Tektronix 1502 schematic

TM 9-6625-2801-14&P

TECHNICAL MANUAL

OPERATOR’S, ORGANIZATIONAL,

DIRECT SUPPORT, AND GENERAL SUPPORT

MAlNTENANCE MANUAL (INCLUDING MAINTENANCE REPAIR PARTS LIST)

FOR

TEST SET,

TEKTRONIX

NSN 6625-04-084-3855

TEKTRONIX, INC.

ELECTRICAL

TYPE 1502-1

HEADQUARTERS, DEPARTMENT OF THE ARMY

AUGUST 1981

WARNING

DRY CLEANING SOLVENT

Dry cleaning solvent or mineral spirits paint thinner is flammable
and should not be used near an open flame.
should be provided when these materials are used.

Fire extinguishers

Use only in

well-ventilated areas.

WARNING

Be extremely careful when working in the vicinity of batteries
when the battery case is open.

Do not use uninsulated tools.

Do not wear rings or watches. Metal articles will, if allowed
to contact connectors, cause severe arcing with possible injury
to personnel and damage to the battery.

TM 9-6625-2801-14&P

TECHNICAL MANUAL
NO. 9-6625-2801-14&P

DIRECT SUPPORT, AND GENERAL SUPPORT

MAINTENANCE MANUAL (INCLUDING MAINTENANCE REPAIR PARTS LIST)

You can help improve this manual. If you find any mistake
or if you know of a way to improve the procedures, please
let us know.
Changes to Publication and Blank Forms) , or DA Form
2028-2 located in the back of this manual direct to:
Commander, U.S. Army Armament Materiel Readiness
Command, ATTN:
A reply will be furnished to you.

HEADQUARTERS

DEPARTMENT OF THE ARMY

Washington, DC, 20 August 1981

OPERATOR’S , ORGANIZATIONAL,

FOR

TEST SET, ELECTRICAL

TEKTRONIX TYPE 1502-1*

REPORTING OF ERRORS

Mail your letter, DA Form 2028 (Recommended

DRSAR-MAS , Rock Island, IL 61299.

1

CHAPTER

Section

CHAPTER

Section

CHAPTER

Section

*NOTE

Throughout the text,

is in lieu of the authorized Federal nomenclature.

INTRODUCTION

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

I.

II.

Description . . . . . . . . . . . . . . ....... . . . .

2

OPERATING INSTRUCTIONS

I.

Controls and Indicators . . . . . . . . . . . . . . . . . . .

Operation . . . . . . . . . . . . . . . . . . . . . .......

II.

3

SERVICE AND PREVENTIVE MAINTENANCE

I.

Service on Receipt of Material . . . . . . . . . . . . . . .

II. Repair Parts,

III.

Lubrication . . . . . . . . . . . . . . . . . . . . . . . . . . .

IV.

Preventive Maintenance . . . . . . . . . . . . . . . . .

this is referred to as a Time Domain Reflectometer or a TDR. This

Special Tools and Equipment . . . . . .

Paragraph

1-1
1-6

2-1
2-2

3-1
3-3
3-4
3-5

Page

1-1
1-1

2-1
2-3

3-1

3-1
3-1

3-1

i

TM 9-6625-2801-14&P

CHAPTER

Section

CHAPTER

Section

CHAPTER

Section

CHAPTER

Section

CHAPTER

Section

4
5

I.

II.

III.

6
I.

II.

7
I.

II.

8
I.

II.

9
I.

II.

III.

Paragraph

FUNCTIONAL ANALYSIS . . . . . . . . . . . . . . . . . . . . 4- 1

PERFORMANCE CHECKS/FAULT ISOLATION

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1

Performance Checks . . . . . . . . . . . . . . . . . . . . . . . . 5-2

Fault Isolation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5

MAINTENANCE INSTRUCTIONS

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1

Maintenance Instructions . . . . . . . . . . . . . . . . . . . . 6-2

REPAIR INSTRUCTIONS

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1

Repair of TDR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3

FINAL INSPECTION

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1

Final Inspection Checks. . . . . . . . . . . . . . . . . . . . . 8-2

PREPARATION FOR SHIPMENT AND STORAGE

Preparation for Travel.. . . . . . . . . . . . . . . . . . . . . 9-1

Shipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-2

Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-3

Page

4-1

5-1
5-1

5-11

6-1
6-1

7-1

7-1

8-1
8-1

9-1
9-1

9-1

APPENDIX

A

REFERENCES

B

MAINTENANCE ALLOCATION CHART (MAC)

