Keithley 3940 User manual
WARRANTY
Keithley Instruments, Inc. warrants this product to be free from defects in material and workmanship for a
period of 1year from date of shipment.
Keithley Instruments, Inc. warrants the following items for 90days from the date ofshipment: 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 bede-
fective.
To exercisethis warranty, write or call your local Keithley representative, or contact Keithley headquarters in
Cleveland, Ohio. You will begiven prompt assistanceand return instructions. Sendthe product, transporta-
tion 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 90days.
LIMITATION OF WARRANTY
This warranty doesnot apply to defectsresulting from product modification without Keithley’s expresswrit-
ten consent, or misuse of any product or part. This warranty also does not apply to fuses, software, non-re-
chargeable batteries, damage from battery leakage,or problems arising from normal wear or failure to follow
instructions.
THIS WARRANTY ISIN LIEU OF ALL OTHER WARRANTIES, EXPRESSEDOR IMPLIED, INCLUDING
ANY IMPLIED WARRANTY OF MERCHANT ABILITY OR FITNESS FOR A PARTICULAR USE. THE
REMEDIES PROVIDED HEREIN ARE BUYERS SOLEAND 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 USEOF ITS INSTRUMENTS AND SOFTWARE EVEN IF KEITHLEY INSTRUMENTS, INC., HAS
BEEN ADVISED IN ADVANCE OF THE POSSIBILITY OF SUCH DAMAGES. SUCH EXCLUDED DAM-
AGES SHALL INCLUDE, BUT ARE NOT LIMITED TO: COSTSOF REMOVAL AND INSTALLATION,
LOSSESSUSTAINED AS THE RESULT OF INJURY TO ANY PERSON,OR DAMAGE TO PROPERTY.
INSTRUMENTS
Instruments Division, Keithley Instruments, Inc.
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28775 Aurora Road
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Cleveland, Ohio 44139 * (216) 248-0400
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Fax: 248-6168
WEST GERMANY: Keithky Instruments CmbH
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Heiglhofstr. 5
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Munchen 70
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089-71002-O
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Telex: 52-12X%
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Fax: 089-7100259
GREAT BRITAIN: Koitbley Instruments, Ltd.
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The Minster
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St?,Portman Road
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Reading, Berkshire RG 3 IEA
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01144 734 575 666
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Fax: 01144 734 596 469
FRANCE Keitbky Instruments SARL
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3 Allee des Garays . B.P. 60.91124 Palaiseau/Z.I.
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I-6-0115 155. Telex: 600 933
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Fax: 1-6.0117726
NIXHERLANDS: Keithley Instruments BV
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Avelingen West 49
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4202 MS C&in&an
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P.O. Box 559
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4200 AN Gortnchem .0X+0-35333. Telex: 24 684
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Fax: 01830-30821
SWITZERLAND: Keithley Instruments SA 0 Kriesbachstr. 4
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t%W Dubendorf
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01-821-9444
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Telex 828 472
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Fax: 0222-315366
AUSTRIA: Keitbley Instruments GesmbH
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Rosenhugelstrasse 12
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A-1120 Vienna
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(0222) 84 65 48 e Telex: 131677
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Fax: (0222) 8403597
ITALY: Keitbley Instruments SRL
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Vi&S. Gbnignano 4/A -20146 Mtlano .02-4120360 or M-4156540
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Fax 02-4121249
Safety Precautions
The following safety precautions should be observed before using the Model 3940Multifunction Synthesizer and any
associated instruments.
This instrument is intended for useby qualified personnel who recognize shock hazards and arefamiliar with the safety
precautions required to avoid possible injury. Read over this manual carefully before using the instrument.
Exercise extreme caution when ashock 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 cablesand test leads for possible wear, cracks, or breaks before eachuse.
For maximum safety, do not touch the test cablesor any instruments while power is applied to the circuit under test.
Turn off the power and discharge any capacitors before connecting or disconnecting cablesfrom 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 adry, insulated surface capable of with-
standing the voltage being measured.
Instrumentation and accessoriesshould not be connected to humans.
