herein purports solely to describe the product, and does not create any
warranties.
Within the scope of the attached manual, it is impossible to take into account every
eventuality that may arise with technical equipment in service. Please consult an STS
USA local sales representative in the event of any irregularities with our product.
STS USA expressly disclaims liability resulting from any improper handling or use of our
equipment, even if these instructions contain no specific indication in this respect. We
strongly recommend that only approved STS USA spare parts are used as
replacements.
© Property of Hitachi Rail STS USA, Inc., 2019 all rights reserved– the copying,
reproduction and use of this work in any form whatsoever is forbidden without
the written authorization of Hitachi Rail STS USA, Inc.
1000 Technology Drive, Pittsburgh, PA USA 15219-3120
645 Russell Street, Batesburg, SC 29006
sts.hitachirail.com

ATT-20 Audio Track Transceiver
Copyright 2019 SM 6299 Rev. 3, March 2019 ii
Revision History
REV. DATE NATURE OF REVISION
0
April 1997
Initial issue
1.0 June 2008
Revised to current template.
Updated parts lists and drawings.
Incorporated ECO EE-1223 (2/00).
Miscellaneous minor grammatical
changes. Proof read comments
resolved.
2 December 2015
Revised Figure 1-1 and Figure 6-1 to
add R14 and label. Revised Table 6-4
and Figure 6-1 for items 126 and 127.
Revised Table 6-5 to correct ATT-20
Unit part numbers.
3
March 2019
Hitachi Rail STS Branding

ATT-20 Audio Track Transceiver
Copyright 2019 SM 6299 Rev. 3, March 2019 iii
Table of Contents
1. GENERAL INFORMATION ...............................................................................................................1-1
1.1. Introduction ............................................................................................................................... 1-1
1.2. Physical Description ................................................................................................................. 1-1
1.3. Specifications............................................................................................................................ 1-1
1.3.1. Power Requirements ....................................................................................................1-1
1.3.2. Transceiver Characteristics ..........................................................................................1-2
1.3.3. Receiver Characteristics...............................................................................................1-2
1.3.4. Miscellaneous ...............................................................................................................1-3
2. APPLICATION, INSTALLATION, AND ADJUSTMENTS ................................................................2-1
2.1. General ..................................................................................................................................... 2-1
2.2. Shunt Mode Track Circuit Application ...................................................................................... 2-1
2.3. Series Mode Track Circuit Application...................................................................................... 2-2
2.4. Terminal Connections............................................................................................................... 2-3
2.5. Mounting Requirements............................................................................................................ 2-3
2.6. General Considerations ............................................................................................................ 2-3
2.7. Shunt Mode Operation.............................................................................................................. 2-4
2.7.1. Shunt Mode Installation ................................................................................................2-4
2.7.2. Shunt Mode Adjustment ...............................................................................................2-5
2.8. Series Mode Operation............................................................................................................. 2-5
2.8.1. Series Mode Installation ...............................................................................................2-6
2.8.2. Series Mode Adjustment without Cable Compensating PCB.......................................2-6
2.8.3. Series Mode Adjustment with Cable Compensating PCB ............................................2-7
2.9. Lightning Protection .................................................................................................................. 2-7
3. FUNCTIONAL DESCRIPTION ..........................................................................................................3-1
3.1. General ..................................................................................................................................... 3-1
3.2. Shunt Mode Track Circuit ......................................................................................................... 3-1
3.3. Series Mode Track Circuit ........................................................................................................ 3-1
3.4. Detailed Circuit Description ...................................................................................................... 3-1
3.4.1. Transmitter....................................................................................................................3-1
3.4.2. Receiver........................................................................................................................3-2
4. FIELD MAINTENANCE .....................................................................................................................4-1
4.1. General ..................................................................................................................................... 4-1
4.2. Test Equipment......................................................................................................................... 4-1
4.3. General Checks ........................................................................................................................ 4-1
4.4. Shunt Mode Checks ................................................................................................................. 4-1
4.5. Series Mode Checks................................................................................................................. 4-3
5. SHOP MAINTENANCE .....................................................................................................................5-1
6. PARTS LISTS....................................................................................................................................6-1
6.1. ATT-20 Audio Track Receiver Kits ........................................................................................... 6-1

ATT-20 Audio Track Transceiver
Copyright 2019 SM 6299 Rev. 3, March 2019 iv
6.2. ATT-20 Audio Track Transceiver Units .................................................................................... 6-1
6.3. ATT-20 Audio Track Receiver Parts List .................................................................................. 6-2
6.4. Cable Compensating PCB Parts List........................................................................................ 6-5
7. RAIL TEAM AND TECHNICAL SUPPORT ......................................................................................7-1
List of Figures
Figure 1-1. ATT-20 Dimensions ......................................................................................................... 1-3
Figure 2-1. Shunt Mode Track Circuit Application.............................................................................. 2-1
Figure 2-2. Series Mode Track Circuit Application ............................................................................. 2-2
Figure 2-3. Lightning Arrester and Surge Ripple Filter for Shunt Mode Application .......................... 2-9
Figure 2-4. Lightning Arrester and Surge Ripple Filter for Series Mode Application .......................2-10
Figure 3-1. Transmitter PCB Schematic Diagram .............................................................................. 3-3
Figure 3-2. Receiver PCB Schematic Diagram .................................................................................. 3-5
Figure 4-1. ATT-20 Test Circuit for Shunt Mode Application ............................................................. 4-2
Figure 4-2. ATT-20 Test Circuit for Series Mode Application............................................................. 4-3
Figure 6-1. ATT-20 Parts Illustration .................................................................................................. 6-4
Figure 6-2. ATT-20 Wiring Diagram ................................................................................................... 6-5
Figure 6-3. Cable Compensating PCB Parts Layout and Schematic Diagram .................................. 6-6
List of Tables
Table 1-1. Adjacent Frequency Rejection ......................................................................................... 1-2
Table 2-1. Terminal Assignments...................................................................................................... 2-3
Table 2-2. Ring-by Parameters for 0.1 Ohm Shunting...................................................................... 2-5
Table 2-3. Cable Length vs. Frequency ............................................................................................ 2-6
Table 6-1. ATT-20 Unit Kits............................................................................................................... 6-1
Table 6-2. ATT-20 Unit (Only) ........................................................................................................... 6-1
Table 6-3. Miscellaneous Application Units ...................................................................................... 6-1
Table 6-4. ATT-20 Unit Parts List...................................................................................................... 6-2
Table 6-5. ATT-20 Part Tabulation.................................................................................................... 6-3
Table 6-6. Cable Compensating PCB Parts List ............................................................................... 6-5