C

MAINTENANCE REPAIR PARTS LIST

A-1
B-1
C-1

A-1

B-1

C-1

ii

LIST OF ILLUSTRATIONS

TM 9-6625-2801-14&P

Figure

1-1
2-1
2-2
2-3
2-4
2-5
2-6
2-7
2-8
2-9

2-10
2-11
2-12
4-1
4-2
5-1
5-2
5-3
5-4
5-5
5-6
5-7
5-8
5-9

5-10

7-1

C-1

C-2

Title

Time domain reflectometer, Tektronix 1502-1, cover removed. . . . . .

TDR front panel controls and indicators . . . . . . . . . . . . . . . . . . . . . .

Battery connector polarity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

230 Vac transformer wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Incident and reflecting pulses.. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

X-Y output module strap.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Crt display of pulse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TDR display of R

vs ZO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

L

Impedance nomograph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Open able . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ........

Shorted cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Crimped cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Frayed cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Simplified block diagram.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Simplified sampling diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Pulse display . . . . . . . . . . . . . . . . . . . . . . . . . . . ...... . . . . . . . . .

Jitter check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Position check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Rise time and fall time... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Power Supply board test points and adjustments . . . . . . . . . . . . . . .

Pulse display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Loop gain adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

PC board location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Vertical amplifier/slow ramp board . . . . . . . . . . . . . . . . . . . . . . . . . .

Output amplifier board fog adjustment . . . . . . . . . . . . . . . . . . . . . . . .

Power supply board DC fuse location . . . . . . . . . . . . . . . . . . . . . . . .

Replaceable electrical parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Standard accessories . . . . . . . . . . . . . . . .. . ..... .......

Page

1-0
2-1
2-4
2-4
2-5
2-6
2-8
2-9
2-9
2-10
2-10
2-10
2-11

4-1
4-2
5-2
5-3
5-4

5-4

5-6
5-7

5-8
5-9
5-9

5-10
7-1

C-4
C-5

Number

1-1
1-2
2-1
5-1
6-1
8-1
C-1

C-2

LIST OF TABLES

Title

Page

TDR accessories storage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. ...2-2

Tabulated data system... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...1-2

TDR front panel controls and indicators . . . . . . . . . . . . . . . . . . . . . . . 2-2

TDR troubleshooting procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . ...5-11

Maintenance effort . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...6-1

TDR final inspection checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...8-1

Replaceable electrical parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..C-3

Standard accessories . . . . . . . ............. ...... .. . . C-3

This technical manual is an authentication of the manufacturers’
commercial literature and does not conform with the format and
content specified in AR 310-3, Military Publications. This
technical manual does, however, contain available information
that is essential to the operation and maintenance of the
equipment.

iii/(iv blank)

TM 9-6625-2801-14&P

INSTRUCTIONS FOR REQUISITIONING PARTS

NOT IDENTIFIED BY NSN

When requisitioning parts not identified by National Stock Number, it

is mandatory that the following information be furnished the supply
officer.

1

- Manufacturer’s Federal Supply Code Number - 80009

2

- Manufacturer’s Part Number exactly as listed herein.

Nomenclature exactly as listed herein, including

3-

dimensions, if necessary.

4

- Manufacturer’s Model Number. Tektronix Type 1502-1

5-

Manufacturerfs Serial Number (End Item)

6

- Any other information such as Type, Frame Number, and
Electrical Characteristics, if applicable.

7

- If DD Form 1348 is used, fill in all blocks except 4, 5,

6, and Remarks field in accordance with AR 725-50.

Complete Form as Follows:

(a) In blocks 4, 5,

Supply Code Number - 80009, followed by a colon and

manufacturer’s Part Number for the repair part.

(b) Complete Remarks field as follows:

Noun:
For:

Manufacturer:

Model:

Serial: (of end item)

Any other pertinent information such as Frame

Number, Type, Dimensions, etc.

1502-1

and 6, list manufacturer's Federal

(nomenclature of repair part)

NSN:
Tektronix, Inc.
P.O. Box 500
Beaverton, Oregon 97005

6625-01-084-3855

v

TM 9-6625-2801-14&P

1-0

Figure 1-1. Time domain reflectometer, Tektronix1502-1, cover removed

CHAPTER 1

INTRODUCTION

TM 9-6625-2801-14&P

Section I.

