Tektronix 7B85 User manual

Tektronix, Inc.
P.O. Box 500
Beaverton, Oregon 97077
INSTRUCTION MANUAL
Serial Number
Scans by ArtekMedia O 2006
First Printing, DEC 1975

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Copyright @ 1975 by Tektronix, Inc., Beaverton,
Oregon. Printed intheUnitedStatesof America. All
rights resewed.Contentsof thispublicationmaynot
be reproduced in any form without permission of
Tektronix, Inc.
U.S.A. and foreign TEKTRONIX products covered
by
U.S. andforeignpatentsand/orpatentspending.
TEKTRONIX isaregisteredtrademarkof Tektronix,
Inc.
Scans by AttekMedia O 2006

7B85 Operators
TABLE OF CONTENTS
PAGE
LIST OF ILLUSTRATIONS
.................... ii
LIST OF TABLES ........................... ii
SAFETY SUMMARY
........................ iii
SECTION
1 OPERATING INSTRUCTIONS
INSTALLATION
..................... 1-1
CONTROLS. CONNECTORS.
AND INDICATORS
.................... 1-1
FUNCTIONAL CHECK ................. 1-1
Setup Procedure
.................... 1-4
Sweep Functions
.................... 1-4
NORMALSWEEP
................. 1-4
DELAYINGAND DELAYEDSWEEP
.... 1-4
A (DIFFERENTIAL)TIME ........... 1-5
Triggering Functions
................. 1-5
GENERAL OPERATING INFORMATION
.... 1-6
Triggering Switch Logic
............... 1-6
Triggering Modes .................... 1-6
P-P AUTO
...................... 1-6
AUTO
......................... 1-6
NORMAL
...................... 1-6
SINGLE SWEEP
.................. 1-6
Trigger Coupling
.................... 1-7
AC
........................... 1-7
AC LF REJ
..................... 1-7
AC HF REJ
..................... 1-7
DC
........................... 1-7
Trigger Source
..................... 1-7
INTERNAL
..................... 1-7
PAGE
LINE ......................... 1-7
EXTERNAL
..................... 1-7
Trigger Slope
...................... 1-7
Trigger Level
...................... 1-7
............... Horizontal Sweep Rates 1-9
.................. Time Measurement 1-9
Sweep Magnification
................. 1-9
................... Variable Hold Off 1.10
................ Delay-Time Operation 1.10
................... A Time Operation 1.10
A TIME OPERATION INA
DUAL-BEAMOSCILLOSCOPE
MAINFRAME
................... 1.12
Mainframe Operating Modes
............ 1.12
APPLICATIONS
........................ 1.13
DELAYED-SWEEP MEASUREMENTS
....... 1.13
Time-Interval Measurements
(Delay-TimeMode)
.................. 1.13
Differential Time-Interval Measurements
(A Time Mode) ..................... 1.14
Delayed-SweepMagnification ........... 1.15
Triggered Delayed-SweepMagnification
..... 1.18
INDEPENDENT TIME-IIV'TERVAL
MEASUREMENTS .................... 1.18
SECTION
2 SPECIFICATION
STANDARD ACCESSORIES
............... 2-4
SECTION
3 INSTRUMENTOPTIONS
CHANGE INFORMATION
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7B85 Operators
FIGURE
NO.
Frontis-
piece
1-1
1-2
LIST OF ILLUSTRATIONS
PAGE FIGURE
NO.
7885 Features .................... iv
............ Locationof release latch. 1-1
Front-panelcontrols, connectors,
................... and indicators. 1-2
Effectsof LEVELcontrol and SLOPE
switch on crt display
............... 1-8
Area of graticule used for most accurate
time measurements
................ 1-9
Effect of sweep magnifier on crt display
. . 1-9
(A)Delaying-sweepdisplay producedby
7885 in the A horizontal compartment.
(B) Delayed-sweepdisplay producedby
companion time-baseunit inthe B hori-
zontal compartment.
.............. .l-10
Typical
A (differential)Time Operation. . .l-11
TABLE
NO.