Table of Contents
SECTION 1 - General Information
1.1 INTRODUCTION .............................................................. l-l
1.2 FEATURES ................................................................... l-l
1.3 WARRANTYINFORMATION .................................................... l-2
1.4 MANUALADDENDA .......................................................... l-2
1.5 SAFETY TERMS AND SYMBOLS .................................................. l-2
1.6 UNPACKING AND REPACKING ................................................. l-2
1.6.1 Unpacking ................................................................. l-2
1.6.2 Shipment Contents ........................................................... l-2
1.6.3 Operator’sManual ........................................................... l-2
1.6.4 Repacking For Shipment ....................................................... l-2
1.7 OPTIONAL ACCESSORIES ...................................................... l-3
1.8 SPECIFICATIONS ............................................................. l-3
SECTION 2 - Getting Started
2.1 INTRODUCTION .............................................................. 2-l
2.2 INSTALLATION .............................................................. 2-1
2.2.1 InstallationLocation.. ........................................................ 2-l
2.2.2 Fan.. ..................................................................... 2-l
2.3 LINE VOLTAGE SUPPLY ........................................................ 2-2
2.3.1 Line Voltage Selector Switch .................................................... 2-2
2.3.2 Line Receptacle Connection ..................................................... 2-2
2.3.3 LineFuse .................................................................. 2-2
2.4 KANDLINGPRECAUTIONS ..................................................... 2-3
2.5 BASICOPERATION ............................................................. 2-3
2.5.1
FrontPanelSummary
......................................................... 2-3
2.5.2 Typical Test Connections ...................................................... 2-3
2.5.3 Operating Examples .......................................................... 2-5
SECTION 3 - Operation
3.1 INTRODUCTION .............................................................. 3-l
3.2 FRONT PANEL AND REAR PANEL DESCRIPTION ................................... 3-l
3.2.1 Front Panel Description ........................................................ 3-l
3.2.2 RearPanelDescription ........................................................ 3-12
3.3 Input and Output Connections .................................................... 3-14
3.3.1 InputConnections ........................................................... 3-14
3.3.2 OutputConnections .......................................................... 3-15
3.4 STARTUP .................................................................... 3-16
3.5 OPERATING PROCEDURES ..................................................... 3-17
3.5.1 Setting Parameters Using Numeric Keys ........................................... 3-17
3.5.2
3.5.3
3.5.4
3.5.5
3.5.6
3.5.7
3.5.8
3.5.9’
3.5.10
3.5.11
3.5.12
3.5.13
3.5.14
Setting Parameters with MODIFY ................................................ 3-18
ErrorCodes ................................................................ 3-18
UnitsConversion ............................................................ 3-22
Frequency Programming ....................................................... 3-22
Amplitude Programming ...................................................... 3-23
DC Offset Programming ....................................................... 3-23
AC Amplitude and DC Offset Relational Restrictions ................................. 3-24
Waveform Selection, Square-Wave Duty Factor, and Synchronous Output .................. 3-26
Oscillation Mode and Trigger Source Selection ...................................... 3-28
Mark, Space,and PhaseParameter Programming .................................... 3-29
StopLeveland~S~C ........................................................ 3-32
SynchronousOperation ....................................................... 3-34
Frequency Sweep Operation .................................................... 3-34
SECTION 4 - GPIB Interface
4.1
4.1.1
4.1.2
4.1.3
4.1.4
4.1.5
4.1.6
4.1.7
4.1.8
4.1.9
4.2
4.2.1
4.2.2
4.3
4.3.1
4.3.2
4.4
4.5
4.6
INTRODUCTION .............................................................. 4-l
GPIBOverview .............................................................. 4-l
Major GPIB Specifications ...................................................... 4-l
Bus Line Signals and Operation .................................................. 4-2
GPIBHandshaking ........................................................... 4-2
Data Transfer Example ........................................................ 4-3
BasicTalkerFunctions ......................................................... 4-3
BasicListener Functions ....................................................... 4-4
BasicControllerFunctions ...................................................... 4-4
Multi-Line Interface Messages ................................................... 4-4
OVERVIEW OF MODEL 3940GPIB INTERFACE ...................................... 4-6
Introduction ................................................................ 4-6
Specifications ............................................................... 4-6
MODEL 3940PROGRAM CODES .................................................. 4-13
