Tektronix 3910 User manual

ordains

Publication Date: June 1991
Document Number: 3910-900-01 Rev. A

perating

nformation

WARRANTY

Keithley Instruments, Inc. warrants this product to be free from defects in material and workmanship for a
period of 1 year from date of shipment.

Keithley Instruments, Inc. warrants the following items for 90 days from the date of shipment: probes, cables,
rechargeable batteries, diskettes, and documentation.

During the warranty period, we will, at our option, either repair or replace any product that proves to be de­fective.

To exercise this warranty, write or call your local Keithley representative, or contact Keithley headquarters in
Cleveland, Ohio. You will be given prompt assistance and return instructions. Send the product, transporta­tion prepaid, to the indicated service facility. Repairs will be made and the product returned, transportation
prepaid. Repaired or replaced products are warranted for the balance of the original warranty period, or at
least 90 days.

LIMITATION OF WARRANTY

This warranty does not apply to defects resulting from product modification without Keithley’s express writ­ten consent, or misuse of any product or part. This warranty also does not apply to fuses, software, non-re­chargeable batteries, damage from battery leakage, or problems arising from normal wear or failure to follow
instructions.

THIS WARRANTY IS IN LIEU OF ALL OTHER WARRAN TIES, EXPRESSED OR IMPLIED, INCLUDING
ANY IMPLIED WARRANTY OF MERCHANTABILIIY OR FlTNESS FOR A PARTICULAR USE. THE
REMEDIES PROVIDED HEREIN ARE BUYERS SOLE AND EXCLUSIVE REMEDIES.

NEITHER KEITHLEY INSTRUMENTS, INC. NOR ANY OF ITS EMPLOYEES SHALL BE LIABLE FOR
ANY DIRECT, INDIRECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT
OF THE USE OF ITS INSTRUMENTS AND SOFIWARE EVEN IF KEITHLEY INSTRUMENTS, INC., HAS
BEEN ADVISED IN ADVANCE OF THE POSSIBILITY OF SUCH DAMAGES. SUCH EXCLUDED DAM­AGES SHALL INCLUDE, BUT ARE NOT LIMITED TO: COSTS OF REMOVAL AND INSTALLATION,
LOSSES SUSTAINED AS THE RESULT OF INJURY TO ANY PERSON, OR DAMAGE TO PROPERTY.

INSTRUMENTS

Instruments Division, Keithley Instruments, Inc. l 28775 Aurora

WEST GERMANY:

GREAT BRITAIN:
FRANCE Keithky Instruments SARL -3 Allee des Garays l B.P. 60.91124 P&iseau/Z.L l I-6-0115 155 l Telex: 600 933 l Fax: l-6-0117726
NEIXERLANDS: Keithley Instruments BV l Avehgen West 49 l 4202 MS Gorinchem l P.O. Box 559 l 4200 AN Gorinciwn l 01830-35333 l Telex: 24 684. Fax: [phone]
SWITZERLAND:
AUSTRIA: Keithley Instruments GesmbH L Rosenhugelstrasse 12 l A-1120 Vienna l (0222) CC4 65 48 l Telex: 131677 l Fax: [phone]
ITALY: Keithky Instruments SRL l Vi&S. Giiignano 4/A 0 20146 Milano l 02-4120360 or 02-4156540 l Fax M-4121249

Keithky Instruments GmbH l Landsbugers&. 65 l D-8034 Gemwring l 089-??49307-0 l Telex: 52-12160 l Fax: 089+?4930759
Keithky Instmments, Ltd. l The Mnster l 58, Portman Road l Reading, Berkshire RG 3 IEA l 01144 734 575 666 l Fax [phone]

Keithky Instruments SA l Kriesbachstr. 4 l 8600 Dubendorf l 01-821-V444 l Telex: 828 472 l Fax: [phone]

Road l Cleveland, Ohio 44139 l [phone] l Fax: [phone]

Operator’s Manual

Model 3910

Function Synthesizer

01991, Keithley Instruments, Inc.

