Tektronix 1503 User manual

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Tektronix,
Inc.
P.O.
Box
500
Beaverton,
Oregon
97077
070-1865-01
Product Group
27
COMMITTED
TO
EXCELLENCE
PLEASE CHECK FOR CHANGE INFORMATION.
AT
THE REAR OF THIS MANUAL.
1503
TIME
DOMAIN
REFLECTOMETER
INSTRUCTION
MANUAL
Serial
Number
______
_
First Printing OCT 1975
Revised
AUG
1982

Copyright ©1975, 1980Tektronix,Inc. All rightsreserved.
Contents of this publication may not
be reproduced in
anyform withoutthewritten permission ofTektronix, Inc.
Products of Tektronix, Inc. and its subsidiaries are
covered by U.S. and
foreign patents and/or pending
patents.
TEKTRONIX, TEK, SCOPE-MOBILE, and
~ are
registered trademarks of Tektronix, Inc. TELEQUI
P-
MENT is a registered trademark of Tektronix U.K.
Limited.
Printed in U.S.A. Specification and price change
privileges are reserved.
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TABLE OF CONTENTS
Page
LIST
OF ILLUSTRATIONS . . . . . . . . . . . . . . . . . ii
OPERATORS SAFETY SUMMARY . . . . . . . . • . . . iv
SERVICE SAFETY SUMMARY . . . . . . . . . . . . . . . v
Section 1 SPECIFICATION . . . . . . . . . . . . . . .
1-1
Section 2 OPERATING INSTRUCTIONS . . . . . . 2-1
I WARNING I
THE FOLLOWING SERVICE INSTRUCTIONS ARE FOR
USE
BY QUALIFIED PERSONNEL ONLY. TO AVOID
PERSONAL INJURY, DO NOT PERFORM ANY SER-
VICING OTHER THAN
THAT CONTAINED IN
OPERATING INSTRUCTIONS UNLESS YOU ARE
QUALIFIED TO DO SO.
@
Section 3
Section 4
Section 5
Section 6
Section 7
Section 8
Section 9
THEORY
OF OPERATION
........
CALIBRATION PROCEDURE ......
Performance Check
...........
Adjustment Procedure
.........
MAINTENANCE ................
OPTIONS ....................
REPLACEABLE ELECTRICAL PARTS
DIAGRAMS AND ILLUSTRATIONS ..
REPLACEABLE MECHANICAL PARTS
1503
Page
3-1
4-1
4-2
4-4
5-1
6-1
7-1
8-1
9-1