Model 3940Parameter-Setting Messages ........................................... 4-13
Model 3940Inquiry Messages ................................................... 4-26
TYPICAL EXECUTION TIMES .................................................... 4-35
PROGRAM CODE SUMMARY TABLE .............................................. 4-40
SAMPLEPROGRAMS .......................................................... 4-45
List of Illustrations
SECTION 2 - Getting Started
Figure 2-l FrontPanelSummary...................................................... 2-4
Figure 2-2 Typical Test Connections . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
SECTION 3 - Operation
Figure 3-l FrontPanel .............................................................. 3-2
Figure 3-2 RearPanel .............................................................. 3-12
Figure 3-3 Logic Input Circuits ....................................................... 3-14
Figure 3-4 Analog Input Circuit ....................................................... 3-14
Figure 3-5 Main Synthesizer Sync Output ............................................... 3-15
Figure 3-6 Sub Synthesizer Sync Output ................................................ 3-15
Figure 3-7 Sweep Marker and Sync Outputs ............................................. 3-15
Figure 3-8 Relational Range for Allowed AC Amplitude Voltage and DC Offset Voltage ............ 3-25
Figure 3-9 PhaseRelationship Between Waveform and Synchronous Output ..................... 3-27
Figure 3-10 BURSTOscillation ........................................................ 3-28
Figure 3-l 1 TriggerOscillation ........................................................ 3-29
Figure 3-12 GateOscillation .......................................................... 3-29
Figure 3-13 Waveforms and PhaseDefinitions ............................................. 3-31
Figure 3-14 Waveform Examples with Hold Stop Level ...................................... 3-32
Figure 3-15 Waveform Examples with ResetStop Level ...................................... 3-32
Figure 3-16 PhaseSync Operation ...................................................... 3-33
Figure 3-17 PhaseRelationship after PhaseSync ............................................ 3-33
Figure 3-18 Sweep Frequency and Sweep Output ........................................... 336
Figure 3-19 SweepOperation ......................................................... 3-37
SECTION 4 - GPIB Interface
Figure 4-l Interface Connector ....................................................... 4-2
Figure 4-2 Handshake Timing Diagram ................................................. 4-3
Figure 4-3 Data Transfer Example ..................................................... 44
Figure 4-4 Program Code Syntax ...................................................... 4-7
Figure 45 ResponseOutput Format ................................................... 4-9
List of Tables
SECTION 2 - Getting Started
Table 2-l FuseReplacement......................................................... 2-3
SECTION 3 - Operation
Table 3-l Main Synthesizer Amplitude Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-20
Table 3-2 Sub Synthesizer Amplitude Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-20
SECTION 4 - GPIB Interface
Table 4-l Multi-Line Interface Messages ................................................ 4-5
Table 4-2 InterfaceFunctions.. ...................................................... 4-6
Table 4-3 BusDriverSpecifications ................................................... 4-6
Table 4-4 Responsesto Interface Messages .............................................. 4-7
Table 4-5 StatusByte.. ............................................................ 412
Table 4-6 Main Synthesizer Parameter Setting Messages .................................... 4-13
Table 4-7 Sub Synthesizer Parameter Setting Messages ..................................... 4-16
Table 4-8 Main Synthesizer Trigger Parameter Setting Messages .............................. 4-18
Table 4-9 Main Synthesizer Sweep Parameter Setting Messages .............................. 420
Table 4-10 Miscellaneous Parameter Messages ............................................ 4-23
Table 4-l 1 ARB Waveform Write and Readout Messages .................................... 4-24
Table 412 Parameters Specific to GPIB ................................................. 4-25
Table 4-13 Main Synthesizer Parameter Inquiry Messages ................................... 4-26
Table 4-14 Sub Synthesizer Parameter Inquiry Messages .................................... 4-28
Table 4-15 Main Synthesizer Trigger Parameter Inquiry Messages ............................. 4-29
Table 416 Main Synthesizer Sweep Parameter Inquiry Messages .............................. 4-30
Table 4-l 7 Inquiry Messagesfor Miscellaneous Parameters .................................. 4-32
Table 4-18 Inquiry Messagesfor ARB Waveform Write and Readout Parameters .................. 4-33
Table 4-19 Inquiry Messagesfor Parameters Specific to GPIB ................................. 434
Table 420 Typical Execution Times .................................................... 4-35
Table 4-21 Program Codes Summary ................................................... 4-40
SECTION 1
General Information
1.l INTRODUCTION
The Model 3940 Multifunction Synthesizer is a multi-
function oscillator integrated with two frequency synthe-
sizers: the OHzto 2OMHz main synthesizer and the OHz
to 1OOkHzsub synthesizer. The Model 3940can generate
the entire frequency band at aresolution of O.lmHz, with
an accuracy of tippm.
