HP 1744A User Manual

OPERATORS GUIDE

OSCILLOSCOPE

1744A

HEWLETT PACKARD

SAFETY SUMMARY

The following general safety precautions must be observed during operation of this instrument. Failure to comply with these precautions or with specific warnings elsewhere in this manual violates safety standards of design, manufacture, and intended use of the instrument. Hewlett-Packard Company assumes no liability for the customer's failure to comply with these requirements.

GROUND THE INSTRUMENT.

minimize shock hazard, the instrument chassis and cabinet must be connected to an electrical ground. The

instrument is equipped with a three-conductor ac power cable. The power cable must either be plugged into an approved three-contact outlet or used with a three-contact to two-contact adapter with the grounding wire

(green) firmly connected to an electrical ground (safety ground) at the power outlet. The power jack and mating plug of the power cable meet International Electrotechnical Commission (IEC) safety standards.

DO NOT OPERATE IN AN EXPLOSIVE ATMOSPHERE.

Do not operate the instrument in the presence of flammable gases or fumes. Operation of any electrical instrument in such an environment constitutes a definite safety hazard.

DO NOT REMOVE INSTRUMENT COVERS.

Operating personnel must not remove instrument covers. Component replacement and internal adjustments

must be made by qualified maintenance personnel.Service instructions for this instrument are provided in a separate Operating and Service Manual.

DANGEROUS PROCEDURE WARNINGS.

Warnings such as the example below, precede potentially dangerous procedures throughout this manual!

Instructions contained in the warnings must be followed.

WARNING

Dangerous voltages, capable of causing death, are present in this instrument.

Use extreme caution when handling, installing or operating.

OPERATORS GUIDE

MODEL 1744A

OSCILLOSCOPE

Operators Guide Part Number 01744-90902 Microfiche Part Number 01744-90802

HEWLETT

1900 GARDEN OF THE GODS ROAD, COLORADO SPRINGS, COLORADO, U.S.A.

PACKARD COMPANY/COLORADO SPRINGS DIVISION

1978

PRINTED: AUGUST 1978

Table of Contents

Model 1744A

TABLE OF CONTENTS

GeneralInformation

Description AccessoriesFurnished Accessories and Options Available

Preparationfor Use ................................ 8

PowerCord PowerRequirements Controlsand Connectors

Turn-on Procedure ................................ 18

Checking Instrument Performance

TraceAlignment Astigmatismand Focus ProbeCompensation VerticalAccuracy Check SweepTime Accuracy TriggerSelection Table

ObtainingBasic Displays

NormalSweep Display MagnifiedSweep Display DelayedSweep Display MixedSweep Display X-Y Display

Variable Persistance - Storage Operation

AutoErase AutoStore Mode ContinuousScan

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20 21 21 21 21 21 23 24 25 25 26 26 26 28

1 8 8

8 9

EliminatingFlicker Storinga Trace Display Brightness Control

MeasurementTechniques

Introduction

VoltageMeasurements Absolute Voltage Measurements Peak-to-peak Voltage Measurements Average Voltage Measurements Amplitude Comparison Measurements Method1 Method2 CommonMode Rej ection

Time-interval Measurements

PeriodMeasurements

Repetition Rate or Frequency Measurements .... 38

Transition Time Measurements DelayedSweep

Measuring Phase Difference by Time Delay ..... 43

Avs B Phase Measurements

Triggering

TriggerView ... Eliminating Multiple Triggering an

ComplexWaveforms .......................... 47

Measuring CRT Writing Speed .................... 48

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Model 1744A

Operators Guide

MODEL 1744A OPERATORS GUIDE

OPERATING INSTRUCTIONS

GENERAL INFORMATION.

This Operators Guide will acquaint you with the Model 1744A features, capabilities, accessories, power require- ments, and controls. To aid in operating the oscillo- scope, initial turn-on instructions, calibration proce- dures, and a performance check are provided. Detailed explanations in the Applications Section show how you can use varied capabilities of the 1744A to best ad- vantage in a variety of electrical measurements. Speci- fiications and general characteristics for the 1744A are listed in tables 1 and 2. Service information is available in a separate service manual.

DESCRIPTION.

