Positron Teleline Isolator 7501-16A Operating and installation instructions

Plug-in OPX Card
7501-16A, B and C
Description and Installation

DOCUMENT CONTROL INFORMATION
Document Part Number: 7501-24-16, Rev. 7
Project Level: 7
Publication Date: January 09, 2003
Document ID: o02i1100.fm
CONFIDENTIALITY NOTICE
The information contained in this document is the property of Positron Inc. Except as specifically
authorized in writing by Positron Inc., the holder of this document: 1) shall keep all information
contained herein confidential and shall protect same in whole or in part from the disclosure and
dissemination to all third parties, and 2) shall use same for operating and maintenance purposes only.
DISCLAIMER NOTICE
Although Positron Inc. has made every effort to ensure the accuracy of the information contained
herein, this document is subject to change without notice.
TECHNICAL CUSTOMER SUPPORT
Should a problem arise, contact your customer support department. If the problem cannot be resolved
by your support department or if you have any questions, contact Positron’s Technical Customer
Support department at 1-888-577-5254.
© 2003 Positron Inc.
Teleline Isolator is a registered trademark of Positron Inc.
Product names, other than Positron’s, mentioned herein may be trademarks and/or registered trademarks
of their respective companies.

Contents i
o02i1100TOC.fm
1. The Plug-in OPX Card . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2. Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Hardware Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4. Technical Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
5. Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
6. Service and Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

(22 pages) Plug-in OPX Card 1
7501-16A, B, C
o02i1101.fm
1. The Plug-in OPX Card
The Plug-in Off Premise Extension (OPX) Card is used to provide high voltage
isolation for a wide variety of telephone voice grade applications involving the
bi-directional transmission of AC and DC voltage.The unit is a plug-in card
designed for use with the Teleline Isolator multi-card shelf. It is available in three
options, as listed below:
•Model 7501-16A is designed for a floating 130 V dc source.
•Model 7501-16B is designed for a -24 V dc source referenced to station
ground.
•Model 7501-16C is designed for a -48 V dc source, also referenced to station
ground.
Its features include the following:
•The card may be used with both the old and the new generation Three, Five
and Eight-card Teleline Shelf.
•The OPX Card is completely bi-directional to all loop signalling, i.e. line
voltages can originate from either Station or Central Office (CO) side loops.
Bi-directional modulator/demodulators are used to realize a circuit which
behaves as an ideal 1:1 isolation device.
•Varistors provide transient voltage protection to the isolation device.
•The OPX Card provides low loss, full duplex DC to voice band
communication.
•The OPX Card transmits on/off-hook, dial pulses or touch tone signalling,
ringing, polarity reversals, AC and DC voltage and current levels.
•Impedances applied to either side of the card are reflected to the opposite
side.
Model variations A, B, and C are all visually similar. For a view of the Plug-in
OPX Card, refer to Figure 1.

7501-16A, B, C
2 Plug-in OPX Card
Figure 1 Model 7501-16A Component Layout (Only Major
Components Shown)
POSITRON
7501-16A
O.P.X MODULE
7-7/16"
12"
STATION SIDE
CO SIDE
2"
ISOLATION
GAP
4¼"
ISOLATION
TRANSFORMER
ISOLATION
TRANSFORMER
mA
C.O.
mA
STATION
EQUALIZE
mA
MONITORING JACK
MONITORING JACK
TRIM
POTS
NOTE: The faceplates of models 7501-16B and C will bear their respective model
numbers, instead of 7501-16A. The rest of the units are visually similar.
1
2
3
4
5
6
GROUND
-24 V dc
TIP (+)
RING (-)
-48 Vdc from shelf
PCB +130 V dc (RU GEN from shelf)
TIP (+)
RING (-)
RMT GND

Plug-in OPX Card 3
7501-16A, B, C
2. Applications
The applications of the OPX Card include the following:
•OPX. For an illustration of this application, refer to Figure 3.
•Direct Inward Dial (DID) loop start. For an illustration of this application,
refer to Figure 4.
•Automatic ring down. For an illustration of this application, refer to Figure
5.
•Radio keying. For an illustration of this application, refer to Figure 6.
•Loop start telephone
•Call waiting pulse
•Forward disconnect
•Caller ID
•Coin telephone (two cards required)
•Simplex continuity when used with four-wire DX signalling
•Fax and dial-up “smart”modems (up to 56.6 Kb modem, speed of 45.3 Kb/s
if line permits)
Refer to Figure 2 for applications.

7501-16A, B, C
4 Plug-in OPX Card
Figure 2 High Voltage Interface Applications
Plug-in OPX Card
Model 7501-16A, B or C
Communications Cable
300 Volt
Point
300 Volt
Point
300 Volt
Point
Zone of Influence
Metal
Conduit
PVC
Conduit
Lightning
Arrestor
CENTRAL OFFICE
HIGH VOLTAGE INTERFACE
SUBSTATION
Fax or Modem
Telephone, PBX

Plug-in OPX Card 5
7501-16A, B, C
Figure 3 Typical Off Premises Extension (OPX) Application
STATION A
STATION B
ISOLATION
CARD
MODEL 751321
OPX CARD
PBX
EXT.
*Note: The isolation card is only required if a ground potential rise is
possible at the remote site (Station B). If Station B is not a power plant,
the telephone card can be omitted.
A
B

7501-16A, B, C
6 Plug-in OPX Card
Figure 4 Typical Direct Inward Dial (DID) Application
CENTRAL OFFICE
SUBSTATION
OPX CARD
PBX
Ring Tip