Five output waveforms, %,%,-rL,n,and\,are
available. In addition, arbitrary waveforms set with the
GPlB (IEEE-4881interface can be generated by the main
synthesizer. Maximum output voltage for all waveforms
is 20V p-p (no load).
Since frequencies are synthesized directly by a custom
LSI digital IC, accuracy and stability arehigh, and the fre-
quency switching time is short. Mother advantage is the
continuity of phase at frequency switchover.
Frequency sweep, half-cycle unit bursts of up to 32,768
cycles, trigger oscillation, and gate oscillation are avail-
able with the main synthesizer. The square-wave duty
cycle is also variable. In addition, external signals can be
combined with the oscillator output to generate custom
waveforms.
Frequency, amplitude, waveform, and phase can be in-
dependently set on the sub synthesizer, which is not de-
pendent upon the main synthesizer. The sub synthesizer
can also be used asa trigger oscillator for the main syn-
thesizer.
Since the sub synthesizer and the main synthesizer use
the same clock source, the phase will not deviate when
the frequency is setwith a whole number ratio.
The Model 3940usesatwo-line, 40-character liquid crys-
tal display to display selectedfunctions, parameters, and
pertinent messages.Parameter settings are easily made
using both the numeric keys and the modify knob.
The Model 3940 is equipped with a standard GPIB
(IEEE-4881interface, and can be programmed over the
bus for the same operating modes and parameters that
can be controlled from the front panel.
The Model 3940 can be used as a multiphase oscillator
when combined with multiple identical units and used
with the optional synchronous cable.
1.2 FEATURES
1. Two integrated independent frequency synthesiz-
ers:Main Synthesizer and Sub Synthesizer
l-l
SECTION 1
GeneralInformation
2.
3.
4.
5.
6.
Wide bandwidth; tippm frequency accuracy; and
phase continuity at frequency switchover.
Main Synthesizer: OHzto 2OMHz
(resolution: O.lmHz)
Sub Synthesizer: OHzto 1OOkHz
(resolution: O.lmHz)
Five output waveforms available:
and\,( b th vb-L A,
su syn esizer and main synthesizer); ar-
bitrary waveforms, variable duty factor for square
waves (main synthesizer only).
External signals can be added to the main synthe-
sizer waveform output to synthesize additional
waveforms.
Burst, trigger, gate oscillation, and frequency sweep
function (main synthesizer only).
Multiphase oscillator operation with the use of the
optional synchronous cable and additional Model
3940units.
1.3 WARRANTY INFORMATION
Warranty information is located on the inside front cover
of this operator’s manual. Should your Model 3940 re-
quire warranty service, contact the Keithley representa-
tive 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.
1.4 MANUAL ADDENDA
Any improvements or changes concerning the instru-
ment or manual will be explained in an addendum in-
cluded with the unit. Besure 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 arefound on the
instrument or used in this manual.
The’
A
symbol on the instrument indicates that the
user should refer to the operating instructions.
The
WARNING
heading used in this manual explains
dangers that might result in personal injury or death. Al-
ways read the associated information very carefully be-
fore performing the indicated procedure.
The
CAUTION
heading used in this manual explains
hazards that could damage the instrument card. Such
damage may invalidate the warranty.
1.6 UNPACKING AND REPACKING
1.6.1 Unpacking
After carefully unpacking the instrument from its ship-
ping carton, inspect it for any obvious signs of physical
damage. Report any such damage to the shipping agent
immediately. Savethe original packing carton for storage
or possible future shipment.
1.6.2 Shipment Contents
The following items are included with every Model 3940
order:
Model 3940Multifunction Synthesizer
Model 3940Operator’s Manual.
Power cord
Fuse2A, 25OV,5.2x 20mm (contained in fuse holder as
spare fuse)
BNC to BNC signal cable
Additional accessoriesasordered.