ATT-20 Audio Track Transceiver
Copyright 2019 SM 6299 Rev. 3, March 2019 1-1
1. GENERAL INFORMATION
1.1. Introduction
This manual provides application, installation and maintenance information for the STS
USA Audio Track Transceiver, Model ATT-20.
The ATT-20 is a short-range transceiver operating in the audio frequency range of 12 to
20 KHz. The high frequency range was chosen to provide sharp block definition. The
ATT-20 can be used in applications such as highway crossings, island circuits, switch
lock release and general train detection in non-electrified and DC electrified territories.
In most cases, insulated joints are not required and track circuits up to 300 feet in length
can be realized. Units are available for operation in either shunt mode or series mode
applications.
1.2. Physical Description
The ATT-20 is a single unit transceiver containing separate transmitter and receiver
printed circuit boards, mounted on a common chassis. The chassis is housed in a sheet
metal box. The top cover of the unit is the faceplate to which Association of American
Railroads (AAR) terminal posts are mounted.
1.3. Specifications
1.3.1. Power Requirements
Power Supply Voltage: 9.8 - 15.2 VDC
Maximum Ripple: 1 Vpp
Load Current: 600 mA.
Fuse: 3 / 4 Amp fast blow

ATT-20 Audio Track Transceiver
Copyright 2019 SM 6299 Rev. 3, March 2019 1-2
1.3.2. Transceiver Characteristics
CAUTION
The ATT-20 may be operated from a constant potential
rectifier (CPR) supply, batteries floating on a CPR, or an
electronically regulated supply. Regardless of the supply
used, a surge ripple filter (STS USA N451590-0301) must be
used between the supply and the ATT-20 Transceiver.
Shunt Mode Output Voltage: 1.0 Vrms (modulated) into a 5-ohm load
Series Mode Output Voltage: 0.25 Vrms (modulated) into a 1-ohm load
Available Operating Frequencies: 12.28 KHz, 15.0 KHz, 20 KHz.
Carrier Frequency Tolerance: + 0.5 %
Modulation Frequency (All Units): 390 Hz + 0.5%
Harmonic Output: -30 dB at second harmonic with 12 ohm load in shunt
mode
7 ohm shunt mode; 1 ohm series mode
1.3.3. Receiver Characteristics
Sensitivity: 70 mVrms (modulated signal) + 14 mV
Input Impedance: 7 ohms shunt mode, 1 ohm series mode
Output Voltage: 7.65 VDC into 400 ohms
Table 1-1. Adjacent Frequency Rejection
ATT-20 Frequency
(KHZ)
Adjacent Frequency of
Concern (KHz)
Rejection of Adjacent
Frequency (dB)
12.28 15.0 -18.0
15.0
12.28
18.0*
20.0
-30.0
-21.0
-27.0
20.0 15.0
18.0*
-44.0
-23.0
* Of concern where joint detectors are used.

ATT-20 Audio Track Transceiver
Copyright 2019 SM 6299 Rev. 3, March 2019 1-3
1.3.4. Miscellaneous
Reverse battery protection: Built-in
Operating temperature range: - 40°C to +70°C
Maximum block length: 300 ft. shunt mode at 3 ohm/1000 ft. ballast; 150 ft.
series mode at 3 ohms/1000 ft. ballast.
Recommended Relay: PN-150B, 400 ohm coil, (STS USA N322500-
701)
Overall Dimensions: Refer to Figure 1-1.
Mounting Hole Dimensions: 2¼" x 8½"
Weight: 4 lbs., 14 oz.
Terminal Connections: AAR
RCV
(REF)
2
AUDIO TRACK
TRANSCEIVER
MODEL,ATT-20
(REF)
LOWER
6 1/16
2 1/8
8
+
RELAY
-
(REF)
TL5
TL6
SHUNT
MODE
UNIT
2 1/4 (REF)
PC.NO.
SER.NO.
FREQ.
RE V.
7 5/8
4
5
8
7
(REF)
+
BATTERY
-XMT
1
4 5/8 (REF)
9 /41
3
RELAY VOLTS
TL1
RAISE
(REF)
6
TL2
TL3
TL4
3B3.0001.01
R14
Figure 1-1. ATT-20 Dimensions

ATT-20 Audio Track Transceiver
Copyright 2019 SM 6299 Rev. 3, March 2019 1-4