Tektronix 7844 User manual
Tektronix
COMMITTED
TO
EXCELLENCE
PLEASE
CHECK
FOR
CHANGE
INFORMATION
AT
THE
REAR
OF
THIS
MANUAL.
7844/R7844
DUAL-BEAM
OSCILLOSCOPE
WITH
OPTIONS
OPERATOR
INSTRUCTION
MANUAL
Tektronix,
Inc.
P.O.
Box
500
Beaverton,
Oregon
97077
Serial
Number
070-1675-00
First
Printing
AUG
1974
Product
Group
Revised
NOV
1981
a
Copyright
©
1974
Tektronix,
Inc.
All
rights
reserved.
Contents
of
this
publication
may
not
be
reproduced
in
any
form
without
the
written
permission
of
Tektronix,
Inc.
Products
of
Tektronix,
inc.
and
its
subsidiaries
are
covered
by
U.S.
and
foreign
patents
and/or
pending
patents.
TEKTRONIX,
TEK,
SCOPE-MOBILE,
and
are
registered
trademarks
of
Tektronix,
Inc.
TELEQUIPMENT
is
a
registered
trademark
of
Tektronix
U.K.
Limited.
Printed
in
U.S.A.
Specification
and
price
change
privileges
are
reserved.
INSTRUMENT
SERIAL
NUMBERS
Each
instrument
has
a
serial
number
on
a
parel
insert,
tag,
or
stamped
on
the
chassis.
The
first
number
or
letter
designates
the
country
of
manufacture.
The
last
five
digits
of
the
serial
number
are
assigned
sequentially
and
are
unique
to
each
instrument.
Those
manufactured
in
the
United
States
have
six
unique
digits.
The
country
of
manufacture
is
identified
as
follows:
B000000
Tektronix,
Inc.,
Beaverton,
Oregon,
USA
100000
Tektronix
Guernsey,
Ltd.,
Channel
Islands
200000
Tektronix
United
Kingdom,
Ltd.,
London
300000
Sony/Tektronix,
Japan
700000
Tektronix
Holland,
NV,
Heerenveen,
The
Netherlands
7844/R7844
Operators
TABLE
OF
CONTENTS
PAGE
List
of
illustrations
iti
List
of
Tables
ili
SECTION
7
OPERATING
INSTRUCTIONS
FEATURES
1-1
PRELIMINARY
OPERATION
1-1
Safety
Information
1-1
Operating
Voltage
1
Operating
Temperature
1-2
Operating
Position
1-2
PLUG-IN
UNITS
1-2
Installation
of
Plug-In
Units
1-2
CONTROLS
AND
CONNECTORS
1-2
Front-Panel
Color
Coding
1-2
FAMILIARIZATION
PROCEDURE
1-2
Set-Up
Information
1-3
Display
Controls
1-3
Vertical
System
and
Calibrator
7-8
Horizontal
System
1-9
Graticule
and
Readout
Pulsed
Operation
7-10
DETAILED
OPERATING
INFORMATION
1-11
Crt
Display
Intensity
Controls
1-11
Display
Focus
1-17
Trace
Alignment
1-12
Graticule
1-12
Light
Filters
1-12
Graticule
Illumination
4-12
Readout
Display
1-12
Beamfinder
1-13
Control
Hlumination
1-14
Calibrator
Output
1-14
Probe
Power
4-14
Horizontal
Display
Mode
Combinations
1-14
Vertical
Display
Mode
Combinations
1-14
Beam
2
Display
Characteristics
1-14
Amplifier
Unit
Alternate
Operation
1-15
7844/R7844
Operators
TABLE
OF
CONTENTS
(CONT.)
PAGE
SECTION
1
(continued)
Trigger
Source
1-15
Intensity
Modulation
1-15
Remote
Grat/Readout
Single
Shot
1-15
Single
Sweep
Input/Output
1-15
Output
Signals
1-16
Display
Photography
1-16
APPLICATIONS
1-16
Vertical
Amplifier
Plug-In
Units
1-17
Time-Base
Plug-In
Units
1-17
Sampling
Displays
1-17
Special
Purpose
Plug-In
Units
1-18
X-Y¥
Operation
1-18
Raster
Display
1-19
SECTION
2
SPECIFICATION
INTRODUCTION
2-1
SYSTEM
ELECTRICAL
SPECIFICATION
2-9
STANDARD
ACCESSORIES
2-12
SECTION3
RACKMOUNTING
INSTRUCTIONS
INTRODUCTION
3-1
INSTRUMENT
DIMENSIONS
3-1
RACK
DIMENSIONS
3-1
Height
3-1
Width
3-1
Depth
3-1
SLIDE-OUT
TRACKS
3-1
MOUNTING
PROCEDURE
3-2
REMOVING
OR
INSTALLING
THE
INSTRUMENT
3-3
SLIDE-OUT
TRACK
LUBRICATION
3-3
SECTION4
INSTRUMENT
OPTIONS
INTRODUCTION
41
OPTION
3
4-1
OPTION
21
4-7
7844/R7844
Operators
TABLE
OF
CONTENTS
(CONT.)
SECTION
4
(continued)
OPTION
78
OPTION
22
Controls
and
Connectors
Display
Photography
CHANGE
INFORMATION
FIGURE
NO.
4-1
1-2
4-3
1-4
2-1
3-1
3-2
3-3
3-4
3-5
3-6
4-1
TABLE
NO.
2-4
2-2
2-3
2-4
2-5
2-46
4-1
LIST
OF
ILLUSTRATIONS
Frontispiece
Front-panel
controls
and
connectors.
Rear-panel
controls
and
connectors.
Definition
of
measurement
lines
on
the
7844/R7844
graticule,
Location
of
readout
display
on
the
crt
identifying
the
originating
plug-in
and
channel.
7844
dimensional
drawing.
Stide-out
track
assembly.
Vertical
mounting
position
of
the
stationary
section
and
location
of
the
thumb
screw
securing
hole
(left
stationary
section
shown).
Details
for
mounting
stationary
sections.
Installing
and
removing
the
instrument.
Adjustment
of
the
slide-out
tracks
for
smooth
sliding
action.
R7844
dimensional
drawing.
Location
of
Readout
Mode
Switch
on
the
Readout
circuit
board.
LIST
OF
TABLES
Electrical
7844/R7844
Oscilloscope
System
Vertical
Specification
7844/R7844
Oscilloscope
System
Horizontal
Specification
Special
Purpose
and
Sampling
Plug-in Units
Environmental
Physical
Option
Information
Locator
PAGE
PAGE
2-4
2-9
2-10
2-10
2-11
2-11
4-3
ili
7844/R7844
Operators
7844
DUAL-BEAM
OSCILLOSCOPE
R7844
OPTION
21
DUAL-BEAM
OSCILLOSCOPE
1675-12
Section
1-7844/R7844
Operators
OPERATING
INSTRUCTIONS
FEATURES
The
Tektronix
7844/R7844
Dual-Beam
Oscilloscope
is
a
solid-state,
wide
bandwidth,
dual-beam
oscilloscope.
The
instrument
accepts
Tektronix
7000-Series
plug-in
units
to
form
a
complete
measurement
system. The
flexibility
of
the
plug-in
feature
and
variety
of
plug-in
units
available
allow
the
system
to
be
used
for
many
measurement
applica-
tions.
The
7844/R7844
provides
separate
vertical
and
horizontal
deflection
systems,
FOCUS,
INTENSITY,
and
BEAMFIND-
ER
functions
for
each
beam.