The Hewlett-Packard Model 1744A is a dual-channel,

100-MHz, delayed-sweep variable persistence storage oscilloscope designed for single-shot transients and low duty cycle waveform analysis in the bench or field environment. The writing speed specification of 1800 cm/µs permits full screen capture of transients at the maximum slew rate of the vertical amplifier system. The

dual-channel dc to 100 MHz vertical deflection system has 12 calibrated deflection factors from 5 mV/div to 20 V/div. A maximum sensitivity of 1 mV/div to 30 MHz is provided an both channels by means of a 5X vertical magnification feature. Selectable input impedance of 50 ohms or 1 megohm permits selection of that impedance which best meets measurement requirements. The hori-

zontal deflection system has calibrated sweep rates from 2 s/div to 0.05 µs/div and delayed sweep rates from 20 ms/div to 0.05 gs/div. A 10X magnifier expands all sweeps by a factor of 10 and extends the fastest sweep to 5 ns/div. In alternate or chop modes, a trigger-view control will display three signals: the channel A signal, the channel B signal, and the trigger signal. This allows you to correlate time between the trigger signal and the channel A and channel B signals. In trigger-view operation, center screen represents the trigger threshold point, allowing you to see the triggering level location. With the A VS B control, an X-Y mode of operation is possible. The channel A input (Y-axis) is plotted versus the channel B input (X-axis).

A trigger-view control provides capability for observing

the channel A signal, channel B signal, and an external

Operators Guide

Model 1744A

Table 1. Specifications

VERTICAL AMPLIFIERS (2)

Bandwidth and Rise Time at all deflection factors from 0°C to +55°C.

BANDWIDTH: DC-Coupled:

input modes.

AC-Coupled:

divider probes.

BANDWIDTH LIMIT:

20 MHz.

RISE TIME:

of a 5 div input step.

DEFLECTION FACTOR Ranges:

in 1, 2, 5 sequence, accurate within 3%.

Vernier:

extends maximum deflection factor to at least 50 V/div. UNCAL light indicates when vernier is not in CAL position.

POLARITY:

pushbutton.

INPUT RC (selectable) AC or DC: 50 Ohm: MAXIMUM INPUT AC or DC:

(p-p ac at 1 kHz or less).

3 dB down from 6 div reference signal.

dc to 100 MHz in both 50f1 and 1 Mn

approx 10 Hz to 100 MHz; 1 Hz with 10:1

mits upper bandwidth to approx

<3.5 ns, measured from 10% to 90% points

5 mV/div to 20 V/div (12 calibrated positions)

continuously variable between all ranges,

channel B may be inverted, front panel

1 MCi ±2% shunted by approx 20 pF.

50n ±3%.

250 V (dc + peak ac at 1 kHz or less) or 500 V

50 Ohms: 5 A+B OPERATION

Amplifler: bandwidth and deflection factors are un-

changed; channel B may be inverted for A-B opera- tion.

Differential (A-B) Common Mode:

dB from dc to 20 MHz. Common mode signal ampli- tude equivalent to 6 divisions with one vernier adjusted for optimum rejection.

V rms.

CMRR is at least 20

VERTICAL MAGNIFICATION (X5)

BANDWIDTH: DC-Coupled:

AC-Coupled:

RISE TIME:

5 div input step).

DEFLECTION FACTOR:

and 10 mV/div deflection factor settings by a factor of 5 for a maximum sensitivity of 1 mV an channels A and B.

3 dB down from 6 div reference signal. dc to approx 30 MHz. approx 10 Hz to 30 MHz.

-<12 ns (measured from 10% to 90% points of

increases sensitivity of the 5

TRIGGER SOURCE

Selectable from channel A, channel B, composite, or line frequency.

CHANNEL A: all display modes triggered by channel A

signal.

Mode! 1744A

Operators Guide

Table 1. Specifications (Cont'd)

CHANNEL B:

all display modes triggered by channel B

signal.

COMPOSITE:

all display modes triggered by displayed signal except in Chop. In Chop mode, trigger signal is derived from channel A.

LINE FREQUENCY:

trigger signal is derived from

power line frequency.

