Tektronix 453 schematic

TM 11-6625-1722-15

TECHNICAL MANUAL

OPERATOR’S, ORGANIZATIONAL, DIRECT SUPPORT

GENERAL SUPPORT, AND DEPOT MAINTENANCE

MANUAL

OSCILLOSCOPE AN/USM-273

(NSN 6625-00-930-6637)

This copy is a reprint which includes current

pages from Changes 1.

HEADQUARTERS,

DEPARTMENT OF THE ARMY

JANUARY 1972

THIS MANUAL IS AN AUTHENTICATION OF THE MANU­FACTURER’S COMMERCIAL LITERATURE WHICH,
THROUGH USAGE, HAS BEEN FOUND TO COVER THE
DATA REQUIRED TO OPERATE AND MAINTAIN THIS
EQUIPMENT. SINCE THE MANIJAL WAS NOT PREPARED
IN ACCORDANCE WITH MILITARY SPECIFICATION, THE
FORMAT HAS NOT BEEN STRUCTURED TO CONSIDER
LEVEL OF MAINTENANCE NOR TO INCLUDE A FOR­MAL SECTION ON DEPOT MAINTENANCE STANDARDS.

WARNING

DANGEROUS VOLTAGES

EXIST IN THIS EQUIPMENT

DON’T TAKE CHANCES!

CAUTION

Special 3% silver solder is required on the ceramic terminal

strips in this equipment. A 40- to 75-watt soldering iron
should be used and it should be tinned with the same special

solder. Additional quantities of the solder may be procured
under FSN 3439-912-8698. Ordinary solder may be used
only in dire emergency.

This Manual Contains Copyrighted Material Reproduced

Tektronix, Inc. All Rights Reserved

Permission Of

By

TM 11-6625-1722-15

T

ECHNICAL MANUAL

HEADQUARTERS

DEPARTMENT OF THE ARMY

NO. 11–6625–1722–15

ASHINGTON

, D.C., 10 January 1972

W

Operator’s Organizational, Direct Support, General Support, and Depot

Maintenance Manual Including Repair Parts and Special Tools Lists

OSCILLOSCOPE AN/USM–273

S

ECTION A.

INRODUCTION

1.

CHARACTERISTICS

2.

OPERATING INSTRUCTIONS . .. . . . . . . . . . . . . . . . . . . . .

CIRCUIT DESCRIPTION . . . . . . . . . . . . . . . . . .

3.

4.

MAINTENANCE

PERFOR0MANCE CHECK . . . . . . . . . . . . . . . . . . . . .

5.

Page

A-1
1-1
2–1
3–1
4–1
5-1

6.

7.

8.

9.

10,

APPENDIX A.

B.

C.
D.

CALIBRATION

PREVENTIVE MAINTENANCE INSTRUCTIONS . . . . . . . . . . . . . . . . .

MECHNICAL PARTS IDENTIFICATION . . . . . . . . . . . . . . . . . . . . . . .

DIAGRAMS
RACKMOUNTING
REFERENCES

ITEMS COMPRISING AN OPERABLE EQUIPMENT . . . . . . . . . . . . . . . .

MAINTENANCE ALLOCATION . . . . . . . . . . . . . . .

REPAIR PARTS AND SPECIAL TOOLS LIST . . . . . . . . . . . . . .

6–1
7–1
8-1
9-1
10-1
A–1
B–1
C-1
D-1

TM 11-6625-1722-15

Fig. 1-1. Top; the Type 453 Oscilloscope. Bottom; the Type R453 Oscilloscope.

A-O

SECTION 0

INSTRUCTIONS

TM 11-6625-1722-15

0-1.

maintenance instructions.

Scope

This manual describes Oscilloscope

AN/USM-273 (fig. 1-1) and provides

Throughout this manual, the AN/USM-273 is re-

ferred to as the Tektronix Type 453 Oscilloscope. The maintenance allo-

cation chart appears in appendix C.

Repair parts and special tools lists

are contained in TM-6625-1722-24P.

0-2.

Indexes of Publications

a. DA Pam 310-4.

Refer to the latest issue of DA Pam 310-4 to deter-

mine whether there are new editions, changes, or additional publications
pertaining to the equipment.

DA Pam 310-7.

b.

Refer to DA Pam 310-7 to determine whether there

are modification work orders (MWO’S) pertaining to the equipment.

0-3.

Maintenance Forms, Records, and Reports

Reports of Maintenance and Unsatisfactory

a.

Equipment.

Department

of the Army forms and procedures used for equipment maintenance will be
those prescribed by TM 38-750, The Army Maintenance Management System.

Report of Packaging and Handling Deficiencies.

b.

Fill out and for-

ward DD Form 6 (Packaging Improvement Report) as prescribed in AR 700-58/

NAVSUPINST 4030.29/AFR 71-13/MCO P4030.29A, and DLAR 4145.8.

Discrepancy

c.

in Shipment Report (DISREP) (SF 361). Fill out and

forward Discrepancy in Shipment Report (DISREP) (SF 361) as prescribed in

AR 55-38/NAVSUPINST 4610.33B/AFR 75-18/MCO P4610.19C and DLAR 4500.15.

0-1

TM 11-6625-1722-15

0-4.

us an EIR.

don’t like about your equipment.

design.

(Quality Deficiency Report).

and Electronics Materiel Readiness Command, ATTN:

Monmouth, NJ 07703.

0-5.

Reporting Equipment Improvement Recommendations (EIR)

If your Oscilloscope AN/USM-273 needs improvement, let us know.

You,

the user,

are the only one who can tell us what you

Send

Let us know why you don’t like the

Tell us why a procedure is hard to perform.

Put it on an SF 368

Mail it to Commander, US Army Communications

DRSEL-ME-MQ, Fort

We’ll send you a reply.

Administrative Storage

Administrative storage of equipment issued to and used by Army activi-

ties shall be in accordance with TM 740-90–1.

0-6

Destruction of Army Electronics Materiel

Destruction of Army electronics materiel to prevent enemy use shall be

in accordance with TM 750-244-2.

0-7.

Reporting Errors and Recommending Improvements

You can help improve this manual. If you find any mistakes or if you

know of a way to improve the procedures, please let us know. Mail your

letter or DA Form 2028 (Recommended Changes to Publications and Blank

Forms) to

Readiness Command, ATTN:

either case,

Commander, US Army Communications and Electronics Materiel

DRSEL-ME-MQ, Fort Monmouth, NJ 07703. In

a reply will be furnished direct to you.

0-2

Change 1

SECTION 1

CHARACTERISTICS

TM 11-6625-1722-15

Introduction

The Tektronix Type 453 Oscilloscope is a transistorized
portable oscilloscope designed to operate in a wide range
of environmental conditions. The light weight of the Type
453 allows it to be easily transported, while providing the
performance necessary for accurate high-frequency meas­urements.
provides calibrated deflection factors from 5 millivolts to
10 volts/division. Channels 1 and 2 can be cascaded using
an external cable to provide a one millivolt minimum defect­ion factor (both VOLTS/DIV switches set to 5 mV).

The trigger circuits provide stable triggering over the full
range of vertical frequency response. Separate trigger con­trols are provided to select the desired triggering for the A
and B sweeps. One of three sweep modes can be selected
for the A sweep; automatic, normal or single sweep. The
horizontal sweep provides a maximum sweep rate of 0.1
microsecond/division (10 nanosecond/division using 10X
magnifier) along with a delayed sweep feature for accurate
relative-time measurements.
can be made with Channel 2 providing the vertical deflection,
and Channel 1 providing the horizontal [deflection. (TRIGGER
switch set to CH 1 ONLY, HORIZ DISPLAY switch set to EXT
HORIZ). The regulated DC power supplies maintain con-

The dual-channel DC-to-50 MHz vertical system

Accurate X-Y measurements

ELECTRICAL CHARACTERISTICS

VERTICAL DEFLECTlON SYSTEM

stant output over a wide variation of line voltages and fre­quencies.
approximately 90 watts.

Information given in this instruction monual applies to the
Type R453 also unless otherwise noted. The Type R453 is
electrically identical to the Type 453 but is mechanically
adapted for mounting in a standard 19-inch rack. Rack­mounting instructions, a mechanical parts list and a dimen­sional drawing for the Type R453 are provided in Section

10 of this manual.

The electrical characteristics which follow are divided
into two categories. Characteristics listed in the Performance
Requirement column are checked in the Performance Check
and Calibration sections of this manual. Items listed in the
Operational Information column are provided for reference
use and do not directly reflect the measurement capabili­ties of this instrument. The Performance Check procedure
given in Section 5 of this manual provides a convenient
method of checking the items listed in the Performance
Requirement column. The following electrical characteristics

apply over a calibration interval of 1000 hours at an am­bient temperature range of -15°C to +55°C, except as

otherwise indicated. Warm-up time for given accuracy is
20 minutes.

Total power consumption of the instrument is

. .

Characteristic

Deflection Factor

Deflection Accuracy

Variable Deflection Factor

Bandwidth at Upper -3 dB
point (with or without P6010
Probe)

20 mV to 10 VOLTS/DIV
10 mV/DIV
5 mV/DIV

Channels land 2 cascaded

Risetime (calculated). With or

without P6010 Probe.
20 mV to 10 VOLTS/DIV

10 mV/DIV
5 mV/DIV
Channels 1 and 2 cascaded

Performance Requirement

5 millivolts/division to 10 volts/division in 11
calibrated steps for each channel. One millivolt/
division when Channel 1 and 2 are cascaded.

Within ±3Y% of indicated deflection with VARl­ABLE control set to CAL. Cascaded deflection
factor uncalibrated.

Uncalibrated deflection factor at least 2.5 times
the VOLTS/DIV switch indication. This provides
a maximum uncalibrated deflection factor of 25
volts/division in the 10 volts position.

