Tektronix 3B5 User manual

INSTRUCTION
MANUAL
Serial Number _____________
TYPE 3B5
AUTOMATIC/
PROGRAMMABLE
TIME BASE
Tektronix, Inc.
S.W. Millikan Way • P. O. Box 500 • Beaverton, Oregon 97005 • P one 644-0161 • Cables: Tektronix
070-0538-00
666

WARRANTY
All Tektronix inst-uments are warranted
against defective materials and workman 
s ip for one year. Tektronix transformers,
manufactured in our own plant, are war 
ranted for t e life of t e instrument.
Any questions wit respect to t e war 
ranty mentioned above s ould be taken
up wit your Tektronix Field Engineer.
Tektronix repair and replacement-part
service is geared directly to t e field,
t erefore all requests for repairs and re 
placement parts s ould be directed to t e
Tektronix Field Office or representative in
your area. T is procedure will assure you
t e fastest possible service. Please include
t e instrument Type and Serial or Model
Number wit all requests for parts or
service.
Specifications and price c ange privi 
leges reserved.
Copyrig t c 1966 by Tektronix, Inc.,
Beaverton, Oregon. Printed in t e United
States of America. All rig ts reserved.
Contents of t is publication may not be
reproduced in any form wit out permission
of t e copyrig t owner.
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
Type 3B5

CONTENTS
Section
Section
Section
Section
Section
Section
1
2
3
4
5
6
C aracteristics
Operating Instructions
Circuit Description
Maintenance
Performance C eck
Calibration
Abbreviations and Symbols
Parts Ordering Information
Section 7 Electrical Parts List
Mec anical
Parts List Information
Section 8 Mec anical
Parts
List
I
j
Section 9
Diagrams
Mec anical Parts
List Illustrations
Accessories
t is manual
Abbreviations and symbols used in
are based on, or taken directly from, IEEE
Standard 260 “ Standard Symbols for Units ”
MIL-STD-12B and ot er standards of t e elec 
tronics industry. C ange information, if any,
is located at t e rear of t is manual.
■®1
Type 3B5

Fig. 1-1. Type 3B5 Auto atic/Progra able Ti e Base unit.
Type 3B5

SECTION 1
CHARACTERISTICS
T e Tektronix Type 3B5 Automatic/Programmable Time
Base unit provides automatic and programmable time-base
features, in addition to conventional time-base features, for
Tektronix oscilloscopes w ic accept 3-series time-base units 1 .
T e Type 3B5 provides automatic sweep rate and trigger
seeking on Seek command eit er from t e front-panel SEEK
button, from a remote-seeking probe (t roug an associated
automatic/programmable amplifier unit) or from an external
source (t roug eit er t e front-panel PROGRAM connector
or t e program connector of t e associated automatic/pro 
grammable amplifier unit). All front-panel control functions
(except variable sweep rate) can be externally programmed
t roug t e front-panel PROGRAM connector. T e MANUAL
TIME/DIV switc provides selection of sweep rates from 5
seconds/division to 10 nanoseconds/division wit delayed
1 Except the Type 561 (SN 5000 and below). When used in a Type
565, a vertical sweep is provided.
sweep magnification of 10 and 100 times (up to a maximum
magnified sweep rate of 0.1 microseconds/division).
A front-panel illuminated readout panel indicates sweep
rate, magnified sweep (wit correct indication of magnified
sweep rate), non-triggered sweep and uncalibrated sweep.
T e readout panel functions in all modes of operation.
T e c aracteristics w ic follow are divided into two cate 
gories. C aracteristics listed in t e Performance Requirement
column are c ecked in t e Performance C eck and Calibra 
tion sections of t is manual. Items listed in t e Supplemental
Information column are provided for reference use and do
not directly reflect t e measurement capabilities of t is
instrument. T e Performance C eck procedure given in
Section 5 of t is manual provides a convenient met od of
c ecking t e Performance Requirements listed in t is section.
T e following c aracteristics apply over an ambient tempera 
ture range of 0° C to +50° C, except as ot erwise indicated.
Warm-up time for given accuracy is five minutes.
ELECTRICAL CHARACTERISTICS
TRIGGERING
C aracteristic
Performance Requirement
Supplemental Information
Source
Internal or external
Coupling
AC internal
AC or DC external
Polarity
Sweep can be triggered from positive-going
or negative-going portion of trigger signal.
Slope c anged automatically eac time
CHANGE SLOPE button is pressed.
Mode
Auto triggering
Normal triggering adjustable for desired level
Internal Trigger Sensitivity
AUTO and AC
0.5 division of deflection, minimum, 50 Hz to
20 MHz
C ecked wit Type 3A5 signal dis 
played, 10 millivolts/division or greater
sine wave. Typically — 3 dB down at
10Hz
External Trigger Sensitivity
AC
1.0 volt, peak to peak, 50 Hz to 20 MHz Typically — 3 dB down at 10 Hz
DC
1.0 volt, peak to peak, 10 Hz to 20 MHz
2.5 volts, peak to peak, DC to 10 Hz
Trigger LEVEL Control Range
INT-AC At least + and — 10 volts
EXT-AC At least + and — 20 volts
EXT-DC
At least + and — 10 volts
AUTO
Approximately 10% and 90% of trigger
signal transition wit a minimum of 0.5
division, (10 millivolts/division or greater)
1 kHz sine wave displayed wit Type 3A5
External Program Trigger
Level Range
Same as front-panel range wit current
c ange between about 0 and 400 micro 
amps
External Trigger Input
RC C aracteristics
Approximately 150 kilo ms paralleled by
about 22 pF
Maximum Input Voltage at
EXT TRIG INPUT connector
100 volts, DC + peak AC
1-1