All Rights Reserved

Instruments Division

Cleveland, Ohio, U. S. A.

document Number: 3910-900-01

All Keithley product names are trademarks or registered trademarks of Keithley Instruments, Inc.
Other brand and product names are trademarks or registered trademarks of their respective holders.

Safety Precautions

The following safety precautions should be observed before using the Model 3910 Function Synthesizer and any associ­ated instruments.

This instrument is intended for use by qualified personnel who recognize shock hazards and are familiar with the safety
precautions required to avoid possible injury. Read over this manual carefully before using the instrument.

Exercise extreme caution when a shock hazard is present at the test circuit. The American National Standards Institute

(ANSI) states that a shock hazard exists when voltage levels greater than 30V rms or 42.4V peak are present. A good

safety practice is to expect that hazardous voltage is present in any unknown circuit before measuring.

Inspect the connecting cables and test leads for possible wear, cracks, or breaks before each use.

For maximum safety, do not touch the test cables or any instruments while power is applied to the circuit under test.
Turn off the power and discharge any capacitors before connecting or disconnecting cables from the instrument.

Do not touch any object which could provide a current path to the common side of the circuit under test or power line
(earth) ground. Always make measurements with dry hands while standing on a dry, insulated surface capable of with­standing the voltage being measured.

Instrumentation and

accessories

should not be connected to humans.

Table of Contents

SECTION 1

1.1

1.2

1.3

1.4

1.5

1.6

1.6.1

1.6.2

1.63

1.6.4

1.7

1.8

- General Information

INTRODUCTION
FEATURES
WARRANTY INFORMATION
MANUALADDENDA

sAFETyTERMsANDsyMBoLs...........................................:

UNPACKlNGANDREPACKJNG

Unpacking
Shipment Contents
Operatofsb.nual

Repacking For Shipment
OPTIONALACCESSORIES
SPECIFICATIONS

...................................................................

.................................................................

SECTION 2 - Getting

2.1

2.2

2.2.1

2.2.2

2.3

2.3.1

2.3.2

2.3.3

2.4

2.5

2.5.1

2.5.2

2.5.3

INTRODUCTION
INSTALLATION

Installation Location

cooling

LINEPOWERSUPPLY.................,...................~

LINE Voltage Selector Switch ...................................................

Line Receptacle Connection .....................................................

LineFuse

HANDLING PRECAUTIONS .....................................................

BASICOPERATION

Front Panel Summary .........................................................

Typical Test Connections ......................................................

OperatingExamples

....................................................................

..................................................................

..............................................................

....................................................

..........................................................

.................................................

...........................................................

...........................................................

.......................................................

......................................................

.............................................................

Started

..............................................................

..............................................................

..................

............................................................

..........................................................

..C .....................................

.....................

l-1
l-l
1-2
l-2

...... 1-2

1-2
1-2
1-2
1-2
l-2
1-3
l-3

2-1
2-l
2-l
2-l
2-2
2-2
2-2
2-2
2-2
2-3
2-3
2-3
2-4

SECTION 3

3.1

3.2

3.2.1

3.2.2

3.3

3.3.1

3.3.2

3.4

3.5

3.5.1

INTRODUCTION

FRONT PANEL AND REAR PANEL DESCRIPTION ...................................

Front Panel Description

RearPanelDescription

INPUT AND OUTPUT CONNECTIONS ............................................

InputConnection

OutputConnections
STARTUP
OPERATING PROCEDURES

ErrorCodes

- Operation

..............................................................

........................................................

........................................................

............................................................

..........................................................

....................................................................

.....................................................

................................................................

3-1
3-l
3-1
3-4
3-5
3-5
3-5
3-6
3-7
3-7

’ 35.2 FrequencySetting

3.5.3 OutputAmplitude

3.5.4

3.5.5 Waveform Selection, Square-Wave Duty Cycle, and Synchronous Output

3.5.6 OscillationMode

3.5.7

DCOffset

Trigger Parameters

..................................................................

............................................................

...........................................................

.............................................................

........................................................... 3-11

..................