DC to 50 MHz or greater

DC to 45 MHz or greater

DC to 40 MHz or greater

DC to 25 MHz or greater

Less than 7 nanoseconds
Less than 7.8 nanoseconds
Less than 8.75 nanoseconds
Less than 14 nanoseconds

Operational Information

Steps in 1-2-5 sequence

With gain correct at 20 mV

Driven from 25-ohm source

Measured at one millivolt/division

Risetime calculated from bandwidth
measurement using the formula:

Where:

= Risetime in nanoseconds.

t

r

BW = Bandwidth in megahertz.

1-1

TM 11-6625-1722-15

Characteristic

Input RC Characteristics

Maximum lnput Voltage

lnput Coupling Modes

AC Low-Frequency Response

(lower -3 dB point)
Without probe

With P6010 Probe

Trace Shift Due to Input Gate

Current (at 25°C)

Vertical Display Modes

Chopped Repetition Rate

Attenuator Isolation
Common Mode Rejection Ratio

Linear Dynamic Range Useful

for Common-Mode Relection
in ADD Mode

Polarity Inversion
Signal Delay Line

Low-Frequency

Vertical Linearity

Trace Drift (after 20 minute

warm up)
20 mV to 10 VOLTS/DIV

10 mV/DIV

5 mV/DIV

VERTICAL (cont)

Performance Requirement

AC or DC, selected by front-panel switch

Negligible

Channel 1 only
Channel 2 only

Dual-troce, alternate between channels
Dual-trace, chopped between channels
Added algebraically

Approximately one-microsecond segments from
each channel dispiayed at repetition rate of 500

kHz, ±20%.
Greater than 10,000:1, DC to 20 MHz

Greater than 20:1 at 20 MHz for common-mode
signals less than eight times VOLTS/DIV switch
setting.

Signal on Channel 2 can be inverted

Less than 0.15 division compression or expansion

of two division signal when positioned to vertical

extremes of display area

Operational Information

Typically 1 megohm (±2%), paralleled

by 20 pF (±3%)

600 volts DC + peak AC (one kilohertz

or less). Peak-to-peak AC not to exceed
600 volts.

Typicaily 1.6 Hz, Input Coupling switch

set to AC
Typically 0.16 Hz

With optimum GAIN
frequency

Less than 10% incremental signal dis-

tortion for instantaneous input voltage

-10 or +10 times VOLTS/DIV

of
switch setting

Approximately 140 nanoseconds

Includes CRT linearity. Measured with

one-kilohertz square wave.

Time

Typically less than Typically less than

0.03 division/hour

Typically less than

0.05 division/hour

Typically less than

0.08 division/hour

adjustment at low

Temperature

0.0075 division/de­gree C

Typically less than

0.0125 division/de­gree C

Typically less than

0.02 division/de-

gree C

Source

Coupling

Polarity

1-2

TRIGGERING (A AND B SWEEP)

Internal from displayed channel or from Channel

1 only
Internal from AC power source
External
External divide by 10

AC

AC low-frequency reject
AC high-frequency reject

DC

Sweep can be triggered from positive-going or

negative-going portion of trigger signal

TRIGGERING (cont)

TM 11-6625-1722-15

Characteristic

Internal Trigger Sensitivity

AC

LF REJ

HF REJ

DC

External Trigger Sensitivity

AC

LF REJ

HF REJ

DC

Auto Triggering (A sweep only)

Single Sweep (A sweep only)

Display Jitter

Maximum Input Voltage

External Trigger Input RC

Characteristics (approximate)

LEVEL Control Range

Performance Requirement

0.2 division of deflection, minimum, 30 Hz to 10
MHz; increasing to 1 division at 50 MHz

0.2 division of deflection, minimum, 30 Hz to 10

0.2 division of deflection, minimum, 30 kHz to 10

0.2 division of deflection, minimum, 30 Hz to 50
kHz

0.2 division of deflection, minimum, DC to 10
MHz; increasing to 1 division at 50 MHz

50 millivolts, minimum, 30 Hz to 10 MHz; increas­ing to 200 millivolts at 50 MHz

50 millivolts, minimum, 30 kHz to 10 MHz; increas­ing to 200 millivolts at 50 MHz

50 millivolts, minimum, 30 Hz to 50 kHz

50 millivolts, minimum, DC to 10 MHz; increas-

ing to 200 millivolts at 50 MHz
Stable display presented with signal amplitudes

given under Internal and External Trigger Sensi­tivity above 20 Hz. Presents a free-running sweep
for lower frequencies or in absence of trigger
signal.

A Sweep Generator produces only one sweep

when triggered. Further sweeps are locked out

until RESET button is pressed. Trigger sensitivity
same as given above.

Less than 1 nanosecond at 10 nanoseconds/divi­sion sweep rate (MAG switch set to X10)

At least ±2 volts, SOURCE switch in EXT posi­tion. At least ±20 volts, SOURCE switch in EXT

÷10 position

Operational Information

Typical -3 dB point, 16 Hz

Typical -3 dB point, 16 kHz

Typical -3 dB points, 16 Hz and 100
kHz

Typical -3 dB point, 16 Hz

Typical -3 dB point, 16 kHz

Typical -3 dB points, 16 Hz and 100

kHz

600 volts DC + peak AC (one kilohertz

or less). Peak-to-peak AC not to exceed

600 volts.
1 Megohm paralleled by 20 pF, except

in LF REJ

Sweep Rates

A Sweep

B sweep

Sweep Accuracy-A and B

Sweep
5 s to 0.1 s/DIV

50 ms to 0.1 µs/DIV

Variable Sweep Rate

HORIZONTAL DEFLECTION SYSTEM

A and B Sweep Generator

0.1 microsecond/division to 5 seconds/division in

24 calibrated stem

0.1 microsecond/division to 0.5 second/division

in 21 calibrated steps

0°C to +40°C

Within ±3% of indi- Within ±5% of indi-

cated sweep rate

Within ±3% of indi- Within ±4% of indi-

cated sweep rate

Uncalibrated sweep rate to at least 2.5 times the

TIME/DIV indication, or a maximum of at least

12.5 seconds/division in the 5 s position (B sweep,

maximum of 1.25 seconds/division in the .5 s

position.

-15°C to +55°C

cated sweep rate

cated sweep rate

A sweep is main and delaying sweep

B sweep is delayed sweep

A VARIABLE and B TIME/DiV VARl­ABLE controls set to CAL

1-3

TM 11-6625-1722-15

A and B Sweep Generotor

Characteristic

Sweep Length

A sweep

B sweep

Sweep Hold-off-A sweep

5s to 10

Sweep Magnification

Magnified Sweep Accuracy 1% tolerance added to speclfled sweep accuracy
Magnified Sweep Linearity

Normal/Magnified Registration

Calibrated Delay Time Range

DELAY-TIME MULTIPLIER

Dial Range

Delay Time Accuracy

5s to 0.1 s/DIV

50 ms to 1

Incremental Multiplier Linearity
Delay Time Jitter

Variable from less than 4 divisions to 11.0, ±0.5
division

11.0 divisions, ±0.5 division

Less than one times the A TIME/DIV switch set-

ting

Less than 2.5 microseconds

Each sweep rate can be increased 10 times the Extends fastest sweep rate to 10 nano-

indicated sweep rate by horizontally expanding seconds/division
the center division of display

±1.5% for any eight division portion of the
total magnified sweep length (excluding first

and last 60 nanoseconds of magnified sweep)

±0.2 division, or less, trace shift at graticuie
center when switching MAG switch from X10
to OFF

Continuous from 50 seconds to 1 microsecond A VARIABLE control set to CAL for indi-

0.20 to 10.20
0°C to +40°C -15° C to +55° C
Within ±2.5% of indi-

cated delay cated delay Includes incremental multiplier linearity
Within ±1.5% of indi-

cated delay cated delay

±0.2%
Less than 1 part in 20,000 of 10 times A TIME/

DIV switch setting

Performance Requirement

Sweep Magnifier

Sweep Delay

Within ±3.5% of indi-

‘Within ±2% of indi-

±0.3%.

Operational Information

A TIME/DIV switch set to 1 ms

B TIME/DIV switch set to 1 ms

cated delay

Equal to 0.5 division, or less, with the A
TIME/DIV switch set to 1 ms and the B
TIME/DIV switch set to 1

Input to Channel 1 (TRIGGER

switch in CH 1 ONLY)
Deflection factor

Accuracy

X Bandwidth at Upper -3 dB

Point

Input RC characteristics

Phase difference between X

and Y amplifiers at 50 kHz

Input to EXT HORIZ Connector

Deflection factor

1-4

External Horizontal Amplifier

5 millivolts/division to 10 volts/division in 11 cali­brated steps

0°C to +40°C
Within ±5% of indi- Within ±8% of indi-

cated deflection

5 MHz or greater

Less than 3°

B SOURCE switch in EXT; 270 millivolts/division,
±15%.
B SOURCE switch in EXT

±20%

cated deflection

Steps in 1-2-5 sequence.