The
plug-in
unit
in
either
vertical
compartment
can
be
selected
to
provide
vertical
de-
flection
for
either
beam.
The
plug-in
units
in
either
horizon-
tal
compartment
may
be
selected
to
provide
horizontal
de-
flection
for
either
beam.
The
7844/R7844
features
regulated
de
power
supplies
to
ensure
that
the
performance
is
not
affected
by
variations
in
line
voltage
and
frequency,
or
by
changes
in
load
due
to
vary-
ing
power
requirements
of
the
plug-in
units.
The
7844/R7844
operates
from
a
115
valt
or
230
volt
(50
Hz
to
400
Hz)
nominal
line
source.
Other
features
include
a
dual-gun
full-overlap
crt
with
a
graticule
area
of
8
x
10
centimeters.
The
instrument
also
provides
a
crt
display
of
alphanumeric
information
encoded
by
the
plug-in
units.
The
READOUT
display
indicates
plug-
in
unit
status
such
as
deflection
factor,
sweep
rate,
and
other
plug-in
dependent
parameters.
The
Option
21
instrument
is
basically
the
same
as
the
stan-
dard
7844/R7844
except
that
the
vertical
deflection
system
is
dedicated.
The
amplifier
unit
in
the
LEFT
VERT
compart-
ment
controls
the
vertical
deflection
of
beam
1
and
the
am-
plifier
unit
in
the
RIGHT
VERT
compartment
controls
the
vertical
deflection
of
beam
2.
The
VERTICAL
MODE
switch
and
VERT
SEP
control
have
been
deleted.
Refer
to
the
Options
section
for
details.
PRELIMINARY
OPERATION
To
effectively
operate
this
instrument,
the
user
must
be-
come
familiar
with
the
operation
and
capabilities
of
the
in-
strument.
This
section
describes
how
to
use
the
front
and
rear-panel
controls
and
connectors.
REV.
C
JAN
1977
Safety
Information
This
instruction
manual
contains
warning
information
which
the
user
must
follow
to
ensure
safe
operation
of
the
instru-
ment.
Warning
information
is
intended
to
protect
the
opera-
tor
and
Caution
information
is
intended
to
protect
the
instrument.
WARNING
}
This
instrument
is
intended
to
be
operated
from
a
single-phase
earth-referenced
power
source
having
one
current-carrying
conductor
{the
Neu-
tral
Conductor)
near
earth
potential,
Operation
from
power
sources
where
both current-carry-
ing
conductors
are
live
with
respect
to
earth
(such
as
phase-to-phase
on
a
three-wire
system)
is
not
recommended,
since
only
the
Line
Con-
ductor
has
over-current
{fuse}
protection
with-
in
the
instrument.
This
instrument
has
a
three-wire
power
cord
with
a
three-terminal polarized
plug
for
connec-
tion
to
the
power
source
and
safety-earth,
The
safety-earth
terminal
of
the
plug
is
directly
con-
nected
to
the
instrument
frame.
For
electric-
shock
protection,
insert
this
plug only
in
a
mat-
ing
outlet
with
a
safety-earth
contact
or
other-
wise
connect
the
frame
to
a
safety-earth
system.
The
color-coding
of
the
cord
conductors
is
in
accordance
with
recognized
standards.
Power
Cord
Conductor
Identification
Conductor
Color
Alternate
Color
Ungrounded
(Line)
Brown
Black
Grounded
(Neutral)
Blue
White
Grounding
(Earthing)
Green-Yellow Green-Yellow
Operating
Voltage
The
7844/R7844
has
a
VOLTAGE
SELECTOR
switch
which
allows
selection
of
either
a
115
volt
or
230
volt
nominal
line
voltage source.
When
changing
the
Voltage
Selector
switch
position,
disconnect
the
power
cord
and
use
a
small
screw-
driver
to
move
the
Voltage
Selector
switch
to
the
desired
range.
1-1
Operating
instructions—7844/R7844
Operators
(ey
°
CAUTION
PPL
LLL
PS
Damage
to
this
instrument
may
occur
if
the
Voltage
Selector
switch
is
set
to
an
incorrect
position
for
the line
voltage
applied.
Voltage
Selector
Switch
Pasition
115
Vv
230
V
Regulating
Range
90
to
132
volts
180
to
264
volts
Operating
Temperature
The
7844/R7844
can
be
operated
where
the
ambient
air
temperature
is
between
0°C
and
+50°C.
After
storage
at
temperatures
beyond
the
operating
limits,
allow
the
chassis
temperature
to
come
within
the
operating
limits
before
power
is
applied.
The
7844
is
cooled
by
air
drawn
in
through
holes
in
the
side
and
bottom
panels
and
blown
out
through
the
fan
ex-
haust.
To
ensure
proper
cooling
of
the
7844,
maintain
the
clearance
provided
by
the
feet
on
the
bottom
and
allow
2
inches
clearance
on
the
top,
sides,
and
rear
(more
clearance,
if
possible}.
The
R7844
is
cooled
by
air
drawn
in
through
the
air
filter
on
the
rear
panel and
blown
out
through
holes
located
on
the
side
panels.
To
ensure
proper
cooling
of
the
R7844,
refer
to
the
dimensional
drawing
in
Section
3
of
this
manual
(Fig.
3-6).
A
thermal
cutout
disconnects
power
from
this
instrument
if
the
internal
temperature
exceeds
a
safe
operating
level.
Power
is
automatically
restored
when
the
temperature
re-
turns
to
a
safe
level.
Operating
Position
A
bail-type
stand
is
mounted
on
the
bottom
of
the
7844.
This
stand
permits
the
instrument
to
be
tilted
up
about
10°
for
more
convenient
crt
viewing.
PLUG-IN
UNITS
The
7844/R7844
accepts
up
to
4
Tektronix
7000-Series
plug-in
units.
This
feature
allows
selection
of
bandwidth,
sensitivity,
display
mode,
etc.,
and
provides
for
future
ex-
pansion
of
the
system.
The
overall
capabilities
of
the
system
are
determined
mainly
by
the
characteristics
of
the
plug-ins
selected.
Some
typical
combinations
are
given
under
Applications,
in
this
manual,
along
with
simplified
set-up
instructions,
For
information
on
other
plug-in
units,
refer
to
the
current
Tektronix
catalog.
installation
of
Plug-In Units
Plug-in
units
can
be
installed
or
removed
without
turning
the
instrument
power
off.
To
install
a
plug-in
unit
into
a
compartment,
align
the
slots
in
the
top
and
bottom
of
the
plug-in
unit
with
the
associated
guide
rails
in
the
plug-in
compartment.
Insert
the
plug-in
unit
into
the
compartment
until
it
locks
into
place.
To
remove
a
plug-in
unit,
pull
the
release
latch
on
the
plug-in
unit
to
disengage
it.
To
meet
emi
specifications,
all
unused
plug-in
compartments
should
be
covered
with
an
emi-shielded,
blank
plug-in
panel,
Tek-
tronix
Part
016-0155-00.
The
7844/R7844
Calibration
procedure
given
in
the
Service
manual
normalizes
the
vertical
and
horizontal
gains.
This
allows
plug-in
units
to
be
interchanged
between
plug-in
com-
partments
without
recalibration.
The
basic
calibration
of
the
plug-in
units
should
be
checked
when
installed
to
verify
their
accuracy
(refer
to
plug-in
operating
instructions}.
CONTROLS
AND
CONNECTORS
Figure
1-1
and
Figure
1-2
show
the
front
and
rear
panels.