1.6.3 Operator’s Manual
If an additional manual is required, order the manual
package, Keithley part number 3940-900-00.The manual
package includes an operator’s manual and any perti-
nent addenda.
1.6.4 Repacking For Shipment
Should it become necessaryto return the Model 3940for
repair, carefully pack the unit in its original packing car-
ton or the equivalent. Besure to use a cardboard box of
sufficient strength.
Include the following information:
o Advise asto the warranty status of the instrument.
l-2
SECTION 2
GeneralInformation
l
Write ATTENTION REPAIR DEPARTMENT on the
shipping label.
l
Fill out and include the service form located attheback
of this manual.
1.7 OPTIONAL ACCESSORIES
The following accessoriesare available for use with the
Model 3940.
Model 3949 Synchronous Cable:
The Model 3949allows
multiple Model 3940 units to be connected together to
form amultiphase oscillator.
Models 3900-l and 3900-2 Rack Mounting Kits:
The
Model 3900-2 mounts one Model 3940in a standard 19
inch rack. The Model 3900-2 mounts two Model 3940s
side by side in a standard 19inch rack. Both kits include
all necessary hardware for proper rack mounting of the
instruments.
Model 7007 Shielded IEEE-488 Cables:
The Model
7007-l (lm, 3.3ft.j and Model 7007-2 (2m, 6.6ft.j can be
used to interface the Model 3940to the IEEE488 bus.
Model 7051-2 BNC-to-BNC Cable:
The Model 7051-2is
5OQBNC to BNC cable (RG-58C) 2ft. (0.6m) in length.
The Model 7051-2is terminated with male BNC connec-
tors on both ends.
Model 7051-5 BNC-to-BNC Cable:
The Model 7051-5is
5OQBNC to BNC cable (RG-58C) 5ft. (1.2m) in length.
The Model 70515 is terminated with male BNC connec-
tors on both ends.
Model 7051-10 BNC-to BNC Cable:
The Model 7051-10is
similar to the Models 7051-2and 70515 except that it is
loft. in length.
Model 7754-3 BNC-to-Alligator Cable:
The Model
7754-3 is a 3ft. (0.9m) 5OQ cable (RG-58C), terminated
with amale BNC connector on one end and two alligator
clips on the other end.
Model 7755 5OQFeed-Through Terminator:
The Model
7755is a BNC to BNC adapter that is terminated with a
5OQresistor. VSWR is ~1.1,DC to 25OMHz.
1.8 SPECIFICATIONS
Detailed Model 3940specifications may be found in Ap-
pendix B.
l-3
SECTION 2
Getting Started
2.1 INTRODUCTION
This sections contains basic information on installation
and power line connections; it also provides typical sim-
ple operating examples.
2.2 INSTALLATION
The following paragraphs discuss Model 3940 installa-
tion. In particular, use adequate carewhen installing the
unit. Improper installation will adversely affect the life,
reliability, and safety of the unit.
The Model 3940weighs about 12lbs. Becareful when car-
rying the unit or mounting it in a rack.
2.2.1 Installation Location
The allowable ambient temperature and humidity
ranges for the Model 3940are.
Operating: 0” to 4O”C,10to 9O%RH
Storage: -10” to SO’C,10to 8O%RH
Besure to install the unit in alocation that satisfies these
temperature and humidity conditions. Also the environ-
ment must be free of dust and vibration, and the Model
3944
must not be exposed to direct sunlight.
The Model 3940usesaline filter, but pulse noise or strong
magnetic or electric fields may causeincorrect 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 pro-
tectrear panel connectors and should not beused asaleg
for installation. Do not stand the unit vertically on the
rear guard becauseit may fall over, causing instrument
damage or personal injury.
2.2.2 Fan
The Model 3940isair-cooled by afan. Insufficient air flow
may causecomponents in the unit to fail. Follow the in-
structions given below.
CAUTION
Observe the following precautions to pre-
vent damage to the unit:
l An air intake port is provided on the rear
panel of the unit. Allow a space of at least
2-l
SECTION 2
Gettim Started
four inches between the rear panel and a
wall or other obstruction.
l An exhaust port 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 material between the bottom
of the unit and the surface underneath. An-
other exhaust port is located on the top panel
of the unit. Be careful not to block the top
port by placing an object on top of the unit.