Characteristics — Type 3B5
HORIZONTAL DEFLECTION SYSTEM
C aracteristic
Performance Requirement
Supplemental Information
Sweep Rates
Manual Mode
5 seconds/division to 10 nanoseconds/division
in 27 calibrated steps. Sweep rate indicated
on readout panel
Selected by front-panel MANUAL TIME/
DIV switc . Steps in 1-2-5 sequence
Seek Mode
5 seconds/division to 3.1 microseconds/divi-
sion in 24 calibrated sleps. Sweep rate indi 
cated on readout panel
Automatically selected w en seek com 
mand is received. Steps in 1-2-5 sequence
External Mode
5 seconds/division to 10 nanoseconds/division
in 27 calibrated steps. Sweep rate indicated
on readout panel
Selected by external program connected
to PROGRAM connector. Steps in 1-2-5
sequence
Sweep Accuracy (at 25° C, ±5°)
1 s to 10 ns
Wit in ±3% of indicated sweep rate
VARIABLE control fully clockwise (UN 
CAL readout off) and DLY'D SWP MAG
switc set to OFF (MAG'D SWP readout
off). 10, 20 and 50 ns accuracy must be
c ecked in accordance wit Performance
C eck
5 s and 2 s
Wit in ±5% of indicated sweep rate
Variable Sweep Rate
Uncalibrated sweep rate to 2.5 times, or
greater, t e indicated sweep rate. s/DIV read 
out turns off and UNCAL readout turns on
w en VARIABLE control is not set to CAL posi 
tion
Slowest sweep rate 12.5 seconds/divi 
sion, or greater, in 5 s position
Sweep Lengt
DLY ’ D SWP MAG at OFF
10.3 to 11.3 divisions
Measured at 1 ms/DIV sweep rate
DLY'D SWP MAG on
12 to 15 divisions
Delayed Sweep Magnification
Basic sweep rates between 5 s and 1 μ s can be
magnified wit t e Del a yed Sweep Magnifier.
Calibrated DELAY control selects portion to be
magnified. Basic sweep rates between 5 s and
10 μ s can be magnified 100 times; basic sweep
rates between 5 s and 1 μ s can be magnified
10 times
Readout panel indicates correct magni 
fied sweep rate
Magnified Sweep Accuracy
(at 25° C, ±5°)
1 S to 1 JUS
Wit in ± 3% of sweep rate indicated on read 
out panel
VARIABLE control fully clockwise (UN-
CAL readout off)
5 s and 2 s
Wit in ±5% of sweep rate indicated on read 
out panel
Calibrated Delay Range
Continuous from 0 to 10 divisions from t e start
of t e trace
Delay Accuracy Wit in ±1.5% of fu l l scale at 1 ms/DIV.
Wit in ±3% of full scale at all ot er sweep
rates
Calibrated at 1 ms/DIV. Exclude first
0.2 division of display. Includes incre 
mental DELAY dial linearity
Incremental DELAY Dial Linearity
Wit in ±0.4% of full scale
Exclude first 0.2 division of display
Delayed Sweep Magnifier Jitter
3 parts or less per 10,000
Equal to 0.3 division or less w en meas 
ured wit x1 00 magnification at 1 ms/
DIV basic sweep rate
Output DC Level
4-180 volts, ±10 volts
Beam positioned to CRT electrical center
SEEK MODE
Cycles Per Sweep Between two and six cycles wit nominal
CYCLES/SWEEP setting obtained in Calibra 
tion procedure
Automatically selected w en seek com 
mand is received. Front-panel CYCLES/
SWEEP adjustment provides range of
about 0.5 to 3 times t is nominal setting
Automatic Seek Cycling Time One to two seconds W en seek command is continuous
Automatic Seeking Time 500 milliseconds or less wit 10 MHz
sine wave input and Trigger Function
switc set to INT-AUTO
Frequency Range for Seek Mode
Operation
30 Hz to 20 MHz
Seek Mono Pulse Widt 1.0 to 1.8 seconds
1-2

Characteristics — Type 3B5
PROGRAMMABLE FUNCTIONS
C aracteristic
Performance Requirement
Supplemental Information
Trigger Function
Int Auto — If not programmed
Int AC — Terminal 31
Ext AC — Terminal 30
Ext DC — Terminal 28
Grounding (zero volt) digital logic to
given terminal of PROGRAM connector
activates function
Trigger Slope
+ Slope — If not programmed
— Slope — Terminal 27
Trigger Level
Analog current c ange between about 0
and 400 microamps at terminal 15 of
PROGRAM connector provides same trig 
ger level range as front-panel LEVEL
control
Sweep Rate
Multiplier
X 1 — Terminal 2
X2 — Terminal 3
X5 — Terminal 5
Sweep multiplier, sweep decade and
decade enable must be programmed for
eac sweep rate. Grounding (zero volt)
digital logic to given terminals of PRO 
GRAM connector activates function
Enable
A — Terminal 23
B — Terminal 24
Decade
Enable Logic
Terminal
A
B
1 s
0.1 s
6
10 ms
1 ms
8
0.1 ms
10 μ s 9
1 μ s
0.1 μ s
11
10 ns
26
Horizontal Position
Analog current c ange between about
0 and 500 microamps at terminal 14 of
PROGRAM connector provides ±3 divi 
sion external orizontal position range
Delayed Sweep Magnifier
OFF — Terminal 33
X10 — Terminal 34
X 1 00 — Terminal 36
Grounding (zero volt) digital logic to
given terminal of PROGRAM connector
activates function
Magnifier Delay
Analog current c ange between about
350 and 200 microamps at terminal 17
of PROGRAM connector provides 0 to
10 division external delay range
External Mode Command
Type 3B5 switc es to External Mode w en
terminal 21 of PROGRAM connector is
grounded
Remote Seek
Type 3B5 switc es to Seek Mode (except
w en External Mode Command is present)
w en terminal 12 of PROGRAM connector is
grounded
Momentary ground produces two to six
cycles (nominal adjustment) display; con 
tinuous ground recycles unit every one to
two seconds
Single Sweep
+ 125-volt external oldoff lockout ap 
plied to terminal 7 and — 12-volts reset
momentarily applied to terminal 25 of
PROGRAM connector provides single 
sweep operation
ADDITIONAL FUNCTIONS AVAILABLE
AT PROGRAM CONNECTOR
External Horizontal Input
Deflection factor
Applied to terminal 4 of PROGRAM
connector. Sweep lockout at terminal 7,
external unblanking at terminal 13 and
orizontal position centering at terminal
14 also necessary.
5 volts/division ±5%
Bandwidt
DC to 750 kHz, or greater
Maximum input voltage
75 volts, DC + peak AC
Input resistance
Approximately 100 kilo ms
1-3

