HP 1821A User manual

HP
1821A
TIME BASE AND
DELAY GENERATDR
1821A
0OI'
000
HEWLETT hp PACKARD
HP
1821A

CERTIFICATION
The Heivlett-Packard Company certifies that this instrument was
thoroughly tested and inspected and found to meet its published
specifications ivhen it was shipped from the factory. The Hewlett-
Packard Company further certifies that its calibration measure-
ments are traceable to the U.S. National Bureau of Stayidards to
the extent allowed by the Bureau’s calibration facility.
WARRANTY AND ASSISTANCE
All Hewlett-Packard products are warranted against defects in
materials and workmanship. This warranty applies for one year
from the date of delivery, or, in the case of certain major compo-
nents listed in the operating manual, for the specified period. We
will repair or replace products which prove to be defective during
the warranty period provided they are returned to Hewlett-
Packard. No other warranty is expressed or implied. We are not
liable for consequential damages.
Service contracts or customer assistance agreements are available
for Hewlett-Packard products that require maintenance and re-
pair on-site.
For any assistance, contact your nearest Hewlett-Packard Sales and
Service Office. Addresses are provided at the back of this manual.

^MANUAL CHANGES
MODEL 1821A
TIME BASE AND DELAY GENERATOR
Manual Serials Prefixed: 809-
Manual Printed: JUNE 1968
Make all changes in this manual according to the Errata below. Also check the following table for your
instrument serial prefix (3 digits) and/or serial number (8 digits) and make any listed change(s) in the manual:
Serial Prefix or Number Make Manual Changes Serial Prefix or Number Make Manual Changes
ERRATA Table 6-2, Replaceable Parts,
A3: Change description to A: sweep time (inci A2 and A4).
Add A4: HP Part No. 01821-61905; TO 1; A: sweep time switch.
C501: Change to HP Part No. 01 60-3355; TO 1; C: fxd poly 1uF
5% 200 vdcw (preferred replacement).
AC504, C526: Change to HP Part No. 0160-3540; TQ 2; C: fxd poly 0.001 uF5% 100 vdcw
(preferred replacement).
AC503, C525; Change to HP Part No. 0160-3541; TQ 2; C: fxd poly 0.01 uF 5% 100 vdcw
(preferred replacement).
AC502, C524; Change to HP Part No. 0160-3542; TQ 2; C: fxd poly 0.01 uF 5% 100 vdcw
(preferred replacement).
LI 02, LI 03, LI 07, L1 10. L201, L302, L305, L306: Change to HP Part No. 9140-0179;
TQ 8; L; fxd 22 uh 10% (Preferred Replacement).
Q412: Change to HP Part No. 5080-0482; Q: Si fet (selected)
(Preferred Replacement).
MISCELLANEQUS;
HP Part No. 01821-01204: Change to Bracket: plug (P2).
HP Part No. 01821-04101 :Change to Plate: mounting (J1).
Page 8-5, Figure 8-4,
L102, L103, L107, L1 10: Change value to 22 uh.
Page 8-7, Figure 8-6,
L201 :Change value to 22 uh.
Page 8-9, Figure 8-7,
L302, L305, L306: Change value to 22 uh.
CHANGE 1Table 6-2, Replaceable Parts,
VR201,VR403: Change to HP Part No. 1902-0688; VR: breakdown, 53.6V.
Page 8-7, Figure 8-6, Schematic,
VR201: Change to 53.6V.
Page 8-11, Figure 8-8, Schematic,
VR403: Change to 53.6V.
Page 8-14, Figure 8-11,
J1: Move -1-1 5V power from pin 21 to pin 20.
CHANGE 2Table 6-2, Replaceable Parts,
Add C108, C304: HP Part No. 0140-0149; TQ 2; C: fxd mica 470 pF 5% 300 vdcw.
Q101: Change to HP Part No. 1854-0215.
R113: Change TQ to 6.
R114, R305: Change to HP Part No. 0757-0442; TQ 6; R: fxd metfim 10 kohms 1% 1/8W,
11 December 1969 R1 40: Delete TQ.
A=Latest additions to this change sheet.
This change sheet supersedes all prior change sheets for this manual. Supplement Afor
01821-90904

Model 1821 APage 2/2
Instrument Serial Prefix Make Manual Changes Instrument Serial Prefix Make Manual Changes
809-03295 &higher 11
821- 11
905- 1,2 1
907- 1,2,3
CHANGE 2(Cont'd) Page 8-5, Figure 8-4, schematic.
Add C108, 470 pf, on S102 between ACS position and ground (next to R1 13).
R1 14: Change value to 10 kohms.
Page 8-9, Figure 8-7, schematic.
Add C304, 470 pf, on S302 between ACS poistion and ground (next to R304).
R305; Change value to 10 kohms.
CHANGE 3Table 6-2, Replaceable Parts,
R103, R301 :Change to hp Part No. 0698-6400; TQ2; R: fxd metfim 900 kohms 1% 1/4 w.