* Avoid mounting two or more units vertically
(for example, when using two or more units
synchronously). Placing one unit on top of
another will obstruct the exhaust port.
l Dust collecting in the fan filter will prevent
sufficient air flow. In clean operating envi-
ronments, wash the filter with a mild deter-
gent every three months. When operating
the unit in adusty environment, wash the fil-
ter with a mild detergent at least once a
month.
l Immediately turn off the power to the unit if
the fan ceases to operate. Operating the in-
strument with the fan inoperative may result
in damage to the instrument.
2.3 LINE VOLTAGE SUPPLY
The Model 3940 operates with a lOOV, lZOV, 22OV,or
240V flO%, 48 to 62Hz, single-phase AC power supply.
The power consumption is 84VA.
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
sameasthe voltage available in the country to which the
unit is shipped.
To change the power supply voltage, first disconnect the
line cord, and setthe supply voltage switch in the correct
position. Wait at least five seconds before turning the
power back on after turning it off.
2-2
WARNING
Disconnect the power cord from the instru-
ment 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 in-
correct voltage may cause damage to the unit.
2.3.2 Line Receptacle Connection
Connect the supplied power cord to the rear panel LINE
receptacle and to
a
grounded AC power receptacle sup-
plying the correct voltage.
WARNING
The Model 3940 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
rounded, the rear panel ground terminal
b
L must be connected to safety earth
ground using #18AWG (or larger) wire be-
fore use.
2.3.3 Line Fuse
The line fuse,which is integral with the power line recep-
tacle, protects the instrument from over-current situ-
ations. To replace the fuse, first disconnect the line cord,
then pry out the fuse compartment (immediately to the
left of the FUSE marking) with a small screwdriver. A
sparefuseis located in the compartment with the fusebe-
ing used. Replacethe blown fuseonly with the type listed
in Table 2-1,then close the compartment.
WARNING
Disconnect the line cord from the instru-
ment before replacing the fuse.
CAUTION
Use only a fuse of the rating listed in
Table 2-1, or instrument damage may occur.
SECTION2
Geffitw Sfarfed
Table
2-l.
Fuse Replacement
2.4 HANDLING PRECAUTIONS
A flat keyboard coated with a polyester film forms the
control panel surface of the Model 3940.Becareful not to
damage the keyboard surface by cutting it with a sharp
instrument or touching it with ahot object.
When the panel or casebecomesdirty, clean it with asoft
cloth. If the panel or caseis too dirty for cleaning with a
dry cloth, dampen the cloth in mild detergent, and wipe
the panel or casewith the damp clothNever usesolvents
such as thinner or benzene, or chemical dust cloths to
avoid damaging caseor front panel surfaces.
2.5 BASIC OPERATION
The following paragraphs summarize front panel operat-
ing controls, give typical test connections, and discuss
typical operating examples for the Model 3940.
2.5.1 Front Panel Summary
Figure 2-l summarizes each front panel feature. For de-
tailed information on eachoperating feature, refer to Sec-
tion 3.
2.5.2 Typical Test Connections
Figure 2-2 shows typical tests connections between the
Model 3940main synthesizer and aDUT (subsynthesizer
connections areessentially the same).Note that 5OQchar-
acteristic impedance cables such as the Model 7051
should be used for all signal connections.