Characteristics — Type 3B5
Additional Functions (cont)
C aracteristic
Performance Requirement Supplemental Information
Sweep Out
0.05 milliamp/division, ±10%, at termi 
nal 16 of program connector 2
External Unblanking — 12 volts DC unblanks CRT
Apply to terminal 13 of PROGRAM con 
nector
Current Available from PROGRAM
Connector (maximum)
Supply Terminal Current
+ 125 V
18
30 mA
-12.2 V 1
75 mA
-100 V 19
1 mA
ENVIRONMENTAL CHARACTERISTICS
T e following environmental test limits apply w en tested
in accordance wit t e recommended test procedure. T is
instrument will meet t e electrical performance requirements
given in t is section following environmental test. Complete
details on environmental test procedures, including failure
criteria, etc., may be obtained from Tektronix, Inc. Contact
your local Tektronix Field Office or representative.
C aracteristic
Performance Requirement
Supplemental Information
Temperature
Operating
0° C to +50° C
Non-operating
-40° C to +65° C
Altitude
Operating
15,000 feet maximum
Non-operating
50,000 feet maximum
May be tested during non-operating
temperature tests
Vibration
Operating Vibrate for 15 minutes along eac axis at a
total displacement of 0.015 inc (1.9 g at 50
c/s) wit t e frequency varied from 10-50-10
c/s in one-minute cycles. Hold at any resonant
point for t ree minutes. If no resonant points
are found, vibrate at 51) c/s for t ree minutes
on eac axis.
Instrument secured to vibration platform
during test. Total vibration time about
55 minutes.
S ock
Non-operating
One s ock of 30 g, one- alf sine, 11 milli 
second duration along eac major axis.
Guillotine type s ock
Transportation
Package vibration
Meets National Safe Transit type of test w en
correctly packaged
Vibrate for one our slig tly in excess of 1 g
Package s ould just leave vibration sur 
face
Package drop
Drop from a eig t of 30 inc es on one corner,
all edges radiating from t at corner and all
flat surfaces
Total of 10 drops
MECHANICAL CHARACTERISTICS
Si ilar output available at ter inal 18 of the interconnecting plug.
C aracteristic
Information
Construction
C assis
Aluminum alloy
Panel Aluminum alloy wit anodized
finis
Circuit boards
Glass-expoxy laminate
Dimensions
Fits 3-series compartments of 560-
series Oscilloscopes
Connectors
EXT TRIG INPUT BNC
PROGRAM
37-terminal connector. Mates wit
Cinc No. DC-37P-C33 (Tektronix
Part No. 131-0422-00)
STANDARD ACCESSORIES
Standard accessories supplied wit t e Type 3B5 are listed
on t e last pullout page at t e rear of t is manual. For
optional accessories available for use wit t is instrument,
see t e current Tektronix, Inc. catalog.
1-4

SECTION 2
OPERATING INSTRUCTIONS
General Infor ation
To effectively use t e Type 3B5, t e operation and capa 
bilities of t e instrument must be known. T is section
describes t e operation of t e front-panel controls and con 
nectors, gives first time and general operating information,
External Mode programming information and lists some
basic applications for t is instrument.
T e Type 3B5 operates wit t e indicator oscilloscope and
an amplifier unit to form a complete oscilloscope system.
W en used wit an automatic programmable amplifier unit, a
remote-seeking probe and an external programmer, a com 
plete system is formed w ic as manual, automatic seeking,
remote seeking and external programming measurement
capabilities.
Installation
CAUTION
Turn off t e oscilloscope power before inserting
or removing t e plug-in unit.
T e Type 3B5 is designed for use in t e Horizontal plug
in compartment of a 560-series indicator oscilloscope. How 
ever, t e Type 3B5 can be inserted into t e Vertical plug-in
compartment of t e indicator oscilloscope to provide a sweep
t at runs vertically on t e CRT screen (no blanking provided
and instrument may not meet performance requirements given
in Section 1 if used in t is manner). Since t e orizontal and
vertical deflection plate sensitivities of t e oscilloscope are
different, t e Type 3B5 must be recalibrated to provide an
accurate display for vertical deflection use. T roug out t is
manual, it is assumed t at t e Type 3B5 is used to provide
orizontal deflection in t e conventional manner.
To install t e Type 3B5 in t e oscilloscope, insert it into
t e plug-in compartment and pus it in as far as possible.
Be sure t e securing latc at t e bottom of t e panel is out
of t e way (turn knob counterclockwise) to prevent damage
to t e oscilloscope front panel. Secure t e plug-in into t e
compartment by turning t e securing-latc knob clockwise
until it is tig t. To remove t e plug-in from t e compartment,
turn t e securing-latc knob several turns counterclockwise.
T en, pull t e plug-in partially out of t e compartment wit
t e knob and take old of t e plug-in by t e support rods
to remove it from t e oscilloscope.
W enever t e Type 3B5 is transferred from one oscillo 
scope to anot er, t e sweep calibration s ould be c ecked
and adjusted if necessary to provide accurate measurements
wit t e complete system. See Horizontal Gain Adjustment
in t is section for adjustment procedure.
Cooling
T e Type 3B5 does not require special cooling ot er t an
t at provided by t e indicator oscilloscope. W en operated
wit in t e ambient temperature range given in Section 1,
t e Type 3B5 provides accurate measurements (note excep 
tion for sweep accuracy).
FRONT-PANEL CONTROLS AND CONNECTORS
Introduction
All controls and connectors required for t e operation of
t e Type 3B5 are located on t e front panel of t e unit (see
Fig. 2-1). To make full use of t e capabilities of t is instru 
ment, t e operator s ould be familiar wit t e function and
use of eac of t ese controls and connectors. A brief descrip 
tion of t e function or operation of t e front-panel controls
and connectors follows. More detailed information on con 
trol operation and use is given under General Operating
Information.
Trigger Controls
EXT TRIG Input connector for external trigger signal.
INPUT
Trigger Function
(not labeled)
SLOPE
Lever switc w ic selects t e trigger
source, coupling and mode.
INT-AUTO — Permits normal triggering on
repetitive waveforms wit repetition
rates ig er t an 50 Hz. For lower repe 
tition rates or w en t ere is no trigger
signal, t e sweep generator free runs at
t e sweep rate to w ic it is set to pro 
vide a reference trace. Auto Trigger
lig t indicates w en unit is in t e auto
trigger mode.
INT-AC — Sweep triggered by internal sig 
nal from amplifier unit. Trigger circuit
rejects DC and attenuates AC signals
below about 50 Hz.
EXT-AC — Sweep triggered by external sig 
nal applied to t e EXT TRIG INPUT con 
nector. Trigger circuit rejects DC and
attenuates AC signals below about
50 Hz.
EXT-DC — Sweep triggered by external sig 
nal applied to t e EXT TRIG INPUT con 
nector. Trigger circuit accepts AC and
DC signals.
(+) and ( — ) lig ts indicate w ic slope of
t e trigger signal starts t e sweep. W en
t e ( — ) lig t is on, t e sweep can be trig 
gered on t e negative-going slope of t e
trigger signal; t e (+) lig t indicates t at
t e sweep can be triggered on t e positive 
going slope of t e trigger signal. Trigger
slope is c anged by pressing t e CHANGE
SLOPE button in t e center of t e LEVEL
control.
2-1