OPERATING AND SERVICE MANUAL
MODEL 1821A
TIME BASE AND DELAY GENERATOR
SERIALS PREFIXED: 809
See Section VII For Instruments
With Other Prefixes
Copyright HEWLETT-PACKARD COMPANY/ CO LOR ADO SPRINGS DIVISION 1966
1900 GARDEN OF THE GODS ROAD, COLORADO SPRINGS, COLORADO, U. S. A.
02591-4 PRINTED: JUNE 1968

Table of Contents Model 1821A
TABLE OF CONTENTS
Section Page
IGENERAL INFORMATION 1-1
1-1. Instrument Description 1-1
1-5. Scope of Manual 1-1
1-7. Instrument Identification •••1-1
1-
9. Manual Changes 1-1
II INSTALLATION 2-1
2-
1. Initial Inspection 2-1
2-4. Claims 2-1
2-7. Repackaging for Shipment •••2-1
2-
10. Preparation for Use 2-1
ni OPERATION 3-1
3-
1. Introduction 3-1
3-3. Controls and Connectors ••••3-1
3-16. Trigger Signal Requirements ••3-2
3-
18. Operating Instructions 3-2
IV PRINCIPALS OF OPERATION 4-1
4-
1. Introduction 4-1
4-6. Main Sweep 4-1
4-8. Block Diagram Description •4-1
4-13. Circuit Details 4-2
4-26. Delayed Sweep 4-3
4-28. Block Diagram Description •4-3
4-32. Circuit Details 4-3
4-
39. Sweep Display 4-4
VPERFORMANCE CHECK AND
ADJUSTMENTS 5-1
5-
1. Introduction 5-1
5-3. Test Equipment 5-1
5-5. Performance Check 5-1
5-9. Preliminary Set-Up 5-1
5-11. Initial Control Setting .... 5-1
5-12. Triggering 5-1
5-13. Trigger Point and Slope •••5-2
5-14. Main Sweep Time 5-2
Section Page
5-15. Main Sweep Vernier 5-2
5-16. Magnified Sweep 5-2
5-17. Delayed Sweep Time 5-2
5-18. Delayed Sweep Vernier • • •5-3
5-19. Delay Time Accuracy ••••5-3
5-20. Delay Time Linearity •• ••5-3
5-21. Jitter 5-3
5-22. Delayed Trigger Output . . .5-3
5-23. Mixed Sweep 5-3
5-24. Single Sweep 5-3
5-25. Adjustments 5-3
5-27. Preliminary 5-3
5-29. Initial Control Settings •... 5-3
5-30. Output Level 5-4
5-31. Trigger Symmetry 5-4
5-32. Main Sweep Length 5-4
5-33. Delayed Sweep Length .... 5-4
5-34. Main Sweep Time 5-4
5-35. Delayed Sweep Time 5-4
5-36. Sweep Comparator •• • •5-5/5-6
VI REPLACEABLE PARTS 6-1
6-1. Introduction 6-1
6-4. Ordering Information 6-1
VII manual changes and options •••7-1
7-1. Manual Changes 7-1
7-5. Options
7-7. Special Instruments 7-1
VIII SCHEMATICS AND TROUBLESHOOTING 8-1
8-1. Introduction .8-1
8-3. Schematic Diagrams .... .8-1
8-6. Component Identification • • .8-1
8-8. Troubleshooting .8-1
8-12. Repair and Replacement •••8-1
11 02591-2