2-3
SECTION 2
Gettinf Started
SUB SYNTHESIZER OUTPUTS
r
SYNC OUT: TTL Sync signal
at programmed
frequency
FCTN OUT: Analop output
GPIB: Prcqwns address
and terminator
OSPL
SWEEP
Rehlrns display
to namsl
MAIN SYNTHESIZER OUTPUTS
FCTN OUT: Analog waveform
RCL: Recalls setups
I
DATA I
04, r Enters numeric
data
RUB OUT: Deletes current
number
I
ENTRY I
FREQ: Sets frequency
(main crab)
AMPTD: Sets output amplitude
(main crab)
OFFSET: Sets DC offset (main only)
FCTN: Sets waveform type
(main and sub)
MODE: Sets operating mode
(main only)
Adds shifted function
to scme other keys
L
Allows sub synthesizer
TRIG
MAN: Manually trf~rs unit
MARK: Selects number of
cscillatlon cycles
SPACE: Selects number of
stql cycles
START FREQ. Programs start frequency
STOP FREQ. Prcgrams stop frequency
cm sets center frequency
CTR 4: Transfers marker to centa
SPAN: Sets span frequency
MKR: Sets marker frequency
SWEEP FCTN: Sets function
SWEEP TIME: Sets time
SWEEP OPR
START: Sixk single or
continuous sweep
SWEEP OFF: Cancels sweep mode
STATE: Sets sweep starV
stop state
HOLD/FtESM: Pauses/resumes sweep
Figure 2-l. Front PanelSummary
2-4
SECTION 2
Getting Started
Model 3940
I
Main
Function
output
(Model 7051)
Figure 2-2. TypicaI TestConnections
2.5.3 Operating Examples
The following examples give step-by-step instructions
for setting basic Model 3940 operating parameters. All
examples except for Example 7describe
main
synthesizer
operation. Sub synthesizer operation for frequency, am-
plitude, and function is similar to main synthesizer op-
eration. Offset, mode, and sweep parameters do not ap-
ply to the sub synthesizer.
Example I: Selecting the Waveform Type (Function)
The waveform type can be selected using the FCTN key
asfollows:
1. Press FCTN and note that the instrument displays
the current function and the available functions.
2. Pressthe number key corresponding to the desired
function (O-61,or rotate the MODIFY knob until the
desired function number is displayed. For example,
press 3 to choose select the square wave function.
The waveform will immediately change to the se-
lected function.
3. PressDSPL to return to the normal display mode.
Example 2: Setting the Waveform Frequency or Period
Use FREQ to set the frequency or period of the output
waveform asfollows:
1. Press FREQ to enter the frequency programming
mode. The instrument will display the allowable fre-
quency range for the selected waveform.
2. To directly enter a completely new numeric fre-
quency value, key in the desired number followed
by the appropriate units key (Hz, kHz, or MHz). For
example, to enter a frequency of lO.lkHz, press: 1
O.lkHz.
3. To simply modify an existing frequency value, place
the cursor on the digit to be changed using 4 or b,
then use the MODIFY knob to setthe digit to the de-
sired value. Repeat as necessary for all digits to be
changed. Note that you canpress the STEPSIZE key
to multiply or divide by 2 or by 10.
4. To display the time period of the waveform fre-
quency, press the set key. You can then key in anew
time period or modify the existing period, if desired.
5. PressHz, kHz, or MHz to return to frequency dis-
play.
6. PressDSPL to return to normal display.
Example 3: Setting the Output Amplitude
Use the AMMD key to setthe output voltage amplitude
asfollows:
1. PressAM??TD,and note that the instrument displays
the current amplitude and allowed amplitude range.
2. To enter a completely new amplitude value in p-p
units, key in the numeric value, then press V or mV,
asrequired. For example, to enter a30mV p-p ampli-
tude, press: 3 0 mV.
3. To simply modify the existing amplitude value, use
the cursor keys and the MODIFY knob to set the
value asrequired.
4. kess DSPL to return to normal display.
2-5
SECTION 2
Getfing Started
Example 4: Programming the DC Offset
The OFFSETkey allows you tosetthe DC or average level
of the main synthesizer output waveform, as in the fol-
lowing example:
1.
2.
3.
PressOFFSETand note that the instrument displays
the current offset value and allowed range.
Either key in the desired offset, or use the MODIFY
knob and cursor keys to change the value.
PressDSPL to return to normal display.
Example 5: Selecting the Operating Mode
The Model 3940main synthesizer canbeoperated in con-
tinuous, burst, trigger, or gate modes. The operating
mode can be setwith the MODE key asin the following
example:
1. PressMODE and note that the instrument displays
the current mode and available modes (continuous,
burst, trigger, and gate).
2. Press the number of the desired mode (or rotate
MODIFY to choose the desired operating mode).
3. PressDSPL to return to normal display.
Example 6: Controlling Sweep Operation
The Model 3940main synthesizer can be used to sweep
acrossadesired frequency range. The SWEEPkeys allow
you to program sweep parameters, while the SWEEP
OPRkeys control sweep operation. Perform the stepsbe-
low to demonstrate basic sweep operation:
1. PressSTARTFREQ,and key in or useMODIFY to set
the sweep start frequency. For example, press 1kHz
to program a 1kHz start frequency.