TRIGGER VIEW

Displays internal or external trigger signal. In Alter- nate or Chop mode, channel A, channel B, and the trigger signals are displayed. In Channel A or B mode, Trigger View overrides that channel. Internal trigger signal amplitude approximates vertical sig-

nal amplitude. External trigger signal deflection factor is approx 100 mV/div or 1 V/div in EXT =10. Triggering point is approx center screen. With id- entically timed signals to a vertical input and the external trigger input, trigger signal delay is <3.5 ns.

MAIN AND DELAYED TIME BASES

RANGES

Main: 50 ns/div to 2 s/div (24 ranges) in 1, 2, 5 sequence.

Delayed:

sequence.

50 ns/div to 20 ms/div (18 ranges) in 1, 2 5

Accuracy:

Sweep Time/Div

50 ns to 20 ms

*Add 1% for 50 ms to 2 s ranges.

MAIN SWEEP VERNIER:

(over center 8 div)

*Accuracy X1

±3% ±4% 0°C to +15°C

±2% ±3%

Temp Range

X10

±3% +15°C to +35°C ±4% +35°C to +55°C

continuously variable be- tween all ranges, extends slowest sweep to at least 5 s/div. UNCAL light indicates when vernier is not in CAL position.

MAGNIFIER (X10):

expands all sweeps by a factor of

10, extends fastest sweep to 5 ns/div.

CALIBRATED SWEEP DELAY

DELAY TIME RANGE:

settings of 100 ns to 2 s (minimum delay 150 ns).

DIFFERENTIAL TIME MEASUREMENT ACCURACY:

Main Time Base Setting

100 ns/div to 20 ms/div

50 ms/div to 2 s/div

*Add 1% from 0°C to +15°C and +35°C to +55°C.

0.5 to 10 X Main Time/Div

*Accuracy

(

15°C

+35°C)

±(0.5% +0.1% of full scale)

±(1% +0.1% of füll scale)

Operators Guide

DELAY JITTER:

delay in each step from +15°C to +35°C; <0.005% (1 part in 20 000) from 0°C to +15°C and +35°C to

+55°C.

<0.002% (1 part in 50000) of maximum

TRIGGERING

INTERNAL:

division or more vertical deflection, increasing to 1 division of vertical deflection at 100 MHz in all display modes (required signal level is increased by 2 when in Chop mode and by 5 when X5 vertical magnifier is used). Triggering on Line frequency is also selectable.

EXTERNAL:

more increasing to 100 mV p-p at 100 MHz (required signal level is increased by 2 when in Chop mode).

EXTERNAL INPUT RC:

prox 20 pF.

MAXIMUM EXTERNAL INPUT:

kHz or less) or 500 V (p-p ac at 1 kHz or less).

LEVEL and SLOPE Internal:

of the displayed waveform.

External:

either slope of the trigger signal, +10 V to -10 V in divide by 10 mode (=10).

COUPLING:

dc to 25 MHz on signals causing 0.3

dc to 50 MHz on signals of 50 mV p-p or

approx 1 Mfl shunted by ap-

250 V (dc + peak ac at 1

at any point on the positive or negative slope

continuously variable from +1 V to -1 V on

AC, DC, LF REJ, or HF REJ.

Table 1. Specifications (Cont'd)

AC:

attenuates signals below approx 20 Hz.

LF Reject (Main Sweep):

approx 4 kHz.

HF Reject (Main Sweep):

approx 4 kHz.

CALIBRATED MIXED TIME BASE

Dual time base in which the main time base drives the First portion of sweep and the delayed time base completes the sweep at the faster delayed sweep. Also operates in single sweep mode. Accuracy, add 2% to main time base accuracy.

B OPERATION

BANDWIDTH Channel A (Y-AXIS): Channel B (X-AXIS): DEFLECTION FACTOR:

calibrated positions) in 1, 2, 5 sequence.

PHASE DIFFERENCE BETWEEN CHANNELS:

to 100 kHz.

CATHODE-RAY TUBE AND CONTROLS

Z-AXIS INPUT (INTENSITY MODULATIONS):

X50 ns width pulse blanks trace of any intensity

usable to 10 MHz for normal intensity. Input R, 1 kf1 ±10%. Maximum input ±20 V (dc ± peak ac).

Model 1744A

attenuates signals below

attenuates signals above

same as channel A. dc to 5 MHz.