1-1. Scope.

a. Purpose.

ual is to provide information and instruc­tion for the direct support maintenance
of the Time Domain Reflectometer, Tek-

tronix 1502.1 (hereafter referred to as

the TDR) including accessory equipment
and external test cable assemblies (see
figure 1-1),

b. Content Summary. This manual

contains the following information:

(1)

A description of the equipment.

Corrective and preventive main-

(2)

tenance

dures.

tions (appendix A).

instructions.

Checkout procedures.

(3)

(4)

Repair instructions.

(5)

Shipment and storage proce-

(6)

References to all related publica-

(7) Maintenance allocation chart

The purpose of this man-

GENERAL

defining maintenance level responsi­bilities (appendix B).

(8) Maintenance repair parts list

(appendix C).

1-2. Forms and Records. Refer to TM 38­750 for instructions on the use of
appropriate forms, records and reports.

1-3. Calibration.
for the TDR are provided in Technical
Bulletin TB 11-6625-2860-35.

1-4. Destruction of Material to Prevent
Enemy Use.
tion of materiel to prevent enemy use re­fer to TM 750-244-2.

1-5. Reporting Equipment Improvement
Recommendations (EIR). EIR’s will be
prepared using SF 368, Quality Deficiency
Report (QDR).
EIR’s are provided in TM 38-750, The
Army Maintenance Management System

(TAMMS).
to Commander, U.S. Army Armament Mat­eriel Readiness Command, Attention:
DRSAR-MAO, Rock Island, IL 61299. A
reply will be furnished directly to you.

For information on destruc-

EIR’s should be mailed directly

Calibration procedures

Instructions for preparing

Section II.

1-6. Description.

General.

a.
portable Time Domain Reflectometer which
uses radar principles to test cables and
provides a visual display of cable faults.

The test pulses are transmitted via the

CABLE output jack. Reflections are re­ceived at the same jack and displayed on
the cathode-ray tube (crt).

The Tektronix 1502-1 is a

DESCRIPTION AND DATA

Calibrated distance controls allow an op­erator to examine up to 100 feet of cable
with segments as small as 1 foot displayed
horizontally across the 10-division crt
screen.
feet may be examined at 100 feet per divi­sion or 200 feet per division. The horizon­tal crt scale is calibrated directly in dis­tance units from 0. 1 foot per division to

200 feet per division in a 1-2-5 sequence.

Low-loss cables as long as 2000

1-1

TM 9-6625-2801-14&P

A 3-digit, direct reading dial indicates
the distance to any cable discontinuity
when the dial is used to horizontally posi–
tion the discontinuity’s reflection to a crt
reference line.

b. Description.

(1) Main case.

gedized portable instrument that can be
used in the field as well as in the labora–
tory.

Class 2, Style A instrument as specified
in MIL-T-28800 were used as a guideline

for the environmental specifications. The

TDR has a ruggedized case that provides

protection when the instrument is stored
in exposed areas.

is not being used, the accessories, including

the Operators manual, may be packed in

the front of the instrument. Table 1-1
indicates which accessories may be placed
in the cover of the TDR.

The requirements for a Type II,

(2) Accessories. When the instrument

The TDR is a rug-

1 TDR Slide Rule
1 TDR Application Note #1
1 X-Y Output Module
1 Instruction Manual 070-1792-00

1-7. Tabulated Data. The characteristics
given in table 1-2 apply after the instru­ment has been calibrated and will perform
to the requirements given in Chapter 5.

Termination
Pulse Amplitude

Into 50 Load

Accessories Not Stored in Cover

Accessory

Table 1-2.

Characteristics

Tabulated Data System

Tektronix part

number

003-0700-00
062-1538-00
016-0606-00

Performance

50 within ±2%.

225 mV Nominal.

Table 1-1.

Accessories Stored in Cover

Accessories

1 50 BNC Terminator
1 Precision 50 Cable

1 Viewing Hood
1 Operators Manual

1 BNC Connector

Female-to-Female

2 Replacement Fuses

(for front panel)

For 115 Vac
Operation

or

For 230 Vac

Operation (Option 6)
1 Power Cord
1 Filter, Mesh (crt)

TDR Accessories Storage

Tektronix parts

number

011-0123-00

012-0482-00
016-0297-00
070-1790-00

103-0028-00

159-0029-00

159-0054-00
161-0066-00
378-0055-00

Vertical System

Deflection Factor

(7 steps, 1-2-5

sequence)

Accuracy
Gain (screwdriver

control)

Displayed Noise

Low Noise Operation

Horizontal System

Distance Controls

5 /div to 500
/div.