2.
3.
4.
5.
6.
7.
8.
PressSTOPFREQ and set the sweep stop frequency
as desired. For example, to program
a
1OkHz stop
frequency, press 10 kII2.
Press CTR and SPAN to view the center and span
frequencies. With 1kHz and 1OkHz start and stop
frequencies, the center and span frequencies wilI be
5.5kHz and 9kHz respectively. NOTE: If you change
the center or span frequencies, the start and stop fre-
quencies will beautomatically changed accordingly.
PressSWEEPFCTN, and choose the type of sweep.
For example, press 2 to select a linear, ascending
sweep type.
PressSWEEPTIME, and program the sweep time as
required. For example, press5set to program afive-
second sweep time.
To generate a single sweep, press SINGL START.
The unit will generate one sweep based on selected
sweep parameters.
To generate continuous sweeps,pressSHIFT START
CONT. The Model 3940 will generate sweeps con-
tinuously based on selected sweep parameters.
PressSWEEPOFF to stop a sweep.
Example 7: Using the Sub Synthesizer
Sub synthesizer parameters can be programmed in the
sameway asthe equivalent main synthesizer. The steps
below demonstrate how to program the sub synthesizer
function, frequency, and amplitude.
1. To program the sub synthesizer function, press SUB
FCTN, then choose the desired waveform.
2. Program the sub synthesizer frequency by pressing
SUBFREQ, then key in or modify the frequency, as
required.
3. To set the sub synthesizer output amplitude, press
SUBAMPTD, then setthe amplitude asneeded
4. PressSUBDSPL to display sub synthesizer parame-
ters.
2-6
SECTION 3
Operation
3.1 INTRODUCTION
This section contains detailed information on front panel
operation of the Model 3940.For detailed GPIB (IEEE-488
bus) operation, refer to Section 4.
3.2 FRONT PANEL AND REAR PANEL
DESCRIPTION
3.2.1 Front Panel Description
The front panel of the Model 3940is shown in Figure 3-1.
The front panel is made up of atwo-line, 40-character liq-
uid crystal display and acontrol panel with abuilt-in flat
keyboard. The liquid crystal display presents informa-
tion useful for the operation of the Model 3940,such as
the value of eachparameter and the range of permissible
parameter values.
The keyboard includes aSHIFT key, which gives certain
other keys secondary functions. A key which is shaded
with the same color as the SHIFT key requires that you
press SHIFT first before accessing the function of that
particular key.
The keyboard also includes the SUB key, which allows
you to control sub synthesizer parameters. Pressing SUB
followed by FREQ,for example, allows you to setthe fre-
quency of the sub synthesizer.
Most settings aremaintained in battery backed-up mem-
ory. As a result, the Model 3940automatically assumes
the previous settings when the power is first turned on.
3-1
SECTION 3
Operation
SYNTHESIZER
V3-1. Front Panel
Key Representations
This section usesspecial representation such as[SHIFT],
[SUB], LMODIFYI, or [SIZE] in the explanation of certain
keys. This representation indicates the following:
EmI
Press the applicable key after press-
ing the SHIFI key to access the
shifted key function. The liquid crys-
tal display indicates “SHIFT” in the
upper left comer when the Model
3940is in the shift mode.
wJa
Pressthe applicable key after press-
ing the SUB key to put the Model
3940in the sub mode, which allows
you to set sub synthesizer parame-
ters. The liquid crystal display indi-
cates “SUB” in the upper left comer
when the Model 3940 is in the sub
mode.
[MODIMI
Either key in the value using the
DATA keys or change agiven setting
value with the MODIFY knob. The
up/down step sizewhen increment-
ing or decrementing a value is fixed
at 1, and the cursor position is also
fixed.
[MODIFYI [SIZE] Either key in the value using the
DATA keys or change agiven setting
value with the MODIFY knob. You
can specify the digit to be modified
by placing the cursor on the desired
digit using 4 orb. In addition, you
can change the modify up/down in-
crement using the STEPSIZE key.
3-2
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