‘3-7

3-8
3-8
3-8

3-9

SECTION

4.1 INTRODUCTION

4.1.1 GPIBOverview

4.1.2 Major GPIB Specifications

4.1.3 Bus Line Signals and Operation

4.1.4 GPIBHandshaking

4.1.5

4.1.6

4.1.7 Basic Listener Functions

4.1.8 BasicControllerFunctions

4.1.9 Multi-line Interface Messages

4.2

4.2.1

4.2.2 Specifications

4.3 MODEL 3910 PROGRAM CODES

4.4 TYPICAL EXECUTION TIMES

4.5

4 - GPIB Interface

..............................................................

..............................................................

......................................................

...........................................................

Data Transfer Example
BasicTalkerFunctions

OVERVIEW OF MODEL 3910 GPIB INTERFACE

Introduction

SAMPLEPROGRAMS

................................................................

...............................................................

........................................................

.........................................................

.......................................................

......................................................

.................................................... 4-12

..........................................................

.................................................. 4-1

...................................................

......................................

..................................................

4-l
4-1
4-1

4-2
4-3
4-3

4-3
4-3
4-3

4-6
4-6
4-6

4-9

4-13

List of Illustrations

SECTION 2 -

Figure 2-1
Figure 2-2

SECTION 3

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

Figure 3-6
Figure 3-7
Figure 3-8

SECTION 4

Figure 4-1
Figure 4-2 Handshake Timing Diagram
Figure 4-3
Figure 44

Getting Started

Frontpanelsummary...............................................,...... 2-3

TypicalConnections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

- Operation

Model 3910 Front Panel
Mode13910RearPanel
LogicInputCircuit

oLltputCircuit
Phase Relationship between FCTN OUT Waveform and SYNC OUT
Relationship between Trigger Signal and Oscillation in TRIG Mode
Relationship between Trigger Signal and Oscillation in GATE Mode
Definition of Phase of each Waveform

...........................................................

..................................................... 3-2

.....................................................

........................................................

- GPIB Interface

Interface Connector

Data Transfer Example

ProgramCodeSyntax ......................................................

.......................................................

.....................................................

2-4

3-4
3-5

3-6

...................

....................

................... 3-11

.......................................... 3-12

................................................. 4-3

3-9
3-10

4-2

4-4
4-8

List of Tables

SECTION 2

Table 2-l

SECTION 4

Table 4-1
Table 4-2
Table 4-3
Table 4-4
Table 4-5
Table 4-6
Table 4-7

- Getting Started

Fuse Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

- GPIB Interface

Multiple-line Interface Message
InterfaceFunctions..
BusDriverSpecifications
Response to Interface Messages
StatusByte..
Model 3910 Main Parameter Setting Messages
TypicalExecutionTimes

............................................................

......................................................

....................................................

..............................................

...................................................

...............................................

....................................

2-2

4-5
4-6
4-6
4-7
4-9
4-10
4-12

SECTION 1

t General Information

1 .I INTRODUCTION

The Model 3910 Eunction Synthesizer can generate fre­quencies between O.lmHz and 1MHz. The Model 3910
can generate the entire band at a resolution of O.lmHz,
with a high-frequency accuracy of f30ppm.

Q 2/,squarelX,ris-

Five AC waveforms, sine
ing sawtooth/l, and falling sawtooth\ are available. A

maximum of tlOV DC can be added onto each output.
Maximum output voltage for all waveforms is 20V p-p/
no load or lOVp-p/5On load.

Since frequencies are synthesized directly by a custom
LSI digital IC, accuracy and stability are high, and the fre-

quencyswitching time is short. Another advantage is the
continuity of phase at frequency switchover.

In addition to continuous oscillation, burst oscillation,

trigger oscillation, and gate oscillation are available. The

Model 3910 also provides a continuous output of direct

current voltage. An external trigger input provides an ex­ternal trigger signal during trigger or gate oscillation. The
square-wave duty cycle is also variable.

The Model 3910 uses a single line, ll-character LED dis­play to display the values of oscillation frequency, pa-

, triangle

,

rameters, and other values. Settings are easily made us­ing push-button keys and rotary knobs.