Channel 1 VARIABLE control does not
affect horizontal deflection

With external horizontal gain correct

at 20 mV

Typically 1 megohm (±2%), paralleled

by 20 pF (±3%)

External Horizontal Amplifier (cont)

X Bandwidth at Upper -3 5 MHz or greater

TM 11-6625-1722-15

Operational Information

—

Input RC characteristics

(approximate]

Phase difference between X

and Y amplifiers at 50kHz

CALIBRATOR

Waveshape
Polarity
Output Voltage

Output Current

Square wave
Positive going with baseline at zero volts

0.1 volt or 1 volt, peak to peak

5-milliamperes through PROBE LOOP on side

Repetition Rate

Voltage Accuracy

.­Current Accuracy
Repetition Rate Accuracy
Risetime
Duty CycIe

±0.5%

Less than 1 microsecond

49% to 51%

Output Resistance

Z AXIS INPUT

Sensitivity

5 volt peak-to-peak signal produces noticeable

modulation
Usable Frequency Range DC to greater than 50 MHz
Input Resistance at DC
Input Coupling DC coupled
Polarity of Operation

1 megohm, paralleled by 20 pF

Less than 3°

Selected by CALIBRATOR switch on side

panel

±1.5%

Approximately 200 ohms in 1 V position.
Approximately 20 ohms in .1 V position.

Approximately 47 kilohms

Positive-going input signal decreases
trace intensity
Negative-going signal increases trace

Maximum Input Voltage

A and B Gate

Waveshape
Amplitude
Polarity
Duration

Output resistance

Vertical Signal Out (CH 1 only)

Output voltage

Bandwidth

Output coupling

Output resistance

OUTPUT SIGNALS

—

Rectangular pulse

Posltlve-going with baseline at about -0.7 volts.

I Same duration as the respective sweep

I

25 millivolts, or greater/division of CRT display
into 1 megohm load.

DC to 25 MHz or greater when cascaded with

Channel 2 or into 50-ohm load.

DC coupled

200 volts combined DC and peak AC

A GATE duration variable between
about 4 and 11 times the A TIME/DIV
switch setting

with the A SWEEP

LENGTH control.
Approximately 1.5 kilohms

Approximately 50 ohms

1-5

TM 11-6625-1722-15

Characteristic

Line Voltage
Voltage Ranges (AC, RMS)

115-volts nominal

230-volts nominal

Line Frequency

Maximum Power Consumption

at 115 Volts, 60 Hz

Tube Type
Phosphor

Accelerating Potential

Graticule

Type

Area

Illumination

Unblinking

Raster Distortion

Trace Finder

POWER SUPPLY

Performance Requirement

115 volts nominal or 230 volts nominal

90 to 110 volts
104 to 126 volts
112 to 136 volts

180 to 220 volts
208 to 252 volts
224 to 272 volts

———
48 to 440 Hz

CATHODE-RAY TUBE (CRT)

I

Internal
Six divisions vertical by 10 divisions horizontal.

Each division equals 0.8 centimeter.

0.1 division or less total

Limits display within graticule area when pressed.

Operational Information

.—

Line voltage and range selected by Line
Voltage Selector assembly on rear
panel. Voltage ranges apply for wave­form distortion which does not reduce
the peak line voltage more than 5%
below the true sine-wave peak value.

92 watts (105 volt-amperes)

Tektronix T4530-31-1 rectangular

P31 standard. Others available on

special order.
Approximately 10 kV total (cathode

potential -1.95 kV).

Variable edge lighting
Bias-type, DC coupled to CRT grid.
Adjustable with Geometry and Y Axis

Align adjustments.

Characteristic

Temperature

Operating

Non-operating

Altitude

Operating

Non-operating

Humidity

Non-operating

Vibration

Operating and
non-operating

Shock

Operating and
non-operating

ENVIRONMENTAL CHARACTERISTICS

The following environmental test limits apply when tested in accordance with the recom­mended test procedure. This instrument will meet the electrical characteristics given in this
section following environmental test.
including failure criteria, etc., may be obtained from Tektronix, Inc. Contact your local
Tektronix Field Office or representative.

Performance Requirement

-15°C to +55°c

-55° to +75°C

15,000 feet maximum

50,000 feet maximum

Five cycles (120 hours) of Mil-Std-202C, Method
106B

15 minutes along each of the three major axes
at a total displacement of 0.025-inch peak to peak
(4 g at 55 c/s) with frequency varied from 10-55­10 c/s in one-minute cycles. Hold at 55 c/s for
three minutes on each axis.

Two shocks of 30 g, one-half sine, 11 millisecond

duration each direction along each major axis.

Complete details on environmental test procedures,

Supplemental Information

Fan at rear circulates air throughout ins­trument.
cutout protects instrument from over­heating.

Derate maximum operating tempera-

ture by 1°C/1000 feet change in altitude
above 5000 feet.

Exclude freezing and vibration

Instrument secured to vibration platform
during test. Total vibration time, about
55 minutes.

Guillotine-type shocks.
Total of 12 shocks

Automatic resetting thermal

1-6

ENVIRONMENTAL CHARACTERISTICS (cont)

TM 11-6625-1722-15

Characteristic

Transportation

Package vibration

Package drop

Type 453
Type R453

MECHANICAL CHARACTERISTICS

Characteristic

Construction

Chassis

Panel

Cabinet
Circuit boards

Overall Dimensions, Type

453 (measured ot maxi­mum points)
Height

Width

Length

Overall Dimensions, Type

R453 (measured at maxi­mum points)

Height

Performance Requirement

Meets National Safe Transit type of test when

packaged as shipped from Tektronix, Inc.
One hour vibration slightly in excess of 1 g.

30-inch drop on any corner, edge or flat surface.

18-inch drop on any corner, edge or flat surface.

Width

Information

Length

Aluminum alloy
Aluminum alloy with ano-

dized finish
Blue vinyl-coated aluminum
Glass-epoxy laminate

Connectors

Z AXIS INPUT
All other connectors

Net Weight

Type 453 (includes front

cover without accessor-

Type R453 (without ac-

handle positioned for carry­ing.

Standard accessories supplied with the Type 453 and R453
are listed on the last pullout page of the Mechanical Parts
List illustrations.

7 inches

Operational Information

Package should just leave vibration sur­face

19 inches

panel;

Binding post
BNC

Approximately 29 pounds.

ies)

Approximately 32 pounds.

cessories)

STANDARD ACCESSORIES

1-7

SECTION 2

OPERATING INSTRUCTIONS

General

O effectively use the Type 453, the operation and capa-

T
bilities of the instrument must be known. This section de­scribes the operation of the front-, side- and rear-panel
controls and connectors, gives first time and general operat­ing information and lists some basic applications for this
instrument.

Front Cover and Handle

The front cover furnished with the Type 453 provides a
dust-tight seal around the front panel. Use the cover to
protect the front panel when storing or transporting the
instrument. The cover also provides storage space for probes
and other accessories (see Fig. 2-1).

TM 11-6625-1722-15

Fig. 2-1. Accessory storage provided in front cover.

The handle af the Type 453 can be positioned for carrying

or as a tilt-stand for the instrument. To position the handle,

press in at both pivot points (see Fig. 2-2) and turn the
handle to the desired position. Several positions are pro­vided for convenient carrying or viewing. The instrument

may also be set an the rear-panel feet for operation or
storage.

Operating Voltage

The Type 453 can be operated from either a 115-volt or

a 230-volt nominal line-voltage source. The Line Voltage

Fig. 2-2. Handle positioned to provide a stand for the instrument

Selector assembly on the rear panel converts the instrument
from one operating range to the other. In addition, this
assembly changes the primary connections of the power
transformer to allow selection of one of three regulating
ranges. The assembly also includes the two line fuses. When
the instrument is converted from 115-volt to 230-volt nominal
operation, or vice versa, the assembly connects or discon­nects one of the fuses to provide the correct protection for
the instrument. Use the following procedure to convert this
instrument between nominal line voltages or regulating
ranges.

1. Disconnect the instrument from the power source.

2. Loosen the two captive screws which hold the cover
onto the voltage selector assembly; then pull to remove the
cover.

3. To convert from 115-volts nominal to 230-volts nomi­nal line voltage, pull out the Voltage Selector switch bar
(see Fig. 2-3]; turn it around 180° and plug it back into the
remaining holes. Change the line-cord power plug to match
the power-source receptacle or use a 115- to 230-volt
adapter.

4. To change regulating ranges, pull out the Range
Selector switch bar (see Fig. 2-3); slide it to the desired
position and plug it back in. Select a range which is cen­tered about the average line voltage to which the instru­ment is to be connected (see Table 2-1).

5. Re-install the cover and tighten the two captive screws.

6. Before applying power to the instrument, check that
the indicating tabs on the switch bars are protruding through
the correct holes for the desired nominal line voltage and

regulating range.

2-1

TM 11-6625-1722-15

Fig. 2-3. Line Voltage Selector assembly on the rear panel (shown
with cover removed).

CAUTION

The Type 453 should not be operated with the
Voltage Selector or Range Selector switches in the

wrong positions for the line voltage applied.
Operation of the instrument with the switches in
the wrong positions may either provide incorrect
aperotion or damage the instrument.

TABLE 2-1

more frequently. The air filter should be cleaned occasion-

ally to aII

OW the maximum amount of cooling air to enter

the instrument. Cleaning instructions are given in Section 4.

The Type 453 can be operated where the ambient air

temperature is between

-15°C and +55°C. Derate the
maximum operating temperature 1°C for each additional
1000 feet of altitude above 5000 feet. This instrument can
be stored in ambient temperatures between –55°C and

+75°C. After storage at temperatures beyond the operating
limits, allow the chassis temperature to come within the
operating limits before power is applied.

Rackmounting

Complete information for mounting the Type R453 in a

cabinet rack is given in Section 10 of this manual.

CONTROLS AND CONNECTORS

A brief description of the function or operation
front-, side- and rear-panel controls and connectors
(see Fig. 2-4). More detailed information is given

of the
follows
in this

section under General Operating Information.

Cathode-Ray Tube

INTENSITY
FOCUS

Controls brightness of display.
Provides adjustment for a well-defined dis-

play.
SCALE ILLUM
TRACE FINDER

Controls graticule illumination.

Compresses display within graticule area

independent of display position or appli-

ed signals.