1503
Fig.
No.
2-1
2-2
2-3
2-4
2-5
2-6
2-7
2-8
2-9
2-10
2-11
2-12
2-13
3-1
3-2
3-3
3-4
3-5
3-6
3-7
3-8
4-1
4-2
4-3
4-4
4-5
4-6
4-7
4-8
4-9
5-1
5-2
5-3
5-4
5-5
5-6
5-7
5-8
ii
LIST
OF
ILLUSTRATIONS (
1503 Time Domain Reflectometer
Page
2-1
Battery connector
polarity.
. . . . . . . . . . 2-2
Front panel controls . . . . . . . . . . . . . . . 2-3
Test pulse at reference line . . . . . . . . . . 2-4
TDR display
of
RL
vs
Zo
. . . . . . . . . . . . 2-7
X-Y
Output
Module strap . . . . . . . . . . . 2-7
Open
Tip
and Ring . . . . . . . . . . . . . . . . 2-9
Loading Coil . . . . . . . . . . . . . . . . . . . . 2-9
Shorted
tip
and ring
...............
2-10
Building-out
network
..............
2-10
67-ohm splice at 4000
feet.
. . . . . . . . . . 2-11
Split and re-split pair . . . . . . . . . . . . . . 2-12
Bridge
top
at 4000 feet . . . . . . . . . . . . . 2-13
Simplified Block diagram . . . . . . . . . . .
3-1
Sampling diagram
................
3-2
Timing
diagram . . . . . . . . . . . . . . . . . . 3-4
Sampling
Circuit
timing
. . . . . . . . . . . . 3-7
Functional
block
diagram of
the
Slow Ramp
Generator . . . . . . . . . . . . . . . . . . . . . . 3-8
Block diagram
of
1503 Power Supply
...
3-10
Chart Recorder
logic
..............
3-12
X-Y
Output
Module strap
...........
3-13
Power Supply
testpoints
and adjustment
location . . . . . . . . . . . . . . . . . . . . . . . . 4-5
Sampling Efficiency Pulse . . . . . . . . . . . 4-7
First
Blow-by
Compensation Adjustments 4-8
Second
Blow-by
Compensation
Adjustments . . . . . . . . . . . . . . . . . . . . . 4-8
Fast Ramp test
point.
. . . . . . . . . . . . . . 4-9
External Calibration connection
.......
4-10
Fast Ramp test
point.
. . . . . . . . . . . . . . 4-11
External Calibration connection . . . . . . . 4-12
X-Y
Output
Module strap . . . . . . . . . . . 4-13
DC protection
link
location . . . . . . . . . . 5-2
Transistor and IC lead configuration . . . 5-3
Rear view
of
the HV board . . . . . . . . . . 5-4
Power Transformer
wiring
. . . . . . . . . . . 5-5
Subpanel, Identification
of
Parts . . . . . . 5-7
Rubber Seals, Edge Sealing
for
Subpanel 5-8
Detail
of
Implosion Shield Sealing . . . . . 5-8
Front Panel, Identification
of
Parts
for
Assembly Steps 8
through
26
. . . . . . . . 5-9
Fig.
No.
5-9
5-10
5-11
5-12
5-13
5-14
5-15
5-16
5-17
5-18
5-19
5-20
5-21
5-22
5-23
5-24
5-25
5-26
5-27
5-28
5-29
5-30
5-31
5-32
5-33
5-34
5-35
5-36
5-37
5-38
5-39
Page
Detail
of
Plug-in Compartment Seal . . . . 5-10
Detail
of
BNC
Connector
and Washer . . 5-10
Detail
of
Pushbuttons and Their Shafts 5-10
Detail
of
Subpanel Screwhole Sealing
..
5-11
Detail
of
Fuseholder Installation
......
5-11
Detail
of
Fuseholder Caps
...........
5-12
Application
of
Sealant
to
Battery Meter 5-12
Alignment
of
Battery Meter . . . . . . . . . . 5-12
Application
of
Sealant
to
FOCUS and
INTENSITY Controls
..............
5-12
Application
of
Sealant
to
FINE Control
Bushing
........................
5-13
Application
of
Sealant
to
Fl
NE Control Nut 5-13
Installation
of
Distance Meter
........
5-13
Application
of
Sealant
to
ZERO
REFERENCE
Control
Bushing . . . . . . . . 5-14
Application
of
Sealant
to
ZERO
REFERENCE Control Nut
...........
5-14
Application
of
Sealant
to
RECORD Toggle-
(
switch Bushing
.................
. 5-14
Application
of
Sealant
to
RECORD Toggle-
switch
Nut
.....................
. 5-15
Installation
of
Rubber Cap-seal on
RECORD
toggle-switch.
. . . . . . . . . . . . 5-15
Application
of
Sealant
to
the
Q-dB
SET
Control Bushing . . . . . . . . . . . . . . . . . . 5-15
Detail Showing Lubrication and Sealing
for
the Variable Resistor. ; . . . . . . . . . . . . . 5-15
Lubrication
of
the
0-rings
and Sealing
for
the Cam-switches . . . . . . . . . . . . . . . . . 5-16
Installation
of
the
POWER SWITCH
....
5-16
Lubrication
of
POSITION Control Knobs 5-17
Installation
of
Knob on Shaft . . . . . . . . . 5-17
Lubrication
of
ZERO REFERENCE Knob 5-17
Installation of Knob on ZERO REFERENCE
Control . . . . . . . . . . . . . . . . . . . . . . . . 5-17
Lubrication
of
FOCUS and INTENSITY
Control Knobs
...................
5-18
Sealing
of
Battery Pack Screwholes
....
5-18
Application
of
Dielectric
Type
Compound 5-18
Detail
of
Front Panel Jacks
..........
5-19
Detail
of
X-Y
Module
Thumbscrews
....
5-19 (
Sealing of Latch Assembly Screwholes. . 5-20 ·
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1503
LIST OF ILLUSTRATIONS (cont)
Fig.
No. Page
Option
1-1 Front-panel controls . . . . . . . . . . . . . . . 6-1
Option
1-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2
Option
1-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3
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iii

1503
OPERATORS SAFETY SUMMARY
The general safety information in this part of the summary
is
for both operating and servicing personnel. Specific
warnings and cautions will be found
throughout the
manual where they apply, but may not appear in this
summary.
TERMS
In This Manual
CAUTION statements identifyconditions or practicesthat
could resultindamage to theequi pr:nent or otherproperty.
WARNING statements identify conditions or practices
that could result in personal
injury or loss of life.
As Marked on Equipment
CAUTION indicates a personal InJUry hazard not im-
mediately accessible as one reads the marking, or a
hazard
to property including the equipment itself.
DANGER indicates a personal
injury hazard immediately
accessible
as one reads the marking.
SYMBOLS
In This Manual
This symbol indicates where applicable
cautionary
or other information is 'to be
found.
As Marked on Equipment
~ DANGER -High voltage.
@ Protective ground (earth) terminal.
_A ATTENTION- refer to manual.
Power Source
This product is intended to operate from a power source
that will not apply more than 250 volts rms between the
iv
supply conductors or between either supply conductor
and ground. A protective
ground connection bywayof the
grounding conductor in the power cord is essential for
safe operation.
Grounding the Product
This product is grounded through the grounding conduc-
tor of the power cord. To avoid electrical shock, plug the
power cord into a properly wired receptacle before
connecting to the product input or output terminals. A.
protective ground connection by way of the grounding
conductor in the power cord is essential
for safe opera-
tion.
Danger Arising From Loss of Ground
Upon loss of the protective-ground connection, all
accessible conductive parts (including knobs and con-
trols that may appear
to be insulating) can render an
electric shock.
Use the Proper Power Cord
Use only the power cord and connectorspecified for your
product.
Refer cord and connector changes to qualified service
personnel.
Use the Proper Fuse
To avoid fire hazard, use only the fuse of correct type,
voltage rating and current rating as specified in the parts
list
for your product.
Refer fuse replacement
to qualified service personnel.
Do Not Remove Covers or Panels
To avoid personal injury, do not remove the product
covers or panels. Do not operate
the product without the
covers and panels properly installed.
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1503
SERVICE SAFETY SUMMARY
FOR
QUALIFIED
SERVICE
PERSONNEL
ONLY
Refer a/so
to
the
preceding
Operators Safety Summary.
Do Not Service Alone
Do not perform internal service or adjustment of this
product unless another person capable of rendering first
aid and resuscitation is present.
Use Care When Servicing With Power On
Dangerous voltages exist at several points in
this
product.
To avoid personal injury,
do
not touch exposed connec-
tions and components while power is on.
@
Disconnect power before removing protective panels,
soldering, or replacing components.
Power Source
This product is intended
to
operate from a power source
that will not apply more than 250 volts rms between the
supply conductors
or
between either supply conductor
and ground. A protective
ground
connection
byway
ofthe
grounding conductor in the power cord is essential
for
safe operation.
v