A GPIB (IEEE-488) interface is available as an option for
the Model 3910. With the exception of the AMPTD, am­plitude setting; DC OFFSET, added quantity setting; and
DUTY VAR, duty ratio setting; a GPIB equipped Model
3910 can be programmed over the bus for the same oper­ating modes and parameters that can be controlled from
the front panel.

1.2 FEATURES

l Wide bandwidth: O.lmHz to 1MHz (resolution

O.lmHz).

0 &30 ppm frequency accuracy.

l Phase continuity, at frequency switchover.
l Five ACwaveformsavailable: %,2/,n,n,andl

l The duty cycle can be set to values between 10% and

90% for frequencies up to 1OOkHz.

l High output: 2OVp-p/no load, lOVp-p/50Qload.

0 Low distortion: 0.3% or less (1OHz to IOOkHz).

l DC output voltages

fiV/5OQ load.

l Burst oscillation mode: Repeats oscillation of wave

number specified by mark wave (l-16) and space wave
number (l-16).

o Trigger oscillation and gate oscillation:

Trigger source: External by front panel BNC plug or
push-button key.

available: flOV/no load,

l-l

SECTION 1

General Information

Start/stop phase: -360” to +360”.
Input voltage: ‘ITL level (pulls up 74HC14 input by

5.1K). Minimum pulse width ZOOnsec.
Trigger: Oscillates wave number specified by wave
number (l-16) by trigger signal.
Gate: Integral wave number oscillation by trigger
signal.

Waveform and frequency range:

Sine wave, square wave (duty fixed); O.lmHz to
IMHZ.
Triangle wave, square wave (duty variable), rising
sawtooth wave, falling sawtooth wave; O.lmHz to

lOOkHz, oscillation possible up to 1MHz.
Each parameter setting can be modified using the
MODIFY knob and the CURSOR keys. The single line,

11 character LED display, clearly displays all neces-

sary information; oscillation frequency, GPIB address

(when installed), start/stop phase, mark wave num­ber, and space wave number.
Battery backed-up memory stores the configuration in
effect when power is turned off.
Optional GPIB interface allows the Model 3910 to be
programmed over the GPIB (IEEE-488 interface bus).

1.3 WARRANTY INFORMATION

Warranty information is located on the inside front cover
of this operator’s manual. Should your Model 3910 re­quire warranty service, contact the Keithley representa­tive or authorized repair facility in your area for further
information. When returning the instrument for repair,
be sure to fill out and include the service form at the back
of this manual in order to provide the repair facility with
the necessary information.

The WARNING heading used in this manual explains
dangers that might result in personal injtuy or death. Al­ways read the associated information very carefully be­fore performing the indicated procedure.

The

CAUTION

hazards that could damage the instrument. Such damage
may invalidate the warranty.

heading used in this manual explains

1.6 UNPACKING AND REPACKING

1.6.1 Unpacking

After carefully unpacking the instrument from its ship­ping carton, inspect it for any obvious signs of physical
damage. Report any such damage to the shipping agent
immediately. Save the original packing carton for storage
or possible future shipment.

1.62

The following items are included with every Model 3910
order:

l

Model 3910 Function Synthesizer

0 Model 3910 Operator’s Manual

l

Power Cord

l

Fuse (lA, 25OV, 5.2 x 2Omm)

l

BNC to BNC signal cable

l

Additional accessories as ordered.

Shipment Contents

1.4 MANUAL ADDENDA

Any improvement or changes concerning the instrument
or manual will be explained in an addendum included
with the unit. Be sure to note these changes and incorpo­rate them into the manual before using the unit.

1.5 SAFETY TERMS AND SYMBOLS

The following safety terms and symbols are found on the
instrument or used in this manual.

A

The

user should refer to the operating instructions.

l-2

symbol on the instrument indicates that the

1.6.3 Operator’s Manual

If an additional manual is required, order the manual
package, Keithley part number 3910-900-00. The manual
package includes an operator’s manual and any perti­nent addenda.

1.6.4 Repacking For Shipment

Should it become necessary to return the Model 3910 for
repair, carefully pack the unit in its original packing car­ton or the equivalent. If the original carton is not available
or damaged, be sure to use a cardboard box of sufficient

strength and room. Pad the empty spaces in the carton
with adequate packing material to hold the unit firmly in
place.