Operating Temperature

The Type 453 is cooled by air drawn in at the rear and

blown out through holes in the top and bottom covers. Ade­quate clearance on the top, bottom and rear must be pro­vided to allow heat to be dissipated away from the instru-

ment. The clearance provided by the feet at the bottom and

rear should be maintained. If possible, allow about one
inch of clearance on the top. Do not block or restrict the air
flow from the air-escape holes in the cabinet.

A thermal cutout in this instrument provides thermal pro­tection and disconnects the power to the instrument if the
internal temperature exceeds a safe operating level. Opera­tion of the instrument for extended periods without the covers
may cause it to overheat and the thermal cutout to open

Vertical (both

VOLTS/DIV

VARIABLE

UNCAL

POSITION
GAIN

Input Coupling
(AC GND DC)

channels except as noted)

Selects vertical deflection factor (VARl­ABLE control must be in CAL position for
indicated deflection factor).

Provides continuously variable deflection
factor between the calibrated settings of

the VOLTS/DIV switch.
Light indicates that the VARIABLE control

is not in the CAL position.
Controls vertical position of trace.
Screwdriver adjustment to set gain of the

Vertical Preamp. Line between adjust­ment and 20 mV VOLTS/DIV position in­dicates that gain should be set with
VOLTS/DIV switch in this position.

Selects method of coupling input signal
to Vertical Deflection System.

AC: DC component of input signal is

blocked. Low frequency limit -3 dB
point) is about 1.6 hertz.

GND: Input circuit is grounded (does not

ground applied signal).

2-2

TM 11-6625-1722-15

Fig. 2-4. Front-, side- and rear-panel controls and connectors.

2-3

TM 11-6625-1722-15

DC: All components of the input signal are

passed to the Vertical Deflection System.

STEP ATTEN

BAL

INPUT

MODE

TRIGGER

INVERT (CH 2

only)

A and B Triggering (both where applicable)

EXT TRIG

INPUT

SOURCE

Screwdriver adjustment to balance Verti­cal Deflection System in the 5, 10 and 20
mV positions of the VOLTS/DIV switch.

Vertical input connector for signal.
Selects vertical mode of operation.

CH 1: The Channel 1 signal is displayed.
CH 2: The Channel 2 signal is displayed.
ALT: Dual trace display of signal on both

channels. Display switched at end of
each sweep.

CHOP: Dual trace display of signal on

both channels. Approximately one-mi­crosecond segmerlts from each channel
displayed at a repetition rate of about
500 kilohertz.

ADD: Channel 1 and 2 signals are alge-

braically added and the algebraic sum
is displayed on the CRT.

Selects saurce of internal trigger signal
from vertical system.

NORM: Sweep circuits triggered from dis-

played channel(s). Channel 1 signal

available at CH 1 OUT connector.

CH 1 ONLY: Sweep circuits triggered only

from signal applied to the Channel 1

INPUT connector. No signal available
at CH 1 OUT connector. CH 1 lights,
located beside A and B SOURCE switch­es indicate when the TRIGGER switch is
in the CH 1 ONLY position.

Inverts the Channel 2 signal when pulled

out.

Input connector for external trigger signal.
Connector in B Triggering section of front
panel also serves as external horizontal
input when HORIZ DISPLAY switch is in
EXT HORIZ position and B SOURCE switch
is in EXT position.

Selects source of trigger signal.
INT: Internal trigger signal obtained from

Vertical Deflection System. When CH

1 light is on, trigger signal is obtained

only from the Channel 1 input signal;
when the light is off, the trigger signal

is abtained from the displayed chan-

nel(s). Source of internal trigger signal

is selected by the TRIGGER switch.

LINE: Trigger signal obtained from a sam-

ple of the line voltage applied to this

instrument.

EXT: Trigger signal obtained from an ex-

ternal signal applied to the EXT TRIG
INPUT connector.

nal approximately 10 times.

CH 1

COUPLING

SLOPE

LEVEL

HF STAB Decreases display jitter for high-frequency

(A Trigger­ing only) sweep rates.

A and B Sweep

DELAY-TIME

MULTIPLIER

A SWEEP

TRIG’D

UNCAL A

OR B

A AND B

TIME/DIV
AND DELAY
TIME

Light indicates that the internal trigger sig­nal is abtained only from the signal con­nected to the Channel 1 INPUT connector
(see TRIGGER switch).

Determines method of coupling trigger
signal to trigger circuit.

AC: Rejects DC and attenuates signals be-

low about 30 hertz. Accepts signals
between abaut 30 hertz and 50 mega­hertz.

LF REJ: Rejects DC and attenuates signals

below about 30 kilohertz. Accepts sig­nals between about 30 kilohertz and 50
megahertz.

HF REJ: Accepts signals between about 30

hertz and 50 kilohertz; rejects DC and
attenuates signals outside the above
range.

DC: Accepts all trigger signals from DC to

50 megahertz or greater.

Selects portion of trigger signal which

starts the sweep.

+: Sweep can be triggered from positive-

going portion of trigger signal.

-: Sweep can be triggered from negative­going portion of trigger signal.

Selects amplitude point on trigger signal

at which sweep is triggered.

signals. Has negligible effect at lower

Provides variable sweep delay between

0.20 and 10.20 times the delay time indi-

cated by the A TIME/DIV switch.

Light indicates that A sweep is triggered
and will produce a stable display with
correct INTENSITY and POSITION control
settings.

Light indicates that either the A or B

VARIABLE control is not in the CAL posi-

tion.

A TIME/DIV switch (clear plastic flange)

selects the sweep rate of the A sweep

circuit for A sweep only operatian and
selects the basic delay time (to be multi-

plied by DELAY-TIME MULTIPLIER dial
setting) for delayed sweep operation.

B TIME/DIV (DELAYED SWEEP) switch
selects sweep rate of the B sweep circuit

Attenuates external trigger sig-

2-4

TM 11-6625-1722-15

A VARIABLE

B SWEEP

MODE

HORIZ

DISPLAY

MAG

A SWEEP

MODE

for delayed sweep operation only. VARl­ABLE controls must be in CAL positions for
calibrated sweep rates.

Provides continuously variable A sweep
rate to at least 2.5 times setting of the
A TIME/DIV switch. A sweep rate is cali­brated when control is set fully clockwise
to CAL.

Selects B sweep operation mode.
TRIGGERABLE AFTER DELAY TIME: B

sweep circuit will not produce a sweep
until a trigger pulse is received follow­ing the delay time selected by the
DELAY TIME (A TIME/DIV) switch and

the DELAY-TIME MULTIPLIER dial.

B STARTS AFTER DELAY TIME: B sweep

circuit runs immediately following delay
time selected by the DELAY TIME switch

and DELAY-TIME MULTIPLIER dial.
Selects horizontal mode of operation.
A: Horizontal deflection provided by A

sweep.

B sweep inoperative.

A INTEN DURING B: Sweep rate deter-

mined by A TIME/DIV switch. An inten-

sified portion appears on the sweep

during the B sweep time. This position

provides a check of the duration and
position of the delayed sweep (B) with
respect to the delaying sweep (A).

DELAYED SWEEP (B): Sweep rate deter-

mined by B TIME/DIV switch with the
delay time determined by the setting of
the DELAY TIME (A TIME/DIV) switch
and the DELAY-TIME MULTIPLIER dial.
Sweep mode determined by B SWEEP

MODE switch.

EXT HORIZ: Horizontal deflection pro-

vided by an external signal.

Increases sweep rate to ten times setting
of A or B TIME/DIV switch by horizontally
expanding the center division of the dis­play. Light indicates when magnifier is

on.

Determines the operating mode for A
sweep.

AUTO TRIG: Sweep initiated by the ap-

plied trigger signal using the A Trig-

gering controls when the trigger signal
repetition rate is above about 20 hertz.
For lower repetition rates or when there
is no trigger signal, the sweep free runs
at the sweep rate selected by the A
TIME/DIV switch to produce a bright
reference trace.

NORM TRIG: Sweep initiated by the ap-

plied trigger signal using the A Trig-

gering controls. No trace is displayed
when there is no trigger signal.

RESET

A SWEEP

LENGTH

POSITION
FINE

1 kHz CAL
POWER ON

Side Panel
ASTIG

B TiME/DIV­VARIABLE

PROBE LOOP

A GATE

B GATE

CH 1 OUT

SINGLE SWEEP: After a sweep is display-

ed, further sweeps cannot be presented
until the RESET button is pressed. Dis­play is triggered as for NORM opera­tion using the A Triggering controls.

When the RESET button is pressed (SIN­GLE SWEEP mode), a single display will
be presented (with correct triggering) when
the next trigger pulse is received. RESET
light (inside RESET button) remains on
until a trigger is received and the sweep is
completed. RESET button must be pressed
before another sweep can be presented.

Adiusts length of A sweep. In the FULL

position (clockwise detent), the sweep is
about 11 divisions long. As the control is
rotated counterclockwise, the length of A
sweep is reduced until it is less than four
divisions long iust before the detent in
the fully-counterclockwise position is reach­ed. In the B ENDS A position (counter­clockwise detent), the A sweep is reset
at the end of the B sweep to provide the
fastest possible sweep repetition rate for
delayed sweep displays.

Controls horizontal position of trace.
Provides more precise horizontal position

adjustment.
Calibrator output connector.
Light: Indicates that POWER switch is

on and the instrument is connected to
a line voltage source.

Switch: Controls power to the instrument.

Screwdriver adjustment used in conjunc­tion with the FOCUS control to obtain a
well-defined display. Does not require
readjustment in normal use.

Provides continuously variable sweep rate
to at least 2.5 times setting of B TIME/DIV
switch. B sweep rate is calibrated when
control is set fully clockwise to CAL.