Model 1821A List of Illustrations
List of Tables
LIST OF ILLUSTRATIONS
Number Title Page
1-1. Model 1821A Time Base and
Delay Generator 1-0
1-
2. Sweep Combinations 1-2/2-0
2-
1. Plug-In Mating 1-2/2-0
3-
1. Controls and Connectors 3-0
3-2. Trigger Amplitude Requirements •••3-2
3-3. Main Sweep Operation 3-3
3-4. Mixed Sweep Operation 3-4
3-5. Rise Time Measurements 3-5
3-6. Time Differential Measurements •••3-6
3-
7. Single Sweep Operation and Intensity
Ratio Adjustment 3-7
4-
1. Model 1821ABlock Diagram 4-0
4-2. Main Sweep Circuit Block Diagram •••4-1
4-3. Delayed Sweep Circuit Block Diagram •4-4
4-4. Sweep Displays 4-5
Number Title Page
5-1. Main Triggering Test Set-Up 5-1
5-2. Delayed Triggering Test Set-Up •••5-2
7-
1. Sweep Display Switch 7-0
8-
1. Over -All Troubleshooting Tree 8-3
8-2. Adjustment Location and Component
Identification 8-3
8-3. Component Identification, A1 8-4
8-4. Main Trigger Schematic Diagram •••8-5
8-5. Component Identification, A2 8-6
8-6. Main Sweep Schematic Diagram ••8-7
8-7. Delayed Trigger Schematic Diagram ••8-9
8-8. Delayed Sweep Schematic Diagram •••8-11
8-9. Component Identification, A3 8-12
8-10. Sweep Time Switch Schematic Diagram 8-13
8-11. Plug and Jack connections 8-14
LIST OF
Number Title Page
1-
1. Specifications 1-0
2-
1. Shipping Test Strengths 2-1
3-
1. Trigger Signal Requirements 3-2
5-1. Required Test Equipment 5-0
5-2. Main Sweep Performance 5-2
5-3. Delayed Sweep Performance 5-3
TABLES
Number Title Page
5-4. Main Sweep Time 5-4
5-
5. Delayed Sweep Time 5-4
Performance Check Record .... 5-7/5-8
6-
1. List of Reference Designators and
Abbreviations 6-1
6-2. Replaceable Parts 6-2
8-1. Schematic Diagram Notes 8-2
111
02591-3

Section I
Figure 1-1 and Table 1-1 Model 182 lA
Figure 1-1. Model 182 lA Time Base and Delay Generator
Table 1-1. Specifications
MAIN SWEEP:
RANGE:
0. 1psec/divto 1sec/div, 22 ranges in a1, 2,
5sequence; accuracy ±3%; vernier provides
continuous adjustment between ranges and ex-
tends slowest range to at least 2. 5sec/div;
Horizontal Magnifier, on Model 180- series
Oscilloscopes, expands fastest range to 20
nsec/div (X5) or 10 nsec/div (XIO) with 5%
accuracy.
TRIGGERING:
NORMAL:
Triggering Coupling: DC, AC, ACF, ACS:
AC attenuates signals below approximately
20 Hz; ACF attenuates signals below approxi-
mately 15 kHz; ACS attenuates signals above
approximately 30 kHz.
Internal: see manual for Vertical Plug-In.
External: 0. 5vpk-pkfrom dc to 50 MHz
(depending on Trigger Coupling) increas-
ing to 1Vpk-pk at 90 MHz.
Line: power-line waveform is used for
triggering.
Slope: selectable, positive or negative.
Trigger Point: adjustable ±3 vover selected
trigger signal (±30 vin EXT 10).
AUTOMATIC:
Bright baseline displayed in absence of trig-
jger signal. Triggering is same as normal
except that lower frequency limit of trigger
signal is 40 Hz.
DELAYED SWEEP:
RANGE:
0. 1psec/div to 50 msec/div, 18 ranges in a
1, 2, 5sequence: accuracy ±3%; vernier pro-
vides continuous adjustment between ranges
and extends slowest range to at least 125
msec/div; Horizontal Magnifier, onModel 180-
series Oscilloscopes, expands fastest range to
20 nsec/div (X5)or 10 nsec/div (XIO) with 5%
accuracy.
TRIGGERING:
AUTOMATIC:
Delayed sweep starts automatically at end
of delay time. Slope, Trigger Point and
Trigger Coupling are not selectable.
NORMAL:
Delayed sweep starts on first trigger signal
after delay time.
Trigger Coupling: DC, AC, ACF, ACS:
AC attenuates signals below approximately
20 Hz; ACF attenuates signals below approxi-
mately 15 kHz; ACS attenuates signals above
approximately 30 kHz.
Internal: see manual for Vertical Plug-In.
1-0 02591-3