Operating Instructions — Type 3B5
Fig, 2-1. Front-panel controls and connectors of the Type 3B5.
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
2-2

Operating Instructions — Type 3B5
Auto Trigger
(not labeled)
Lig t indicates t at sweep is triggered in
t e auto trigger mode.
LEVEL
Normal Triggering — Selects amplitude
point on trigger signal w ere sweep is
triggered.
Auto Triggering — Selects trigger level
w ic is always wit in t e peak-to-peak
range of t e trigger signal (typically
adjustable between 10% and 90%).
TRIG LEVEL
CENTERING
Screwdriver adjustment to set t e trigger
circuit for correct operation (see Calibra 
tion procedure for adjustment).
MANUAL Selects t e sweep rate of t e sweep gen-
TIME/DIV erator in t e Manual Mode of operation.
W en in Seek Mode operation, mode auto 
matically c anges from SEEK to MAN w en
t e MANUAL TIME/DIV switc setting is
c anged.
VARIABLE Provides continuously variable sweep rate
to at least 2.5 times t e readout indicated
in t e CAL position. Sweep rate is cali 
brated only w en t e control is set fully
clockwise to CAL. s/DIV readout turns off
and UNCAL readout turns on w en VARI 
ABLE control is not set to CAL.
Mode Controls
EXT W en t e EXT button is lit, t e instrument
operates in t e External Mode. T e instru
ment c anges to, and remains in, t e Exter 
nal Mode of operation w en an external
programmer is connected to t e PROGRAM
connector and a program is selected. T e
External Mode overrides t e ot er modes.
MAN Pus button to select t e Manual Mode of
operation (except w en EXT lig t is on).
W en t e MAN button is lit, t e instrument
operates in t e Manual Mode. All func 
tions can be controlled by t e front-panel
controls in t is mode of operation. T e
instrument c anges to t e Manual Mode of
operation w en t e MAN button is pressed,
w en t e MANUAL TIME/DIV switc set 
ting is c anged w en in t e Seek Mode, or
w en t e external program is disconnected
SEEK Pus button to select t e Seek Mode of
operation (except w en EXT lig t is on).
W en t e SEEK button is lit, t e instrument
operates in t e Seek Mode. T e instrument
c anges to t e Seek Mode of operation
w en a seek command is received from
t e front-panel SEEK button, a remote 
seeking probe t roug t e associated auto-
matic/programmable amplifier unit, re 
mote seek from t e front-panel PROGRAM
connector or remote seek from t e pro 
gram connector of t e associated auto-
matic/programmable amplifier unit.
Sweep Controls
Delayed Sweep Magnifier Controls
DELAY Provides variable delay for t e starting
point of t e magnified sweep. May be
delayed between 0 and 10 divisions from
t e start of t e trace.
DLY'D SWP
MAG
Increases sweep rate after end of delay
period selected by DELAY control.
OFF — Normal sweep at sweep rate indi
cated on readout panel.
X10 — Sweep rate increased 10 times after
end of delay period (for basic sweep
rates of 1 μ s/DIV or slower). MAG'D
SWP readout lig ts and t e sweep-rate
readout is corrected for t e magnified
sweep rate.
XI 00 — Sweep rate increased 100 times
after end of delay period (for basic
sweep rates of 10 μ s/DIV or slower).
MAG'D SWP readout lig ts and t e
sweep-rate readout is corrected for t e
magnified sweep rate.
External Progra
PROGRAM 37-terminal connector for external pro 
gramming of t e unit. Also provides out 
put and input connections for various ot er
instrument functions.
Readout Panel
MAG'D SWP
Indicates t at t e sweep rate is magnified.
T e sweep rate readout is automatically
corrected to indicate t e magnified sweep
rate.
CAL
Screwdriver adjustment to set t e orizontal
gain of t e unit. Used to set basic timing
of t is unit and to compensate for t e dif 
ferences in CRT deflection factor w en
c anging indicator oscilloscopes.
NOT TRIG'D
UNCAL
Indicates t at sweep circuits are not trig 
gered.
CYCLES/SWEEP Screwdriver adjustment to select t e nomi 
nal number of cycles displayed in t e
Seek Mode of operation.
POSITION Controls orizontal position of trace.
Indicates t at VARIABLE control is not in
CAL position. s/DIV readout turns off
w en UNCAL readout is on.
. - 5 - 1 - 2 -
0 - m - μ . -
s/DIV
Indicates sweep rate in all modes of opera 
tion. Automatically corrected w en sweep
is magnified.
2-3