Current loop providing five-milliampere
square-wave current from calibrator cir­cuit.

Output connector providing a rectangular

pulse coincident with A sweep.
Output connector providing a rectangular

pulse coincident with B sweep.
Output connector providing a sample of

the signal applied to the Channel 1 lN-

PUT connector when the TRIGGER switch

is in the NORM position.

2-5

TM 11-6625-1722-15

CALIBRATOR

TRACE

ROTATION

Rear Panel

Z AXIS INPUT

Line Voltage

Selector

The following steps will demonstrate the use of the con­trols and connectors of the Type 453. It is recommended
that this procedure be followed completely for familiariza­tion with this instrument.

Setup Information

1. Set the front-panel controls as follows:

CRT Controls

INTENSITY
FOCUS
SCALE ILLUM Counterclockwise

Vertical Controls (both channels if applicable)

VOLTS/DIV 20 mV
VARIABLE
POSITION Midrange

INPUT COUPLING
MODE
TRIGGER

INVERT

Triggering Controls (both A and B if applicable)

LEVEL
SLOPE
COUPLING
SOURCE

Sweep Controls

DELAY-TIME

MULTIPLIER
A and B TIME/DIV
A VARIABLE
B SWEEP MODE

Switch selects output voltoge of Calibrator.

1-volt or 0.1-volt square wave available.

Screwdriver adjustment to align trace with
horizontal graticule lines.

Input connector for intensity modulation
of the CRT display.

Switching assembly to select the nominal
operating voltage and the line voltage
range.
line fuses.

Voltage Selector: Selects nominal operat-

Range Selector: Selects line voltage range

FIRST-TIME OPERATION

The assembly also includes the

ing voltage range (115V or 230V).

(low, medium, high).

Counterclockwise
Midrange

CAL

DC
CH 1
NORM
Pushed in

Clockwise (+)

+

AC

INT

0.20

.5 ms

CAL

B STARTS AFTER

DELAY TIME

HORIZ DISPLAY
MAG
POSITION
A SWEEP LENGTH
A SWEEP MODE
POWER

Side-Panel Controls

B TIME/DIV VARIABLE
CALIBRATOR

2. Connect the Type 453 to a power source that meets
the voltage and frequency requirements of the instrument.
If the available line voltage is outside the limits of the Line
Voltage Selector assembly position (on rear panel), see
Operating Voltage in this section.

3. Set the POWER switch to ON. Allow about five minutes
warmup so the instrument reaches a normal operating tem­perature before proceeding.

CRT Controls

4. Advance the INTENSITY control until the trace is at
the desired viewing level (near midrange).

5. Connect the 1 kHz CAL connector to the Channel 1

INPUT connector with a BNC cable.

6. Turn the A LEVEL control toward 0 until the display

becomes stable. Note that the A SWEEP TRIG’D light is on

when the display is stable.

7. Adiust the FOCUS control for a sharp, well-defined
display over the entire trace length. (If focused display can-

not be obtained, see Astigmatism Adjustment in this section.)

8. Disconnect the input signal and move the trace with
the Channel 1 POSITION control so it coincides with one of
the horizontal graticule lines.
the graticule line, see Trace Alignment Adjustment in this

section.

9. Rotate the SCALE ILLUM control throughout its range
and notice that the graticule lines are illuminated as the

control is turned clockwise (most obvious with mesh or smoke­gray filter installed). Set control so graticule lines are
illuminated as desired.

Vertical Controls

10. Change the CH 1 VOLTS/DIV switch from 20 mV to 5
mV. If the vertical position of the trace shifts, see Step
Attenuator Balance in this section.

11. Set the CH 1 VOLTS/DIV switch to 20 mV and set the
Channel 1 Input Coupling switch to AC. Connect the 1 kHz
CAL connector to both the Channel 1 and 2 INPUT con­nectors with two BNC cables and a BNC T connector.

If the BNC cables and BNC T connector are not

available, make the following changes in the pro­cedure. Place the BNC jack post (supplied ac­cessory) on the 1 kHz CAL connector and connect

A
OFF
Midrange
FULL
AUTO TRIG
OFF

CAL
.1 V

If the trace is not parallel with

NOTE

2-6

TM 11-6625-1722-15

the Channel 1 and 2 INPUT connectors. Connect
the probe tips to the BNC jack post. Set the CALI­BRATOR switch (on side-panel) to 1 V.

12. Turn the Channel 1 POSITION control to center the
display. The display is a square wave, five divisions in
amplitude with about five cycles displayed on the screen. If
the display is not five divisions in amplitude, see Vertical

Gain Adjustment in this section.

13. Set the Channel 1 Input Coupling switch to GND ond

position the trace to the center horizontal line.

14. Set the Channel 1 Input Coupling switch to DC. Note
that the baseline of the waveform remains at the center
horizontal line (ground reference).

15. Set the Channel 1 Input Coupling switch to AC. Note
that the waveform is centered about the center horizontal
line.

16. Turn the Channel 1 VARIABLE control throughout its
range. Note that the UNCAL light comes on when the VARl-

ABLE control is moved from the CAL position (fully clock­wise). The deflection should be reduced to about two divi­sions. Return the VARIABLE control to CAL.

17. Set the MODE switch to CH 2.

18. Turn the Channel 2 POSITION control to center the

display. The display will be similar to the previous display
for Channel 1. Check Channel 2 step attenuator balance and
gain as described in steps 10 through 12. The Channel 2

input Coupling switch and VARIABLE control operate as

described in steps 13 through 16.

19. Set both VOLTS/DIV switches to 50 mV.

20. Set the MODE switch to ALT and position the Channel

1 waveform to the top of the graticule area and the Chan-

nel 2 waveform to the bottom of the graticule area. Turn

the A TIME/DIV switch throughout its range. Note that the
display alternates between channels at all sweep rates.

Triggering

25. Set the CALIBRATOR switch to 1 V. Rotate the A LEVEL
control throughout its range. The display free runs at the
extremes of rotation. Note that the A SWEEP TRIG'D light
is on only when the display is triggered.

26. Set the A SWEEP MODE switch to NORM TRIG. Again
rotate the A LEVEL control throughout its range. A display
is presented only when correctly triggered. The A SWEEP
TRIG'D light operates as in AUTO TRIG. Return the A SWEEP
MODE switch to AUTO TRIG.

27. Set the A SLOPE switch to -. The trace starts on the
negative part of the square wave. Return the switch to +;
the trace starts with the positive part of the square wave.

28. Set the A COUPLING switch to DC. Turn the Chan­nel 1 POSITION control until the display becomes unstable
(only part of square wave visible). Return the A COUPLING

switch to AC; the display is again stable. Since changing

trace position changes DC level, this shows how DC level

changes affect DC trigger coupling. Return the display to

the center of the screen.

29. Set the MODE switch to CH 2; the display should be

stable. Remove the signal connected to Channel 1; the dis-

play free runs.

Set the TRIGGER switch to NORM; the dis-

play is again stable. Note that the CH 1 lights in A and B

Triggering go out when the TRIGGER switch is changed to

NORM.

30. Connect the Calibrator signal to both the Channel 2

INPUT and A EXT TRIG INPUT connectors. Set the A

SOURCE switch to EXT. Operation of the LEVEL, SLOPE
and COUPLING controls for external triggering are the same
as described in steps 25 through 28.

31. Set the A SOURCE switch to EXT
is the same as for EXT. Note that the A LEVEL control has
less range in this position, indicating trigger signal attenua­tion. Return the A SOURCE switch to INT.

32. Operation of the B Triggering controls is similar to
A Triggering.

21. Set the MODE switch to CHOP and the A TIME/DIV
Note the switching between channels as

shown by the segmented trace. Set the TRIGGER switch to

CH 1 ONLY; the trace should appear more solid, since it is
no longer triggered on the between-channel switching trans-

ients. Turn the A TIME/DIV switch throughout its range. A
dual-trace display is presented at all sweep rates, but unlike
ALT, both channels are displayed on each trace on a time­sharing basis. Return the A TIME/DIV switch to .5 ms.

22. Set the MODE switch to ADD. The display should be
four divisions in amplitude. Note that either POSITION con­trol moves the display.

23. Pull the INVERT switch. The display is a straight line
indicating that the algebraic sum of the two signals is zero
(if the Channel 1 and 2 gain is correct).

24. Set either VOLTS/DIV switch to 20 mV. The square-

wave display indicates that the algebraic sum of the two

signals is no longer zero.

Return the MODE switch to CH 1

and both VOLTS/DIV switches to .2 (if using 10X probes,

set both VOLTS/DIV switches to 20 mV). Push in the INVERT
switch.

Normal and Magnified Sweep

33. Set the A TIME/DIV switch to 5 ms and the MAG
switch to X10. The display should be similar to that obtain­ed with the A TIME/DIV switch set to .5 ms and the MAG
switch to OFF.

34. Turn the horizontal POSITION control throughout its
range; it should be possible to position the display across
the complete graticule area. Now turn the FINE control. The

display moves a smaller amount and allows more precise
positioning. Return the A TIME/DIV switch to .5 ms, the

MAG switch to OFF and return the start of the trace to the
left graticule line.

Delayed Sweep

36. Pull the DELAYED SWEEP knob out and turn it to 50

(DELAY TIME remains at .5 ms). Set the HORIZ DISPLAY
switch to A INTEN DURING B. An intensified portion, about
one division in length, should be shown at the start of the
trace. Rotate the DELAY-TIME MULTIPLIER dial throughout
its range; the intensified portion should move along the dis­play.