PAGE
LIST OF TABLES
Measuringtime intervalsfrom a triggering
event (start of sweep) toany point on
a
..................... waveform. .l-14
Measuring rise time, fall time, period,
frequency, or pulse width inthe
A (dif-
.............. ferential) time mode .l-15
Magnifying
a selected segment of the
delaying (A)sweep inthe delay-time
mode with mainframe alternate or
........ chopped horizontal operation .l-16
Time-interval measurementsin the
delay-time and
A (differential)time
mode with mainframe alternate or
chopped operation.
............... .l-17
Examiningan event that occurs within
aselected time interval after
a known
..... delay time in the delay-time mode .l-18
........... 7B85 dimensionaldrawing 2-4
PAGE
2-1 Electrical Characteristics. ............ 2-1
2-2 Environmental Characteristics
......... 2-4
............. 2-3 PhysicalCharacteristics. 2-4
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7B85 Operators
SAFETY SUMMARY
This manualcontains safety informationwhich the user must follow toensure safe operation of this instrument. WARIUING
information is intended to protect the operator, CAUTION information is intendedto protect the instrument. The following
are general safety precautionsthat must be observedduring all phases of operation.
Ground the Instrument
Toreduce electrical-shock hazard, themainframe (oscilloscope)chassis must beproperly grounded. Refer to the mainframe
manual forgrounding information.
Do NotOperate in Explosive Atmosphere
Donot operate this instrument in an area whereflammablegases or fumesare present. Such operation could cause an
explosion.
Avoid Live Circuits
Electrical-shock hazards arepresent in this instrument. Theprotective instrument coversmust notbe removed by operating
personnel. Component replacementand internal adjustments must be referred to qualifiedservicepersonnel.
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7B85 Operators
7685 Features
The 7B85 Delaying Time-Baseunit providescalibrated sweep rates from 5 seconds to 10 nanoseconds and triggering to400
megahertz for 7700-, 7800-, and 7900-seriesoscilloscopes. The XI0 Magnifier increases each sweep rate by afactor of 10
and a VARIABLE control allows continuously variable sweep rates betweencalibrated steps. Variable hold off and alpha-
numeric readout are provided. Also, when operating in the AUTO TRIGGERING MODE,
a bright baseline trace is displayed
in the absence of atrigger signal.
Other features include independent sweep operation or continuously variable sweep delay (DELAYTIME) and differential
sweep delay
(A TIME) with acompanion time-base unit. Delay time or differential delay time readout is displayed on the
mainframe cathode-ray tube.
Scans by ArtekMedia O 2006

Section 1-7B85
OPERATING INSTRUCTIONS
The 7885Time-Base unit operates with aTektronix 7700-, 7800-, or 7900-seriesoscilloscope mainframe and a 7A-series
amplifier unit to form acomplete oscilloscopesystem. This section describes the operation of the front-panel controls and
connectors, provides general operating information, a functional check procedure, and basic applications for this instrument.
IIVSTALLATION CONTROLS, CONNECTORS, AND INDICATORS
The time-baseunit is designed to operate in the horizontal All controls, connectors, and indicators required for the
plug-incompartment of the mainframe. This instrument operation of the time-base unit are located on the front
can also be installed in avertical plug-incompartment to panel. Figure 1-2shows and providesa brief description of
provide avertical sweep on the crt. However, when used in all front-panel controls, connectors, and indicators. More
this manner, there are no internal triggering or retrace detailed information is given in the General Operating
blanking provisions, and the unit may not meet the specifi- Instructions.
cations given in Section 2.
To install the unit in a plug-incompartment, push it in until
itfits firmly into the compartment. The front panel of the
unit should be flush with the front panel of the mainframe.
Even though the gain of the mainframe is standardized, the
sweep calibration of the unit should be checked when in-
stalled. The procedure for checking the unit
is given under
Sweep Functions in the Functional Check procedure inthis
section.
To remove the unit, pull the release latch (see Figure 1-1)
todisengage the unit from the mainframe, and pull it out of
the plug-in compartment.