Operating Instructions — Type 3B5
FIRST-TIME OPERATION
T e following steps will demonstrate t e basic function of
t e controls and connectors of t e Type 3B5 and also dem 
onstrate t e basic operation of t is unit. It is recommended
t at t is procedure be followed completely for first-time
familiarization wit t e instrument.
T e first 12 steps of t is procedure describe t e met od of
setting up t e system for correct time measurements. T ese
steps may be used to set up t e unit w en it is installed in
an oscilloscope ot er t an t e one wit w ic it was cali 
brated.
NOTE
T e following procedure is written using a Tek 
tronix Type 561A or 564. Ot er units may require
slig t c anges in t is procedure.
Set-up Infor ation
1. Wit t e indicator oscilloscope power turned off, insert
t e Type 3B5 into t e orizontal plug-in compartment (com 
plete installation instructions are given earlier in t is sec 
tion).
2. Insert a 3-series amplifier unit into t e left plug-in com 
partment. (T is procedure is written assuming t at an auto 
matic/programmable amplifier unit is used; if ot er units are
used, some of t e demonstrations may not apply.)
3. Set t e oscilloscope intensity control counterclockwise.
4. Connect t e oscilloscope to a power source w ic meets
its voltage and frequency requirements.
5. Turn on t e oscilloscope power switc . Allow about
five minutes warm up so t e units reac a normal operating
temperature before proceeding.
6. Set t e front-panel controls as follows:
Type 3B5
Mode
MAN
POSITION
Midrange
DLY'D SWP MAG
OFF
DELAY
5.00
MANUAL TIME/DIV
5 ms
VARIABLE
CAL
Trigger Function INT-AUTO
LEVEL
Midrange
SLOPE
+
A plifier Unit
Position
Midrange
Input coupling
DC
Volts/division
20 Millivolts
Mode
Manual
Indicator Oscilloscope
Focus Adjust for correct display
Intensity Adjust for visible display
Calibrator
Scale illumination
Power
0.1 volts
As desired
On
7. Connect t e oscilloscope calibrator output connector to
t e input of t e amplifier unit wit a BNC cable.
8. Press t e SEEK buttons on bot t e automatic/program 
mable amplifier unit and t e Type 3B5. T e display s ould
be between two and five divisions vertically wit two to six
cycles displayed orizontally.
9. Pus t e Type 3B5 MAN button and c eck t e display
for t ree complete cycles. More or less cycles may indicate
incorrect CAL adjustment (applies for 60-Hz calibrator fre 
quency only). See Horizontal Gain Adjustment in t is section.
10. Hold t e SEEK button depressed and note t e readout
panel indication and number of cycles in t e display. T en,
turn t e CYCLES/SWEEP adjustment counterclockwise. Note
t at t e sweep rate indicated on t e readout panel increases
and fewer cycles are displayed.
11. Hold t e SEEK button depressed and turn t e CYCLES/
SWEEP adjustment clockwise. Note t at t e sweep rate
decreases and more cycles are displayed.
12. Hold t e SEEK button depressed and adjust t e
CYCLES/SWEEP adjustment for t e desired number of cycles
in t e display (determines nominal number of cycles in Seek
Mode display; sweep rate increases in 5-2-1 sequence).
Normal adjustment is near midrange wit between two and
six cycles displayed. Release t e SEEK button after t e
nominal range is obtained.
Operating Mode
13. Turn t e MANUAL TIME/DIV switc to .1 ms. Note
t at t e SEEK lig t goes off and t e MAN lig t comes on
w en t e MANUAL TIME/DIV switc is turned. Also, note
t at t e sweep-rate readout c anges as various sweep rates
are selected.
14. Press t e SEEK button. Note t at t e display returns
to t e same display as obtained in step 12.
15. Turn t e MANUAL TIME/DIV switc to 20 ms.
16. Press t e SEEK button. Note t at t e display again is
t e same as in step 12.
Sweep and Delayed Sweep Magnifier
17. Turn t e VARIABLE control t roug out its range. Note
t at t e UNCAL readout comes on and t e s/DIV readout
turns off w en t e VARIABLE control is moved from t e CAL
position (fully clockwise). T e sweep rate is slower by about
2.5 times w en in t e fully counterclockwise position as
indicated by more cycles displayed on t e CRT. Return t e
VARIABLE control to CAL.
18. Press t e MAN button and set t e DLY'D SWP MAG
switc to X10. Note t at t e CRT display is expanded
starting at about t e center of t e display. Also note t at
t e MAG'D SWP readout is on and t e sweep rate as indi 
cated by t e readout panel is 10 times faster t an t e setting
of t e MANUAL TIME/DIV switc .
2-4

Operating Instructions — Type 3B5
19. Set t e DLY'D SWP MAG switc to OFF. Turn t e
POSITION control to move t e rig t end of t e trace to t e
center of t e display. Now, return t e DLY'D SWP MAG
switc to t e X10 position. Note t at t e sweep lengt is
increased several divisions w en t e magnifier is turned on.
Return t e start of t e trace to t e left edge of t e graticule.
20. Turn t e DELAY dial to 0.00. Note t at t e entire dis 
play is magnified.
21. Set t e DLY'D SWP MAG switc to X 1 00. Note t at
t e display is magnified furt er and t e sweep-rate as indi 
cated by t e readout panel is 100 times faster t an t e
setting of t e MANUAL TIME/DIV switc .
22. Press t e SEEK button. Note t at a two to six division
display is presented. Now turn t e DELAY dial to about
0.50 and press t e SEEK button again. Notice t at t e dis 
play c anges. Finally, set t e DELAY dial to about 1.00 and
press t e SEEK button again. Once again t e display
c anges. T is step illustrates t at t e desired magnified
display may not be obtained w en using t e SEEK MODE.
23. Set t e DLY'D SWP MAG switc to OFF, MANUAL
TIME/DIV switc to 5 ms and press t e SEEK button.
Triggering
24. Press t e CHANGE SLOPE button. Note t at eac
time t e button is pressed t e display starts on t e opposite
polarity and t e SLOPE lig t c anges from (+) to ( — ) or
from ( — ) to (+).
25. Rotate t e LEVEL control t roug out its range. T e dis 
play s ould remain stable at all positions indicating t at t e
LEVEL control operates between about 10% and 90% of
t e triggering slope for auto triggering. Press t e amplifier
unit manual button and note t at t e LEVEL control operates
t e same even t oug t e signal amplitude as c anged
(applies to auto triggering only). Return t e LEVEL control
to midrange and t e amplifier unit to t e seek mode.
26. Disconnect t e input signal. Note t at a reference
trace is displayed and t e NOT TRIG'D readout is on. Re 
connect t e input signal.
27. Set t e Trigger Function switc to INT-AC and adjust
t e LEVEL control for a stable display. T en, press t e SEEK
button. Note t at t e trace is stable and t e Auto Trigger
lig t is off.
28. Rotate t e LEVEL control clockwise w ile watc ing
t e readout panel. Note t at after several degrees of rota 
tion t e NOT TRIG'D readout comes on briefly and t en
goes off again. Also note t at t e display remains stable
and t e Auto Trigger lig t as come on. Return t e LEVEL
control to midrange. T is step illustrates t at t e unit auto 
matically seeks a stable display w en in t e Seek Mode.
Press t e SEEK button and note t at t e Auto Trigger lig t
goes off, indicating t at t e display is again triggered from
t e applied signal in t e internal AC mode.
29. Press t e MAN button. T e display s ould be stable.
Turn t e LEVEL control t roug out its range. Note t at t e
display disappears and t e NOT TRIG'D readout comes on
after several degrees of rotation in eit er direction from t e
center point. Return t e LEVEL control to midrange.
30. Set t e Trigger Function switc to EXT-AC. Note t at
t e NOT TRIG ’ D readout comes on. Press t e SEEK button
and note t at a stable, automatically triggered display (Auto
Trigger lig t is on) is presented even t oug t e unit is set
for external triggering and no trigger signal is connected to
t e EXT TRIG INPUT connector.
31. Connect t e calibrator signal to bot t e amplifier unit
input connector and t e EXT TRIG INPUT connector wit a
BNC T connector and two BNC cables.
32. Set t e indicator oscilloscope calibrator for 1.0 volts
output.
33. Press t e MAN button. T e trigger controls s ould
operate as described for INT-AC. Operation in t e EXT-DC
position is muc t e same also except t e display is trig 
gered at a specific DC level as selected by t e LEVEL con 
trol. Set t e LEVEL control for a stable display.
34. Press t e SEEK button on bot t e amplifier unit and
t e Type 3B5. T e display s ould be stable and t e Auto
Trigger lig t s ould be off, indicating t at t e unit is cor 
rectly triggered in t e external AC mode. Disconnect t e
signal from t e EXT TRIG INPUT connector and note t at
t e display remains stable and t e Auto Trigger lig t comes
on (Seek Mode only).
35. Disconnect t e input signal and set t e Trigger Func 
tion switc to INT-AUTO.
Re ote Seek
36. If a remote-seeking probe is available, t e remote
seek feature of t is instrument can be demonstrated. Con 
nect t e probe to t e automatic/programmable amplifier unit
input connector and t e remote seek lead to t e remote
seek connector.
37. Connect t e probe tip to a signal source (suc as t e
calibrator output). Press t e seek button on t e probe. Note
t at bot t e amplifier unit and t e Type 3B5 switc to t e
Seek Mode and a stable, correct display is s own. Now
connect t e probe to a signal wit a different amplitude and
frequency wit in t e capabilities of t e instrument. Press t e
probe seek button and note t at a correct display is again
presented.
External Progra
38. If a programmer is available, t e external program 
mable features of t is instrument can be demonstrated.
Connect t e programmer to t e front-panel PROGRAM
connectors. Set up t e desired program(s) and turn t e
programmer on. Note t at t e EXT button lig ts and t e
readout panel indicates t e programmed settings rat er
t an t e front-panel control settings.
39. Turn t e programmer off or disconnect t e program
connections. Note t at t e unit returns to t e Manual Mode
as indicated by t e MAN button.
40. T is completes t e basic operating procedure for t e
Type 3B5. Instrument operation not explained ere, or opera 
tions w ic need furt er explanation will be discussed under
General Operating Information.
2-5