Within ±3%.
At least 3.5:1

from calibrated
point.

±5 or less,
NOISE FILTER
switch “Out”.

±2 or less,
NOISE FILTER

switch “In”.

0 to 2000 feet

total.

1-2

TM 9-6625-2801-14&P

Table 1-2.

Tabulated Data
System - Continued

Horizontal System - Continued

Characteristics

Distance Dial

At X1 Multiplier

Range
Accuracy

I

At X1 Multiplier

Range
Accuracy

FEET/DIV Control

At X.1 Multiplier

Range
Scales

(8 steps,
1-2-5

sequence)

Accuracy

(All scale

settings)

(With scale
set at 20
ft/div)

At X1 Multiplier
Range

Scales

(8 steps,

1-2-5
sequence)

Accuracy

All scale
settings Within ±2%.

200 ft/div
scale

Dielectric Scales

SOLID PTFE Vp/V
SOLID POLY

Performance

0 to 100 feet.

Within ±2%, ±0.5
foot.

0 to 1000 feet.

Within ±2 %, ±1
Digit.

To 20 feet/div

0.1 foot/div to 20
feet/div.

Within ±2%.

Within ±1%

To 200 feet/div.

1 foot/div to 200

feet/div.

Within ±1%.

= 0.70

air

V

p/Vair

= 0.66

Characteristics

OTHER-VAR

Accuracy

Recorders

External Recorder
Interface for X-Y
Recorders

Horizontal

Vertical

Pen Lift

Mode 1

Source V

Sink

Mode 2 (inverted

Mode 1)

Source

Sink

Line Voltage

Battery Pack

(C size, 9 cell)

Operation

(+20oC to +25°C
charge and dis–
charge tempera­ture)

Full Charge Time

Performance

V

= 0.55 to 1

p/Vair

Within ±2%.

0.1 V/div;
(source impedance
10 K ).

0.09 to 0.13 V/div

adjustable (source)

impedance 10 k

= 5 V Nominal

s

with R
< 10 mA (V out

< 0.5 V).

Vs = 5 V Nominal

with R

< 0.5 mA (V out

<0.6V).
—

Power System

117 Vac ±20%, 48
to 410 Hz; fused
at 0.3 A.

234 Vac ±20%, 48

to 410 Hz; fused

at 0.15 A.

At least 5 hours.

16 hours

= 10 k

s

= 10 k

s

1-3

TM 9-6625-2801-14&P

Table 1-2.

Tabulated Data - Continued

Power System - Continued

Characteristics

Typical Charge
Capacity

Charge Tempera­ture

0oC

o

C to +25°C

+20

o

C

+40

Description

Discharge Tempera­ture

65% 100% 85%

40%

65% 55%

Physical Characteristics

Characteristics

Description

Weight with panel cover 18 pounds

and accessories
Without panel cover

16 pounds

and accessories
Height
Width with handle

Without handle
Depth including panel

5.0 inches

12.4 inches

11.8 inches

16.5 inches

cover
Handle extended

18.7 inches

1-4

CHAPTER 2

OPERATING INSTRUCTIONS

TM 9-6625-2801-14&P

Section I.

2-1.

tors.
pose of each front panel connector,
pushbutton,

Front Panel Controls and Indica-

A brief description of the pur-

control, and screwdriver

CONTROLS AND INDICATORS

adjustment follows.

controls of the plug-in module is also
included.
location.

Refer to figure 2-1 for their

A description of the

Legend for fig. 2-1:

1.

CABLE connector
FOCUS control

2.

3.

INTENSITY control

4.

POSITION control

5.

/DIV switch

6.

POWER switch

7.

GAIN adjustment

8.

NOISE FILTER switch

9.

BATTERY meter

10.

ZERO REF CHECK switch

Figure 2-1.

11.

ZERO REF SET control

12.

multiplier switch

13.

DISTANCE control

14.

FEET/DIV switch

15.

CABLE DIELECTRIC switches and
control

16.

RECORD/CAMERA switch

17.

AC LINE fuses

18.

X-Y OUTPUT MODULE

19.

External

TDR front panel controls and

chart recorder controls

indicators

2-1

TM 9-6625-2801-14&P

Table 2-1.