5 mV/div to 20 V/div (12

<3°, dc

+4 V,

Model 1744A

PERSISTENCE Variable: STORAGE WRITING SPEED:

6 x 8 div (with viewing hood).

STORAGE TIME Display Mode: Store Mode: Wait Time: ERASE TIME:

approx 100 ms to 1 minute.

>,1800 cm/µs over center

at least 10 s at 22°C.

at least 30 s at 22°C.

at least 60 s at 22°C.

approx 300 ms.

GENERAL

REAR PANEL OUTPUTS:

V to >+2.5 V capable of supplying approx 5 mA.

main and delayed gates, +0.8

Table 1. Specifications (Cont'd)

AMPLITUDE CALIBRATOR (0°C to +55°C)

Output Voltage

Rise Time

Frequency

POWER:

VA max.

WEIGHT: net, 13.8 kg (30.4 lb); shipping, 16.6 kg (36.6

lb).

OPERATING ENVIRONMENT

Temperature:

Humidity: Altitude: Vibration:

0.254 mm (0.010 in.) excursion, 10 to 55 Hz.

100,120, 220, 240 Vac, ±10%, 48 to 440 Hz;100

to 4600 m (15 000 ft).

Operators Guide

1 V

p-p into <-1 MSl

0.1 V p-p into 50f1 1 1

0°C to +55°C.

to 95% relative humidity at +40°C.

vibrated in three planes for 15 min. each with

0.1 µs

approx 1.4 kHz

±1%

Operators Guide

VERTICAL DEFLECTION

VERTICAL DISPLAY MODES

Channel A; channel B; channels A and B displayed alternately on successive sweeps (ALT); channels A and B displayed by switching between channels at an approximate 250 kHz rate with blanking during switching (CHOP); channel A plus channel B (al- gebraic addition); and trigger view.

DELAY LINE:

view leading edge of input pulse without advanced trigger.

INPUT COUPLING:

ground. Ground position disconnects input connect- or and grounds amplifier input.

input signals are delayed sufficiently to

selectable AC or DC, 50(1 (dc), or

HORIZONTAL DISPLAY MODES

Main, main intensified, mixed, delayed, mag X10, and A vs B.

TRIGGERING

MAIN SWEEP

Normal: sweep is triggered by internal or external

signal.

Automatic:

input signal. Above 45 Hz, triggering is same as normal. For stable triggering at approx 45 Hz and below, use Normal trig

bright baseline displayed in absence of

gering.

Table 2. General Characteristics

Single: automatically switches triggering to Normal

and the sweep occurs once with same triggering as Normal, reset pushbutton arms sweep and lights indicator. Single sweep is also initiated with Erase pushbutton, sweep is armed after the erase cycle.

DELAYED SWEEP (SWEEP AFTER DELAY) Auto:

delayed sweep automatically starts at end of

delay.

Trig:

delayed sweep is armed and triggerable at end of

delay period.

TRIGGER HOLDOFF (Main Sweep):

holdoff time in all ranges.

CATHODE-RAY TUBE AND CONTROLS

TYPE: Hewlett-Packard, 12.7 cm (5 in.) rectangular

CRT, post accelerator, approx 7.5 kV accelerating potential, aluminized P31 phosphor.

GRATICULE: 8

nonparallax graticule, 0.2 subdivision marking on major horizontal and vertical axes, with markings for rise time measurements. Graticule illumination is achieved with Persistence control set to minimum.

BEAM FINDER:

of setting of horizontal and vertical controls.

OPERATING MODES:

and auto erase.

REAR PANEL CONTROLS:

and display brightness.

DIMENSIONS:

Model 1744A

increases sweep

x 10 div (1 div = 0.72 cm) internal,

returns trace to CRT screen regardless

write, store, display, auto store,

astigmatism, trace align,

see outline

drawing.

Model 1744A

NOTES:

Table 2. General Characteristics (Contil)

DIMENSIONS ARE FOR GENERAL

INFORMATION ONLY. IF DIMENSIONS ARE REQUIRED FOR BUILDING SPECIAL ENCLOSURES, CONTACT YOUR HP FIELD ENGINEER.

DIMENSIONS ARE IN MILLIMETRES AND (I

NCHES).

