Tektronix 7812 User manual

Tektronix, Inc.
P.O. Box 500
Beaverton, Oregon
070-1244-00
Product Group 42
97077
Tektrone<
COMMITTED TO EXCELLENCE
PLEASE CHECK FOR CHANGE INFORMATION
AT THE REAR OF THIS MANUAL.
7812
TDR/SAMPLER
S/N B020000-up
INSTRUCTION MANUAL
Serial Number
First Printing NOV 1971
Revised JUN 1986

Copyright © 1971 Tektronix, Inc. All rights reserved.
Contents of this publication may not be reproduced in any
form without the written permission of Tektronix, 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. TELEQUIPMENT
is a registered trademark of Tektronix U.K. Limited.
Printed in U.S.A. Specification and price change privileges
are reserved.
INSTRUMENT SERIAL NUMBERS
Each instrument has a serial number on a pariel insert, tag,
or stamped on the chassis. The first number or letter
designates the country of manufacture. The last five digits
of the serial number are assigned sequentially and are
unique to each instrument. Those manufactured in the
United States have six unique digits. The country of
manufacture is identified as follows:
Bo00000 Tektronix, Inc., Beaverton, Oregon, USA
100000 Tektronix Guernsey, Ltd., Channel Islands
200000 Tektronix United Kingdom, Ltd., London
300000 Sony/Tektronix, Japan
700000 Tektronix Holland, NV, Heerenveen,
The Netherlands

SECTION 1
SECTION 2
SECTION 3
SECTION 4
7812
TABLE OF CONTENTS
CHARACTERISTICS
Description
Electrical Characteristics
Physical Characteristics
Environmental Characteristics
OPERATING INSTRUCTIONS
General Information
Installation
Controls and Connectors
First Time Operation
Voltage Reflection Coefficient
Impedance Scale Overlays
Time or Distance Measurements
High Resolution
Single Sweep Operation
PRESET Calibration
Application Connections
Using TDR Slide Rule
CIRCUIT DESCRIPTION
Introduction
Vertical Circuits Block Diagram
Horizontal Circuits Block Diagram
Circuit Description
MAINTENANCE
Introduction
Lubrication
Troubleshooting
Tape Dial Removal
Tape Dial Installation
Tape Dial Alignment
Revised NOV 1984
Page
1-1
1-1
1-5
1-5
2-1
2-1
2-1
2-5
2-8
2-8
2-11
2-11
2-12
2-12
2-14
3-1
3-1
3-4
3-10
4-4
4-4
4-1
4-2
4-2
4-2
SECTION 4 MAINTENANCE (cont)
SECTION 5
SECTION 6
SECTION 7
SECTION 8
Page
Readout Symbol Adjustment
} and XJ 4-2
Repackaging for Shipment 4-3
PERFORMANCE
CHECK/ADJUSTMENT
Introduction 5-1
Equipment Required 5-1
Performance Check and Adjustment
Record and Index 5-2
7812 Checks 5-3
S-6, S-52 and 7S12 System Checks 5-5
S-5, S-54 and 7S12 System Checks 5-7
Adjustment Procedure 5-9
ELECTRICAL PARTS LIST
DIAGRAMS AND CIRCUIT BOARD
ILLUSTRATIONS
Symbols and Reference Designators
Schematic Diagrams and Component
Board Locations
MECHANICAL PARTS LIST
Mechanical Parts List
Mechanical Parts List Illustration
Accessories

7$812
—-o
S-6 SAMPLING HEAD
Fig. 1-1. 7S$12 TDR/Sampler unit.