Figure 2-1

index no

1

2

3

4

5

6

7

8

TDR Front Panel Controls

and Indicators

Control or

indicator

CABLE

FOCUS

INTENSITY

POSITION/
FINE

/DIV

POWER

GAIN

NOISE
FILTER

Function

BNC Connector­delivers 110 ps
risetime pulse to
the test cable and
receives the re–
fleeted return
pulse.

Adjusts the focus
of the crt elec–
tron beam.

Controls the
brightness of crt
display.

Controls vertical
position of the crt
display. The
outer control is a
coarse adjust–
ment and the
inner control is
a fine adjustment.

Selects the verti­cal deflection
factor--5 /div
to 500 /div
(5-2-1 sequence).

Push-pull, off-on
switch (pull for
on) – does not
affect the battery

charging circuit.

Screwdriver ad-

just to set the

gain of the verti-

cal amplifier.

Reduces displayed
noise.

rate is reduced by

a factor of 10.

Display

Figure 2-1

index no.

9

10

11

12

13

Control or

indicator

BATTERY

ZERO

REF

CHECK

ZERO
REF
SET

MULTI-

PLIER

DISTANCE

Function

Meter to indicate

the relative charge

of the power pack.

Momentary contact
Pushbutton. When
pushed, checks

the horizontal lo­cation of the inci–
dent pulse on the
crt when the DIS­TANCE dial is
being used.

horizontal pulse
position control
for crt display.
Sets the incident

pulse edge to a

vertical reference

line of the crt

when the DIS-

TANCE dial is at

000 or the ZERO

REF CHECK but-

ton is pushed.

Two-position

switch (red con–

trol) for X.1 or

X1 multiplier.

Affects both the

DISTANCE dial

and the FEET/

DIV control.

Inicates the dis-

tance from the

TDR to the point

on the cable where

the display win-

dow begins. Two

ranges:
at X.1 or 1000
feet at X1. Dis-

abled when the

FEET/DIV is at

200 (FIND).

100 feet

2-2

TM 9-6625-2801-14&P

Table 2-1.

Figure 2-1

index no

14

15

16

TDR Front Panel Controls

and Indicators – Continued

Control or

indicator

FEET/DIV

CABLE
DIELEC­TRIC

SOLID
POLY

SOLID
PTFE

OTHER
VAR

RECORD/
CAMERA

Function

Selects the hori­zontal deflection
factor:

X1=1 - 200 ft/
div.

X.1=0.1 - 20
ft/div.

Three pushbuttons
and a screwdriver
adjust.
the proper velocity
of propagation.
VAR from 0.55 to

1.0 when the
OTHER pushbutton
is pressed. Fully
cw if for air die–
lectric.
trol has reference
marks every 30°
to indicate rela­tive propagation
constants.

Two-position lever
switch; pushed up
and then released,
it initiates X-Y
Recorder or a

Selects

VAR con-

Figure 2-1

index no.

17

18

19

Control or

indicator

AC LINE
FUSES

X-Y
OUTPUT
MODULE

X, Y,
and PEN
LIFT

Function

Chart Recorder;
pushed down, it
floods the crt ­during retrace to
display graticule
for photography.

Protection fuses
for line power
and battery charg­ing circuits (0.3
A fuses for 115
Vac; 0.15 A fuses
for 230 Vac).

The standard plug­in module for the
TDR. Used to
drive an external
X-Y Chart Re­corder.

Six front panel
jacks used for

driving an ex-

ternal X-Y re­corder.
are for horizon­tal drive.
are for vertical

drive.

jacks are for pen

control.

X jacks

Y jacks

PEN LIFT

Section II.

Be extremely careful when working
in the vicinity of batteries when the
battery ease is open. Do not use
uninsulated tools. Do not wear
rings or watches. Metal articles will,
if allowed to contact connectors,
cause severe arcing with possible
injury to personnel and damage to
the battery.

OPERATION

2-2. Operating Power Selection.

When substituting a dc power

supply or external battery for
the battery pack, be sure the
polarity is correct (see figure

2-2).

2-3

TM 9-6625-2801-14&P

Figure 2-2. Battery connector polarity

a.

Battery Connections. A 12 Vdc
power supply may be substituted for the
TDR battery pack by removing the pack
from the unit and connecting the power

supply to the terminals inside the battery

pack compartment.

The power pack can be stored at any
temperature between -40oC and +50°C
with the battery cells either fully or
partially charged.
rate of the cell increases with increased
temperature.
will lose about 50% of its charge in 3 to 4
months if stored at +20°C to +25°C.
Therefore, the battery pack should be

completely recharged before using if it
has been stored without power supplied

to its charging circuit for more than a
month.