1503
·
1865-01A
•
1503
Time
Domain
Reflectometer.
vi
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Section
1-1503
SPECIFICATION
General Information
The TEKTRONIX 1503 is a portable Time Domain
Reflectometer
which
uses pulse techniques
to
test cables
and provides a visual
display
of cable faults. The test
pulses are transmitted via
the
CABLE
output
jack. Reflec-
tions
are received at
the
same
jack
and displayed on the
cathode-ray
tube
(crt).
NOTE
All
distances are shown in feet followed
by
metresin
parenthesis.
Metric
units
are not
direct conversions
from the measurements shown in teet,
but
represent
the
calibrated
ranges
of
the
metric
option
1503.
Multiplier
settings
tor
the
metric
options are
in-
dicated
in
the same manner.
Calibrated distance
controls
allow
an
operator
to
examine
up
to
50,000 feet
(1
0,000 metres) of cable.
Up
to
7,500 feet
(1
,500 metres)
of
cable can be examined
with
the
multiplier
control
at X10 (X1) from
which
50
to
5000
feet (10 metres
to
1000 metres) can be displayed across
the 10-division horizontal (X-axis) crt scale
with
an
additional 0
to
2500 feet (0
to
500 metres) of distance
covered by
the
DISTANCE dial.
Up
to
50,000 feet (10,000
metres)
of
cable can be examined when the
multiplier
control is at
X1
00
(X1
0)
of
which
500
to
50,000 feet
(1
00
to
10,000 metres) can be examined across the crt face. With
the FEET/DIV (METRES/DIV) control set at
50,
('100)
and
X1
00
(X1
0)
up
to
50,000 feet
(1
0,000 metres) of cable can
be
displayed on
the
crt
screen, but in this position
the
DISTANCE dial is disabled. The horizontal crt scale is
calibrated in distance units from 5 feet
(1
metre) per
division
to
5000 feet
(1
000 metres) per division in a1-2.5-5
sequence. Distance calibration accuracy on
the
crt
scale
is
within
±2%
of
indication.
There are
three
externally selectable
dielectric
con-
stants.
Two
of
these are calibrated
for
foamed
polyethylene (FOAM POLY) and solid polyethylene
(SOLID POLY). The
third
is obtained by
"default"
con-
ditions; both pushbuttons depressed or both pushbuttons
released. When both pushbuttons (FOAM POLY and
SOLID POLY) are depressed
or
released,
the
effective
dielectric constant is variable, being
controlled
by
a
@
screwdriver adjustment labeled "VAR". The
fully
clockwise position
of
the
"VAR"
control setsthe dielectric
constant
for
air.
Vertical (Y-axis) deflection of
the
crt beam is
propor-
tional
to
the amplitude of
the
reflected signal. The vertical
scale is a linear representation
of
the
return pulse and is
ordinarily
calibrated so that
two
divisions represent
"0
dB"
when the reference level is set
to
"0
dB". The dB
reference level isselectablein 7calibrated stepsfrom 0
dB
to
60
dB
plus a 0
to
18
dB
vernier adjustment.
The transmitted pulse is an impulse signal of ap-
proximately 5 V
into
a
50
0,
75
0,
93
0,
or
125 0 load.
Half-sine shaped pulse
durations
of
10
ns,
100
ns,
or
1000 ns are selectablefrom
the
front
panel. Durations are
measured at the half
amplitude
points.
The 1503 plug-in
compartment
will accept either
the
X-
V
Output
Module
or
the
TEKTRONIX
Y-T Chart Recorder.
The X-Y
Output
Module
is a standard accessory
for
the
1503 and provides
an
interface
for
an
X-Y recorder. The
TEKTRONIXY-T Chart Recorderis an optional accessory.
This recorder uses a heated stylus
to
record on 4
em
wide,
heat-sensitive chart paper. The chart recording length
represents the entire crt screen and is controlled by
the
1503.
The 1503 is a ruggedized portable instrument that can
be used in the field
as
well as
in
the
laboratory. The 1503
meets requirements
for
a
Type
Ill, Class
3,
Style A
instrument
as
specified in MIL-T-28800. The 1503 has a
ruggedized case that provides protection whentheinstru-
ment is stored in exposed areas. When
the
instrument is
not being used,
the
accessories,
including
the
Operators
manual, may
be
packed
in
the
instrument cover and
latched
tightly
on the
front
of
the
instrument. Table
1-1
indicates which accessories
may
be placed in the cover
of
the
1503.
The characteristics given in Table 1-2 apply over an
ambient temperature range
from
-15°C
to
+55°C
after
the instrument has been calibrated at
+25°
C,
±5°
C.
1-1