Operating Instructions — Type 3B5
CONTROL SETUP CHART
Fig. 2-2 s ows t e front panel of t e Type 3B5 along wit
an enlarged view of t e PROGRAM connector. T is c art
can be reproduced and used as a test-setup record for
special measurements, applications or procedures, or it may
be used as a training aid for familiarization wit t is
instrument.
GENERAL OPERATING INFORMATION
Horizontal Gain Adjust ent
W enever t e Type 3B5 is inserted into a plug-in com 
partment ot er t an t e one in w ic it was calibrated, t e
CAL adjustment s ould be c ecked and readjusted if neces 
sary. Allow about five minutes warm up before making t is
adjustment (procedure given for 50- or 60- ertz line-frequency
calibrator; use t e Calibration procedure for ot er calibrator
frequencies).
1. Connect a one-volt square wave from t e indicator
oscilloscope calibrator to t e amplifier unit input connector.
2. Set t e MANUAL TIME/DIV switc to 5 ms (2 ms for
50 Hz), t e Trigger Function switc to INT-AUTO and t e
LEVEL control to midrange.
3. Press t e amplifier unit seek button.
4. Press t e Type 3B5 MAN button.
5. CHECK — CRT display for t ree complete cycles over
t e 10-division display area (one complete cycle for 50-Hz
calibrator).
6. ADJUST — CAL adjustment for t ree complete cycles
over t e 10-division display area (one complete cycle for
50-Hz calibrator).
NOTE
Alt roug t e preceding met od provides a fairly
accurate adjustment for most measurements, better
accuracy can be obtained using t e procedure
given in t e Calibration section of t is manual.
Adjusting Nu ber of Cycles in Seek Mode
Display
T e CYCLES/SWEEP adjustment on t e front panel permits
t e operator to adjust t e Type 3B5 for t e nominal range of
cycles displayed w en in t e Seek Mode of operation. Use
t e following procedure to adjust t e CYCLES/SWEEP adjust 
ment (for more information on operation in t e Seek Mode,
see Seek Mode Operation in t is section).
1. Connect a signal (calibrator output or one-millisecond
markers recommended) w ic is wit in t e frequency and
amplitude capabilities of t e Seek Mode to t e amplifier
unit input connector.
2. Press t e amplifier unit seek button.
3. Press t e Type 3B5 SEEK button.
4. CHECK — CRT display for desired number of cycles.
5. ADJUST — Hold t e Type 3B5 SEEK button depressed
and adjust t e CYCLES/SWEEP adjustment for t e desired
display. Allow time for t e seek circuits to recycle between
adjustments (one to two seconds).
NOTE
T is adjustment selects a nominal range of opera 
tion and t e exact number of cycles displayed for
a particular signal will vary due to t e sweep rate
selected by t e Seek Circuit. T e sweep rate always
increases in a 5-2-1 sequence.
Trigger Level Centering Adjust ent
T e TRIG LEVEL CENTERING adjustment s ould not be
readjusted during normal use. A complete adjustment pro 
cedure is given in t e Calibration section of t is manual.
Trigger Source
Internal. For most applications, t e sweep can be trig 
gered internally. In t e INT positions of t e Trigger Function
switc (or w en selected by external program), t e trigger
signal is obtained from t e amplifier unit. Two met ods of
internal triggering are provided; AUTO and AC. T ese
met ods are described fully under Trigger Coupling and
Auto Triggering.
External. An external signal connected to t e EXT TRIG
INPUT connector can be used to trigger t e sweep in t e
EXT positions of t e Trigger Function switc (or w en selected
by external program). T e external signal must be time-
related to t e displayed signal to produce a stable display.
Use an external trigger signal to provide a triggered display
w en t e internal signal is too low in amplitude for correct
triggering or contains signal components on w ic it is not
desired to trigger. It is also useful w en signal tracing in
amplifiers, p ase-s ift networks, wave-s aping circuits, etc.
T e signal from a single point in t e circuit under test can
be connected to t e EXT TRIG INPUT connector t roug a
signal probe or cable. T en, t e sweep is triggered by t e
same signal at all times and allows amplitude, time relation 
s ip or wave s ape c anges of signals at various points in
t e circuit to be examined wit out resetting t e trigger
controls.
T e external trigger signal can be eit er AC or DC
coupled (see Trigger Coupling for furt er information).
Since DC trigger coupling is provided only in t e EXT source
position, t e sweep must be triggered from an external
signal to take advantage of t is feature.
Trigger Coupling
AC. AC trigger coupling is provided in bot t e INT and
EXT positions of t e Trigger Function switc . T e DC com 
ponent of t e trigger signal is blocked and all AC signals
below about 50 Hz are attenuated. In general, AC coupling
can be used for most applications. However, if t e sweep is
to be triggered at a certain DC level, DC coupling (EXT
position) must be used.
T e triggering point in t e AC position depends upon t e
average voltage level of t e trigger signal. If trigger signals
occur randomly, t e average voltage level will vary, w ic
causes t e triggering point to vary also. T is s ift of t e
2-6