A fully charged battery

The self-discharge

2-3. Turn-on Procedures.

If crt displays no signal, check
fault isolation paragraph 5-6.

Figure 2-3.

Preparation.

a.

NOTE

230 Vac transformer wiring

When the TDR is wired for 230
Vac, be sure that the two front
panel fuses are changed to 230 V,

0.15A slow-blow fuses and the
proper plug is installed on the
ac cable.

b.

230 Volt Operation. The battery

charger is factory wired for 115 Vac or

230 Vac if Option 6 is ordered. The
standard 115 Vac unit can be changed to
230 Vac operation by rewiring the line
transformer.
per wiring configuration for 230 V opera­tion.

Figure 2-3 shows the pro-

2-4

(1) To gain access to the front panel,

pull the two side latches forward and re-

move cover.
TDR as a stand, position it to raise the
unit to a convenient operating position

(figure 1-1).

(2) The battery pack is fully charged

in 16 hours when connected to an ac power

source and the unit is switched off. The

TDR may be operated while the battery

pack is charging; however, the charging

time will increase.

overcharge if the charger is left on long-

er than 16 hours.

may remain connected to an ac source
without damaging the batteries. Approxi-

mately once a month or every 15 -charge–
discharge cycles, the batteries should be
charged for approximately 24 hours.

Using the handle of the

The batteries will not

Therefore, the TDR

Approximately 30 minutes of operating
time can be expected from a 1-hour partial
charge. To avoid reverse charging, the
full 16 hour charge should be completed
in preference to a partial charge when­ever possible.

Control Settings (TDR).

b.

(1) Set front panel controls as

follows:

TM 9-6625-2801-14&P

FOCUS

INTENSITY

ZERO REF
POSITION
/DIV

DISTANCE
FEET/DIV

X1-x1
CABLE DIE-

LECTRIC

POWER

(2) Adjust INTENSITY and FOCUS

controls for a clear bright trace.

(3) Adjust POSITION controls to set

trace 2 divisions below horizontal center–

line.

(4) Attach precision 50 cable (012-

0482-00) to CABLE connector (stored in

cover).

(5) Turn ZERO REF SET button ccw
until incident pulse edge is located on a
vertical reference line. The incident
pulse edge is the initial rise of the step
pulse. The vertical reference line may be
any line you choose from center line to
left side of crt graticule. An arrow in
the second vertical line indicates a
commonly used reference line.

The reflected pulse from the open

end of the 50 cable should ap-

pear three horizontal divisions to
right of reference line. Open end
of cable is indicated by start of a

second rise in trace (see figure

2-4).

Midrange
Full range
Fully cw
Midrange

500
000

1
X1
SOLID POLY

ON

NOTE

Figure 2-4. Incident and reflected pulses

(6) Turn ZERO REF SET button
throughout its range to see that the inci–
dent pulse edge can be set on any verti­cal graticule line.
edge on vertical reference line.

(7) Set DISTANCE dial to 050 and
check that top of step (open cable re–
flection) is displayed.

(8) Press ZERO REF CHECK button
and check that incident pulse edge re­turns to vertical reference line of grati­cule.

POSITION controls so top of incident
pulse is on horizontal centerline.

and check for a reduction in displayed
noise as well as a reduction in scan rate.
Reset /DIV to 500, and release (by
depressing a second time) NOISE FILTER
button.

Note crt display; entire crt should be
flooded on retrace to illuminate graticule
when taking photographs. Release
CAMERA switch.

Reset DISTANCE dial to 000.

(9) Change /DIV to 50 and adjust

(10) Press NOISE FILTER pushbutton

(11) Press and hold CAMERA switch.

Set incident pulse

2-5

TM 9-6625-2801-14&P

(12) Lift up and hold RECORD switch.
Check that bright spot appears at left
edge of crt.

(13) Release RECORD switch. Slow

scan of spot will trace displayed wave­form.
automatically return to its normal mode
of scanning.

When scan is complete TDR will

c.

Control Settings (Accessories).

NOTE

The X-Y OUTPUT MODULE is
wired for either a positive or

negative pen lift signal. Be-

fore using the X-Y OUTPUT
MODULE , be sure that the pen
lift circuit on the etched cir­cuit board is properly connected.
Figure 2-5 shows the proper
connection for either a positive
or negative pen lift signal.