General Information

SECTION 1

Include the following information:

l Advise to the warranty status of the instrument.
l Write ATTENTION REPAIR DEPARTMENT on the

shipping label.

o Fill out and include the service form located at the back

of this manual.

1.7 OPTIONAL ACCESSORIES

The following accessories are available for use with the
Model 3910.

Models 3900-l and 3900-2 Rack Mounting Kits: The

Model 3900-l mounts one Model 3910 in a standard

IPinch rack. The Model 3900-2 mounts two Model 3910s
side by side in a standard 19-inch rack. Both kits include
all necessary hardware for proper rack mounting of the
instruments.

Model 7007 Shielded IEEE-488 Cables:

7007-l (lm, 3.3ft.j and Model 7007-2 (2m, 6.6ft.j can be
used to interface the Model 3910 tothe IEEE-488 bus.

The Model

Model 7051-2 BNC-to-BNC Cable:

50R BNC to BNC cable (RG-58C) 2ft. (0.6m) in length.

The Model 7051-2 is terminated with male BNC connec-

tors on both ends.

Model 7051-5 BNC-to-BNC Cable:
5OQ

BNC to BNC cable (RG-58C) 5ft. (1.2m) in length.

The Model 7051-5 is terminated with male BNC connec-

tors on both ends.

Model 7051-10 BNC-to-BNC Cable:

is similar to the Models 7051-2 and 70516 except that it is

lOft..(2.4m) in length.

Model 7754-3 BNC-to-Alligator Cable:

7754-3 is a 3ft. (0.9m) 5Ofi cable (RGd8C), terminated
with a male BNC connector on one end and two alligator
clips on the other end.

Model 7755 5Oa Feed-Through Terminator:

7755 is a BNC to BNC adapter that is terminated with a
5OQ resistor. VSWR is ~1.1, DC to 25OMHz.

The Model 7051-2 is

The Model 7051-5 is

The Model 7051-10

The Model

The Model

Model 3911 IEEE-488 Interface:

tion a maximum of 15 Model 3910s can be connected on
the same bus, data line transfer uses a 3-line handshake
mefhod, enabling reliable data transfer between data
sending (talkers) and receivers (listeners) having differ­ing data transfer rates.

With the Model 3911 op-

1.8 SPECIFICATIONS

Detailed Model 3910 specifications may be found in Ap­pendix B.

l-3

SECTION 2

Gettina Started

2.1 INTRODUCTION

This sections contains basic information on installation,

power line connections, and it also provides typical sim­ple operating examples.

2.2 INSTALLATION

The following paragraphs discuss Model 3910 installa­tion. In particular, use adequate care when installing the
unit. Improper installation will adversely affect the life,
reliability, and safety of the unit.

The Model 3910 weighs about 7 lbs; be careful when car­rying the unit or mounting it in a rack.

2.2.1 installation Location

The allowable ambient temperature and humidity
ranges for the Model 3910 are.

Operating: 0 to 4O”C, 10 to 9O%RH
Storage: -10 to 5O”C, 10 to 8O%RH

Be sure to install the unit in a location that satisfies these
temperature and humidity conditions. Also the environ-

ment must be free of dust and vibration, and the Model
3910 must not be exposed to direct sunlight.

The Model 3910 uses a line filter, but pulse noise or strong
magnetic or electric fields may cause incorrect operation
of the unit. Do not install the unit near a source of pulse
noise or strong magnetic or electric fields.

The guard on the rear panel of the unit is designed to pro­tect rear panel connectors and should not be used as a leg
for installation. Do not stand the unit vertically on the
rear guard because it may fall over, causing instrument

damage or personal injury.

