Tektronix 7A29 User manual
Tektronix,
Inc.
P.O.
Box
500
Beaverton,
Oregon
070-2320-00
Product
Group
42
97077
Tektronix
COMMITTED
TO
EXCELLENCE
PLEASE
CHECK
FOR
CHANGE
INFORMATION
AT
THE
REAR
OF
THIS
MANUAL.
7A29
AMPLIFIER
WITH
OPTIONS
INSTRUCTION
MANUAL
Serial
Number
First
Printing
APR
1979
Revised
JUL
1986
Copyright
©
1979
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
pañel
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
7A29
Instruction
SERVICE
SAFETY
INFORMATION
FOR
QUALIFIED
SERVICE
PERSONNEL
ONLY
The
following
are
safety
precautions
which
appear
in
the
service
information
sections
of
this
manual.
This
Service
Safety
information
is
in
addition
to
the
Operators
Safety
Information
given
previously.
WARNING
|
DO
NOT
SERVICE
ALONE
Do
not
attempt
internal
service
or
adjustment
unless
another
person,
capable
of
rendering
first
aid
and
resuscitation,
is
present.
DISCONNECT
INSTRUMENT
POWER
To
avoid
electrical-shock
hazard,
disconnect
the
instrument
from
the
power
source
before
removing
protective
panels,
soldering,
or
replacing
components.
SL
LB
Sa
EL
DEIS,
?
CAUTION
PON
LON
OLN
MA
EN
INS
AVOID
EXCESSIVE
MOISTURE
Circuit
boards
and
components
must
be
dry
before
applying
power
to
prevent
damage
from
electrical
arcing.
Pins
2
and
3
of
U246
and
U266
are
especially
sensitive
to
moisture.
Excessive
moisture
in
this
area
of
the
circuit
board
will
cause
the
trace
to
wander
irregularly
and
possibly
leave
the
screen
area.
EXERCISE
CARE
WHEN
SOLDERING
The
Main
Amplifier
circuit
board
is
a
multilayer
type
with
two
identical
conductive
paths
laminated
between
the
top
and
bottom
board
layers.
All
soldering
on
this
board
should
be
done
with
care
to
prevent
breaking
the
connections
to
the
center
conductors.
Only
experienced
maintenance
personnel
should
attempt
repair
of
any
circuit
board.
USE
PROPER
CLEANING
AGENTS
Avoid
the
use
of
chemical
cleaning
agents
which
might
damage
the
plastics
used
in
this
instrument.
Use
a
nonresidue
type
of
cleaner,
preferably
isopropyl
alcohol,
totally
denatured
ethyl
alcohol,
or
a
fluorinated
solvent
(Le.
trifluorotrichloroethane),
such
as
Freon
TF
cleaner
or
Spray-On
#2002.
Before
using
any
other
type
of
cleaner,
consult
your
Tektronix
Service
Center
or
representative.
DO
NOT
USE
PIN
SOCKETS
FOR
CONNECTION
POINTS
The
spring
tension
of
the
pin
sockets
ensures
a
good
connection
between
the
circuit
board
and
the
pin.
This
spring
tension
can
be
destroyed
by
using
the
pin
sockets
as
a
connecting
point
for
spring-loaded
probe
tips,
alligator
clips,
etc.
7529
Instruction
7A29
FEATURES
The
7A29
is
a
wide-bandwidth
Amplifier
Plug-In
Unit
designed
primarily
for
use
in
vertical
compartments
of
the
7000-
Series
Oscilloscopes.
The
input
is
50-ohm
impedance
with
selectable
DC
or
AC
coupling
and
automatic
overload
disconnect.
Seven
calibrated
deflection
factors,
VARIABLE
deflection
factor
and
polarity
INVERT
selections
are
provided.
Readout
encoding
provides
for
deflection
factor
readout
including
coded
probes,
uncalibrated
indication,
polarity
INVERT
and
IDENTIFY
functions.
A
Variable
Signal
Delay
of
+0.5
ns
is
available
with
the
Option
4
instrument.
GENERAL
INFOF
INTRODUCTION
The
Instruction
Manual
is
divided
into
the
following
main
sections:
Section
1—General
Information
contains
instrument
description,
electrical
specifications,
environmental
characteristics,
standard
and
recommended
accessories,
installation,
and
packaging
for
shipment
instructions.