Specification-1503
Characteristics
Impulse
Width
Accuracy
Amplitude
Terminated
Unterminated
Shape
Termination
Jitter
Graticule Deflection
Deflection
Range
Accuracy
Deflection Reference
Accuracy
Variable
1-2
Table 1-1
STANDARD ACCESSORIES FOR THE 1503
Accessory Tektronix Part Number
2 Replacement Fuses 159-0032-00
(ac-tor front panel) (for 115 Vac)
or
159-0029-00
(for
230 Vac)
1 Power Cord 161-0066-00
1 Viewino Hood 016-0297-00
1
50 0 BNC Terminator 011-0123-00
1 X-V
Output Module 016-0606-00
1 Filter, Mesh (crt) 378-0055-00
1 Operators Handbook 070-1864-00
1 Instruction Manual 070-1865-00
1 Cable Assembly 012-0671-00
1 Calculator, 003-0700-01
TOR Cable Tester
Table 1-2
ELECTRICAL CHARACTERISTICS
Performance Requirements Supplemental Information
Selectable: 10 ns, 100 ns, 1000 ns Measured at half amplitude point.
±20%
5 v±20%
10 v±20%
1/2 sine
50 0, 75 0, 93 0 ±1%. 125 0 ±3% ..
0.2 division maximum At 5 ft/div (1 m/div)
+6 to -18 dB From deflection reference; linear
scale on gratiucle. 0
dB=2 div,
displayed signal
~0.1 div.
±3%
0 to 60 dB 7 steps, 10 dB increments.
±0.1 dB
Oto18dB Additive to step increments.
Fully clockwise is
18 dB ±2.0 dB.
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Specification-1503·
Table
1"'2
(cont)
Characteristics Performance Requirements Supplemental Information
Displayed Noise With proper termination, 10
ns
pulse, and pulse completely
off-screen.
Aberrations
-30
dB peak-to-peak Within first three test pulse
widths after test pulse.
Random
-80
dB rms Beyond first three test pulse
widths after test pulse.
Low Noise Operation
Random
-86
dB rms Three test pulse widths after
initial test pulse.
Test Line
Conductor
Coupling AC coupled
Maximum Input
±400
V (de
+
peak ac
at
maximum frequency of 440 Hz).
Distance Control
Range 0
to
50,000 feet
(0
to
10,000 metres)
Scales 5
ft/div
to
500
ftldiv
@ X10 (X1)
(
(1
m/div
to
100 m/div) 7 steps, 1-2.5-5 sequence.
At 5000
ft/div
(1000 m/div) (FIND),
the
DISTANCE dial is disabled.
Accuracy ±2% Of display screen from 2nd
to
tenth graticule line.
Scale Multipliers X10 and X100
(X1
and X10)
Accuracy ±2% From 2nd
to
tenth graticule
line.
Distance Dial
Range 0
to
2,500 feet At X10 setting
(0
to
500
metres) (At
X1
setting)
0
to
25,000 feet At X100 settings
(0
to
5,000 metres) (At
X1
0 settings)
Accuracy
2%
of reading,
±2ft@
X10,
(±0.2 metres @
X1)
±20
ft
@
X100,
(±2
metres@
X10)
Dielectric Scales
Solid Poly
V/Vair
= 0.66 Used where velocity of propa-
gation is 65.9% C (C=speed of
light.)
Foam Poly
Vp/Vair
=
0.81
Where velocity of propagation
is
81%
C.
@
1-3

Specification-1503
Table 1-2 (cont)
Characteristics Performance Requirements Supplemental Information
VAR
Vp/Vair
=
0.31
to
1.0 Activated when both SOLID POLY
and FOAM POLY buttons released;
~-
or both depressed calibrated
for
air when VAR control set
to
Full
cw position.
Sweep
40Hz
within
+O
Hz,
-10Hz
Noise Filter switch
"out".
Sweep (Chart Recorder Mode)
20
sec/sweep nominal Varies and is dependent on
chart recorder.
Chart Tracking
±2%
from 2nd
to
tenth graticule line
Line Voltage 117 Vac ±20%,
48
to
410Hz
or
234 Vac ±20%,
48
to
410Hz
Line Power 5 W average
Battery Pack Operation At least 5 hours C size, 9 cell
+20°
C
to
+25°
C
charge and discharge temperature.
Full Charge Time
16
hours
Typical Charge Capacity
Charge Temperature Discharge Temperature
+20°C
to
(
-15°C
+25°C
+ssoc
ooc
40%
60%
50%
+20°
C
to
+25°
C
65%
100%
85%
+40°C
40%
65%
55%
External Recorder Interface
for
X-
Y Recorders
Horizontal
0.1
V/div Source impedance
10
kO
Vertical 0.09
to
0.13 V/div (adjustable) Source impedance
10
kn
Pen
Lift
Mode 1
Source
V,
=
5 V Nominal with
R,
=
10
kn
Sink
~
10
mA
Vout
~0.5
V
Mode 2 (inverted
Mode
1)
Source
V,
=
5 V Nominal with
R,
=
10
kn
Sink
~0.5
mA
Vout
~0.6
V
1-4
@