Model 1821A Section I
Paragraphs 1-1 to 1-10
SECTION I
GENERAL INFORMATION
1-1. INSTRUMENT DESCRIPTION.
1-2. The Hewlett-Packard Model 1821A Time Base
And Delay Generator (shown in Figure l-l)isasweep
generating plug-in unit for the hp Model 180-series Os-
cilloscope. Main sweep speeds are selectable in 22
ranges from 0. 1p,sec/ divto 1sec/div. Avernier pro-
vides continuous adjustment between ranges and will
extend the slowest sweep to at least 2. 5sec/div. The
Magnifier switch on Model 180-series Oscilloscopes
can expand the fastest sweep to 10 nsec/div. Delayed
sweep speeds can be selected with 18 ranges from 0. 1
(isec/ div to 50 msec/div; the delayed vernier provides
continuous adjustment between ranges and extends the
slowest sweep speed to at least 125 msec/div. The
main and delayed sweeps can be used either separately
or combined to obtain adual sweep-speed display.
1-3. The delayed sweep feature of the Model 1821A
permits accurate time measurement between arefer-
ence signal and apoint of interest on acomplex wave-
form or pulse train; it also allows for exact time inter-
val measurement between consecutive pulses in apulse
train or burst. The length of time before the delayed
sweep starts is adjustable. The mixed sweep feature
permits viewing simultaneously the character of an
entire complex waveform and an expanded portion of
the same waveform.
1-4. Single sweep operation is possible for any type
of display. This feature may be used with any sweep
speed to facilitate transient waveform photography.
Normal triggering of the Model 1821A main sweep and
delayed sweep may ^e selected to occur on an internal
signal from the verticalplug-inor on an external sig-
nal up to 90 MHz (requires 0. 5v pk-pk up to 50 MHz,
increasing to Iv at 90 MHz). For the main sweep,
automatic triggering provides abright base line in the
absence of an input signal; for the delayed sweep, auto-
matic triggering starts this sweep at the end of the de-
layed period set. Trigger slope level, and coupling
are controlled from the front panel for both the main
and delayed sweeps. Table 1-1 provides complete
specifications for the Model 1821A and Figure 1-2
illustrates typical displays obtainable with the plug-in.
1-5. SCOPE OF MANUAL.
1-6. This manual provides operating and service in-
formation for the hp Model 1821A Time Base AndDe-
lay Generator. This manual supplements the infor-
mation presented in the Operating and Service Manual
for the hp Model 180-sefies Oscilloscope. For specific
information about any plug- in for the Model 180- series
Oscilloscope, refer to the manual for that plug-in.
1-7. INSTRUMENT IDENTIFICATION.
1-8. Hewlett-Packard uses atwo-section eight-digit
serial number to identify instruments. Thefirstthree
digits (preceding the dash) are the serial prefix which
identifies aseries of instruments; the last five digits
identify aparticular instrument in the series. The
serial number appears on aplate located on the rear
panel. All correspondence with aHewlett- Packard
Sales/Service Office in regard to an instrument should
reference the complete serial number.
1-9. MANUAL CHANGES.
1-10. This manual provides complete information for
any Model 1821A with aserial number prefixed (see
Paragraph 1-7) by the three digits indicated on the title
page. If the serial prefix of the instrument is differ-
ent from that on the title page, a"Manual Changes"
sheet supplied, or Section VH of this manual, will de-
scribe changes which willadapt this manual to provide
correct coverage. Technical corrections (if any) to
this manual, due to known errors in print, are called
Errata and are shown on the change sheet. For in-
formation on manual coverage of any hp instrument,
contact the nearest hp Sales/Service Office (addresses
are listed at the rear of this manual).
Table 1-1. Specifications (Cont'd)
External: 0. 5vpk-pkfrom DC to 50 MHz
(depending on Trigger Coupling) increas-
ing to 1vpk-pk at 90 MHz.
Slope: selectable, positive or negative.
Trigger Point: adjustable ±3vover selected
trigger signal (±30 vin EXT 10).
DELAY:
Time: continuously variable from 0. 1psecto
10 sec; accuracy ±1%; linearity ±0.2%; time
jitter is less than 0. 005% of maximum delay of
each range (1 part in 20, 000).
Trigger Output (at end of delay time): approxi-
mately 1. 5Vpulse with rise time less than 50
nsec from Ik ohm impedance.
MIXED SWEEP:
Dual sweep display in which main sweep drives
first portion of display and delayed sweep com-
pletes display at speeds up to 1, 000 times faster.
INTENSIFIED SWEEP:
The intensified section of the main sweep shows
the time of the delayed sweep. It indicates the
portion of the main sweep to be expanded full
screen in delayed operation.
SINGLE SWEEP:
Frontpanel controls permit single sweep operation.
WEIGHT:
Net, 3-3/4 lbs (1,7 kg). Ship, 6-l/41bs(2, 8kg).
02591-3 1-1

Sections Iand II
Figures 1-2 and 2-1 Model 1821A
Figure 1-2. Waveforms illustrating sweep combinations using Model 1821A: (A) normal sweep; (B) intensified
sweep portion covered by delayed sweep is brightened); (C) delayed sweep (intensified portion of Bis expanded
to full 10 div); (D) mixed sweep (faster delayed sweep drives right portion of display).
PLUG JACK LATCH RELEASE
MiH w*o Ootuwe
mmt/ rim/m amm
VERTICAL
PLUG-IN
BULKHEAD
CONNECTORS LATCH HORIZONTAL
PLUG-IN
I80IA-A-IIB
Figure 2-1. Plug-In Mating
1-2
2-0 02591-3