2-7

TM 11-6625-1722-15

37. Set the B SWEEP MODE switch to TRIGGERABLE

AFTER DELAY TIME. Again rolate the DELAY-TIME MULTI-

PLIER dial throughout its range and note that the intensified
portion appears to jump between posltive slopes of the dis­play. Set the B SLOPE switch to -;
begins on the negative slope.

the intensified portion

Rotate the B LEVEL control;
the intensified portion of the display disappears when the B
LEVEL control is out of the trlggerable range. Return the
B LEVEL control to 0.

38. Set the HORIZ DISPLAY switch to DELAYED SWEEP
(B). Rotate the DELAY-TIME MULTIPLIER dial througout its
range; about one-half cycle of the waveform should be

displayed on the screen (Ieading edge visible only at high

INTENSITY control setting). The display remains stable on
the screen, indicating that the B sweep is triggered.

39. Set the B SWEEP MODE switch to B STARTS AFTER

DELAY TIME. Rotate the DELAY-TIME MULTIPLIER dial

throughout its range; the display moves continously across
the screen as the control is rotated.

40. Rotate the DELAYTIME MIULTIPLIER dial fully counter-

clockwise and set the HORIZ DISPLAY switch to A INTEN

DURING B. Rotate the A SWEEP LENGTH control counter-

clockwise; the Iength of the display decreases. Set the con-

trol to the B ENDS A position; now the display ends after
the intensified portion. Rotate the DELAY-TIME MULTIPLIER
dial ond note that the sweep length increases as the display
moves across the screen. Return the A SWEEP LENGTH con-

trol to FULL and the HORIZ DISPLAY switch to A.

Single Sweep

41. Set the A SWEEP MODE switch to SINGLE SWEEP.
Remove the Calibrator signal from the Channel 2 INPUT
connector. Press the RESET button; the RESET light should
come on and remain on. Again apply the signal to the Chan­nel 2 INPUT connector; a single trace should be presented

and the RESET light should go out. Return the A SWEEP

MODE switch to AUTO TRIG.

External Horizontal

42. Connect the Calibrator signal to both the Channel 2

INPUT and EXT HORIZ (B EXT TRIG lNPUT] connectors. Set

the B SOURCE switch to EXT, B COUPLING switch to DC
and the HORIZ DISPLAY switch to EXT HORIZ. lncrease the

INTENSITY control setting until the display is visible (two dots

displayed diagonally). The display should be five divisions
vertically and about 3.7 divisions horizontally. Set the B

10. The display should be reduced
ten times horizontally. The display can be positioned hori­zontally with the horizontal POSITION or FINE control and
vertically with the Channel 2 POSITION control.

43. Connect the Calibrator signal to both the Channel 1
and 2 INPUT connectors. Set the TRIGGER switch to CH 1
ONLY and the B SOURCE switch to INT.

44. The display should be five divisions vertically and
horizontally.

The display can be postioned horizontally

with the Channel 1 POSITION control and vertically with the

Channel 2 POSITION control.

45. Change the CH1 VOLTS/DIV switch to 5. The display
play is reduced to two divisions horizontally. Now set the
CH 2 VOLTS/DIV switch to 5. The display is reduced to two
divisions vertically.

Trace Finder

46. Set the CH 1 and CH 2 VOLTS/DlV switches to 10

mv. The display i

S not visible since it exceeds the scan area

of the CRT.

47. Press the TRACE FINDER button. Note that the dis­is returned to the display area. While holding the

play
TRACE FINDER button depressed, increase the vertical and
horizontal deflection factors until the display is reduced to
about two divisions vertically ond horizontally. Adjust the
Channel 1 and 2 POSITION controls to center the display

about the center lines of the graticule. Release the TRACE

FINDER and note that the display remains within the viewing
area. Disconnect the applied signal.

48. Reduce the INTENSITY control setting to normal, B
SOURCE switch to INT and set the HORIZ DISPLAY switch
to A.

Z-Axis Input

49. If an, External signal is available (five volts peak to
peak minimum] the function of tlhe Z AXIS INPUT circuit can
be demonstrated. Connect the external signal to both the

Channel 2 INPUT connector and the Z AXIS INPUT binding
posts. Set the A TIME/DIV switch to display about five
cycles of the waveform. The positive peaks of the waveform
should be blanked and the negative peaks intensified, indi-

cating intensify modulation.

50. This completes the basic operating procedure for the

Type 453. lnstrument operation not explained here, or opera­tions which need further explanation are discussed under
General Operating Information.

CONTROL SETUP CHART

Fig. 2-5 shows the front, side and rear panels of the Type

453. This chart can, be reproduced and used as a test-setup
record for special measurements, applications or procedures,
or it may be used as a training aid for familiarization with
this instrument.

GENERAL OPERATING INFORMATION

Intensify Control

The setting of the INTENSITY control may affect the cor­rect focus of the display. Slight readjustment of the FOCUS
control may be necessary when the intensity level is changed.

To protect the CRT phosphor, do not turn the INTENSITY
control higher than necessary to provide a satisfactory dis-

play. The light filters reduce the observed light output from

the CRT. When using these filters, avoid odvancing the

INTENSITY control to a setting that may bum the phosphor.

When Ihe highest intensity display is desired, remove the
filters and use the clear faceplate protector. Also, be care­ful that the INTENSITY control is not set too high when
changing the TIME/DlV switch front a fast to a slow sweep

rate, or when changing the HORIZ DISPLAY switch from EXT
HORIZ operation to the norrmal sweep mode.

Astigmatism Adjustment

If a well-defined trace cannot be obtained with the FOCUS

control, adjust the ASTIG adjustment (side panel) as fol-

lows.

2-8

TM 11-6625-1722-15

Fig. 2-5. Control setup chart for the Type 453.

2-9

TM 11-6625-1722-15

NOTE

To check for proper setting of the ASTIG adjust­ment, slowly turn the FOCUS control through the
optimum setting. If the ASTIG adjustment is cor-

rectly set, the vertical and horizontal portions
of the trace will come into sharpest focus at the
same position of the FOCUS control. This setting
of the ASTIG adjustment should be correct for any
display. However, it may be necessary to reset
the FOCUS control slightly when the INTENSITY
control is changed.

1. Connect a 1 V Calibrator signal to either channel and
set the VOLTS/DIV switch of that channel to present a two­division display. Set the MODE switch to display the chan-

nel selected.

2. Set the TIME/DIV switch to .2 ms

3. With the FOCUS control and ASTIG adjustment set to

midrange, adjust the INTENSITY control so the rising portion

of the display can be seen.

4. Set the ASTIG adjustment so the horizontal and verti­cal portions of the display are equally focused, but not

necessarily well focused.

5. Set the FOCUS control so the vertical portion of the

trace is as thin as possible.

6. Repeat steps 4 and 5 for best overall focus. Make final

check at normal intensity.

Graticule

The graticule of the Type 453 is internally marked on the
faceplate of the CRT to provide accurate, no-parallax meas­urements. The graticule is marked with six vertical and 10
horizontal divisions. Each division is 0.8 centimeter square.
In addition, each major division is divided inta five minor
divisions at the center vertical and horizontal lines. The

vertical gain and horizontal timing are calibrated to the

graticule so accurate measurements can be made from the
CRT. The illumination of the graticule lines can be varied
with the SCALE ILLUM control.

Fig. 2-6 shows the graticule of the Type 453 and defines
the various measurement lines. The terminology defined here
will be used in all discussions involving graticule measure­ments.

Fig. 2-6. Definition of measurement lines on Type 453 graticule.

remove the filter, press

down at the bottom of the frame

and pull the top of the filter away from the CRT faceplate

(see Fig. 2-7).

The tinted light filter minimizes light reflections from the
face of the CRT to improve contrast when viewing the dis­play under high ambient light conditions. A clear plastic
faceplate protector is also provided with this instrument for
use when neither the mesh nor the tinted filter is used. The
clear faceplate protector provides the best display for wave­form photographs. It is also preferable for viewing high
writing rate displays.

A filter or the faceplate protector should be used at all
times ta protect the CRT faceplate from scratches. The face­plate protector and the tinted filter mount in the same holder.

Trace Alignment Adjustment

If a free-running trace is not parallel to the horizontal

graticule lines, set the TRACE ROTATION adjustment as fol-

lows. Position the troce to the center horizontal line. Adjust

the TRACE ROTATION adjustment (side panel) so the trace

is parallel with the horizontal graticule lines.

Light Filter

The mesh filter provided with the Type 453 provides shield­ing against radiated EMI (electro-magnetic interference) from
the face of the CRT. It also serves as a light filter to make
the trace more visible under ambient light conditions. To

2-10

Fig. 2-7. Removing the filter or faceplate protector.

TM 11-6625-1722-15

To remove the light filter or faceplate protector from the

holder, press it out to the rear. They can be replaced by
snapping them back into the holder.

Trace Finder

The TRACE FINDER provides a means af locating a display
which overscans the viewing area either vertically or hori­zontally. When the TRACE FINDER button is pressed, the
display is compressed within the graticule area. T

O locate

and reposition an overscanned display, use the following

procedure.

1. Press the TRACE FINDER button.

2. While the TRACE FINDER button is held depressed,
increase the vertical and horizontal deflection factors until
the vertical deflection is reduced to about two divisions and
the horizontal deflection is reduced to about four divisions
(the horizontal deflection needs to be reduced only when in
the external horizontal mode of operation).

3. Adjust the vertical and horizontal POSITION controls
to center the display about the vertical and horizontal cen-

ter lines.

4. Release the TRACE FINDER button; the display should

remain within the viewing area.

Vertical Channel Selection

Either of the input channels can be used for single-trace
displays. Apply the signal to the desired INPUT connector
and set the MODE switch to display the channel used. How­ever, since CH 1 ONLY triggering is provided only in Chan-

nel 1 and the invert feature only in Channel 2, the correct
channel must be selected to take advantage of these fea­tures. For dual-trace displays, connect the signals to both

INPUT connectors and set the MODE switch to one of the
dual-trace positions.