LEVEL
rwe o
TRIGGERING 11'1
."TO LC u "El Llll
" I
$In I
RELEASE
LATCH
FUNCTIONAL CHECK
The following procedures are provided for checking basic
instrument functions. Refer tothe description of the con-
trols, connectors, and indicators while performing this pro-
cedure. If performing the functional check procedure
reveals a malfunction or possible improper adjustment, first
check the operation of the associated plug-in units, then re-
fer to the instruction manual for maintenanceand adjust-
ment procedures.
Setup Procedure
1. Install the 7B85 inthe A horizontal compartment of the
mainframe.
2. Install an amplifier plug-in unit in avertical compart-
ment.
3. Set the 7B85 controls as follows:
SLOPE
MODE
COUPLING
SOURCE
B DELAY MODE
TRACE SEP
POSITION
TIMEIDIV
VARIABLE
(CAL IN)
HOLDOFF
MAG
(+)
P-P AUTO
AC
INT
INDEPENDENT
OFF (fullyclockwise)
Midrange
1 ms
Calibrated (Pushed in)
MIN (fully counter-
clockwise)
XI (pushedin)
Fig. 1-1. Location of release latch.
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Operating Instructions-7B85
Fig. 1-2. Front-panelcontrols, connectors, and indicators.
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Operating Instructions-7685
TRIGGERING
a LEVELControl-Selects a pointonthetrigger signal where triggering occurs.
@ SLOPE Switch- Permits sweep tobetriggered onnegative- or positive-goingportionsof thetrigger signal.
@ READY Indicator-Illuminates when sweep circuit isarmed (SINGLE SWEEP Mode).
@ TRIG'D Indicator-Illuminates when thedisplay is triggered.
@ MODE Pushbuttons-Selects theoperating mode of the triggering circuits.
@ COUPLING Pushbuttons-Selects the method of coupling thetrigger signal totriggering circuit.
@ SOURCE Pushbuttons-Selects source of thetrigger signal.
SWEEP
@ POSITIONControl-Provides horizontal positioning.
@ FINEControl-Provides precise horizontal positioning.
@ HOLDOFF Control-Permits holdoff periodtobe varied toimprovetriggeringstability of repetitivecomplex waveforms.
@ MAG Pushbutton-Selects XI0magnifiedor unmagnified sweep.
@ TlMElDlV Switch-Selects thesweep rateof thesweep generator.
13
VARIABLE Control and CALSwitch-Selects calibrated or uncalibrated sweep rates. Uncalibratedsweep ratescan be
0 continuously reducedtoat least the sweep rateof the next slower position.
14
SWP CALAdjustment-Compensates for basic timing changes due tothedifferences insensitivity of mainframes inwhich
O the 7885 may be used.
EXTERNAL TRIGGER INPUT
@ EXTTRIG ATTENUATOR-Selects attenuation factor for external trigger signals.
@ EXTTRlG INConnector-Connector (BNCtype1 provides input for external trigger signals.
SWEEP MODE
B DELAYMODE Pushbuttons-Selects independent or delaying sweep operation. Inthe B STARTSAFTER DLYand
B TRIGGERABLE AFTER DLYdelayingsweep modes, the DELAY TlME and
A
TlMEfunctions are activated. There
will be a
2 division vertical shift of thetrace when switchingfrom INDEPENDENTtoB STARTSAFTER DELAY.
DELAYTIME
18
DELAYTlME Control-Provides variable delay timebefore thestart of thedelayed sweep producedbycompanion time-
base unit.
19
TRACE SEP Controland Switch-Enables A TlME functions and provides vertical separation of thedelayed sweep
O traces (A TIME operation,.
A TlME Control-Provides differential timemeasurements between 2 selected intensified zones onthedelaying sweep
trace. Twodelayed sweep traces corresponding tothe intensified zones are displayed bythe companion time-base unit.
Differentialtime isdisplayed onthe crt readout.
Fig. 1-2. Front-panelcontrols, connectors, and indicators (cont.).
REV. A, APR. 1977
Scans by ArtekMedia O 2006