Model 1821A Section II
Paragraphs 2-1 to 2-12
SECTION II
INSTALLATION
2-1. INITIAL INSPECTION.
2-2. MECHANICAL CHECK. Check the shipping
carton for damage immediately after receipt. If it is
damaged, ask the carrier's agent to be present when
the instrument is unpacked. Inspect the Model 1821A
for physical damage such as bent or broken parts and
dents or scratches. If damage is found, refer to Para-
graph 2-4 for the recommended claim procedure. If
the Model 1821Aappears undamaged perform the elec-
trical check (Paragraph 2-3). Retain the packaging
material for possible future use.
2-3. ELECTRICAL CHECK. The performance check
is given in Paragraphs 5-5 through 5-24. This check
will determine whether or not the instrument is still
operating within its specifications as listed in Table 1-1.
The initial performance and accuracy of this instrument
are certified as stated on the inside front cover of this
manual. If theModel 1821A does not operate as spec-
ified, refer to Paragraph 2-4 for the recommended
claim procedure.
2-4. CLAIMS.
2-5. If physical damage is found or if the instrument
does not operate within specifications, notify the car-
rier and the nearest Hewlett-Packard Sales Service
Office immediately. The Safts/Service Office will
arrange for the repair or replacement of the instru-
ment without waiting for aclaim to be settled with the
carrier.
2-6. The warranty statementfor allHewlett-Packard
products is on the inside front cover of this manual.
Contact the nearest Sales/Service Office for informa-
tion about warranty claims.
2-7. REPACKAGING FOR SHIPMENT.
2-8. If the instrument is to be shipped to aHewlett-
Packard Sales /Service Office, attach atag to it show-
ing owner and owner's address, instrument's model
number and 8digit serial number, and adescription
of the services required.
2-9. The original shipping carton and packaging
materials, except for the accordion-pleated pads,
should be used for reshipment. If they are not avail-
able or reusable, the instrument should be repackaged
with the following materials:
a. Adouble walled carton (refer to Table 2-1 for
test strength required).
b. Heavy paper or sheets of cardboard to protect
all instrument surfaces (use anonabrasive material
such as polyurethane or acushioned paper such as
Kimpak around all projecting parts).
c. At least 4inches of tightly packed, industry ap-
proved, shock absorbing material, such as extra firm
polyurethane foam.
d. Heavy duty shipping tape to secure outside of
carton.
Table 2-1. Shipping Carton Test Strengths
Gross Weight (lbs) Carton Test Strength (lbs)
up to 10 200
10 to 30 275
30 to 120 350
120 to 140 500
140 to 160 600
2-10. PREPARATION FOR USE.
2-11. The Model 1821A and the Vertical Plug-In are
locked together and inserted as a unit, into the plug-
in compartment of the Model 180-series Oscilloscope.
This procedure is explained below. Power for the
Model 1821A is supplied by the Oscilloscope.
2-12. Install plug-ins as follows:
a. Move locking bar to rear (see Figure 2-1).
b. Fit vertical plug into horizontal jack (make
certain that bulkhead connectors are aligned) and
press plug-ins firmly together.
c. After ensuring that front and rear panels are
aligned, push locking bar forward.
d. Lift the latch release and rotate latch downward.
Insertplug-ins into the Model 180-series Oscilloscope.
e. Rotate latch upward and push forward to lock.
02591-2 2-1

Section III
Figure 3-1 Model 18 21
A
MAIN 0
TRIGGER
LEVEL
TIME/DIV/
^2>50 20^
5f10
SWEEP MODE
NORM AUTO SINGLE
oDELAYED
O
TRIGGER
LEVEL
O
DEWy^(D)V) INT AUTO EXT EXT410
-SLOPE +%-SLOPE +
ACS ACE AC DC W#,,,, ACS ACF AC DC
9<K,-\ OEL-D
\tbig
,ZM/ cVlTPUT
182IA Tine BASE AND DELAY GENERATOR HEWLETT •PACKARD
I82IA- A- 6B
1. Sweep Display. Determines which sweep is
displayed; main, delayed, or combination.
2. TIME/DIV (main). Selects the time represented
by each horizontal centimeter when displaying
the main sweep.
3. VERNIER (main). Adjusts time/div of main
sweep between calibrated positions of the Main
TIME/DIV switch.
4. Trigger Source (main). Selects source of Trig-
ger Signal that starts main sweep.
5. EXT INPUT (main). Connector for applying an
external trigger signal.
6. Trigger Coupling (main). Selects type of trig-
ger signal coupling.
7. SLOPE (main). Determines which slope of
trigger signal starts main sweep.
8. TRIGGER LEVEL (main). Selects point on
trigger signal waveform that starts main sweep.
9. SWEEP MODE (main). Selects type of main
sweep operation.
10. RESET (main). Arms circuit (lamp lights) so
that next trigger will start asingle sweep.
11. DELAY (DIV). Adjusts time between start of
main sweep and arming of delayed sweep circuits.
12. DEL'D TRIG OUTPUT. Connector for applying
positive trigger to external equipment. Trigger
occurs when delayed sweep circuit is armed.
13. INTE NS RATIO. Adjusts the intensity differ-
ence between the normal main sweep and its
intensified section.
Figure 3-1. Controls and Connectors
3-0 02591-3