(4) To position stylus at desired
position on paper, adjust STYLUS POSI­TION screw while RECORD/CAMERA

switch is in the RECORD position.

(5) Release RECORD/CAMERA to
precede with recording. Chart record
circuits automatically shut off when re­cording is completed.

NOTE

In evaluating a graph, the dis-

tance between two dark hori-

zontal lines corresponds to one
vertical division of the crt dis–
play with respect to the
DIV setting; the distance be­tween two dark vertical lines
corresponds to one horizontal
division of the crt display with
respect to the FEET/DIV setting.

d. Use of Accessories.

Figure 2-5.

(1) If not already in place, install
X-Y OUTPUT MODULE into its compart­ment on front panel of TDR.

(2) Connect X, Y, and PEN LIFT
inputs of recorder to corresponding
jacks of X-Y OUTPUT MODULE.

(3) Position and hold RECORD/
CAMERA switch to RECORD to prepare
for recording.

X-Y output module strap

(1) Mesh Filter for the crt. A mesh
filter is provided with the TDR which
makes viewing of the crt easier when the

unit is being used in the sunlight. This

filter is placed over the crt by sliding it
onto the slots of the crt bezel.

provides shading for the crt and can be
installed over the crt by sliding it down
over the crt bezel sides.
must be removed before the viewing hood
will connect to the crt bezel.

If a Camera Adapter (Tektronix Part
Number 016-0327-00) is attached to the
crt bezel of the TDR, a C–30A/31 cam–

era can be used to take photographs of
the crt display.

illumination, the RECORD/CAMERA

switch must be pushed down and held
while the photograph is being taken.
After the trace is completed the entire crt

is flooded to provide a light background

to allow the dark graticule to appear in
the photograph.

.

(2) Viewing Hood. The viewing hood

The mesh filter

(3) Using a Camera with the TDR.

To obtain graticule

2-6

TM 9-6625-2801-14&P

2-4.

the TDR to the BNC connector (CABLE)
on the front panel.

ter as required.

Cable Testing.

Do not connect live circuit cables
to the input of the TDR. Volt­ages in excess of 5 volts can dam­age the sampling gate or tunnel
diode.

Bleed cables before connecting
them to the TDR to remove static
charge from them. The 50 ohm

termination and BNC adapter
supplied may be used to bleed
any cable charge.

When testing antennas, be sure
that you are not close to trans-

mitters that can be keyed at the
antennas receiving frequency.
Keying of transmitters in close
proximity can cause damage to
the TDR.

Connecting a Cable for Testing.

a.

(1) Connect cables to be tested by

Use connector/adap-

150 feet long, set

and the multiplier

Use the X.1 multiplier whenever
possible to lessen the effects of
jitter.

(2) Measure the distance between

the incident pulse rise and the reflected

pulse rise.

The distance from the sampling

bridge to the CABLE connector

(2. 5 inches) should be taken in­to account when measuring
cables less than 2 feet in length.

(3) To more accurately locate the

discontinuity, set the FEET/DIV control
to a lower setting. (The reflected
pulse does not need to be in the display

window).
button and adjust the ZERO REF SET
control so that the incident pulse rise is

set at a convenient vertical reference

graticule line.
contol may have to be readjusted when

changing the FEET/DIV control.

Push the ZERO REF CHECK

the FEET/DIV to 200

at X.1.

NOTE

NOTE

The ZERO REF SET

(2) Adjust FOCUS and INTENSITY
controls for a sharp and bright display
on the crt.

b. Locating a Discontinuity in a Cable.

The DISTANCE dial and the FEET/DIV
control make it possible to evaluate cables
as long as 2000 feet. The entire length
can be displayed directly on the crt if
desired.
only that portion of the trace seen on the
crt will be recorded on the graph. To
check cables using the crt, proceed as
follows:

(1) Set crt display window so it is

longer than the cable under test by set-

ting the FEET/DIV control and the X1/
X.1 control,

If a chart recorder is used,

For example, if the cable is

NOTE

Always set the incident and re­flected pulse to the 10% points of
their amplitude (see figure 2-6).

(4) Turn the DISTANCE dial clock-

wise until the reflected pulse is located
on the reference graticule line. The
reading on the DISTANCE dial times the

multiplier gives the length from the
CABLE connector to the end of the cable

(or to the discontinuity).