A
brief
description
of
each
contro!
and
connector
is
given.
Re-
a
fer
to
Detailed
Operating
Information
in
this
manual
for
additional
operating
information.
Front-Panel
Color
Coding
Portions
of
the
7844/R7844
front-panel
are
color-coded.
These
color-coded
areas
are
defined
by
their
functions.
Red
identifies
the
nomenclature
and
controls
that
will
uncalibrate
the
instrument.
Biue
identifies
the
controls
affecting
the
crt
display
mode.
Green
identifies
all
trigger
controls.
Other
colors
such
as
gray,
orange
and
yellow,
have
no
func-
tional
assignments,
but
are
used
as
needed
to
indicate
the
relationship
between
controls
and/or
connectors.
FAMILIARIZATION
PROCEDURE
The
following
procedure
may
be
used
for
familiarization
with
the
7844/R7844
or
as
a
check
of
basic
instrument
op-
eration.
ff
performing
the
Familiarization
Procedure
reveals
improper
calibration
or
instrument
malfunction,
first
check
the
operation
of
the
associated
plug-in
units;
then
refer
to
the
Calibration
and
Maintenance
sections
of
the
7844/R7844
Service
manual.
Set-up
information
for
both
the
standard
7844/R7844
and
Option
21
precedes
each
major
section
of
this
Familiariza-
tion
Procedure,
The
control
settings
for
plug-in
units
and
signal
connections,
when
needed,
are
also
given.
Set-Up
Information
Set
front-panel
controls
as
follows:
POWER
switch
Off
CALIBRATOR
(4
kHz)
READOUT
INTENSITY
OFF
EXT/BEAM
2
GATED
BEAM
2
GATED
{push
button
OUT}
GRAT
ILLUM
wise
EXT/BEAM
2
GATED
BEAM
2
GATED
(push
button
OUT}
A
TRIG
SOURCE
LEFT
B
TRIG
SOURCE
RIGHT
BEAM
1
INTENSITY
Midrange
FOCUS
Midrange
VERTICAL
MODE
LEFT
BEAMFINDER
Push
button
out
HORIZONTAL
MODE
A
HORIZ
SEP
(1)
Midrange
BEAM
2
INTENSITY
Midrange
FOCUS
Midrange
VERTICAL
MODE
RIGHT
BEAMFINDER
Push
butten
out
HORIZONTAL
MODE
B
4
V
push
button
in
Fully
counterclock-
Operating
instructions—7844/R7844
Operators
1.
Connect
the
7844/R7844
to
a
power
source
that
meets
the
voltage
and
frequency
requirements
of
the
instrument.
lf
the
available
line
voltage
is
outside
the
limits
of
the
Vol-
tage
Selector,
see
Operating
Voltage
discussion
in
this
section.
2.
Install
Tektronix
7A-Series
amplifier
units
into
both
the
LEFT
VERT
and
RIGHT
VERT
compartments.
Install
Tek-
tronix
7B-Series
time-base
units
into
the
A
and
B
HORIZ
compartments.
3.
Turn
the
POWER
switch
ON.
4,
Connect
the
4
V
CALIBRATOR
output
to
the
left
and
right
vertical
plug-in
units
with
a
BNC
cable
and
a
dual
in-
put
coupler.
5,
Set
the
deflection
factors
of
both
vertical
units
for
2
divisions
of
displayed
signal
and
center
the
position
controls,
Set
both
units
for
de
input
coupling.
6.
Set
both
time-base
units
for
a
sweep
rate
of
1
millisecond/
division,
Set the
triggering
for
auto
mode
with
ac
coupling
from
the
internal
source
and
the
level
control
for
a
stable
display.
Position
the
display
as
necessary.
Display
Controls
7.
Rotate
the
BEAM
1
and
BEAM
2
INTENSITY
controls
throughout
their
ranges;
then
set
the
INTENSITY
controls
to
a
desired
viewing
level.
8.
Set
the
BEAM
1
FOCUS
control
so
that
the
top
and
bot-
tom
portions
of
the
beam
1
display
are
as
thin
as
possible
but not
elongated.
Set
the
BEAM
2
FOCUS
contro!
so
that
the
top
and
bottom
portions
of
the
beam
2
display
are
as
thin
as
possible
but
not
elongated.
NOTE
This
instrument
contains
circuitry
to
automati-
cally
protect
the
crt
against
damage
due
to
ex-
cessive
crt
beam
current,
If
the
INTENSITY
control
is
set
to
a
point
where
ert
phosphor
damage
could
occur,
this
circuit
limits
the
beam
current
to
a
safe
level.
The
circuit
action
will
also
cause
the
trace
to
defocus
which
indicates
that
the
intensity
should
be
reduced.
There-
fore,
if
the
FOCUS
adjustment
cannot
be
satis-
factorily
made,
reduce
the
INTENSITY
and
repeat
step
8.
4-3
Operating
Instructions—-7844/R7844
Operators
Fig.
1-1.
Front-panel
controls
and
connectors.
1-4
1675-9
Operating
Instructions—7844/R7844
Operators
FRONT-PANEL
CONTROLS,
CONNECTORS,
AND
INDICATORS
a)
POWER
(ON)
Switch—Applies
power
to
instrument,
@)
POWER
Indicator
Lights
when
power
is
on.
@)
BEAM
2
INTENSITY
Control—Controls
brightness
of
beam
2
display.
@)
BEAM
2
FOCUS
Control—Provides
optimum
definition
of
beam
2
display.
G)
BEAM
1
INTENSITY
Control—Controls
brightness
of
beam
1
display.
@)
BEAM
1
FOCUS
Control—Provides
optimum
definition
of
beam
1
display.
@
CALIBRATOR
Connector--Provides
1
kHz
calibrated
square-wave
voltages.
TRACE
ROTATION
Adjustment—Aligns
beam
1
and
bear
2
traces
with
the
graticule
lines.
@)
GRAT
ILLUM
Control—Varies
level
of
graticule
illumination
or
activates
PULSED
GRAT
ILLUM
functions.
GRAT
ILLUM
PRESET
Adjustment
(PULSED
operation
only)—Sets
level
of
iHumination
for
GRAT
ILLUM
PULSED
operation.
a)
GRAT
ELLUM
EXT/BEAM
2
GATED
Control
(PULSED
operation
only}—When
in
EXT
{push
button
IN)
a
signal
to
the
rear-panel
GRAT/READOUT
SINGLE
SHOT
connector
provides
momentary
graticule
illumination.
When
In
BEAM
2
GATED
(push
button
OUT)
momentary
graticule
illumination
is
provided
at
the
end
of
beam
2
sweep.
GRAT
ILLUM
MANUAL
Control
(PULSED
operation
only)—Provides
momentary
graticule
illumination
when
push
button
is
pressed.
(33)
READOUT
MANUAL
Control)
(PULSED
operation
only)--Gne
readout
frame
is
displayed
when
push
button
is
pressed.
(14)
READOUT
EXT/BEAM
2
GATED!
(PULSED
operation
only}
Controi—When
in
EXT
(push
button
IN}
a
signal
to
the
rear-panel
GRAT/READOUT
SINGLE
SHOT
connector
provides
one
readout
frame.
When
in
BEAM
2
GATED
{push
but-
ton
QUT}
one
readout
frame
is
displayed
at
the
end
of
beam
2
sweep.
(5)
READOUT
PRESET
Adjustment
(PULSED
operation
onty)—Sets
PULSED
readout
intensity.
(18)
READOUT
INTENSITY
Control!