Model 182 lA Section III
Paragraphs 3-1 to 3-13
SECTION III
OPERATION
3-1. INTRODUCTION.
3-2. The Model 182 lA produces two linear sweeps
for use as time bases in the Model 180-series Oscil-
loscope. The delayed sweep circuit is armed by the
main sweep after an adjustable delay period. Control
settings determine whether the delayed sweep is auto-
matically triggered immediately after the delay, or if
it is triggered by the next input signal. Waveforms
may be viewed on either time base alone, or on both
time bases combined.
3-3. CONTROLS AND CONNECTORS.
3-4. Locations of controls and connectors are shown
in Figure 3-1 along with abrief description of their
functions. Controls that perform the same function
for both main and delayed sweeps are explained for
main sweep only. The following paragraphs explain
some control functions in more detail.
3-5. SWEEP DISPLAY. The three positions of this
switch are MAIN, MIXED, and DELAYED. The dis-
play obtained in each position is explained below.
a. MAIN. The vertical input signal is displayed
on atime base as set by the Main TIME/DIV control.
With the Delayed TIME/DIV switch set to OFF the en-
tire main sweep display will be of normal intensity.
Any other setting of the Delayed TIME/DIV control will
cause the main sweep to be intensified during the time
the delayed sweep is produced (providing the delayed
sweep is properly triggered).
b. MIXED. In this mode the first part of the pres-
entation is displayed on atime base set by the Main
TIME/DIV switch. The last part of the presentation
is displayed on atime base set by the Delayed TIME/
DIV switch. The delay between the start of the main
sweep and the start of the delayed sweep is determined
in part by DELAY (DIV).
c. DELAYED. The portion of the presentation that
was intensified in MAIN is now displayed on atime
base that is set by the Delayed TIME/DIVcontrol.
3-6. TIME/DIV. The Main and Delayed TIME/DIV
switches determine the time that it takes the main and
delayed sweeps to move one division. The switches
are concentric and interlocked so that the delayed sweep
will always be faster than the main sweep. The Main
TIME/DIV switch can select sweep speeds from 1sec/
div to 0.1 psec/div. The Delayed TIME/DIV switch
can select sweep speeds from 50 msec/div to 0.1
psec/div. The selected main and delayed sweep
speeds may be increased five or ten times by position-
ing MAGNIFIER on the Model 180-series Oscilloscope
to X5 or XIO respectively. The Delayed TIME /DIV
switch should be positioned to OFF to view amain
sweep display of normal intensity.
3-7. VERNIER The Main and Delayed VERNIER
controls provide continuous adjustment of sweep time
between the calibrated steps of their respective
TIME/DIV switches. When the VERNIER control is
settoCAL (fully cw) sweep time can be read directly
from its TIME/DIV switch. As VERNIER is rotated ccw,
the selected TIME/DIV increases. With VERNIER
fully ccw, the TIME/dIV is approximately 2.5 times
greater than the indicated TIME/DIV.
3-8. SWEEP MODE. This lever switch determines
the type of main sweep triggering. The AUTO position
allows the main sweep to free run, providing abright
baseline, in the absence of atrigger signal. Atrigger
signal will override the auto circuit if its frequency is
40 Hz or greater. NORM should be used if the trig-
ger frequency is less than 40 Hz or if triggering is
erratic. NORM, however, will not provide abase-
line in the absence of atrigger. Selecting SINGLE
allow sthe main sweep circuit to be triggered only once.
The sweep circuit must be rearmed manually, by de-
pressing RESET, to be triggered again.
3-9. DELAY (DIV). This control adjusts the delay be-
tween the start of the main sweep and the arming of
the delayed sweep. The delay time is the product of
the DELAY (DIV) setting and the Main TIME/DIV setting.
Note
Asingle DELAY (DIV) reading has little
meaning. Accurate time measurements
can be made only by subtracting one read-
ing from another.
3-10. The delayed sweep starts exactly at the end of
the delay time only if the Delayed Trigger Source switch
is set to AUTO. All other positions of the Delayed
Trigger Source switch cause the delayed sweep to
start on the first trigger after the delay time.
Note
The delayed sweep will not be generated
when DELAY (DIV) is set to less than ap-
proximately 0. 5.
3-11. TRIGGER SOURCE. The Main and Delayed
Trigger Source switches determine the origin of the
main and delayed triggers. WhenINT is selected, the
main and delayed sweeps are triggered by the vertical
deflection signal. When EXT or EXT ~10 is selected
the sweeps are triggered by the signals applied to the
EXT INPUT connectors. EXT 10 attenuates the ex-
ternal trigger and should be used when the trigger sig-
nal is greater than 6vpk-pk.
3-12. Each switch has one position not common to the
other. The LINE position on the Main switch allows
the main sweep to be triggered by the power line wave-
form. The AUTOposition on the Delayed switch causes
the delayed sweep to start precisely at the end of the
delay time set by DELAY (DIV). All other positions of
the delayed switch cause the delayed sweep to start on
the first trigger after the delay time.
3-13. TRIGGER COUPLING. These switches deter-
mine the type of coupling for the main and delayed
02591-3 3-1

