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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. 1
p,sec/ divto
1
sec/
div.
A
vernier
pro-
vides continuous
adjustment between ranges and
will
extend
the
slowest
sweep
to at
least
2.
5
sec/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
a dual
sweep-speed
display.
1-3.
The
delayed
sweep
feature
of
the
Model 1821A
permits accurate time
measurement
between
a refer-
ence
signal
and a
point
of
interest
on a
complex wave-
form
or pulse
train;
it
also allows for exact
time
inter-
val
measurement
between
consecutive pulses
in
a pulse
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 a
bright
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
a two-section
eight-digit
serial
number
to
identify
instruments.
Thefirstthree
digits
(preceding
the
dash) are
the serial prefix
which
identifies
a series
of
instruments;
the
last five digits
identify
a particular instrument
in the
series.
The
serial
number
appears on
a
plate located
on
the
rear
panel.
All
correspondence
with a
Hewlett-
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 a serial
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
1
v
pk-pk
at
90
MHz.
Slope:
selectable, positive
or
negative.
Trigger
Point: adjustable ±
3
v over
selected
trigger signal (±30 v
in
EXT
10).
DELAY:
Time:
continuously variable
from
0.
1
psecto
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.
5
V pulse 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,
8 kg).
02591-3
1-1
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