Operating Instructions — Type 3B5
TYPE 3B5 CONTROL SET-UP CHART
Fig. 2-2. Control set-up chart.
2-7

Operating Instructions — Type 3B5
triggering point may be enoug so it is impossible to main 
tain a stable display. In suc cases, use DC coupling.
DC. DC trigger coupling is available only w en t e
sweep is triggered from an external signal in t e EXT posi 
tion. DC coupling can be used to provide stable triggering
wit low-frequency signals w ic would be attenuated in
t e AC position or wit low-repetition rate signals. T e
LEVEL control can be adjusted to provide triggering at t e
desired DC level on t e waveform.
Trigger Slope
T e Trigger SLOPE lig ts indicate t e portion of t e trigger
signal to w ic t e trigger circuits respond. W en t e minus
( — ) lig t is on, t e display starts on t e negative-going
portion of t e waveform; t e plus (+) lig t indicates t at
t e display starts on t e positive-going portion of t e wave 
form. T e trigger slope can be c anged by pressing t e
CHANGE SLOPE button (or by external program). Eac
time t e button is pressed t e trigger slope c anges from
( — ) to (+) or vice versa. T e operation of t e CHANGE
SLOPE switc in conjunction wit t e LEVEL control is s own
in Fig. 2-3.
W en several cycles of a signal are displayed, t e trigger
slope is often unimportant. However, if only a certain
portion of a cycle is to be displayed, correct slope setting
is important to provide a display w ic starts at t e desired
point on t e input signal.
Trigger Level
T e front-panel Trigger LEVEL control (or external program
level control) selects t e voltage level on t e triggering
waveform at w ic t e sweep is triggered. W en t e LEVEL
control is set in t e clockwise region, t e trigger circuit
responds at a more positive point on t e trigger signal.
W en t e LEVEL control is in t e counterclockwise region,
t e trigger circuits responds at a more negative point on
t e trigger signal. Fig. 2-3 illustrates t is effect for bot
trigger slope conditions.
T e NOT TRIG'D readout on t e readout panel provides
a convenient indication of t e condition of t e trigger circuit.
If t e LEVEL control is correctly adjusted wit an adequate
trigger signal applied, t e readout is off. However, if t e
LEVEL control is misadjusted, t e Trigger Function switc
incorrectly set, or t e trigger signal too low in amplitude,
t e NOT TRIG'D readout lig ts up. T is readout feature
can be used for a general indication of correct triggering
and is particularly useful w en setting up t e trigger circuits
w en a trigger signal is available wit out a trace displayed
on t e CRT (suc as single sweep operation).
To set t e LEVEL control, first select t e trigger source,
coupling and slope. T en set t e LEVEL control to midrange
(except for DC coupling). If t e display does not start at
t e desired point, adjust t e LEVEL control for correct trig 
gering. Wit DC coupling (external trigger only), stable
triggering may be obtained at any setting of t e LEVEL
control as determined by t e DC level of t e trigger signal.
To obtain correct DC trigger level, turn t e LEVEL control
counterclockwise. T en, turn t e LEVEL control clockwise
until t e display is triggered at t e correct DC level on t e
displayed signal.
Auto Triggering
T e sweep is automatically triggered in t e INT-AUTO
position of t e Trigger Function switc (or w en selected by
external program). Auto triggering can be used for most
applications. T is trigger mode provides a stable display
w en a trigger signal is available (above about 50 Hz).
Complete rotation of t e LEVEL control provides a range of
adjustment between about 10% and 90% of t e peak-to-
peak level of t e triggering slope. T e front-panel LEVEL
control also determines t e auto triggering level for External
Mode operation. T e trigger circuit automatically compen 
sates for differences in trigger signal amplitude to provide
t is range of LEVEL control adjustment for all signals w ic
meet t e minimum amplitude requirements. W en t e LEVEL
control is set for t e desired triggering point at a certain
percentage of t e leading edge, it triggers at t is same
point even if t e signal amplitude is increased (e.g., if set
to trigger at t e 30% point on a one-division signal, it also
triggers at t e 30% point if t e amplitude is increased to
eig t divisions; see Fig. 2-4).
NOTE
T e auto trigger mode may not produce t e
desired display of complex signals suc as pulse
trains near t e low-frequency limit of t is mode
(about 50 ertz). T e triggering point may s ift
from t e desired pulse to a lower amplitude pulse
w ic follows. T e resultant display will appear
unstable. In suc cases, use normal internal trig 
gering or external triggering.
T e auto trigger mode is particularly useful w en a
reference trace is needed and no trigger signal is available.
T en, t e Sweep Generator free runs to produce a reference
trace. T e trace also free runs w en t e repetition rate of
t e trigger signal drops below about 50 Hz. W en a trigger
signal is again present, t e free running condition ends
and t e sweep returns to a triggered, stable display.
W en a seek command is received in t e INT-AC, EXT-
AC, EXT-DC positions of t e Trigger Function switc , t e
trigger circuits automatically switc to auto triggering if a
trigger signal is not present or if t e LEVEL control is mis 
adjusted. T en, a stable auto triggered display is presented,
if possible. T is feature assures t at a stable display is
presented, w enever possible, in t e Seek Mode of operation.
Selecting Sweep Rate
T e MANUAL TIME/DIV switc selects t e calibrated
sweep rate for t e Sweep Generator in t e Manual Mode of
operation. T e VARIABLE control provides continuously
variable sweep rates between t e settings of t e MANUAL
TIME/DIV switc . W enever t e UNCAL readout is on,
t e sweep rate is uncalibrated. T e readout is off w en t e
VARIABLE control is set to t e CAL position.
W en making time measurements from t e graticule, t e
area between t e first and nint graticule lines provides t e
most linear time measurements (see Fig. 2-5). T erefore,
t e first and last division of t e display s ould not be used
for making accurate time measurements. Position t e start
of t e timing area to t e first graticule line and set t e
MANUAL TIME/DIV switc so t e end of t e timing area
falls between t e first and nint graticule lines.
2-8

Operating Instructions — Type 3B5
Fig. 2-3. Effects of Trigger LEVEL control and CHANGE SLOPE button (shown for internal triggering or external triggering fro an in-
phase, ti e-related trigger signal).
2-9