—Activates
and
controls
brightness
of
the
alphanumeric
display
or
activates
the
PULSED
readout
functions,
Ground
Connector
(not
marked)—Binding
post
to
establish
common
ground
between
associated
equipment,
(18)
Current
Loop
{not
marked)
7844--Provides
40
mA
square-wave
current
(1
kHz)
when
the
CALIBRATOR
switch
is
set
to
40
mA
position.
R7844—Provides
40
mA
square-wave
current
(1
kHz)
when
optional
current
loop
adapter
is
connected
to
the
CALIBRA-
TOR
connector
and
the
CALIBRATOR
switch
is
set
to
4
V
position.
HORIZ
SEP
(1)
Control—Horizontally
positions
beam
1
display.
ENHANCER
PRESET
Adjustment!
(Option
22
only;
not
shown}.
B
TRIG
SOURCE
Contro!—Selects
LEFT
VERT
or
RIGHT
VERT
compartment
as
the
source
of
internal
trigger
signal
for
B
HORIZ
compartment.
BEAM
2
HORIZONTAL
MODE
Controi~A
HORIZ
or
B
HORIZ
compartments
can
be
selected
to
control
bearn
2.
A
TRIG
SOURCE
Control—Selects
LEFT
VERT
or
RIGHT
VERT
compartment
as
the
source
of
internal
trigger
signal for
the A
HORIZ
compartment.
BEAM
2
BEAMFINDER
(LOCKS
IN)
Control—Iintensifies
and
locates
heam
2
display.
VERT
SEP
(1)
Controi
(deleted
with
Option
21)~-Pravides
positioning
of
beam
1
when
both
beam
1
and
beam
2
are
being
controlled
by
the
same
vertical
compartment.
(26)
REAM
2
VERTICAL
MODE
Controt
{deleted
with
Option
21}-Allows
beam
2
to
be
controfied
by
either
the
LEFT
VERT
or
RIGHT
VERT
compartments.
BEAM
1
VERTICAL
MODE
Control
(deleted
with
Option
21)—Allaws
beam
7
to
be
controlled
by
either
the
LEFT
VERT
or
RIGHT
VERT
compartments.
PROBE
POWER
Connectors
(two)—Provide
power
for
active
probe
systems
(located
on
rear
panel
of
7844),
©)
BEAM
1
BEAMFINDER
(LOCKS
iN}
Controt—intensifies
and
locates
beam
1
display.
BEAM
1
HORIZONTAL
MODE
Control—A
HORIZ
or
B
HORIZ
compartments
can
be
selected
to
control
beam
1.
Camera
Power
Connector
(not
marked}—Three-pin
connector
provides
pawer
for
camera
operation
and
receives
single-
sweep
reset signal.
|
Refer
to
Instrument
Options
section
for
instruments
equipped
with
the
Writing
Speed
Enhancer
(Option
22}.
Fig.
1-1
(cont.}.
Front-panel
controls
and
connectors.
1-5
Operating
instructions—7844/R7844
Operators
Fig.
1-2.
Rear-panel
controls
and
connectors,
1-6
1675-10
@
O
®
©
®
@
COROROROCROROROROROMG)
Operating
Instructions—7844/R7844
Operators
REAR-PANEL
CONTROLS
AND
CONNECTORS
MAIN
and
DLY'D
{A
GATE}
Switch—Selects
between
main
and delay
gates
from
time
base
unit
in
A
HORIZ
compartment.
SINGLE
SWEEP
(A
READY)
Connector—
Output
for
single-sweep
ready
signal
from
time-base
unit
in
A
HORIZ
compart-
ment,
2
AXIS
INPUT
1
Cennector—Input
for
intensity
modulation
of
BEAM
7.
GRAT/READOUT
SINGLE
SHOT
Connector—Input
for
single
shot
graticule
iltumination
and
single
frame
readout,
Z
AXIS
INPUT
2
Connector—Input
for
intensity
modulation
of
BEAM
2.
SINGLE
SWEEP RESET
Connector—input
to
externally
reset
single-sweep
circuits
in
A
HORIZ
and
B
HORIZ
compart-
ments.
SINGLE
SWEEP
(B
READY)
Connector—Output
for
single-sweep
ready
signal
from
time-base
unit
in
B
HORIZ
compart-
ment,
A
GATE
Connector—Positive-going
output
for
gate
signal
from
the
time-base
unit
in
the
A
HORIZ
compartment,
MAIN
and
DLY'D
(B
GATE}
Switch—Selects
between
main
and
delay
gates
from
time
base
unit
in
B
HOREZ
compartment.
B
GATE
Connector—~Positive-going
output
for
gate
signal
from
the
time-base
unit
in
the
B
HORSZ
compartment.
B
SAWTOOTH
Connector—Pasitive-going
sawtooth
from
B
time
base,
A
SAWTOOTH
Connector—Positive-going
sawtooth
from
A
time
base.
CONTROL
ILLUMINATION
Switch—Sets
iNumination
level
of
push-button
switches
on
plug-in
units
(located
on
left
side
panel
of
R7844).
PROBE
POWER
Connectors
(
two)--Provide
power
for
active
probe
systems
{located
on
front
panel
of
R7844),
Voltage
Selector
Switch
(not
labeled)—Selects
from
either
115-volt
or
230-volt
nominal
line
source,
Line
Fuse~4
A
FAST
BLOW.
Fig.
1-2
(cont.).
Rear-panel
controls
and
connectors.
17
Operating
Instructions—7844/R7844
Operators
9.
Rotate
the
GRAT
ILLUM
control
throughout
its
range
Vertical
System
and
Calibrator
and
notice
that
the
graticule
lines
are
illuminated
as
the
"
.
Set-up
status:
control
is
turned
clockwise.
Set
the
GRAT
1LLUM
control
so
that
the
graticule
lines
are
illuminated
as
desired.
10.
Set the
deflection
factor
of
the
right
vertical
unit
to
10
millivolts/division,
Notice
that
the
square-wave
display
is
not
completely
visible
since
the
deflection
exceeds
the
scan
area
of
the
ert.
11,
Press
the
BEAM
2
BEAMFINDER
push
button.
No-
tice
that
the
display
is
returned
to
the
viewing
area,
in
a
compressed
and
defacused
form.
Release
the
BEAMFIND-
ER
switch
and
notice
that
the
display
again
disappears
from
the
viewing
area.
12.
With
the
BEAM
2
BEAMFINDER
switch
depressed,
increase
the
deflection
factor
of
the
right
vertical
unit
un-
til
the
display
is
reduced
to
less
than
2
divisions
vertically.
Adjust
the right
vertical
unit
position
control
to
center
the
compressed
display
about
the
center
of
the
graticule.
Re-
lease
the
BEAMFINDER
and
notice
that
the
display
re-
mains
within
the
viewing
area.
Repeat
steps
10, 11,
and
12
for
BEAM
1
and
the
left
vertical
unit.
13,
Turn
the
READOUT
INTENSITY
control
clockwise
(out
of
detent)
until
the
alphanumeric
display
is
visible
near
the
top
and/or
bottom
of
the
graticule.
Change
the
deflection
factor
of
the
amplifier
plug-in
units.
Notice
that
the
readout
display
corresponds
to
the
deflection
fac-
tor
selected.
Likewise,
change
the
sweep
rate
of
the
time-
base
units,
located
in
the
A
HORIZ
and
B
HORIZ
com-
partments.
Notice
that
the
readout
display
for
the
time-
base
units
corresponds
to
the
sweep
rate
selected.