Section III
Paragraphs 3-14 to 3-19 Model 182 lA
triggers. Direct (DC) coupling is normally used for
any trigger signal from DC to greater than 90 MHz.
Capacitive (AC) coupling should be selected when it
is desirable to block the dc level of the trigger signal.
AC coupling, however, will attenuate signals below 20
Hz. AC fast (ACF) attenuates signals below 15 kHz
and is used, for instance, to eliminate 60 Hz ripple
that might trigger the sweep. AC slow (ACS) attenu-
ates signals above 30 kHz. ACS is used to eliminate
high-frequency noise.
3-14. SLOPE. The setting of this switch determines
whether the sweep triggers on the positive-going (+)
or negative-going (-) portion of the trigger signal.
When Delayed Trigger Source is set to AUTO the de-
layed SLOPE control does not function.
3-15. LEVEL. This control establishes the point on
the trigger waveform that starts the sweep. This point
is adjustable from -3 vto +3 valong the selected slope.
With an external trigger and the Trigger Source switch
in EXT-4-10, the trigger point is adjustable from -30 v
to +30 Valong the selected slope. When the Delayed
Trigger Source switch is in AUTO, the Delayed LEVEL
control does not function. The Main LEVEL control
can always vary the trigger point for the main sweep.
3-16. TRIGGER SIGNAL
REQUIREMENTS.
3-17. Table 3- 1shows the trigger signal requirements
of the Model 182 lA with various combinations of con-
trol settings. Figure 3-2 is used in conjunction with
Figure 3-2. Trigger Amplitude Requirements
the table to determine the typical trigger amplitude
necessary at frequencies up to 100 MHz.
3-18. OPERATING INSTRUCTIONS.
3-19. Figures 3-3 through 3-7 give step-by- step operat-
ing instructions for the Model 182 lA. These instruc-
tions are keyed to the photograph in each figure with
index numbers. The preceding paragraphs contain
additional information and should be read before using
the operating instructions.
Table 3-1. Trigger Signal Requirements
SWEEP
MODE TRIGGER
SOURCE TRIGGER COUPLING TRIGGER
AMPLITUDE LEVEL SLOPE
LINE DC; dc to 90 MHz
AC: 20 Hz to 90 MHz
NORM INT See Figure 3-2 Adjustable
+3 Vto -3 V
EXT ACF: 15 kHz to 90 MHz
ACS; 20 Hz to 30 kHz
EXT-I-IO 10 times that shown
on Figure 3-2 Adjustable
+30 Vto -30 VSelectable
+or -
LINE DC: 40 Hz to 90 MHz
AUTO INT AC: 40 Hz to 90 MHz See Figure 3-2 Adjustable
+3 Vto -3 V
EXT ACF: 15 kHz to 90 MHz
ACS: 40 Hz to 30 kHz
EXT^IO 10 times that shown
on Figure 3-2 Adjustable
+30 Vto -30 V
SINGLE Single may be selected after setting up any display
D
E
AUTO No function Automatically trig-
gered at end of delay No function
L
AINT DC: DC to 90 MHz
AC: 20 Hz to 90 MHz
ACF: 15 kHz to 90 MHz
ACS: 20 Hz to 30 kHz
See Figure 3-2 Adjustable
+3 Vto -3V
Selectable
Y
E
DEXT +or -
EXT^-10 10 times that shown
on Figure 3-2 Adjustable
+30 Vto -30 V
3-2 02591-2

Model 1821A Section III
Figure 3-3
Obtain abaseline as follows:
1. Set Horizontal DISPLAY to INT.
2. Set Sweep Display to MAIN.
3. Position Delayed TIME/DIV to OFF.
4. Set SWEEP MODE to AUTO.
5. Use FIND BEAM with INTENSITY and posi-
tion controls, if necessary, to locate baseline.
Set controls of Vertical Plug-In as desired (refer to
Vertical Plug-In Manual.
)
Adjust Horizontal Display as follows:
6. Set Main Trigger Source as desired (if EXT
or EXT 10 is selected connect trigger to
Main EXT INPUT).
7. Select desired coupling.
8. Select desired slope.
9. Adjust TRIGGER LEVEL for desired trigger
point. (If display is unstable, set SWEEP
MODE to NORMAL and adjust LEVEL.
)
10. Set Main VERNIER to CAL.
11. Set MAGNIFIER to XI.
12. Set Main TIME/DIV as desired.
02591-3
Figure 3-3. Main Sweep Operation
3-3