Vertical Gain Adjustment

To check the gain of either channel, set the VOLTS/DIV

switch to 20 mV. Set the CALIBRATOR switch to .1 V and

connect the 1 kHz CAL connector to the INPUT of the chan-

nel used. The vertical deflection should be exactly five
divisions.

If not, adjust the front-panel GAIN adjustment

for exactly five divisions of deflection.

NOTE

If the gain of the two channels must be closely
matched (such as for ADD mode operation), the
ADJUSTMENT procedure given in the Calibration
section should be used.

The best measurement accuracy when using probes is pro­vided if the GAIN adjustment is made with the probes in­stalled (set the CALIBRATOR switch to 1 V). Also, to provide
the most accurate measurements, calibrate the vertical gain

of the Type 453 at the temperature at which the measurement

is to be made.

Step Attenuator Balance

To check the step attenuator balance of either channel,
set the Input Coupling switch to GND and set the A SWEEP

MODE swich to AUTO TRIG to provide a free-running trace.
Change the VOLTS/DIV switch from 20 mV to 5 mV. If the
trace moves vertically, adjust the front-panel STEP ATTEN

BAL adjustment as follows (allow at least 10 minutes warm
up before performing this adjustment].

1. With the Input Coupling switch set to GND and the

VOLTS/DIV switch set to 20 mV, move the trace to the center

horizontal line of the graticule with the vertical POSITION
control.

2. Set the VOLTS/DIV switch to 5 mV and adjust the
STEP ATTEN BAL adjustment to return the trace to the center
horizonal line.

3. Recheck step attenuator balance and repeat adjustment
until no trace shift occurs as the VOLTS/DIV switch is chang­ed from 20 mV to 5 mV.

Signal Connections

In general, probes offer the most convenient means of con­necting a signal to the input of the Type 453. The Tektronix
probes are shielded to prevent pickup of electrostatic inter­ference. A 10X attenuator probe offers a high input imped­ance and allows the circuit under test to perform very close
to normal operating conditions. However, a 10X probe

also attenuates the input signal 10 times.

The Tektronix
P6045 Field Effect Transistor probe and accessory power
supply offer the same high-input impedance as the 10X
probes. However, it is particularly useful since it provides

wide-band operatian while presenting no attenuation (1X

gain) and a low input capacitance. To obtain maximum
bandwidth when using the probes, observe the grounding
considerations given in the probe manual. The probe-to­connector adapters and the bayonet-ground tip provide the
best frequency response. Remember that a ground strap
only a few inches in length can produce several percent of
ringing when operating at the higher frequency limit of this

system. See your Tektronix, Inc. catalog for characteristics

and compatibility of probes for use with this system.

In high-frequency applications requiring maximum overall
bandwidth, use coaxial cables terminated at both ends in
their characteristic impedance. See the discussion on coax­ial cables in this section for more information.

High-level, low-frequency signals can be connected directly
to the Type 453 INPUT connectors with short unshielded
leads. This coupling method works best for signals below
about one kilohertz and deflection foctors above one volt/
division. When this method is used, establish a common
ground between the Type 453 and the equipment under test.
Attempt to position the leads away from any source of inter­ference to avoid errors in the display. If interference is
excessive with unshielded leads, use a coaxial cable or a
probe.

Loading Effect of the Type 453

As nearly as possible, simulate actual operating condi­tions in the equipment under test. Otherwise, the equipment
under test may not produce a normal signal. The 10X
attenuator probe and field effect transistor probe mentioned
previously offer the least circuit loading. See the probe
instruction manual for loading characteristics of the indivi­dual probes.

2-11

TM 11-6625-1722-15

When the signal is coupled directly to the input of the

Type 453, the input impedance is about one megohm

paralleled by about 20 pF. When the signal is coupled to
the input through a coaxial cable, the effeclive input ca­pacitance depends upon the type and Iength of cable used.
See the following discussion for

inforrnation on obtaining

maximum frequency responspe with coaxial cables.

The signal cables used to connect the signal 10 the type
453 INPUT connectors have a Iarge effect on the accuracy
of the displayed high-frequency waveform.

To maitain the

high-frequency characteristics of the applied signal, high­quality low-loss coaxial cable should be used. The cable
should be terminated at the Type 453 INPUT connector in its
characteristic impedonce.
with differing characteristic impedances,

If it is necessary to use cables

use suitable imped-

ance-matching devices to provide the correct transition, with

minimum loss, from one impedance to the other.

The characteristic impedance, velocity of propagation and
nature of signal lOSSeS in a coaxial cable are determined
by the physical and electrical characteristics of the cable.
Losses caused by energy dissipation in the dielectric are

proportional to the signal frequency. Therefore, much of
the high-frequency information in a fast-rise pulse can be
lost in only a few feet of interconnecting cable if it is not
the correct type. To be sure of the high-frequency response
of the system when using cables longer than about five feet,
observe the transient response of the Type 453 and the

interconnecting cable with a fast-rise

pulse generator (gen-

erator risetime Iess than 0.5 nanoseconds).

DC components. The pre-charging network incorporated
in this unit aII

OWS the input-coupling capacitor to charge to

the DC source voltage level when the Input Coupling switch
is set to GND. The procedure for using this feature is as

follows:

1. Before connecting the signal containing a DC compo­nent to the Type 453 INPUT connector, set the Input Coupling
switch to GND. Then connect the signal to the INPUT
connector.

2. Wait about one second for the coupling capacitor to

charge.

3. Set the Input Coupling switch to AC. The trace (dis­play) will remain on the screen and the AC component of
the signal can be measured in the normal manner.

Deflection Factor

The amount of vertical deflection produced by a signal
is determined by the signal amplitude, the attenuation factor
of the probe (if used), the setting of the VOLTS/DIV switch
and the setting of the VARIABLE VOLTS/DIV control. The

calibrated deflection factors indicated by the VOLTS/DIV
switches apply only when the VARIABLE control is set to
the CAL position.

The VARIABLE VOLTS/DIV control provides variable
(uncalibrated) vertical deflection between the calibrated
settings of the VOLTS/DIV switch. The VARIABLE control

extends the maximum vertical deflection factor of the Type
453 to at least 25 volts/division (10 volts position).

Input Coupling

The Channel 1 and 2 lnput Coupling switches allow a

choice of input caupling. The type of display desired will
determine the coupling used.

The DC position can be used for most applications. How­ever, if the DC component of the signal is much larger than
the AC component, the AC position vvill probably provide a
better display. DC coupling should be used to display AC
signals below about 16 heltz as they will be attenuated in

the AC position.

In the AC position, the DC component of the signal is
blocked by a capacitor in the input circuit. The low-fre­quency response in the AC position is about 1.6 hertz (–3 dB

point). Therefore,

some low-frequency distortion can be
expected near this frequency limit. Distortion will also
appear

in square waves which have low-frequency com-

ponents.

The GND position provides a ground reference at the

input of the Type 453. The signal applied to the input con-

nector is internally disconnected but not grounded. The
input circuit is held at ground potential, eliminating the need
to externally ground the input to establish a DC ground
reference.

The GND position can also be used to pre-charge the
coupling capacitor to the average voltage level of the signal
applied to the INPUT connector. This allows measurement
of only the AC component of signals having both AC and

Dual-Trace Operation

Alternate Mode. The ALT position of the MODE switch

produces a disploy which alternates between Channel 1 and
2 with each sweep of the CRT. Although the ALT mode
can be used at all sweep rates, the CHOP mode provides

a more satisfactory display at sweep rates below about 50

microseconds/division. At these slower sweep rates, alternate
mode switching becomes visually perceptible.

Proper internal triggering in the ALT mode can be ob-

tained in either the NORM or CH 1 ONLY positions of the

TRIGGER switch. When in the NORM position, the sweep is

triggered from the signal on each channel. This provides a
stable display of two unrelated signals, but does not indicate
the time relationship between the signals. In the CH 1 ONLY
position, the two signals are displayed showing true time
relationship. If the signals are not time related, the Channel
2 waveform will be unstable in the CH 1 ONLY position.

Chopped Mode. The CHOP position of the MODE switch

produces a display which is electronically switched between
channels. In general, the CHOP mode provides the best
display at sweep rates slower than about 50 microseconds/
division, or whenever dual-trace, single-shot phenomena are
to be displayed. At faster sweep rates the chopped switch­ing becomes apparent and may interfere with the display.

Proper internal triggering for the CHOP mode is provided
with the TRIGGER switch set to CH 1 ONLY. If the NORM
position is used, the sweep circuits are triggered from the
between-channel switching signal and both waveforms will

2-12

TM 11-6625-1722-15

be unstable. External triggering provides the same result as
CH 1 ONLY triggering.

Two signals which are time-related can be displayed in
the chopped mode showing true time relationship. If the
signals are not time-related, the Channel 2 display will
appear unstable. Two single-shot, transient, or random

signals which occur within the time interval determined by

the TIME/DIV switch (10 times sweep rate) can be compared
using the CHOP mode. To correctly trigger the sweep for
maximum resolution, the Channel 1 signal must precede the

Channel 2 signal. Since the signals show true time relation-

ship, time-difference measurements can be made.

Channel 1 Output and Cascaded Operation

If a lower deflection factor than provided by the VOLTS/
DIV switches is desired, Channel 1 can be used as a wide­band preamplifier for Channel 2. Apply the input signal to
the Channel 1 INPUT connector. Connect a 50-ohm BNC
cable (18-inch or shorter cable for maximum cascaded fre-

quency response) between the CH 1 OUT (side panel) and

the Channel 2 INPUT connectors. Set the MODE switch to
CH 2 and the TRIGGER switch to NORM. With both VOLTS/
DIV switches set to 5 mV, the deflection factor will be less
than one millivolt/division.