It
an
amplifier
unit
with
10X
probe
encoding
is
used,
install
a
10X
probe
on
the
input
connector.
Notice
that
the
de-
flection
factor
indicated
by
the
readout
is
increased
by
10
times
when
the
probe
is
added.
If
any
of
the
plug-in
units
is
a
dual
unit,
notice
that
the
readout
can
appear
within
the
upper
or
lower
graticule
division,
Also,
note
that
the
readout
for
each
plug-in
unit
is
allocated
to
a
specific
location
on
the
graticule.
Set
each
time-base
unit
for
magnified
sweep
operation
(if
time
base
unit
is
equipped
with
a
sweep
magnifier).
No-
tice
that
the
readout
display
changes
to
indicate
the
correct
magnified
sweep
rate.
Return
the
time-base
unit
to
normal
sweep
operation
and
disconnect
the
10X
probe.
1-8
POWER
switch
CALIBRATOR
(1
kHz}
READOUT
INTENSITY
EXT/BEAM
2
GATED
GRAT
fLLUM
EXT/BEAM
2
GATED
A
TRIG
SOURCE
B
TRIG
SOURCE
BEAM
1
INTENSITY
FOCUS
VERTICAL
MODE
BEAMFINDER
HORIZONTAL
MODE
HORIZ
SEP
(1)
BEAM
2
INTENSITY
FOCUS
VERTICAL
MODE
BEAMFINDER
HORIZONTAL
MODE
Left
Vertical
Unit
On
4
V
push
button
in
As
desired
(out
of
PULSED
switch
de-
tent)
BEAM
2
GATED
{push
button
out}
As
desired
(out
of
PULSED
switch
de-
tent)
BEAM
2
GATED
(push
button
out)
LEFT
RIGHT
As
desired
As
desired
LEFT
Push
button
out
A
Midrange
As
desired
As
desired
RIGHT
Push
button
out
B
Set-up
status
for
the
associated
equipment:
Deflection
factor,
7
volt/
division;
position,
cen-
tered
in
the
top
half
of
the
graticule;
input
coupling,
dc.
Right
Vertical
Unit
A
and
B
Horizontal
Units
Deflection
factor,
1
volt/
division;
position,
cen-
tered
in
the
bottom
half
of
the
graticule;
input
coupling,
de.
Sweep
rate
to
1
milli-
Operating
Instructions—7844/R7844
Operators
20.
Select
different
CALIBRATOR
push
buttons
labeled
4
V,0.4
V,
40
mV,
and
4
mV
and
notice
those
outputs
can
be
obtained
(CALIBRATOR
output
must
be
termina-
ted
into
more
than
a
7100
kilohm
load
for
stated
output).
When
the
CALIBRATOR
output
js
terminated
into
50
ohms,
the
output
is
0.1
times
the
stated
output.
second/division;
trigger-
ing
to
auto
mode,
ac
coupling,
internal
source,
level
adjusted
for
stable
display.
14.
Connect
the
CALIBRATOR
output
to
both
the
left
and
right
vertical units
with
a
BNC
cable and
a
dual
input
coupler.
The
display
amplitude
should
be
approximately
2
divisions
{if
not,
adjust
deflection
factor
accordingly}.
15.
Notice
that
the
position
control
for
the
left
vertical
unit
affects
only
the
vertical
position
of
the
beam
1
dis-
played
trace.
16,
(Delete
with
Option
21)
Set the
BEAM
1
VERTICAL
MODE
switch
to
RIGHT.
Notice
that
the
position
control
for
the
right
vertical
unit
affects
the
vertical
position
of
the
beam
1
and
beam
2
displayed
trace.
.
17.
(Delete
with
Option
21)
Rotate
the
VERT
SEP
(1)
control.
Notice
that
the
beam
1
display
is
positioned
with
respect
to
the
beam
2
display.
Set
the
BEAM
2
VERTI-
CAL
MODE
switch
to
LEFT
and
rotate
the
left
vertical
posi-
tion
control,
Note
that
the
left
vertical
positions
only
the
BEAM
2
displayed
trace.
18.
(Delete
with
Option
21}
Set
BEAM
1
VERTICAL
MODE
switch
to
LEFT.
Rotate
the
left
vertical
plug-in
unit
position
control,
in
combination
with
the
VERT
SEP
(1)
control.
Note
that
the
VERT
SEP
(1}
control
posi-
tions
beam
1
display
above
and
below
the
beam
2
display
and
also
that
the
VERT
SEP
(4)
control
is
operational
only
when
both
beams
are
being
controlled
by
the
same
vertical
compartment.
19.
Position
the
start
of
both
traces
to
the
left
graticule
line
with
the
time-base
unit
position
controls.
Check
the
crt
display
for
one
complete
cycle
per
graticule
division.
lf
necessary,
adjust
the
sweep
calibration
adjustment
on
the
front
panel
of
the
associated
time-base
unit
for
one
complete
cycle
per
graticule
division.
Horizontal
System
Set-up
status:
POWER
switch
CALIBRATOR
(1
kHz)
READOUT
INTENSITY
EXT/BEAM
2
GATED
GRAT
ILLUM
EXT/BEAM
2
GATED
A
TRIG
SOURCE
B
TRIG
SOURCE
BEAM
1
INTENSITY
FOCUS
VERTICAL
MODE
BEAMFINDER
HORIZONTAL
MODE
HORIZ
SEP
(1)
BEAM
2
INTENSITY
FOCUS
VERTICAL
MODE
BEAMFINDER
HORIZONTAL
MODE
On
4
V
push
button
{pushed
in}
As
desired
(out
of
PULSED
switch
de-
tent)
BEAM
2
GATED
{push
button
out)
As
desired
(out
of
PULSED
switch
de-
tent}
BEAM
2
GATED
(push
button
out}
LEFT
LEFT
As
desired
As
desired
LEFT
Push
button
out
A
Midrange
As
desired
As
desired
RIGHT
Push
button
out
B
19
Operating
Instructions—7844/R7844
Operators
Set-up
status
for
the
associated
equipment:
CALIBRATOR
4
V
output
connected
to
the
left
and
right
vertical
units
with
a
BNC
cable
and
a
BNC
dual
input
coupler,
Left
Vertical
Unit
Deflection
factor,
1
volt/
division;
position,
left
vertical
display
centered
in
the
top
half
of
the
graticule;
input
coupling,
de.
Right Vertical
Unit
Deflection
factor,
1
volt/
division;
position,
right
vertical
unit
display
centered
in
the
bottom
half
of
the
graticule;
in-
put
coupling,
de.
A
and
B
Horizontal
Units
Sweep
rate
to
1
milli-
second/division;
trigger-
ing
to
auto
mode,
ac
coupling,
internal
source,
level
adjusted
for
stable
display.
21,
Set the
sweep
rate
switch
on
the
B
horizontal
plug-in
unit
to
0.2
millisecond/division.
Disconnect
the
4
V
CALI-
BRATOR
signal
from
the
left
vertical
unit
and
leave
the
CALIBRATOR
signal
connected
to
the
right
vertical
plug-
in.
Set
the
vertical
deflection
factor
for
2
divisions
of
displayed
signal.
Note
that
the
beam
2
display
is
not
trig-
gered.
Set
B
TRIG
SOURCE
to
RIGHT.
Now
the
beam
2
display
should
be
triggered;
if
not,
adjust
the
triggering
controls.
22.
Disconnect
the
4
V
CALIBRATOR
signal
from
the
right
vertical
unit
and
connect
it
to
the
left
vertical.