Specification-1503
Table
1-2
(cont)
Characteristics Performance Requirements Supplemental Information
Y-T Plug-In Chart
Recorder Interface
Vertical 0.2 V/div nominal Source impedance
200
0
(switched)
The TEKTRONIX Chart Recorder,
016-0506-03 is designed
to
operate with the 1503. The chart
uses a heat sensitive stylus
to
record on 4
em
chart paper. Chart
recording length is controlled by
the
1503.
Temperature
Operating
-15°C
to
+55°C
At temperatures other than
20°
C-25°
C,
the battery
efficiency becomes restricted.
Non-Operating
-62°
C
to
+85°
C With batteries removed. If stored
with batteries storage range
is
-40°C
to
+55°C.
Humidity
To
100%
Altitude
Operating 10,000 feet
(
Non-Operating 50,000 feet
Vibration 3.0
g,
5
to
55 Hz, Test time
45
min
Shock, Mechanical
Shock, Pulse
15
g,
1/2 sine shock waveform
of
11
ms duration. Total
of
18
shocks
Bench Handling
Operating 4 drops each face at 4 inches or Case on
45° with opposite edge
as
pivot
Non-Operating 4 drops each face at 4 inches or Case off
45° with opposite edge
as
pivot.
Satisfactory operation after drops
Transit Drop
12
inch drop
Water Resistance
Operating Splash-proof and
drip-proof
with
cover off and instrument operating.
Non-Operating Watertight with three feet of Cover on
water above
top
of the case
for
1
hour
Salt Atmosphere
Structural Parts Withstand 48 hours exposed
to
20%
solution
without
corroding
@
1-5

Specification-1503
Table 1-2 (cont)
Characteristics Performance Requirements Supplemental Information
(
Explosive Atmosphere Operation does not cause
ignition
["
of
an
ambie;:nt-explosive-gaseous
mixture
with
air
Sand and Dust Operates after non-operating, cover
!.
removed, exposed
to
dust test of
MI
L-STD-81
0,
Method 510, Pro
c.
I
Washability Capable of being washed
~~
El
ectromagnetic
Compatibility
f'
El
ectrom
ag
netic Meets requirements specified in CE01, CS01, CS02, CS06, RE02
Interference (EMI) Table X
of
MIL-T-28800A (limited
to
1 GHz), and RS03,
(limited
to
1 GHz).
r~
Fungus Inert Materials used are
fungus
inert
,~
Table 1-3
PHYSICAL CHARACTERISTICS
Characteristics Performance Requirements Supplemental Information
(
Weight
With Panel Cover and 18.0 pounds (8.2 kg)
Accessories
Without
Panel Cover and 16.0 pounds (7.3 kg)
Accessories
Height 5.0 inches (12.7 em)
Width
With Handle 12.4 inches (31.5 em)
Without
Handle 11.8 inches (29.9 em)
Depth
Including Panel Cover 16.5 inches (41.9 em)
Handle Extended 18.7 inches (47.4 em)
1-6 @

(
Section
2-1503
OPERATING
INSTRUCTIONS
This section of
the
manual containsthe basic informa-
tion required
for
the
operation of the 1503 Time Domain
Reflectometer. Included is a brief description of the
purpose of each
front
panel control, general operating
information, care of
the
instrument, and basic
applications.
FRONT COVER AND HANDLE
The watertight
front
cover protects the
front
panel
when the instrument is not in use and thecover is latched
in place. Special operating instructions are printed on
the
lid. A canister containing silica gel is mounted on the rear
of the instrument
to
reduce
the
moisture inside
the
case.
The cover is released from the unit by pulling forward
on the side latches. To secure the cover over
the
front
panel, placethe cover intothegrooved portion of
the
front
panel and push the latches backward towards
the
instru-
ment.
If
the
unit is accidentally left on, it will
be
turned off
when the cover is secured over the
front
panel.
The handle is afriction disc design and will rotate325°.
When the handle is turned so that it is beneath
the
unit, it
will serve
as
a stand (see Fig. 2-1).
POWERING
THE
1503
This equipment has a 3-wire power cord with a 3-
contact plug
for
connection
to
the power source and
to
protective ground. The plug protective-ground contact
connects (through the cord protective-grounding con-
ductor)
to
the
accessiblemetal partsoftheequipment. For
electric-shock protection, insert
this
plug into
an
outlet
that has a securely grounded protective-ground contact.
~
Do not use this
unit
with a power inverter that
produces a square wave
output
because power
inverters
may
damage circuitry.
For confirmation that the outlet ground contact is
securely grounded, refer
to
qualified service personnel.
The 1503 operates from
the
battery supply
for
a
minimum of 5 hours (including
20
chart recordings).
If
a
TEKTRONIX
Y-
T Chart Recorder is used, the 5 hours
operating time will decrease by about 3 minutes
for
each
recording made beyond the
20
specified.
1865-02A
Fig.
2-1. 1503 Time Domain Reflectometer.
@
2-1