To provide calibrated one millivolt/division deflection
factor, connect the .1 volt Calibrator signal to the Channel 1
INPUT connector. Set the CH 1 VOLTS/DIV switch to .1

and the CH 2 VOLTS/DIV switch to 5 mV. Adjust the Chan­nel 2 VARIABLE VOLTS/DIV control to produce a display
exactly five divisions in amplitude. The cascaded deflection
factor is determined by dividing the CH 1 VOLTS/DIV switch
setting by 5 (CH 2 VOLTS/DIV switch and VARIABLE control
remain as set above). For example, with the CH 1 VOLTS/
DIV switch set to 5 mV the calibrated deflection factor will
be 1 millivolt/division; CH 1 VOLTS/DIV switch set to 10 mV,
2 millivolts/division, etc.

The following operating considerations and basic appli-

cations may suggest other uses for this feature.

1. If AC coupling is desired, set the Channel 1 Input
Coupling switch to AC and leave the Channel 2 Input
Coupling switch set to DC. When both Input Coupling
switches are set to DC, DC signal coupling is provided.

2. Keep both vertical POSITION controls set near mid-

range.

one of the POSITION controls being turned away from

midrange, correct operation can be obtained by keeping

the Channel 2 POSITION control near midrange and using

the Channel 1 POSITION control to position the trace near

the desired locatian. Then, use the Channel 2 POSITION
control far exact positioning. This method will keep both

Input Preamps operating in their linear range.

least 25 millivolts/division of CRT display in all CH 1 VOLTS/
DIV switch positions.

DIV control have no effect on the signal available at the
CH 1 OUT connector.

ance matching stage with or without voltage gain. The

If the input signal has a DC level which necessitates

3. The output voltage at the CH 1 OUT connectar is at

4. The MODE switch and Channel 1 VARIABLE VOLTS/

5. The Channel 1 Input Preamp can be used as an imped-

input resistance is one megohm and the output resistance is
about 50 ohms.

6. The dynamic range of the Channel 1 Input Preamp is
equal to about 20 times the CH 1 VOLTS/DIV setting. The
CH 1 OUT signal is nominally at 0 volt DC for a 0 volt DC
input level [Channel 1 POSITION control centered). The
Chanel 1 POSITION control can be used to center the out­put signal within the dynamic range of the amplifier.

7. If dual-trace operation is used, the signal applied to

the Channel 1 INPUT connector is displayed when Channel

1 is turned on. When Channel 2 is turned on, the amplified

signal is displayed. Thus, Channel 1 trace can be used to
monitor the input signal while the amplified signal is dis-

played by Channel 2.

8. In special applications where the flat frequency re-

sponse of the Type 453 is not desired, a filter inserted
between the CH 1 OUT and Channel 2 INPUT connector
allows the oscilloscope to essentially take on the frequency

response of the filter. Combined with method 7, the input can
be monitored by Channel 1 and the filtered signal displayed

by Channel 2.

9. By using Channel 1 as a 5X low-level voltage pre­amplifier (5 mV position), the Channel 1 signal available
at the CH 1 OUT connector can be used for any application

where a low-impedance preamplifier signal is needed.
Remember that if a 50-ohm load impedance is used, the
signal amplitude will be about one-half.

Algebraic Addition

General. The ADD position of the MODE switch can be

used to display the sum or difference of two signals, for
common-mode rejection to remove an undesired signal or for
DC offset (applying a DC voltage to one channel to offset
the DC component of a signal on the other channel).

The common-mode rejection ratio of the Type 453 is
greater than 20:1 at 20 megahertz for signal amplitudes up
to eight times the VOLTS/DIV switch setting. Rejection ratios
of 100:1 can typically be achieved between DC and 5 mega­hertz by careful adjustment of the gain of either channel
while observing the displayed common-mode signal.

Deflection Factor. The overall deflection in the ADD
position of the MODE switch when both VOLTS/DIV switches

are set to the same position is the same as the deflection
factor indicated by either VOLTS/DIV switch. The ampli­tude of an added mode display can be determined directly
from the resultant CRT deflection multiplied by the deflec­tion factor indicated by either VOLTS/DIV switch. How­ever, if the CH 1 and CH 2 VOLTS/DIV switches are set to
different deflection factors, resultant voltage is difficult to
determine from the CRT display. In this case, the voltage
amplitude of the resultant display can be determined accu­rately only if the amplitude of the signal applied to either
channel is known.

Precautions.

be observed when using the ADD mode.

1. Do not exceed the input voltage

453.

The following general

precautions should

rating of the Type

2-13

TM 11-6625-1722-15

2. Do not apply signals that exceed on equivalent of
about 20 times the VOLTS/DIV switch setting. For example,
with a VOLTS/DIV switch setting of .5, the voltage applied
to that channel should not exceed about 10 volts. Larger
voltages may distort the display.

3. Use vertical POSITION control settings which most
nearly position the signal of each channel to mid-screen
when viewed in either the CH 1 or CH 2 positions of the
MODE switch. This insures the greatest dynamic range for
ADD mode operation.

4. For similiar response from each channel, set both Input

Coupling switches to the same position.

Trigger Source

INT. For most applications, the sweep can be triggered

internally. In the INT position of the Triggering SOURCE
switch, the trigger signal is obtained from the Vertical

Deflection System. The TRIGGER switch provides further

selection of the internal trigger signal; obtained from the

Channel 1 signal in the CH 1 ONLY position, or from the
displayed signal when in the NORM position. For single­trace displays of either channel, the NORM position pro­vides the most convenient operation. However, for dual­trace displays special considerations must be made to provide
the correct display. Set Dual-Trace Operation in this section

for dual-trace triggering information.

LINE. The LINE position of the SOURCE switch connects

a sample of the power-line frequency to the Trigger Gen-

erator circuit. Line triggering is useful when the input signal

is time-related to the line frequency. It is also useful for

providing a stable display of a line-frequency component

in a complex waveform.

EXT. An external signal conected to the EXT TRIG INPUT
connector can be used to trigger the sweep in the EXT
position of the Triggering SOURCE switch. The external sig­nal must be time-related to the displayed signal for a stable
display. An external trigger signal can be used to provide
a triggered display when the internal signal is too low in
amplitude for correct triggering, or contains signal com­ponents on which it is not desired to trigger. It is also useful
when signal tracing in amplifiers, phase-shift networks, wave­shaping circuits, etc. The signal from a single point in the
circuit under test can be connected to the EXT TRIG INPUT

connector through a signal probe or cable. The sweep is

then triggered by the same signal at all times and allows
amplitude, time relationship or waveshape changes of
signals at various points in the circuit to be examined with­out resetting the trigger controls.

frequency components of the trigger signal which can trigger
the sweep.

AC. The AC position blocks the DC component of the
trigger signal. Signals with low-frequency components below
about 30 hertz are attenuated. In general, AC coupling can
be used for most applications. However, if the trigger signal
contains unwanted components or if the sweep is to be
triggered at a low repetition rate or a DC level, one of the
remaining COUPLING switch positions will provide a better
display.

The triggering point in the AC position depends on the
average voltage level of the trigger signal. If the trigger
signals occur in a random fashion, the average voltage level
will vary, causing the triggering point to vary also. This shift
of the triggering point may be enough so it is impossible to

maintain a stable display. In such cases, use DC coupling.

LF REJ. In the LF REJ position, DC is rejected and signals

below about 30 kilohertz are attenuated. Therefore, the

sweep will be triggered only by the higher-frequency com-

ponents of the signal. This position is particularly useful

for providing stable triggering if the trigger signal contains

line-frequency components. Also, in the ALT position of the
MODE switch, the LF REJ position provides the best display

at high sweep rates when comparing two unrelated signals

(TRIGGER switch set to NORM).

HF REJ. The HF REJ position passes all low-frequency
signals between about 30 hertz and 50 kilohertz. DC is
rejected and signals outside the given range are attenuated.
When triggering from complex waveforms, this position is
useful for providing stable display of low-frequency compo­nents.

DC. DC coupling can be used to provide stable triggering
with low-frequency signals which would be attenuated in
the AC position, or with low-repetition rate signals. The
LEVEL control can be adjusted to provide triggering at the
desired DC level on the waveform. When using internal
triggering, the setting of the Channel 1 and 2 POSITION
controls affects the DC trigger level.

DC trigger coupling should not be used in the ALT dual­trace mode if the TRIGGER switch is set to NORM. If used,
the sweep will trigger on the DC level of one trace and then
either lock out completely or free run on the other trace.
Correct DC triggering for this mode can be obtained with
the TRIGGER switch set to CH 1 ONLY.

Trigger Slope

same as described for EXT except that the external triggering
signal is attenuated 10 times. Attenuation of high-amplitude
external triggering signals is desirable to broaden the range
of the Triggering LEVEL control.
switch is set to LF REJ, attenuation is about 20:1.

Trigger Coupling

Four methods of coupling the
circuits can be selected with
switches. Each position permits

2-14

When the COUPLING

trigger signal to the trigger

the Triggering COUPLING

selection or rejection of the

The triggering SLOPE switch determines whether the trigger
circuit responds on the positive-going or negative-going
portion of the trigger signal. When the SLOPE switch is in
the + (positive-going) position, the display starts with the
positive-going portion of the waveform; in the - (negative­going) position, the display starts with the negative-going

portion of the waveform (see Fig. 2-8]. When several cycles
of a signal appear in the display, the setting of the SLOPE
switch is often unimportant. However, if only a certain

portion of a cycle is to be displayed, correct setting of the
SLOPE switch is important to provide a display which starts
on the desired slope of the input signal.