Then
set
the
deflection
factor
for
two
divisions
of
displayed
signal.
Set
the
A
TRIG
SOURCE
to
RIGHT
and
note
that
the
beam
1
display
is
not
triggered.
Set
A
TRIG
SOURCE
to
LEFT
and
note
that
beam
1
display
is
now
triggered.
23.
Connect.
the
4
V
CALIBRATOR
signal
to
both
verti-
eal
plug-in units
and
set
the
vertical
deflection
factors
to
display
two
divisions
of
signal.
Note
that
the
A
HORIZ
plug-in
is
displayed
on
beam
1.
Use
the
position
control
of
the
A
HORIZ
plug-in
to
change
the
horizontal
location
of
the
displayed
waveform.
Align
the
start
of
this
trace
with
left
side
of
the
graticule.
24,
Note
that
the
B
HORIZ
plug-in
is
displayed
on
beam
2.
Use
the
position
centro!
of
the
B
HORIZ
plug-in
to
change
the
horizontal
location
of
the
displayed
waveform.
Align
the
start
of
this
trace
with
the
left
side
of
the
grati-
cule.
25.
With
the
HORIZ
SEP
(1)
control,
note
that
the
beam
1
display
can
be
horizontally
positioned
and
that
the
HORIZ
SEP
(1}
control
positioning
is
in
addition
to
that
of
the
beam
1
plug-in
horizontal
positioning.
26.
Set
BEAM
2
HORIZONTAL
MODE
switch
to
A.
Note
that
both
beam
1
and
beam
2
are
being
controlled
by
the
A
HORIZ
plug-in
unit.
Use
the
HORIZ
SEP
(1)
control
to
align
the
beam
1
trace
with
the
beam
2
trace.
27,
Set
BEAM
1
HORIZONTAL
MODE
switch
to
B.
Note
that
either
A
HORIZ
or
B
HORIZ
plug-in
units
can
be
selected
to
control
beam
1
and
beam
2.
Graticule
and
Readout
Pulsed
Operation
Set-up
status:
POWER
switch
On
CALIBRATOR
(17
kHz}
4
V
push
button
{pushed
in}
READOUT
INTENSITY
As
desired
(out
of
PULSED
switch
de-
tent)
EXT/BEAM
2
GATED
BEAM
2
GATED
(push
button
out)
GRAT
ILLUM
As
desired
(out
of
PULSED
switch
de-
tent)
EXT/BEAM
2
GATED
BEAM
2
GATED
(push
button
out}
A
TRIG
SOURCE
LEFT
B
TRIG
SOURCE
RIGHT
BEAM
1
INTENSITY
As
desired
FOCUS
As
desired
VERTICAL
MODE
LEFT
BEAMFINDER
Push
button
out
HORIZONTAL
MODE
A
HORIZ
SEP
(1}
Midrange
BEAM
2
INTENSITY
As
desired
FOCUS
As
desired
VERTICAL
MODE
RIGHT
BEAMFINDER
Push
button
out
HORIZONTAL
MODE
A
28.
Set
the
READOUT
INTENSITY
control
clockwise
to
the
PULSED
(switch
detent)
position.
Set
the
B
HORIZ
plug-in
to
0.2
second/division.
Observe
that
1
READOUT
frame
occurs
for
each
sweep
of
the
beam
2
horizontal
sys-
tem.
Adjust
READOUT
INTENSITY
PRESET
control
to
a
desired
viewing
jevel.
29.
Set
READOUT
EXT/BEAM
2
GATED
push
button
switch
to
EXT.
Depress
the
READOUT
MANUAL
push
button.
Observe
that
1
READOUT
frame
occurs
each
time
the
MANUAL
push
button
is
depressed.
Set
READ-
OUT
EXT/BEAM
2
GATED
push
button
to
BEAM
2
GATED.
30.
Set
GRAT
ILLUM
control
clockwise
to
the
PULSED
detent
position.
Note
that
one
graticule
illumination
oc-
curs
for
each
sweep
of
the
beam
2
horizontal
system.
Set
the
GRAT
1ILLUM
PRESET
control
to
a
desired
viewing
level.
31.
Set
GRAT
ILLUM
EXT/BEAM
2
GATED
push
button
to
EXT.
Depress
the
GRAT
|LLUM
MANUAL
push
button,
Observe
1
graticule
illumination
each time
the
MANUAL
push
button
is
depressed.
NOTE
The
GRAT
ILLUM
and
READOUT
PULSED
functions
can
be
actuated
by
a
remote
signal
applied
through
the
rear-panel
GRAT/READ-
OUT
SINGLE
SHOT
connector.
The
EXT/
BEAM
2
GATED
push
buttons
should
be
set
Operating
Instructions—7844/R7844
Operators
to
EXT
and
a
ground
closure
applied
to
the
GRAT/READOUT
SINGLE
SHOT
connec-
tor.
This
completes
the
Familiarization
Procedure.
DETAILED
OPERATING
INFORMATION
Crt
Display
Intensity
Controls
The
7844/R7844
dual-beam
oscilloscope
has
an
INTENSITY
control
for
each
of
the
two
beams.
Each
of
these
INTEN-
SITY
controls
operate
independently.
The
BEAM
1
INTEN-
SITY
control
varies
the
brightness
of
only
the
beam
1
dis-
play.
Likewise,
the
BEAM
2
INTENSITY
control
varies
brightness
of
only
the
beam
2
display.
WARKING
}
Crt
phosphor
damage
can
occur
under
adverse
conditions,
Avoid
any
condition
where
an
ex-
tremely
bright,
sharply
focused
dot
exists
on
the
crt.
Also
remember
that
the
light
filter
re-
duces
the
apparent
light
output
from
the
ert.
When
the
INTENSITY
controls
are
advanced
to
the
point
where
crt
beam
current
exceeds
a
safe
level,
protection
cir-
cuitry
automatically
limits
the
beam
current.
The
beam
current
is
limited
to an
even
lower
level
during
x-y
mode
of
operation
or
when
either
time-base
unit
is
set
for
a
slow
sweep
rate
(even
if
that
time-base
unit
is
not
selected
for
display
by
the
HORIZONTAL
MODE
switch),
This
reduces
the
danger
of
damaging
the
crt
phosphor
with
a
stationary
or
slowly
moving
spot.
Since
beam-current
limiting
does
not
take
effect
until
after 10
milliseconds,
the
full
display
intensity
is
available
for
most
single-shot
uses.
Display
Focus
The
FOCUS
controls
are
used
to
increase
the
crt
display
de-
finition,
for
a
variety
of
waveforms
and
intensity
settings.
Once
the
FOCUS
controls
have
been properly
set,
the
auto-
matic-focusing
circuits
will
maintain
optimum
focus
for
most
intensity
settings
and display
conditions.
The
optimum
FOCUS
setting
is
most
readily
obtained
with
a
square-wave
signal
displayed
on
the
crt
and
with
a
low
level
of
trace
brightness.
Use
the
following
procedure
to
adjust
the
FO-
CUS
controls:
1.
Set the
vertical
deflection
factor
to
display
2
divisions
of
the
CALIBRATOR
signal.
Operating
instructions—7844/R7844
Operators
2.
Set
the
harizontal
deflection
factor
to
display
5
cycles
of
the
CALIBRATOR
signal.
3.
Adjust
the
FOCUS
control
so
that
the
top
and
bottom
portions
of
the
waveform
are
as
thin
as
possible
but not
elongated.