Operating Instructions — Type 3B5
Fig. 2-4. LEVEL control operation for auto triggering. (A) LEVEL
for , (B) Display still triggers at about the 30% point when the
trol not adjusted for second wavefor ).
control set to trigger at about the 30% point on a one-division wave 
a plitude is increased to produce an eight-division display (LEVEL con-
First
graticule
Ninth
graticule
Fig. 2-5. Area of graticule used for accurate ti e easure ents.
T e sweep rate is selected automatically in t e Seek Mode
or may be externally programmed in t e External Mode.
More information on t ese modes of operation is given
under Seek Mode Operation and External Programming,
respectively.
Sweep Output
T e sawtoot sweep signal is available at terminal 16 of
t e front-panel PROGRAM connector for external applica 
tions. T is signal is also connected to terminal 18 of t e
interconnecting plug for operation of special purpose ampli 
fier units (suc as spectrum analyzer plug-ins).
Delayed Sweep Magnification
T e sweep rate can be increased 10 or 100 times wit
t e DLY'D SWP MAG switc (or by external program) to
magnify t e portion of t e trace w ic follows t e delay
period. T e start of t e magnified portion can be positioned
wit t e DELAY dial (or external program delay) to magnify
any portion after 0 to 10 divisions delay from t e start of
t e trace. Delayed Sweep Magnification is limited to sweep
rates of one microsecond/division or slower. T e sweep
magnification automatically returns to X10 w en set for
X100 wit sweep rates between five microseconds/division
and one microsecond/division; magnification is off (X 1 ) for
sweep rates faster t an one microsecond/division in any
position of t e DLY'D SWP MAG switc .
NOTE
T e sweep rates between 10 ns and .5 μ s can 
not be magnified wit t e delayed sweep magni 
fier. However, t e Delayed Sweep Magnifier
Intensifier circuit is operative in t ese positions
and can be used to provide a brig ter trace (com 
plete trace intensified) wit out readjusting t e
indicator oscilloscope intensity level.
To use t e delayed sweep magnifier, first select a sweep
rate wit t e MANUAL TIME/DIV switc w ic correctly
displays t e portion to be magnified (or press SEEK button).
T en set t e DLY'D SWP MAG switc for t e desired mag 
nification (X10 or X 1 00). Turn t e DELAY dial to position
t e magnified portion so t e desired part of t e sweep is
magnified. Fig. 2-6 s ows a typical waveform as it would
appear magnified 10 times and 100 times (DELAY dial set
to 1.95).
2-10

Operating Instructions — Type 3B5
Un agnified wavefor — DLY'D SWP MAG switch off
(A)
(B)
(Cl
Fig. 2-6. Delayed sweep agnifier operation with DELAY dial set
ting of 1.9S.
T e desired magnified display may not be obtained in
t e Seek Mode. T e seek circuits determine t e sweep rate
during t e first few divisions of t e display to produce a
display s owing between two and six cycles of t e wave 
form (nominal adjustment). If t e last portion of t e display
is magnified, an inadequate display may be presented.
Single Sweep
W en t e signal to be displayed is not repetitive or
varies in amplitude, s ape or time, a conventional display
may produce an unstable presentation. To avoid t is, t e
Type 3B5 can be used in t e single-sweep mode by con 
necting t e circuit s own in Fig. 2-7 to t e PROGRAM con 
nector. T e circuit s own also provides correct input levels
for external orizontal operation (explained under External
Horizontal Deflection w ic follows). T e single-sweep
feature is also useful for p otograp ing non-repetitive signals.
To use t e single-sweep mode, construct t e circuit s own
in Fig. 1-7 and connect it to t e front-panel PROGRAM
connector. T en, make sure t e trigger circuits will trigger
on t e event you wis to display by obtaining t e best
possible display in t e normal manner (for random signals
set t e trigger circuit to trigger on a signal w ic is approxi 
mately t e same amplitude and frequency as t e random
signal). T en set t e switc to t e single sweep position and
press t e reset button. T e reset lig t indicates w en t e
Sweep Generator as been reset and t e lig t goes out
w en t e circuit is locked out at t e end of t e sweep. After
t e reset button is pressed, t e next trigger pulse initiates
t e sweep and a single trace is presented on t e screen.
T en, t e Sweep Generator is locked out until reset. To pre 
pare t e circuit for anot er single-sweep display, press t e
reset button again.
External Horizontal Deflection
In some applications, it is desirable to display one signal
versus anot er (X-Y) rat er t an against time (internal sweep).
T e circuit s own in Fig. 2-7, w ic can be connected to t e
PROGRAM connector, provides a means for applying an
external signal to t e Horizontal Amplifier for t is type of
display. T is circuit provides sweep lockout t roug terminal
7, external unblanking t roug terminal 13, orizontal posi 
tion centering t roug terminal 14 and external orizontal
deflection t roug terminal 4.
Readout Panel
T e readout panel on t e front of t e unit indicates instru 
ment operation in all operating modes. T e readout panel
indicates sweep rate, magnified sweep (wit correct mag 
nified sweep rate), absence of trigger signal and uncalibrated
sweep rate. Since t is panel is easily visible from a distance,
it is particularly useful w en using t e remote-seeking probe.
Seek Mode Operation
In t e Seek Mode of operation, t e Type 3B5 automatically
seeks a stable display at a sweep rate w ic displays
between two and six cycles of t e signal (wit nominal
CYCLES/SWEEP adjustment). A seek command may be
given from t e front-panel SEEK button, a remote-seeking
2-11

Operating Instructions — Type 3B5
Fig. 2-7. Circuit to provide single sweep and
external horizontal input for the Type 3B5.
probe t roug t e associated automatic/programmable
amplifier unit or remote seek t roug t e front-panel PRO 
GRAM connector or t e program connector of t e associated
automatic/programmable amplifier unit. W en t e front 
panel SEEK button is pressed or a seek command is applied
to t e front-panel PROGRAM connector, only t e Type 3B5
seek circuits operate. W en t e seek command is received
t roug t e associated automatic/programmable amplifier
unit, bot units seek but t e Type 3B5 seek circuits operate
after t e amplifier unit as completed its cycle. T e Type
3B5 does not seek w en t e seek button on t e amplifier
unit is pressed.
W en t e Type 3B5 receives a seek command, t e seek
circuits first seek a trigger signal in t e mode selected by
t e Trigger Function switc . If a trigger signal is present,
t e seek circuits t en seek a sweep rate w ic displays
between two and six cycles of t e trigger signal (wit nom 
inal CYCLES/SWEEP adjustment). (Full description of t e
electrical operation of t e seek circuits is given in t e Cir 
cuit Description section.) If a trigger signal is not present
(or t e LEVEL control is incorrectly set), t e seek circuits
switc to auto triggering and again c eck for a trigger
signal. If a trigger signal is present in t e auto trigger
mode, t e seek circuits seek a sweep rate w ic produces
2-12