Operators Guide

33513 3 1

1847 a1

B71T

REAR

Operators Guide

Model 1744A

trigger signal on the same display when operating in ALT or CHOP modes. Automatic storage is provided for capturing single-shot data that occurs at random times. Automatic erase allows continuously repeated erase cycles with continuously variable viewing time between erase cycles. The CRT screen has 8 x 10 major divisions (0.72 cm/div) on an internal graticule.

ACCESSORIES FURNISHED.

A blue light filter, front-panel cover, power cord, vinyl accessory storage pouch, two 10:1 divider probes, a

metal mesh contrast filter, a B-scan jumper filter,

and a collapsible viewing hood are provided with the 1744A.

ACCESSORIES AND OPTIONS AVAILABLE.

Several divider probes are available with various voltage division ratios and cord lengths. Refer to 1744A Operat- ing and Service Manual for model or part numbers.

Option 001

power cord.

Option 090

supplied. You may specify other probes that are more suitable for your requirements.

Option 091

the two divider probes normally supplied.

Option

the two divider probes normally supplied.

has a fixed power cord in lieu of detachable

deletes the two 10:1 divider probes normally

supplies two Model 10042A probes in lieu of

092

supplies two Model 10040A probes in lieu of

Option

the two divider probes normally supplied.

Option 580

dicating compliance with CSA Bulletin 556B. (Cana- dian Standards Association)

Option

uals instead of one. A camera adapter permits use of an oscilloscope camera

with the 1744A. Various testmobiles are available which

accept the 1744A and provide convenient, mobile stands for the oscilloscope. Refer to 1744A Operating and Service Manual for model numbers.

096

supplies two Mode! 10006D probes in lieu of

supplies instrument with CSA Label in-

910

furnishes two Operating and Service Man-

PREPARATION FOR USE.

WARNING

Read the Safety Summary at the front of this

guide before installing or operating the in-

strument.

POWER CORD.

The power cord required depends on the ac input voltage and the country in which the instrument is to be used. Figure 1 illustrates standard power receptacle (wall outlet) configurations. The HP part number shown above each receptacle drawing specifies the power cord equipped with the appropriate mating plug for that

Mode! 1744A

Operators Guide

HP POWER CABLE PART NUMBERS

8120-1692

OPTION 902

•___

8120-1703

OPTION 900

INPUT POWER RECEPTACALE TYPES

Figure 1. Power Receptacles

receptacle. If the appropriate power cord is not included with your instrument, notify the nearest HP Sales/ Service Office and a replacement cord will be provided.

8120-2296

OPTION 906

8120-1369

OPTION 901

8120-1521

STANDARD

POWER REQUIREMENTS.

The oscilloscope requires a power source of 100,120, 220, or 240 volts ac ±10%, single phase 48 to 440 Hz that can deliver at least 100 VA.

LAUTION

Instrument damage may result if the line voltage selection switch is not correctly set for the proper input power source.

The instrument is normally set at the factory for 120 V operation. To operate the instrument from any other ac power source, proceed as follows:

Verify that 1744A power cable is not connected

to a power source.

Stand instrument an rear-panel legs and use blade-type screwdriver to position power selector switch- es through opening in bottom cover (figure 2 shows switches set for 120 V operation).

For 220 V -240 V inputs, replace fuse Fl with 0.5 A slow-blow fuse supplied with instrument (HP Part No. 2110-0202).

Connect 1744A input power Gable to input power

source.

Operators Guide

Figure 2. Line Voltage Selection Switch Settings

100

100V I

—240V

120]

—arm

I I

1741A-036-ß1-77

CONTROLS AND CONNECTORS.

Front- and rear-panel photographs (see figure 32) are

located at the rear of this guide on a fold-out page for

easy reference while you are reading any section. Con-

trol and connector descriptions have index numbers that are keyed to the panel photographs. The following paragraphs provide detailed descriptions of control and connector functions. Refer to the Applications Section for information an using the Model 1744A.

Mode! 1744A

CRT CONTROLS

0 LINE OFF/ON. Switch turne power on and off.

Indicator lights when power is ON.

BEAM FIND. Restricts the display to the view- ing area regardless of control settings. Permits the operator to determine what action is ne-

cessary to return the beam to the viewing area

(reduce input signal amplitude, change deflec- tion factor, increase intensity, change position controls, etc.).