Trace
Alignment
The
TRACE
ROTATION
control
allows
the
trace
to
be
aligned
with
the
horizontal
graticule
lines.
Position
both
beams
to
the
center
horizontal
fine
and
adjust
the
TRACE
ROTATION
adjustment
so
that
the
2
traces
are
parallel
with
the
horizontal
graticule
lines.
Graticule
The
crt
graticule
lines
are
internally
marked
on
the
face
of
the
crt.
This
feature
eliminates
measurement
error
due
to
faceplate
parallex.
The
crt
faceplate
is
divided
into
8
verti-
cal
and
10
horizontal
divisions.
Each
division
is
1
centimeter
square,
each
major
division
is
divided
into
5
minor
divisions.
The
gains
of
the
vertical
and
horizontal
compartments
are
calibrated
to
the
crt
graticule.
Figure
1-3
illustrates the
grati-
cule
and
defines
the
various
measurement
lines.
The
termi-
nology
defined
here
will
be
used
in
all
discussions
involving
graticule
measurements.
NOTE
Two
types
of
ert
graticules
have
been
used
in
some
Tektronix
oscilloscopes,
One
graticule
has
0%
and
100%
risetime
reference
points
that
are
separated
by
6
vertical
graticule
divisions,
The
other
graticule
has
the
0%
and
100%
risetime
reference
points
separated
by
&
vertical
divisions.
In
your
manual,
ilfustrations
of
the
crt
face
or
risetime
measurement
instructions
may
not
correspond
with
the
graticule
markings
on
your
oscilloscope.
Light
Filters
The
tinted
filter
provided
with
the
standard
instrument,
minimizes
light
reflections
from
the
face
of
the
crt
to
im-
prove
contrast
when
viewing
the
display
under
high
ambient
light
conditions.
This
filter
should
be
removed
for
waveform
photographs
or
when
viewing
high
writing
rate
displays.
To
remove
the
filter,
pull
outward
on
the
bottom
of
the
plas-
tic
crt
mask
and
remove
it
from
the
crt.
Remove
the
tinted
filter
(leave
the
metal
fight
shield
in
place)
and
snap
the
plastic
crt
mask
back
into
place.
WARNING
}
Do
not
remove
the
clear
plastic
implosion
shield.
An
optional
mesh
filter
is
available
at
extra
cost
(included
with
Option
3),
This
filter
provides
shielding
against
radiated
emi
(electro-magnetic
interference)
from
the
face
of
the
crt.
1-12
It
also
serves
as
a
light
filter
to
make
the
trace
more
visible
under
high
ambient
light
conditions.
The
mesh
filter
fits
in;
place
of
the
plastic
crt
mask
and
the
tinted
filter.
The
filter
can
be
ordered
by
Tektronix
Part
378-0603-00.
The
apparent
light
output
from
the
crt
is
reduced
when
tinted
and
emi
filters
are
used.
Therefore,
these
filters
should
be
removed
to
obtain
the
best
visible
photographic
writing
rate.
Graticule
Illumination
The
GRAT
ILLUM
control
varies
the
illumination
of
the
graticule
lines.
The
GRAT
ILLUM
can
also
be
operated
in
the
PULSED
mode,
With
the
GRAT
ILLUM
control
set
to
the
PULSED
detent
and
the
EXT/BEAM
2
GATED
switch
set
to
the
BEAM
2
GATED
position,
the
graticule
will
be
illuminated
momentarily
after
beam
2
completes
a
sweep.
With
the
EXT/BEAM
2
GATED
switch
set
to
the
EXT
posi-
tion,
the
graticule
can
be
momentarily
illuminated
either
by
depressing
the
GRAT
I[LLUM
MANUAL
push
button
or
by
SECOND
CENTER
TENTH
VERTICAL
VERTICAL
VERTICAL
LINE LINE
LENE
CENTER
HORIZONTAL,
LINE
1675-7
Fig,
1-3.
Definition
of
measurement
lines
on
the
7844/R7844
grati-
cule,
applying
a
remote
signal
to
the
GRAT/READOUT
SINGLE
SHOT
BNC
connector,
located
on
the
rear
panel
(see
Table
2-1
for
signal
requirements).
When
operating
in
the
PULSED
mode,
the
level of
illumination
is
controlied
by
the
GRAT
ILLUM,
PRESET
screwdriver
adjustment.
Readout
Display
The
Readout
System
displays
alphanumeric
plug-in
unit
scale
factors
on
the
crt.in
conjunction
with
the
displayed
analog
waveform.
Each
installed
plug-in
unit
encodes
the
readout
information
into
a
word.
Up
to
8
words
of
readout
information
can
be
displayed
on
the
crt
(2
channels
from
each
of
the
4
plug-in
compartments}.
Figure
1-4
illustrates
readout
word
placement
on
the
ert.
Notice
that
the
readout
REV.
A,
SEPT,
1975
from
channel
1
of
each plug-in
unit
is
displayed
in
the
top
division
of
the
graticule
and
the
readout
from
channel
2
is
displayed
directly
below
in
the
bottom
division
of
the
grati-
cule.
Only
readout
information
from
plug-in
units,
which
are
selected
for
display
by
the
MODE
switches,
will
appear
in
the
readout
display.
Some
special
purpose
plug-in
units
can
over-ride
the
MODE
switches
and
display
readout
even
through
the
compartment
is
not
selected
for
readout
dis-
play.
A
channel
identification
feature
is
provided
by
the
Readout
System
to
link
the
readout
word
with
the
originating
plug-
in
unit
and
channel
(amplifier
units
only}.
When
the
[den-
tify
button
on
the
amplifier
unit
is
pressed,
the
word
IDENTIFY
appears
in
the
readout
display.
The
word
IDEN-
TIFY
appears
in
the
place
of
the
normal
scale
factor
readout.
Other
readout
words
in
the
display
remain
unchanged.
When
the
!dentify
button
is
released,
the
readout
display
from
this
plug-in
channel
is
again
displayed.
Circuitry
may
also
be
provided
in
the
plug-in
unit
which
produces
a
notice-
able
change
in
the
analog
waveform
display
when
the
Iden-
tify
button
is
pressed
(see
the
plug-in
unit
instruction
man-
uals
for
details).
NOTE
The
READOUT
MODE
switch,
located
inter-
nally
on
the
readout
board,
should
be
set
to
F.R.
(free
running).
This
is
the
recommended
setting
to
insure
proper
operation
of
front
panel controls and external
connectors.
The
READOUT
INTENSITY
control
determines
the
bright-
ness
of
only
the
readout
portion
of
the
display,
independent
of
the
other
traces.
The
Readout
System
is
inoperative
in
the
fully
counterclockwise
OFF
position.
This
may
be
de-
sirable
when
the
top
and
bottom
divisions
of
the
graticule
area
are
to
be
used
for
waveform
display,
or
when
the
trace
interruptions
necessary
to
display
characters
interfere
with
the
waveform
display.
[n
the
normal
free-run
mode,
the
trace
is
interrupted
for
about
20
microseconds
for
each
character
displayed.
NOTE
For
instruments
equipped
with
Option
22
(pho-
tographic
writing
speed
enhancer)
refer
to
Section
4.
One
complete
frame
of
readout
information
can
be
displayed
at
the
end
of
the
beam
2
sweep,
by
rotating
the
READOUT
INTENSITY
control
fully
clockwise
to
the
PULSED
detent
Operating
Instructions-7844/R7844
Operators
and
by
setting
the
EXT/BEAM
2
GATED
switch
to
BEAM
2
GATED.