Operating lnstructions-1503
Charging the Battery
The battery pack can be charged at any temperature
between
oo
C and
+40°
C.
It can
be
operated at any
temperature between
-15°C
and
+55°C.
For maximum
charge capacity, the cells should
be
charged
at
+20°
C
to
+25°C.
The battery pack is
fully
charged)n
16
hours when
connected
to
an
ac power source and the unit is switched
off. The 1503 may
be
operated while the battery pack is
charging, but the charging time will increase. The
batteries will not overcharge
if
the
chargerisleft on longer
than
16
hours. Therefore, the 1503 can remain connected
to
an
ac source
without
damaging the batteries. Ap-
proximately once a month or every
15
charge-discharge
cycles,
the
batteries should
be
charged
for
approximately
24
hours. Approximately
30
minutes of operating
time
can
be
expected from a 1 hour partial charge. For longest
battery life,
the
full
16
hourchargeshould
be
completed in
preference
to
a partial charge.
A battery can be damaged by reverse charging. This
can occur if an individual cell becomes completely
discharged and the current from the other cells
flow
in a
reverse directionthrough the discharged cell. Such acase
can develop due
to
cell aging, partial charging, or
if
acell is
replaced. The battery charger uses SCR protection cir-
cuits
to
prevent accidental reverse charging. The SCR
protection circuits automatically shut off the instrument
whenever battery voltage falls below about
10
V.
Do not
leave the POWER switch on when the instrument hasshut
itself down because it will continue
to
discharge the
battery at a slower rate.
A
12
Vde power supplymay
be
substituted
for
the
1503
battery pack by removing
the
pack from the unit and
connecting
the
power supply
to
the terminals inside the
battery pack compartment.
~
When substituting
a
de power supply
or
external
battery for the battery pack, be sure the
polarity
is
correct.
See
Fig.
2-2.
The power pack can
be
stored
at
any temperature
between
-40°C
and
+55°C
with the battery cells either
fully
or partially charged. The self-discharge rate
of
the
cells increases with increased temperature. A
fully
charg-
ed
battery will loseabout
50%
of itschargein
3to4
months
if
stored at
+20°
C
to
+25°
C.
Therefore, the battery pack
should
be
completelyrecharged before using ifit has been
stored
without
power supplied
to
its charging circuit
for
more than a month.
2-2
"o
WHITE/RED
Fig. 2-2. Battery connector polarity.
230 V Operation
The battery charger is
factory
wired
for
115 V ac or
230
V ac ifOption 6 is ordered. Thestandard 115 Vac unit
can
be
changed
to
230
V ac operation by rewiring the line
transformer. Refer voltage changes
to
qualified service
personnel only.
~
When the 1503 is wired for 230 Vac, be sure that the
two
front-panel fuses are changed and the proper
plugis installedon the accable. Referto the partslist
for the correct parts.
Front Panel Controls (See Fig.
2-3)
1.
CABLE
2.
Impedance
selectors
3.
FOCUS
4.
INTENSITY
Precision bnc connector used
to
transmit
the
impulsesignal
into
the
test cable and receivethereflected
signal.
Two
push buttons used
to
select
the
1503 output impedance.
50
n
pushed in, selects
50
n im-
pedance.
75
n
pushed in, selects
75
n
impedance. Both pushed in,
selects 125 0 impedance. Both
out, selects
93
n
impedance.
Controls sharpness of crt display.
Controls brightness of crt display.
5.
POSITION/FINE Vertical position controls
for
crt
display.
6.
ZERO
REF
CHECK Push button
to
check horizontal
reference location of test impulse(
signal on crt. ·
@
I'
(
r-
r·'
r-
['
r
r
,,
(

5 6 7 8 9
10
11
12 13 14
Fig. 2-3. Front-panel controls.
7.
ZERO REF Horizontal pulse position control
SET
for
crt display. Sets test signal
edge
to
a vertical reference
line
on
the
crt when
the
DISTANCE dial is
at 000 or ZERO
REF
CHECK but-
ton
is pushed.
8.
RET LOSS {dB) Selects
dB
reference level
of
FINE
the
reflected signal. 0-dB
to
60-dB
in seven calibrated steps. FINE
adds
0-18
dB
to
selected steps.
9.
POWER Pull-on, push-off switch. Does not
affect battery charging circuits.
10.
0-dB SET Screwdriver adjust
for
0-dB
reference level. Used
to
set
amplitude of test pulse.
11.
NOISE FILTER Reduces displayed noise. Display
sweep rateis reduced
by
a
factor
of
ten.
12.
BATTERY Indicates relative charge of power
pack.
@
13.
DISTANCE
14.
X10
(X1)
X100 {X10)
15.
FEET/DIV
(METRES/DIV)
16.
IMPLS WIDTH
Operating
lnstructions-1503
15
1865-038
Indicates
the
distancefrom 1503
to
a
point
on
the
test cable; 0
to
25000
feet {Oto500 metres) at X100 (X10).
Disabled when
the
FEET/DIV
{METRES/DIV) control is set
to
50
{100) and
the
multiplier
is set
to
X100 {X10).
Two-position
switch
for
X10
(X1)
or
X100 {X10) multiplier. Affects
both DISTANCE dial and FEET/
DIV (METRES/DIV) control.
Selects horizontal deflection fac-
tor.
X10 (X1) = 5
to
500 feet/div
(1
to
100 metres/div).
X100 (X10)
=50
to
5000 feet/div
(10
to
1000 metres/div).
Selects
width
oftest impulse
for
10,
1
00,
or 1
000
ns.
2-3