ee,
7812
SECTION 1
CHARACTERISTICS
Description
The 7S12 is a dual-purpose plug-in unit for measurement
of recurring fast-rise signals or for time-domain
reflectometry. It occupies two compartments (one vertical
input and one horizontal input) of a Tektronix 7000-series
oscilloscope.
The 7S12 has two compartments for plug-in heads. The
left-hand compartment (labeled SAMPLING on the 7812
front panel) accepts Tektronix S-series Sampling Heads.
The type of sampling head selected determines the vertical
input characteristics of the 7S12. The right-hand compart-
ment (labeled PULSE GENERATOR) accepts S-series pulse
generators, trigger recognizers or trigger count-down heads.
The 7S12 has the following features: The vertical de-
flection factors, i.e., millivolts/div and millirho/div, are
from 2 to 500 in a 1-2-5 sequence. The time/div is cali-
brated from 20 ps/div to 1 Us/div in a 1-2-5 sequence. The
DC OFFSET control offsets the display in a +1 V range.
The Hl RESOLUTION switch reduces the waveform noise
and jitter by signal averaging with a corresponding re-
duction of sweep rate. The LOCATE switch increases the
time/div and intensifies a portion of the display to locate
the time window relative to the total waveform. Front
panel outputs include OFFSET OUT (+10 V_ range),
VERTical SIGnal OUT and SWEEP OUT. Modes of sweep
operation include SINGLE sweep, REPetitive sweep,
MANual scan and EXTernal sweep IN.
The TIME-DISTANCE scale is calibrated for round-trip
time measurements of O to 10 Us and one-way distance
measurements up to 4900 feet (1500 meters) air dielectric
or 3200 feet (975 meters) polyethylene dielectric. The
POLY scale may be calibrated for transmission lines which
have a velocity of propagation equal to or greater than that
of polyethylene. The Time-Distance scale may be ordered
with distance calibrated in metric units.
SECTION 1
ELECTRICAL CHARACTERISTICS
Characteristic
Performance Requirement
Supplemental Information
Deflection Factor
Accuracy Within 3%
Range
2 units/div to 500 units/div in a 1-2-5
sequence. Units/div are labeled on the
sampling head.
Units/Div VARIABLE Range Provides continuous coverage from 1
to 770 units/div (mV or mp)
p CAL Range
Allows calibrated reflection coefficient
(p) with pulse generators supplying
from 200 mV to 1 V pulse amplitude.
DC OFFSET Range
Offsets display at least +1 V to —-1V.
OFFSET OUT
Range
At least +10 V to —10 V. OFFSET
OUT = 10X (DC OFFSET) within 2%
Source Resistance 10 k& within 1%
1-1

Characteristics—7S 12
Characteristic
Performance Requirement
Supplemental Information
VERTical SIGnal OUT
Amplitude
200 mV/div of signal display within
2%
VARIABLE control must be in CAL
position.
Source Resistance
10 kQ within .5%
SWEEP OUT
Amplitude 1 V/div of horizontal deflection within
2%
Range OV to greater than 10 V
Source Resistance
10 kQ within 1%
TIME/DIV
Accuracy
Within 3%
Range
20 ps/div to 1 uUs/div in a 1-2-5
sequence
Time/Div VARIABLE Range
Provides continuous coverage to at
least 8 ps/div.
Display Modes
SINGLE Sweep
Each sweep is initiated by pushing and
releasing the START button.
REPetitive Sweep
Normal resolution: sweep rate is
continuously variable from at least 1
sweep in 20 ms to less than 1 sweep in
55,
H| RESOLUTION: sweep rate is con-
tinuously variable from at least 1
sweep in 200 ms to less than 1 sweep
in 50s.
MANual Sweep
Any portion of the display may be
observed by manual operation of the
SCAN control.
EXTernal Input
Deflection Factor
1 V/div within 5% to at least 15 V/div
Input Resistance
100 k2 within 10%
Maximum Input Voltage
150 V (DC + peak AC)
FINE (ZERO SET) Range
Moves an unmagnified waveform at
least .9 div.
1-2
>