Section
2—Operating
Instructions
contains
information
relative
to
operating
and
checking
the
instrument
operation.
|
WARNING
THE
REMAINING
PORTIONS
OF
THIS
INSTRUCTION
MANUAL
CONTAIN
SERVIC-
ING
INSTRUCTIONS.
THESE
SERVICING
INSTRUCTIONS
ARE
FOR
USE
BY
QUALIFIED
SERVICE
PERSONNEL
ONLY.
TO
AVOID
ELECTRIC
SHOCK
OR
OTHER
PERSONAL
INJURY,
DO
NOT
PERFORM
ANY
SERVICING
OTHER
THAN
THAT
DESCRIBED
IN
THE
OPERATING
INSTRUCTIONS
UNLESS
YOU
ARE
QUALIFIED
TO
DO
SO.
Section
3—Theory
of
Operation
contains
basic
and
general
circuit
analysis
that
may
be
useful
for
servicing
or
operating
the
instrument,
Section
4—Maintenance
describes
routine
and
‘corrective
maintenance
procedures
with
detailed
instructions
for
replacing
assemblies,
subassemblies,
and
individual
components.
Section
5—Calibration
contains
procedures
to
check
the
operational
performance
and
electrical
characteristics
of
the
instrument.
Procedures
also
include
methods
for
adjustment
of
the
instrument
to
meet
specifications.
Section
6—-Instrument
Options
contains
a
description
of
available
options
and
locations
of
incorporated
information
for
those
options.
Section
7—Replaceable
Electrical
Parts
contains
information
necessary
to
order
replaceable
parts
and
assemblies
related
to
the
electrical
functions
of
the
instrument.
Secti
incluc
assen
wave!
locatc
perfoi
portic
Sectic
infor
mech
identi
INITIAI
Da
ins
op
pre
rel
be
This
ins
etectrica
should
t
exceed
inspect
transit.
`
Operatoı
refer
qt
Check
P
damage
Office
o
OPERA
To
Shu
firs
The
7AZ
can
be
i
series
O:
vertical
:
and
low:
and
inse
General
Information—7A29
front
of
the
oscilloscope
and
the
latch
at
the
bottom
left
corner
of
the
7A29
will
be
in
place
against
the
front
panel
when
the
7A29
is
fully
installed.
To
remove
the
7A29,
pull
on
the
release
latch
{inscribed
with
the
unit
identification
"7A29"}
and
the
7A29
will
unlatch.
Continue
pulling
to
slide
the
7A29
out
of
the
oscilloscope.
OPERATING
TEMPERATURE
The
7A29
can
be
operated
where
the
ambient
air
temperature
is
between
0%
and
+50°
C
and
can
be
stored
in
ambient
temperatures
from
-55°
to
+75°
C.
After
storage
at
temperatures
outside
the
operating
limits,
allow
the
chassis
temperature
to
reach
a
safe
operating
temperature
before
applying
power.
PACKAGING
FOR
SHIPMENT
If
this
instrument
is
to
be
shipped
for
long
distances
by
commercial
transportation,
we
recommend
that
the
instrument
be
packaged
in
the
original
manner.
The
carton
and
packaging
material
in
which
your
instrument
was
shipped
should
be
saved
for
this
purpose.
If
this
instrument
is
to
be
shipped
to
a
Tektronix
Service
Center
for
service
or
repair,
attach
a
tag
to
the
instrument
showing
the
following:
Owner
of
the
instrument
(with
address),
the
name
of
the
person
at
your
firm
who
can
be
contacted,
complete
instrument
type
and
serial
number,
and
a
description
of
the
service
required,
H
the
original
packaging
is
unfit
for
use
or
not
available,
package
the
instrument
as
follows:
1.
Obtain
a
corrugated
cardboard
carton
with
at
least
a
200-pound
test
strength
and
dimensions
at
least
six
inches
larger
than
the
instrument’s
dimensions.
2.
Surround
the
instrument
with
polyethylene
sheeting,
or
equivalent,
to
protect
the
instrument.
3.
Allow
a
3-inch
cushion
on
all
sides
by
tightly
packing
dunnage
or
urethane
foam
between
the
carton
and
the
instrument.