Operating lnstructions-1503
17. CABLE
DIELECTRIC
SOLID POLY
FOAM POLY
VAR
18. RECORD
19. AC LINE
FUSES
Plug-in Modules
1. X-Y OUTPUT
MODULE
X, Y and
PEN LIFT
2. Y-T CHART
RECORDER
STYLUS
POSITION
Two push buttons and a screw-
driver adjust. Selects proper
velocity of propagation. VAR
control is activated when both but-
tons are pressed or released. VAR
control is set
to air when fully
clockwise. VAR control has
reference marks every 30° to in-
dicate relative propagation con-
stants.
Two-position toggle switch. Used
to start an X- Y Recorder or
TEKTRONIX
Y- T Chart recorder.
Push up and hold momentarily
to
pre-heat stylus; then release to
start Chart recorder.
Protection fuses
for the battery
charger circuits.
The standard plug-in module
for
the 1503. Used to interface to an
external X- Y chart recorder.
Three dual sets of front-panel
jacks are used
to supply horizon-
tal, vertical, and pen lift informa-
tion to an external X-Y Recorder.
An optional Tektronix Chart Re-
corder which replaces the X-Y
OUTPUT MODULE.
Screwdriver adjustment
to adjust
stylus
to the same level as the crt
display when the RECORD switch
is in RECORD position.
OPERATIONAL CHECKOUT
1. Use the step-by-step procedure for an operational
check of the 1503. First set the controls
as follows:
FOCUS Midrange
INTENSITY Fully clockwise
ZERO
REF
Fully clockwise
RET LOSS (dB) 0 dB
DISTANCE 000
NOISE FILTER Out
FEET/DIV 5
(METRES/DIV) (10)
2-4
X10-X100
(X1-X10)
CABLE DIELECTRIC
IMPLS WIDTH
50/75 n
X10
(X1)
SOLID POLY
100
son
2. Adjust the INTENSITY & FOCUS control for a clear
bright trace.
3. Adjust the POSITION control to set thetrace on the
horizontal center line.
4. Attachthe50 OterminatortotheCABLEconnector.
5. Turn the ZERO REF SET button ccw until the test
pulse leading edge is located on a vertical reference line.
The vertical reference line may
be any vertical line you
choose on the crt graticule. Adjust the 0-dB SET control
for a two division display.
NOTE
Always use the leading edge at the base line of the
pulse for setting reference. (See Fig. 2-4.)
/'
I
'
SET REFERENCE
HERE
1865-04
Fig. 2-4. Test pulse at reference line.
6. Adjast the ZERO REF SET button throughout its
range to see that the test pulse edge can be set on any
vertical graticule line. Set
the test pulse edge on the
vertical reference line.
(
7. Set the DISTANCE dial to 010, press the ZERO REF
1
CHECK button and check that the test pulse edge returns '
@

(
to the vertical reference line of the graticule. Reset the
DISTANCE dial
to 000.
8. Change the RET LOSS control to 10-dB and adjust
the POSITION control so thatthe horizontal baselineison
the bottom crt graticule line.
9. Press the NOISE FILTER button and check for a
reduction in displayed noise
as well as areduction in scan
rate. Reset the RET LOSS switch to 0-dB, release the
NOISE FILTER button (by depressing a second time).
10. Press IMPLS WIDTH (ns) 1000 and check for a 9
division (within 20%) wide pulse.
11. Press IMPLS WIDTH (ns) 10 and set FEET/DIV
(METRES/DIV) to .5 (1) and check for a slightly greater
than one division wide pulse.
12. Lift up and hold the RECORD switch. Check that a
bright spot appears at left edge of the crt.
13. Release the RECORD switch. The spot will slowly
trace the waveform. When the scan is complete
the 1503
will automatically return
to its normal mode.
Connecting a Test Cable to the 1503
I WARNING I
Voltages up to 400 V may be expected on long
twisted-pairlines. These voltages may bepresent on
the front panel of the 1503. The optional isolation
transformer(013-0169-00) is recommended
to avoid
electrical shock to the user.
~
Voltages higherthan 400 Vpeak or lowervoltages at
frequencies higher than 400 Hz
may damage the
Pulser
and/or Sampler circuits of the 1503.
Connect cables, to be tested bythe 1503, to theCABLE
connector on the front panel. Cables of any impedance
may be tested by adjusting the 0-dB SET control and/or
using other than 2 crt divisions as the 0-dB reference.
However, tests at long ranges may be degraded.
@
Operating lnstructions-1503
Table
2-1
OPTIONAL ACCESSORIES FOR THE 1503
Tektronix
Accessories Part Number
Adapter Assembly, Isolation
Transformer 013-0169-00
Terminator,
75 0 BNC 011-0102-00
Connector, BNC Female-to-Clip
Leads 013-0076-00
Adapter, Camera (Extension) 016-0327-01
Chart Recorder 016-0506-03
Chart paper 006-1658-00 or
01
Connector, BNC Female-to-GA 017-0063-00
Connector, BNC Male-to-GR 017-0064-00
Adapter, 50/125 0
017-009Q-OO
Adapter, 50/75 0 017-0091-00
Adapter, 50/93 0 017-0092-00
Connector, BNC Female-to-UHF 103-0015-00
Connector, BNC Female-to-Dual
Banana Plug 103-0090-00
Connector, BNC Male-to-Male 103-0029-00
Connector, BNC Male-to-UHF
Female 103-0032-00
Connector, BNC Male-to-Dual
Binding Post 103-0035-00
Connector, BNC Male-to-N Female 103-0058-00
Connector, BNC Female-to-Dual
Banana Plug 103-0090-00
Locating a Discontinuity in a Cable
The DISTANCE dial and the FEET/DIV (METRES/DIV)
control make it possible
to evaulate cables as long as
50,000 feet (10,000 metres), subject to their transmission
quality. The entire length can be displayed directly on the
crt if desired. If a chart recorder is used, only that portion
ofthe traceseen on the crt will be recorded on the graph.
To check cables using
only the crt display, the
FEET/DIV (METRES/DIV) control and the X10-X100 (X1-
X10) control must be set so that the crt displaywindow is
longerthan the cable. For example, ifthecableis 1500feet
(500 metres) long, set
the FEET/DIV (METRES/DIV)
control to 25 (10) and the multiplier control to X10 (X10).
2-5