Q BEAM INTENSITY. Determines intensity of the

electron beam as it writes on the storage mesh.

Q FOCUS. Adjusts the writing beam for sharp,

well-defined trace. Keep FOCUS adjusted to avoid internal CRT damage.

AUTO ERASE/AUTO

button to select either AUTO STORE or AUTO ERASE mode of operation. Respective lamps light to indicate which mode is selected. The AUTO ERASE lamp is green. AUTO ERASE. In auto erase, the 1744A operates in a repetitive single-shot mode, even when a continuous signal is available. This mode is

STORE.Two-functionpush-

Model 1744A

Operators Guide

also helpful during setup for capture of single-

shot events by making it easier to obtain timum focus and intensity for a particular sig- nal. In addition, if you are viewing more than one trace, such as two or three channels, the

1744A will wait for the required number of sweeps to be displayed before automatically erasing the display. Operating at high drive levels in variable persistence and storage modes may cause the storage mesh to retain residual i

mages. These residual images may appear as a cluttered display when BRIGHTNESS 0 is at or near maximum. Residual traces are conven-

iently removed by operating the 1744A in the auto erase mode for a few minutes with IN- TENSITY Q fully ccw.

NOTE

Pressing ERASE Q terminates the AUTO ERASE cycle allowing the erator to vary the cycle time at slower rates.

AUTO STORE.

Used to set up the 1744A for

applications requiring capture of random sin-

gle-shot events. AUTO STORE is selected by

Op-

pressing SINGLE m, AUTO STORE Q, and WRITE 0 to prevent self-triggering. When the random event occurs, the 1744A automati- cally triggers, sweeps and switches from WRITE mode to STORE mode. To capture another

event, press write 0 and RE SET m or ERASE 0 to arm trigger circuit. AUTO STORE allows the operator to capture high-speed, single-shot, random transients. After triggering occurs the 1744A switches to store. At slower writing rates, the time the operator can view the image before it fades will increase. Therefore, it is to the operator's advantage to use the lowest BRIGHTNESS setting in viewing and storing traces.

Q PERSISTENCE/VIEW TIME.

Two-function po- tentiometer to vary persistence or viewing time of signal, depending an operating mode selected.

PERSISTENCE.

Variable persistence allows you to adjust the trace retention for optimum dis- play when viewing low repetition rate, fast rise time signals. By adjusting persistence to match the sweep rate, you can cause the trace to refresh and provide a continuous display of hard-to-view signals such as low duty-cycle pulse trains.

Operators Guide

Model 1744A

VIEW TIME.

VIEW TIME control establishes the time that the trace is retained on the display before another erase cycle is initiated.

Q ERASE.

cycle to remove stored traces from the CRT

storage mesh. Inoperative when STORE/DIS- PLAY indicators are on to prevent accidental erasure of the stored signal. In auto store mode,

ERASE may be pressed to arm the trigger cir- cuit.

Q BRIGHTNESS.

mages. Store time is inversely proportional to BRIGHTNESS setting, BRIGHTNESS is also used in the WRITE p mode to vary the writing

rate.

Q WRITE.

signals on the display in storage and variable

persistence operation. WRITE lamp lights when WRITE is selected.

STORE/DISPLAY.

when the 1744A is operating in the WRITE 0 mode stores the trace being written, and lights the STORE lamp. Pressing the pushbutton

In AUTO ERASE Q mode, the

Pushbutton which initiates the erase

Adjusts brightness of stored

Conditions the 1744A to write applied

Engaging this pushbutton

again causes both STORE and DISPLAY lamps to light and displays the stored trace on screen. Brightness of the display is increased by rotat- ing the BRIGHTNESS the trace has been examined, press the push- button again to enter STORE mode to achieve longest store time.

VERTICAL AMPLIFIER CONTROLS

m CAL 1 V.

square-wave signal with a frequency of ap- proximately 1.4 kHz (100 mV p-p when ter- minated in 50 ohms).

® 1".

ground.

CHAN A (B) VOLTS/DIV.

deflection factor in a 1, 2, 5 sequence from 0.005 V/div to 20 V/div, accurate within 3% with vernier m in CAL detent.