2.2.2

The Model 3910 is ‘air-cooled by vents. Insufficient air

flow may cause a component in the unit to fail. Follow the
instructions given below.

l

Cooling

CAUTION
Observe the following precautions to pre­vent damage to the unit:

A vent is provided on the bottom panel of the
unit. Install the unit on a rigid, flat surface,
and avoid installing it on soft material such
as a cushion. Be careful not to insert foreign

2-l

SECTION 2
Geffina Started

material between the bottom of the unit and
the surface underneath. Another vent is lo­cated on the top panel of the unit. Be careful
not to block the top vent by placing an object
on top of the unit.

l

Avoid mounting two or more units verti­cally. Placing one unit on top of another will
obstruct the vents.

2.3 LINE POWER SUPPLY

The Model 3910 operates with a lOOV, 12OV, 22OV, or

240.7 *lo%, 48 to 62Hk, single-phase AC power supply.
The power consumption is approximately 25VA.

2.3.1 LINE Voltage Selector Switch

The LINE voltage selector switch on the rear panel allows
you to change operating voltage of the power supply.

The standard setting of the switch is the same as the volt-

age available in the country to which the unit is shipped.

To change the power supply voltage, first disconnect the

line cord, and set the supply voltage switch in the correct
position. Wait at least five seconds before turning the
power back on after turning it off.

WARNING

The Model 3910 is equipped with a 3-wire
power cord that contains a separate ground
wire and is designed to be used with
grounded outlets. When proper connections
are made, instrument chassis is connected to
the power line ground. If the AC outlet is not

ounded, the rear panel ground terminal

=!= must be connected to safety earth

b

ground using #18AWG (or larger) wire be­fore use.

2.3.3

The line fuse, which is integral with the power line recep­tacle, protects the instrument from over-current situ­ations. To replace the fuse, first disconnect the line cord,
then pry out the fuse compartment (immediately to the
right of the FUSE marking) with a small screwdriver. A
spare fuse is located in the compartment with the fuse be­ing used. Replace the blown fuse only with the type listed
in Table 2-1, then replace the fuse holder.

Line Fuse

WARNING
To avoid a shock hazard, disconnect the line
cord from the instrument before replacing
the fuse.

CAUTION
Use only a fuse of the rating listed in Table
2-1, or instrument damage may occur.

WARNING
To avoid a shock hazard, disconnect the
power cord from the instrument before

changing the supply voltage setting.

CAUTION
Be sure to set the line voltage switch to the
correct position for the line power voltage to
be used. Operating the instrument on an in­correct voltage may cause damage to the unit.

2.3.2

Connect the supplied power cord to the rear panel Line
receptacle and to a grounded AC power receptacle sup­plying the correct voltage.

Line Receptacle Connection

2-2

Table 2-1, Fuse Replacement

Fuse Current Keithley

Line Voltage

lOOV, 120v 1A
220,240v

NOTE: Fuses are 5 x2Omm and have UOV, normal blow ratings.

Rating Part No.

FU-96-2

ID-4

FU-96-1

2.4 HANDLING PRECAUTIONS

When the front panel or case becomes

a soft

cloth. If the panel or case is too dirty for cleaning
with a dry cloth, dampen the cloth in mild detergent, and
wipe the panel or case with the damp cloth. Never use
solvents such as thinner or benzene, or chemical dust
cloths to avoid damaging the case or front panel surfaces.

dirty, clean it with

SECTION 2

Gettim?

Started

2.5 BASIC OPERATlON

The following paragraphs summarize front panel operat-

ing controls, give typical test connections, and discuss
typical operating examples for the Model 3910.

2.5.1 Front Panel Summary

Figure 2-l summarizes each front panel feature. For de-

tailed information on each operating feature, refer to Sec­tion 3.

2.5.2

Typical Test Connections

Figure 2-2 shows typical tests connections between the
Model 3910 main synthesizer and a DTJT. Note that 5OL2

characteristic impedance cables such as the Model 7051

should be used for output connections.

%I I11111

LED indicator when

Figure 2-1.

Front Panel Summary

Depressing CLEAR key
first, then either right or
left cursor key will reset
all digits to the right or
left of the cursor column
to 0. Dudng GPIB
operation+ depressing
this key will return
control to LOCAL

mxxn+inn

2-3

SECTION 2
Gettim Started

Model 3910

5052 BNC Coaxial cable

(Model 7051 or equivalent)

OUT

Figure 2-2.