4,
Seal
the
carton
with
shipping
tape
or
with
an
industrial
stapler.
5.
Mark
the
address
of
the
Tektronix
Service
Center
and
your
return
address
in
one
or
more
prominent
locations
on
the
exterior
of
the
shipping
carton.
SPECIFICATIONS
The
electrical
characteristics
listed
in
Table
1-1
apply
when
the
following
conditions
are
met:
(1)
Adjustment
of
the
instrument
must
have
taken
place
at
an
ambient
temperature
between
+20°
C
and
+30°
C,
{2)
the
instrument
must
be
allowed
a
30-minute
warm-up
period,
and
(3)
all
specifications
are
valid
at
an
ambient
temperature
of
0°
to
+50°
C,
unless
otherwise
stated:
TABLE
1-1
Electrical
Characteristics
Characteristics
Performance
Requirement
Deflection
Factor
Calibrated
Range
Attenuator
Accuracy
GAIN
Range
From
10
mV
/div
to
1
V/div
in
7
switch
positions
using
a
1-2-5
switching
sequence.
All
deflection
factors
within
2%
with
gain
adjusted
at
0.1
VOLTS/DIV
when
driven
from
a
50
Q
source.
At
least
2.5:1.
See
Figure
1-1
for
effect
on
bandwidth.
Adjustable
to
at
least
3%
from
nominal
at
0.1
V/div.
1-2
Characteristic
General
Information—
7A29
TABLE
1-1
(CONT.)
Electrical
Characteristics
Frequency
Response
(10
mV/DIV
to
1
V/DIV)
High
Frequency,
AC
or
DC
Coupled
Low
Frequency,
AC
Coupled
Maximum
Input
DC
Coupled
AC
Coupled
Input
Protection
Disconnect
Threshold
Input
Protection
Disconnect
Time
input
Impedance
Resistance
Reflection
Coefficient
VSWR
(Except
Option
4)
DC
Coupled
AC
Coupled
VSWR
(Option
4}
DC
Coupled
AC
Coupled
input
Offset
Current
`
VARIABLE
(VOLTS/DIV}
Balance
Performance
Requirement
When
operated
in
the
vertical
compartment
of
the
following
oscilloscope
series:
7100,
1
GHz
{0°
to
35°
C);
7900,
500
MHz
{0°
to
30°
C};
7800,
400
MHz
(0°
to
35°
C};
7700,
175
MHz;
7600,
100
MHz;
7300,
25
MHz.
NOTE
Use
of
the
VARIABLE
(Vols/Div)
control
affects
frequency
response.
See
Figure
1-1.
1
kHz
or
less
from
a
50
(
source;
200
Hz
or
less
with
a
10X
50
Q
probe.
10
V
rms
or
1-watt-second
pulses
not
exceeding
50
V
peak.
See
Figure
1-2,
and
Detailed
Operating
information,
section
2.
100
V
additional
de
component.
Derate
linearly
to
O
V
additional
at
60
Hz.
;
CAUTION
$
RON
MN
AO
ANANA
NLN
ANAN
Signals
of
more
than
50
V
peak
amplitude
must
be
connected
with
input
switch
in
OFF
position
so
that
input
coupling
capacitor
is
precharged.
+10
V
de
within
2
V
de,
-10
V
de
within
2
V
dc,
or
approximately
10
V
rms
up
to
100
MHz.
Less
than
30
ms
for
50
V
dc
of
either
polarity;
40
ms
to
150
ms
for
25
V
dc
of
either
polarity.
De
coupled:
50
Q
within
1
Q.
Ac
coupled:
50
Q
within
1
Q
in
series
with
at
least
1.6
uF.
0.05
or
less
in
a
1
GHz
120%
time
domain
reflectometer
system.
1.4:1
at
10
mVOLTS/DIV.
1.20:1
from
20
mVOLTS/DIV
to
1
VOLTS/DIV;
de
to
1
GHz.
1.4:1
at
10
mVOLTS/DIV.
1.20:1
from
20
mVOLTS/DIV
to
1
VOLTS/DIV;
1
MHz
to
1
GHz.
1.5:1
dc
to
800
MHz,
1.5:1,
1
MHz
to
800
MHz.
50
pA
or
less.
0.2
div
maximum
trace
shift.
1-3
General
Information—7A29
TABLE
1-1
(CONT.)