Characteristics—7S 12
ELECTRICAL CHARACTERISTICS
SYSTEM PERFORMANCE WITH S-6 AND S-52
Characteristic Performance Requirement Supplemental Information
Risetime 35 ps or less for the incident step, 45 ps
or less for the displayed reflection from a
short-circuited 1 ns test line
Pulse Amplitude At least +200 mV into 50 22
Input Impedance Nominal 50 2
Jitter Less than 10 ps (without signal averaging)
Aberrations Not more than +7%, —7%, total of 10%
P-P within the first 1.8 ns of the step edge
with the reference level at 1.8 ns from the
step edge; not more than +2%, —2%, total
of 4% P-P after 2.5 ns from the step edge
with the reference level at 0.3 us from the
step edge.
TIME-DISTANCE Scale Time scale indicates round-trip time.
Distance scales (AIR and POLY
dielectrics) indicate one-way distance.
The usable TIME-DISTANCE ranges
for TDR measurements are limited by
the S-52 pulse duration.
Accuracy TIME scale within 1% of full scale. Distance scales are calibrated for the
nominal velocity of propagation of the
AIR and POLY dielectrics.
TIME-DISTANCE Multiplier
Karl X1 X10
TIME Range .1 us 1 us 10 us
Maximum of about 150
ns one-way cable delay.
AIR Dielectric Distance 49 feet 490 feet 4900 feet
Range 15 meters 150 meters|1500 meters
Maximum of about 150
feet (46 meters) cable
length.
POLY Dielectric Distance 32 feet 320 feet 3200 feet
Range
9.75 meters |97.5 meters} 975 meters
Maximum of about 100
feet (30 meters) cable
length.
[A] 1-3

Characteristics—7S 12
Characteristic
Performance Requirement
Supplemental Information
PRESET Permits the calibration of the POLY
scale for dielectrics having a velocity
of propagation between those of poly-
ethylene and air.
ELECTRICAL CHARACTERISTICS
SYSTEM PERFORMANCE WITH S-5 AND S-54
Characteristic Performance Requirement Supplemental Information
Risetime 1.5 ns or less for the displayed reflection
from a short-circuited test line
Pulse Amplitude
At least +400 mV into 50 2
Input Impedance
Nominal 50 2
Jitter
Less than 20 ps (without signal averaging)
Aberrations
Not more than +4%, —6%, total of 10%
P-P within the first 17 ns of the step: not
more than +1.5%, —1.5%, total of 3%
after 17 ns.
TIME-DISTANCE Scale
Time scale indicates round-trip time.
Distance scales (AIR and POLY
dielectrics) indicate one-way distance.
TDR events out to 20 us (round-trip
time) may be viewed. This corresponds
to 9800 feet (3000 meters) in AIR
dielectric and to 6400 feet (1950
meters) in POLY dielectric. This
distance is the sum of the displayed
time window (10 us maximum) and
the TIME scale readout (10 us maxi-
mum).
Accuracy
TIME scale within 1% of full scale.
Distance scales are calibrated for the
nominal velocity of propagation of the
AIR and POLY dielectrics.
TIME Range
TIME-DISTANCE Multiplier
X.1 X1 X10
-1 Us 1 ps 10 us
An additional time range may be
viewed.
1-4
—™

Characteristics—7S$ 12
Characteristic
Performance Requirement Supplemental Information
AIR Dielectric Distance
Range
49 feet
490 feet
4900 feet
15 meters 150 meters
1500 meters
An additional distance range may be
viewed (in terms of time).
POLY Dielectric Distance 32 feet 320 feet 3200 feet
Range
97.5 meters 9.75 meters 975 meters
An additional distance range may be
viewed (in terms of time).
PRESET Permits the calibration of the POLY
scale for dielectrics having a velocity
of propagation between those of poly-
ethylene and air.
PHYSICAL CHARACTERISTICS
Characteristic Performance Requirement
“\ Finish Anodized aluminum front panel
Weight
Net 4.7 |b
Domestic Shipping |7.2 Ib
Export Packed 11.7 Ib
Dimensions
Length (ex-
cluding knobs) 13.383 in
Width 5.464 in
Height 4.988 in
ENVIRONMENTAL CHARACTERISTICS
Characteristic Performance Requirement
Temperature
Operating
0°C to +50°C
ENVIRONMENTAL CHARACTERISTICS (cont)
Characteristic
Performance Requirement
Altitude
Operating To 15,000 feet
Non-operating To 50,000 feet
Vibration
Operating 0.025 in P-P displacement at 55 Hz
Shock
Operating To 20 g’s, 1/2 sine, 11 ms duration
Humidity
Non-operating
and Operating
5 cycles (120 hours) to 95% relative
humidity referenced to
MIL-E-16400F (Paragraph 4.5.9
through 4.5.9.5.1, Class 4)
Non-operating
—40°C to +65°C
Transportation
Qualifies under National Safe
Transit Committee test procedure
1A, Category II

NOTES
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