Operating lnstructions-1503
This setting
of
the FEET/DIV (METRES/DIV) control
assures that the return signal will appear in
the
display
window. Measure the distance betweenthetest pulse start
and the return pulse start.
To more accurately locate
the
discontinuity, set
the
FEET/DIV (METRES/DIV) control
to
a
lower
setting. {The
return pulse does not need
to
be in the display window.)
Adjust ZERO REF SET
button
so that
the
test pulse rise is
set
at
a convenient vertical reference graticule line. The
ZERO REF SET control may have
to
be readjusted when
changing the FEET/DIV (METRES/DIV) control.
NOTE
Always use the leading edge at the base line
of
the
test/return pulses for setting the reference. (See Fig.
2-4.)
Now
turn
the
DISTANCE dial clockwise until
the
return
pulse is located on
the
reference graticule line. The
reading on
the
DISTANCE dial times the
multiplier
gives
thelength from the
CABLE
connector
to
the discontinuity.
NOTE
The dB reference
may
have to be increased to
observe the reflection.
The
CABLE
DIELECTRIC push buttons allow
the
1503
to
accurately locate discontinuities in cables with various
relative propagation
velocity
constants
(Vp).
The SOLID
POLY
button
is calibrated
to
check solid polyethylene
dielectric
which
has a
Vp
of
0.66. The FOAM POLY
button
is calibrated
to
check foam polyethelyne
which
has a
Vp
of
0.81.
When both buttons are either
in
or out,
the
effective
dielectric is variable from
0.31
to
1.00 and is
controlled
by
the screwdriver adjustment control VAR. In the
fully
clockwise position it is calibrated
for
air dielectrics
(Vp
1.00).
Evaluating a Discontinuity
The RET LOSS control determines the vertical deflec-
tion that can be seen on the crt, or recorded on agraph
if
a
chart recorder is used. The control is calibrated
to
measure the
dB
loss of
the
return pulse amplitude relative
to
thetest pulseamplitude. Thescrewdriver adjustment, 0-
dB SET, is used
to
set
the
amplitude (number of
crt
graticule divisions) of the test pulse. The RET LOSS
control is then adjusted so that the return pulse
amplitude
is the same
as
the
0-dB
reference amplitude. The return
loss in
dB
is then read
directly
from the RET LOSS control
settings.
2-6
The mathematical
definition
of RET LOSS is
20
log p;
where
p,
the reflection
coefficient
rho, is given by:
ZL-
Zo
p=
ZL
+
Zo
where
Zo
is
the
cable impedance and
ZL
is
the
impedance of the discontinuity, assuming no cable loss.
Fig. 2-5 shows the
two
parts of a TOR display ap-
propriately labeled
to
identify
the
test and return voltage
signals. When the return loss =
oo
dB,
the
cable is
terminated by a resistance equal
to
its characteristic
impedance
(Zo),
since a
perfectly
matched cable
(RL
=
Zo)
gives no reflection. When
the
return loss equals 0 dB
with
a positive return pulse,
the
cable has
an
open termination
(RL
=
oo
0).
When the return loss equals 0 dB
with
a
negative return pulse, then
the
cable is terminated with a
short
(RL
= 0
0).
NOTE
Care
must
be taken to
account
for
cableloss whichis
assumed to bezero in the example
shown
in Fig. 2-5.
Actual
discontinuities are
shown
laterin thissection.
(
Cables with a characteristic impedance other than
50,
75,
93,
or
125
0
can be evaluated by adjusting the 0-dB
SET control
to
correct thetest pulse
for
two
divisionsthen (
proceed
as
normal. Positive
or
negative re-reflections will
be
observed, however, due
to
the
impedance mis-match.
The NOISE FILTER
button
can be used
to
reduce the
noise displayed on the crt. The reduction in noise is
accomplished by changing
the
time
constant of the R-C
filter
and is accompanied
by
a
slowing
of the sweep rate.
1503 ACCESSORIES
Plug-ins
The 1503 plug-in
compartment
will accept
eithertheX-
Y
OUTPUT
MODULE
(provided
as
a standard accessory)
orthe TEKTRONIXY-
TChart
Recorder (Part
Number
016-
0506-03)
which
is supplied
with
Option
4 instruments.
Using an X-Y Recorder
The X-Y
OUTPUT
MODULE
may be wired
for
either a
positive or negative pen
lift
signal. Before using the X-Y
OUTPUT
MODULE, be sure that
the
pen
lift
circuit
on the
etched
circuit
board is
properly
connected. Fig. 2-6shows
the proper connection
for
either a positive or negative pen\.
lift
signal.
@