Vernler.

flection factor between calibrated ranges. Ver- nier range is at least 2.5:1.

Provides a 1 V peak-to-peak (±1%)

Provides convenient front-panel chassis

Provides continuous control of the de-

control cw. After

Selects the vertical

Mode! 1744A

UNCAL.

or CHAN B) is out of CAL detent. Indicates that

VOLTS/DIV setting is uncalibrated.

Coupling.

pedance for the vertical amplifiers. In the AC position, the dc component of the input signal is blocked. The lower 3-dB limit is approximately 10 Hz.

GND.

amplifier, and the amplifier input is grounded.

DC.

to the vertical amplifier. The input impedance is approximately 1 megohm shunted by 20 pF.

50fl.

input impedance is 5051. Pull the lever forward and down to select this position. Do not apply more than 5 V rms to the input connector.

INPUT.

nals to the channel A (Y) or channel B (X) amplifier. Impedance and coupling are select- able by m. Do not apply more than 250 V (dc + peak ac at 1 kHz or less) or more than 500 V (p-p ac at 1 kHz or less).

POSN $ .

display.

Lights when Vernier (either CHAN A

Selects the input coupling and im-

The input Signal is disconnected from the

All elements of the input signal are passed

The input signal is dc coupled, and the

BNC connector to apply external sig-

Controls the vertical position of the

Operators Guide

ALT.

Channel A and B signals are displayed

alternately an consecutive sweeps. m ®

Channel

A +

A. Displays the channel A input signal.

Displays the channel B input signal.

Pressing both channel A m and channel

B ® displays the algebraic sum of the channel

A and channel B input signals. If the channel B display is inverted (press CH B INVT m), an A minus B display results.

CHOP.

Channel A and B signals are displayed simultaneously by switching between channels at 250-kHz rate.

TRIGGER

signal as the trigger signal when INT

A. Selects a sample of the channel A

/EXTm

is INT.

TRIGGER

When in INT m, a sample of the channel B signal is selected as the trigger signal.

CO M P.

When display mode is set for channel A,

channel B, A + B, or ALT, and both ® and

m are pressed, the sweep is triggered by the

displayed signal. When display is set to CHOP, sweep is triggered by channel A signal only.

Operators Guide

Model 1744A

TRIG VIEW.

ger signal with approximately the same sensi- tivity indicated on the corresponding channel VOLTS/DIV ® control. A selected external trigger signal is displayed with a fixed sensi- tivity of approximately 100 mV/div with INT/

EXT m set to EXT (1 V/div if EXT = 10 ® engaged). TRIGGER LEVEL ® positions the trigger signal vertically about the center

horizontal graticule line. Center screen indi- cates the trigger threshold level with respect to the trigger signal. In ALT m or CHOP modes, three signals appear on the same dis- play: channel A, the selected trigger signal (at center screen), and channel B, with no need for erasing between each display. This is extremely useful in applications such as digital circuits where it is necessary to use external trigger sources to maintain proper timing relation- ships and to know the time relationship of the trigger signal to the displayed events. TRIG

VIEW is also helpful in establishing discrete trigger levels.

m MAG

five times, and increases the maximum sensi- tivity to 1 mV/div. The bandwidth is decreased to 30 MHz.

Displays the selected internal trig-

X5.

Magnifies the vertical presentation

BW LIMIT.

A and channel B to approximately 20 MHz.

CH B 1 NVT.

signal. In A + B m & ® mode, pressing CH B INVT m results in an A minus B display.

MAIN TIME BASE CONTROLS

m & m POSITION 4P.

ments position the trace horizontally.

MAIN TRIGGER LEVEL.

level on the input trigger signal where the main sweep is triggered. With external trigger sig- nals, the trigger level is continuously variable from +1.0 V to -1.0 V on either slope of the input trigger signal; +10 V to -10 V in EXT = 10

m mode. With internal trigger signals, the

trigger level control selects any point on the displayed vertical waveform.

POS/NEG.

select either the positive or negative slope of the trigger signal as the starting point for the sweep.

LF REJ.

signals below approximately 4 kHz. This is

Attenuates internal or external trigger

Reduces the bandwidth of channel

Inverts the polarity of the channel B

Coarse m and FINE m adjust-

Selects the voltage

Two-position pushbutton used to

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