The
PULSED
mode
is
very
useful
for
single-shot
photography.
When
the
EXT/BEAM
2
GATED
switch
is
set
to
EXT,
one
complete
frame
of
readout
information
can
be
displayed
by
applying
an
external
signal
to
the
GRAT/
READOUT
SINGLE
SHOT
connector
on
the
rear
panel
(see
Table
2-1
in
the
Specification
section
for
signal
requirements).
One
frame
of
readout
information
is
also
displayed
each
LEFT
VERT
RIGHT
VERT
AHORIZ
BHORIZ
CHANNEL
7
CHANNEL1
CHANNEL
1
CHANNEL
1
o-
it
ox
LEFT
VERT
RIGHT
VERT
AHORIZ
BHORIZ
CHANNEL
2
CHANNEL
2
CHANNEL
2
CHANNEL
2
1675-8
Fig.
1-4.
Location
of
readout
display
on
the
crt
identifying
the
ori-
ginating
plug-in
and
channel,
time
the
READOUT
MANUAL
push
button
is
pressed
{READOUT
PULSED
mode
only).
The
brightness
of
the
readout
display,
when
operating
in
the
PULSED
made,
is
set
by
the
READOUT
PRESET
control.
Beamfinder
The
BEAMFINDER
push
button
switch
aides
in
locating
displays
that
overscan
the
viewing
area
vertically
or
horizon-
tally.
When
the
BEAMFINDER
switch
is
pressed,
the
display
is
compressed
and
defocused
within
the
graticule
area
(the
crt
is
unblanked
by
the
BEAMFINDER).
To
locate
and
re-
position
an
overscanned
display,
use
the
following
procedure:
1.
Depress
the
BEAMFINDER
switch.
While
the
display
is
compressed,
change
the
vertical
and
horizontal
deflection
factors
until
the
vertical
deflection
is
about
two
divisions
and
the
horizontal
deflection
is
about
4
divisions
(the
hori-
zontal
deflection
needs
to
be
reduced
only
when
in
the
X-Y
mode
of
operation}.
Operating
instructions-7844/R7844
Operators
2.
Adjust
the
vertical
and
horizontal
Position
controls
to
center
the
display
on
the
graticule.
3.
Release
the
BEAMFINDER
switch;
the
display
should
remain
within
the
graticule.
Control
Illumination
The
CONTROL
ILLUMINATION
switch
sets
the
illumina-
tion
level
of
the
lighted
push
button
switches
on
the
plug-in
units.
The
positions
available
are
OFF,
LOW
and
HIGH.
This
switch
is
located
on
the
rear
panel
of
the
7844
and
the
left
side
panel
of
the
R7844.
The
CONTROL
ILLUMINA-
TION
switch
does
not
affect
the
function
indicator
lights
(such
as
TRIG’D
lights
or
SINGLE-SWEEP
READY
lights).
Calibrator
Output
The
internal
calibrator
provides
a
convenient
signal
for
checking
basic
vertical
gain
and
sweep
timing.
The
calibra-
tor
signal
is
also
very
useful
for
adjusting
probe
compensa-
tion
as
described
in
the
probe
instruction
manual.
In
addi-
tion,
the
calibrator
can
be
used
as
a
convenient
signal
source
for
application
to
external
equipment.
See
Table
2-1
in
the
Specification
section
for
calibrator
accuracy.
VOLTAGE.
The
calibrator
provides
accurate
output
voltages
at
the
CALIBRATOR
Output
connector
from
4
millivolts
to
4
volts
in
decade
steps
into
loads
of
more
than
100
kil-
ohms.
In
addition,
it
provides
from
0.4
milfivolts
to
0.4
volt
into
a
50
ohm
load.
CURRENT.
The
current
loop
provides
a
40
milliampere
output
which
can
be
used
to
check
and
calibrate
current-
measuring
probe
systems.
The
current
output
is
selected
by
the
CALIBRATOR
switch
when
set to
the
40
mA
position.
The
current
signal
is
obtained
by
clipping
the
probe
around
the
current
loop.
The
arrow
above
the
current
loop
indicates
conventional
current
flow;
i.e.,
from
plus
to
minus.
Forty
milliamperes
is
available
from
the
R7844
when
the
optional
current
loop
adapter
is
used
(Tektronix
part
G12-0031-00)
and
the
CALIBRATOR
is
set
for
a
4
volt
output.
REPETITION
RATE,
The
repetition
rate
of
the
calibrator
is
1
kilohertz.
The
calibrator
circuit
uses
frequency-stable
components
to
maintain
accurate
frequency
and
constant
duty
cycle.
Thus,
the
calibrator
can
be
used
for
checking
the
basic
sweep
timing
of
time-base
units.
WAVE
SHAPE.
The
square
wave
output
signal
of
the
cali-
brator
can
be
used
as
a
reference
wave
shape
when
checking
or
adjusting
the
compensation
of
passive,
high-resistance
probes,
The
square
wave
has
a
flat
top
so
any
distortion
in
the
displayed
waveform
is
due
to
improper
probe
compen-
sation.
Probe
Power
Two
PROBE
POWER
connectors
on
the
rear
panel
of
the
7844
and
the
front
panel
of
the
R7844
provide
power
for
accessories.
Current
from
these
connectors
is
limited,
there-
fore
it is
not
recommended
that
they
be
used
as
a
power
source
for
applications
other
than
the
compatible
probes
or
other
accessories
which
are
specifically
designed
for
use
with
this
system.
Horizontal
Display
Mode
Combinations
The
HORIZONTAL
MODE
switch
allows
both
beam
1
and
beam
2
to
be
controlled
by
either
A
HORIZ
or
B
HORIZ
compartments.
When
both
beams
use
the
same
time-base
unit
as
a
sweep
source,
the
other
unused
horizontal
compart:
ment
can
be
used
for
special
purpose
plug-in
units
such
as
a
counter,
digital
voltmeter,
etc.
The
HORIZ
SEP
(1)
control
provides
horizontal
position-
ing
of
beam
1
in
addition
to
the
Position
control
of
the
horizontal
plug-in
unit
selected
by
the
BEAM
1
HORIZON.
TAL
MODE
switch.
When
the
same
time
base
is
selected
for
horizontal
deflection
of
both
beams,
the
HORIZ
SEP
(1)
control
can
be
used
to
align
an
event
on
the
beam
1
trace
so
that
the
timing
of
both
beams
coincide.
Vertical
Display
Mode
Combinations
The
7844/R7844
Option
21
model
has
dedicated
vertical
plug-in
compartments,
The
left
vertical
compartment
is
directly
connected
to
the
beam
1
trace
and
the
right
vertical
compartment
is
directly
connected
to
the
beam
2
trace.
The
7844/R7844
standard
model
has
vertical
crossover
switching.
The
VERTICAL
MODE
switch
allows
both
the
beam
1
and
beam
2
traces
to
be
controlled
by
either
vertical
plug-in
compartment.
When
both
beams
are
being
controlled
by
the
same
vertical
compartment,
the
VERT
SEP
{1}
con-
trol
becomes
operational.
The
VERT
SEP
(1)
contro!
will
position
the
beam
1
display
above
or
below
the
beam
2
display.
Beam
2
Display
Characteristics
The
readout
display
is
produced
on
a
time-shared
basis
with
the
beam
2
crt
display
in
both
the
PULSED
and
free-run
(non-pulsed)
READOUT
modes.
Other manuals for 7844
1
This manual suits for next models
1
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