Section III
Figure 3-4 Model 1821A
Set up main sweep as explained in Figure 3-3.
1. Set Delayed Trigger Source to AUTO.
2. Rotate Delayed VERNIER fully cw to CAL.
3. Rotate Delayed TIME/DIV switch ccw from OFF and set
the delayed sweep time ten to one -hundred times faster
than the main sweep time (if possible).
4. Set Sweep Display to MIXED.
5. Adjust DELAY (DIV) until desired portion of waveform
is displayed on delayed sweep.
Figure 3-4. Mixed Sweep Operation
3-4 02591-3

Model 1821A Section III
Figure 3-5
Set up main sweep as explained in Figure 3-3.
1. Rotate the Delayed TIME/DIVcontrol ccw from OFF.
2. Set Delayed Trigger Source to INT, EXT, or
EXT -i- 10 as desired. (If EXT or EXT -|- 10 is
selected, connect trigger to EXT INPUT.
)
3. Set Delayed Trigger Coupling as desired.
4. Set Delayed SLOPE as desired.
5. Adjust Delayed TRIGGER LEVEL for an intensified
display. (If intensified display does not appear, set
DIV DELAY to 1.)
6. Adjust DELAY (DIV) to intensify desired signal.
7. Set Sweep Display to DELAYED and observe previous-
ly intensified portion of signal.
8. Set Delayed VERNIER to CAL.
9. Set Delayed TIME/DIV as desired.
Note
The dotted horizontal lines on the CRT
are the 10% and 90% references.
Figure 3-5. Rise Time Measurements
02591-3 3-5

Section III
Figure 3-6 Model 1821A
Set up main sweep as explained in Figure 3-2. 6. Set Sweep Display to MAIN and adjust DE-
1. Set Delayed VERNIER to CAL. LAY (DIV) to intensify second point of inter-
2. Turn the Delayed sweep on by setting Delay- est B.
ed TIME/DIV ten to one-hundred times fast- ,,
er than Main TIME/DIV. ,
3. Set Delayed Trigger Source to AUTO. <
4. Adjust DELAY (DIV) to intensify first point |
*-
of interest, A, on waveform. '^*
5.
Set Sweep Display to DELAYED ana adjust
DELAY (DIV) to set Aon areferency (Typ-
ically the Yaxis). Note setting of DELAY
(DIV).
7. Set Sweep Display to DELAYED and adjust DE-
LAY (DlV)toset Bon same reference line as
A.
Calculate the difference between the setting of DE-
LAY (DIV) in steps #5 and#7. Multiply the MAIN
TIME/DIV setting by this difference to obtain the
time between the two points Aand B.
Figure 3-6. Time Differential Measurements
3-6 02591-3

Model 1821A Section in
Figure 3-7
I82IA-A-5B
SINGLE SWEEP
Perform instructions given in any previous
operating procedure.
Set SWEEP MODE to SINGLE.
Press RESET to arm sweep.
The RESET indicator will light, indicating
sweep is armed. The first trigger input will
start the sweep. The RESET indicator will
extinguish at the end of the sweep.
INTENSITY RATIO
A. Perform steps 1through 5of Figure 3-3.
B. Set Main TIME/DIVto 50 pSEC and Delayed
TIME/DIVto 5pSEC.
C. Set Delayed Trigger Source to AUTO and
DELAY (DIV) to 2. 00.
D. Adjust INTENS RATIO for desired intensity
difference between normal and intensified
section of baseline.
Figure 3-7. Single Sweep Operation And Intensity Ratio Adjustment
02591-3 3-7

Section IV
Figure 4-1
Model 1821A
TRIGGER
SIGNAL
TRIGGER
SIGNAL
MAIIJJ GATE
TT
MAIN MAIN MAIN
TRIGGER
CIRCUITS "T CIRCUITS INTEGRATOR MAIN
SWEER
SWEEP
SWEEP
COMPARATOR
CIRCUIT
K-l
SWEEP
DISPLAY
SWITCH
GATE
DELAYED DELAYED DELAYED
TRIGGER
CIRCUITS yCIRCUITS nINTEGRATOR DELAYED
SWEEP
DELAYED GATe"^
I82IA-C
Figure 4-1. Model 1821A Block Diagram
4-0 02591-2