Typical Connections

2.5.3 Operating Examples

The following examples give step-by-step instructions
for setting basic Model 3910 operating parameters. The
Model 3910 can be connected to an oscilloscope to view

the results of the various operating examples.

Example 1: Selecting the Waveform Type (Function)

The first sequence will adjust the Model 3910 to output a
sine wave, with a continuous sweep.

1. Press DISPLAY SELECT to indicate frequency
(lower LED).

2. Press FCTN to cycle through the five options until
the LED indicates a SINE wave (top LED).

3. Press MODE to indicate CONT (continuous sweep).

Example 2: Setting the Waveform Frequency or Period

This sequence will set the Model 3910 to a frequency of
5OOHz, without regard to any previous setup. You will
have to determine whether to use step 1 or 2 in this se­quence because there is no way to know what setup was
used for the previous test. Since the Model 3910 retains
only one setting in memory, that setting is always the last
one.

1. If the display shows a frequency higher than 500Hz,
use this next sequence. Otherwise skip to step 2.

A. Move the cursor to the seventh position: The sev-

enth position, 1OOHz column, will blink. Press
the CLEAR key and at the same time press the
left cursor key. All digits to the left of the blink­ing digit will return to 0 (erase).

B. The seventh position, 1OOHz column, will be

blinking. Rotate the MODIFY knob UP (clock­wise) to increase or DOWN (counter-clockwise)
to decrease the digit to the correct value, 5 in the
1OOHz column.

C. If any of the lower digits (less significant digits)

in the displayed number are above zero, press
the CLEAR key and at the same time press the

right cursor key. All digits to the right of the
blinking digit will return to 0. The display should
now show the following digits: 5000000
(5OO.OOOOHz).

2. If the display shows a frequency less than 5OOHz
(5000000), use this sequence:

A. Assume the display indicates a frequency of

86Hz. Press the left, or right, cursor as necessary
to make the column to the left of 8 blink. A u will
appear in this column.

B. Rotate the MODIFY knob UP (clockwise) and a

number will appear in the 1OOHz column. Adjust
this number to 5.

C. Press the CLEAR key and at the same time press

the right cursor key. All digits to the right of the
blinking digit will return to 0. The display should
now show the following digits: 5000000
(500.0000Hz).

2-4

SECTION 2

Getting Sfarted

NOTE

The frequency may be increased quickly, us­ing the above method, but no similar action is
available to rapidly reduce the frequency set­ting.

Example 3: Setting the Output Amplitude

This step sets the amplitude of the existing waveform to a
value of lOmVp-p:

Use the cursor down key to set the amplitude range so it
indicates O.O;?Vp-p (2OmVpp). RPotate the AMpTD knob
until the scope indicates lOmVp-p.

Example 4: Changing the Output to a Square Wave

This example changes the output to a square wave with
variable duty cycle, while maintaining the present fre­quency, in continuous mode.

1. Press FCTN twice to indicate a square wave output.
Note that the output waveform has equal time-on
and time-off.

2. Press DUTY VAR to allow variable duty cycle (LED
on). Rotate the associated knob below the key to cre-

ate square waves with different on- and off-times.
Leave the square wave in some extreme variable po­sition; that is, an obviously unequal on- or off-time.

3. Press DUTY VAR key again. The scope presentation
reverts to a square wave with equal on- and off­times.

4.

Press the DUTY VAR key again. The scope should
display the unequal duty cycle from the previous
step.

Example 5: Adjust the DC Offset

This step adjusts the DC offset value based on the center-

line (zero or average) voltage level of the existing
waveform.

1. Press the DC OF!ZSET key (LED on). Rotate the asso­ciated knob and note the vertical movement of CH A
on the scope. This movement corresponds directly

with the offset voltage applied by the rotation of the
knob. Leave the signal with a significant offset and
go to the next step.

2. Press DC OFFSET again (LED off). The scope presen-

tation reverts to the original value of zero offset.
Press the key again and the offset value re-appears
and the CH A display moves off zero. Press the key
once more to return the scope to zero offset (LED
off).

2-5