NOTE

When checking cables longer
than 1000 feet, adjust the DIS­TANCE dial until the reflected
pulse reaches the right-hand

2-7

TM 9-6625-2801-14&P

edge of the graticule, then
add the graticule display dis­tance to that on the DISTANCE
dial for the total length. The
reading of the DISTANCE dial,
plus the number of divisions

(from the reference line) across
the graticule times the FEET/
DIV setting gives the total
length of the cable. Remember
that in the 200 FEET/DIV set­ting the DISTANCE dial is in­operative.

Figure 2-6. Crt display of pulse

(5) The CABLE DIELECTRIC push-

buttons allow the TDR to accurately lo­cate discontinuities in cables of various

relative propagation velocity constant

(Vp).
brated to check solid polyethylene die­lectrics which have a Vp of 0.66. The

SOLID PTFE button is calibrated to check

solid polytetrafluoroethylene (Teflon)
which has a Vp of 0.70. The OTHER
button is variable from 0.55 to 1.00 and
is controlled by the screwdriver adjust–

ment control VAR.
control is turned to the fully clockwise
position, it is calibrated for air dielectrics
which have a Vp of 1.00. If all three of
the CABLE DIELECTRIC buttons are

released, a default condition leaves the
instrument calibrated for air dielectrics

(Vp) = 1.00).

The SOLID POLY button is cali-

When this screwdriver

/DIV control determines the vertical
deflection that can be seen on the crt or
recorded on a graph if a chart recorder

is used.

measure the ratio of the reflected signal
amplitude to the incident signal amplitude
in rho ( ), which is called the voltage

reflection coefficient.

measurement of reflected signal amplitude

and can be used to determine the im–

pedance of a discontinuity. Note that no

reflection is obtained from a cable that
has no discontinuities if the cable is ter-

minated with its characteristic impedance.

If a cable has an open, i.e., a break

(infinite impedance), the reflected step

amplitude is +1 ;

short (zero impedance), the reflected

step amplitude is -1

of a TDR display labeled to identify the
incident and reflected voltage signals.

When =0, the transmission line is ter-

minated by a resistance equal to its

characteristic impedance (Z0) which, in

this case, is 50

the transmission line load is a short. If
the line is terminated by RL > 50
is positive and if the line is terminated by
RL < 50 is negative.

ting reflected pulse amplitude to impe-

dance.

teristic impedance, Z0, of the cable under

test and the load (or the impedance of

the discontinuity), R

Therefore, a can also be defined as:

the cable problems that can be analyzed

with the TDR include opens, shorts, pin-

holes in the cable shield, opens in the

shield, kinks in the cable, mismatched

connectors, and corroded connectors.

c.

Evaluating a Discontinuity. The

This control is calibrated to

Rho ( ) is the

and if a cable has a

(1) Figure 2-7 shows the two parts

.

When equals +1,

(2) Figure 2-8 is a chart for conver-

Rho is dependent on the charac-

, on the cable.

L

Typical Cable Problems. A few of

d.

2-8

TM 9-6625-2801-14&P

Figure 2-7.

TDR display of RL vs Z

O

Figure 2-8.

Impedance nomograph

2-9

TM 9-6625-2801-14&P

Figures 2-9 through 2-12 show typical
examples of these problems.

Figure 2-9. Open cable

e.

Checking Cables with Other than

50 Ohms Impedance.

(1) Cables with a characteristic

impedance other than 50 can be evalu-

ated by adjusting the GAIN control
(screwdriver adjust) to correct the re-

flected pulse for +1 at the open end of
a cable.

incident pulse will no longer be 1

dance other than 50 , either connect

an impedance–matching adapter (50 to

75 , 50 to 93 50 to 125 etc.) to the

CABLE connector and connect a short
length of cable (with impedance the same
as the adapter, i.e., 75 125 etc.)

to the adapter or connect the cable to be

tested to the CABLE connector. With the

/DIV control set at 500, position the

trace on the graticule so that the display

of the cable appears in the display. Now

When the GAIN is changed, the

.

(2) To reset the GAIN for an impe-

Figure 2-10.

Figure 2-11. Crimped cable

Shorted cable

2-10

TM 9-6625-2801-14&P

adjust the GAIN control so that the open
end display (reflected pulse) is set 2
divisions above the cable display (hori-

zontal centerline). This sets the re­flected pulse to +1 from the character­istic impedance.

NOTE

If an impedance adapter is not

used, secondary reflections

will re–appear as discontinu­ities beyond the open end of
the cable.

Figure 2-12.

Frayed cable

2-11/(2-12 blank)