Electrical
Characteristics
Characteristic
Performance
Requirement
POLARITY
Balance
0.5
div
maximum
trace
shift.
IDENTIFY
Deflects
trace
upward
0.2
to
0.4
div.
o
POSITION
Range
9
div
each
direction
from
graticule
center
within
1.0
div.
DC
Drift
Drift
With
Ambient
Temperature
0.04
div/°C
or
less.
{Line
Voltage
Constant)
Delay
Range
{Option
4
only)
|
At
least
1
ns,
1.2
GHz
1.1
GHz
$
1.0
GHz
900
MHz:
800
MHz
TYPICAL
BANDWIDTH
700
MHz
600
MHz
500
MHz
04
05
06
07
08
09
10
MAXIMUM
i
|
|
|
H
CALIBRATED
7
GAIN
RELATIVE
LOW-FREQUENCY
SENSITIVITY
|
.
2320-11
Figure
1-1.
VARIABLE
(Volts/Div)
contro!
effect
on
bandwidth.
RATED
MAXIMUM
RMS
INPUT
VOLTAGE
General
Information—7A29
HHP
“Note:
The
peak
input
voltage
must
not
exceed
50
V
when
de
wii
DURATION
Figure
1-2.
Maximum
rms
input
voltage.
TABLE
1-2
Environmental
Characteristics
Characteristic
ee
eee
RE
ET
Ee
PE
O
OOOO
OOOO
OOOO
Temperature
Calibration
Operating
Performance
Requirement
+20°
to
+30°C
(+68°
to
+86°
F}.
0°
to
50°
C
(4320
to
+122°
F).
Storage
Altitude
Operating
Storage
Tra
nsportation
To
50,000
feet.
-55°
to
#75°
C
(-67°
to
+167°
F}.
To
15,000
feet.
Qualified
under
Nationa!
Safe
Transit
Committee
Test
Procedure
1A,
Category
Il.
1-5
General
Information—7A29
TABLE
1-3
Physical
Characteristic
Overall
Dimensions
Net
Weight
Standard
Instrument
Option
4
Instrument
RECOMMENDED
ACCESSORIES
The
following
accessories
have
been
selected
from
our
catalog
specifically
for
your
instrument.
They
are
listed
as
a
convenience
to
help
you
meet
your
measurement
needs.
For
detailed
information
and
prices,
refer
to
a
Tektronix
Products
Catalog
or
contact
your
local
Tektronix
Field
Representative.
PROBES
P6056
The
P6056
is
a
passive
10X
attenuating
probe
with
a
bandwidth
of
de
to
3.5
gigahertz,
and
a
500
ohm
input
resistance
for
use
with
50
ohm
inputs.
1-6
Characteristics
Performance
Requirement
Compatible
with
all
7000-series
plug-in
compartments;
see
Figure
1-3,
for
dimensional
drawing.
Approximately
2
Ibs.
8
oz.
(1.14
kg).
Approximately
3
tbs.
4
oz.
(1.48
kg).
EEE
EEE
MAN
AN
ANA
ar
ST
Instruction
Manual
P6057
The
P6057
is
a
passive
100X
attenuating
probe
with
a
bandwidth
of
de
to
1.4
gigahertz
and
a
5
kilohm
input
resistance
for
use
with
50
ohm
inputs.
P6201
The
P6201
is
an
active
(FET)
nonattenuating
probe
with
a
bandwidth
from
de
to
900
megahertz,
an
input
impedance
of
100
kilohms
and
3
picofarads
(1
megohm
and
1.5
picofarads
with
10X
and
100X
attenuating
heads}.
General
Information—
7A29
WO
zerzi
ul
98
y
WI
96
9£
(SLNIOd
AINWIXYA
LY
G3HNSVAN)
SNOISNAWIO
TIVYUH3AO
Figure
1-3.
7A29
dimensional
drawing.
7
1
Section
2--7A29
OPERATING
INSTRUCTIONS
To
use
the
7A29
effectively,
the
operation
and
capabilities
of
the
instrument
must
be
known.
This
section
describes
front-panel
control
functions,
general
information
on
signal
input
connections,
and
other
subjects
that
pertain
to
various
measurement
applications.
CONTROLS
AND
CONNECTORS
CAUTION
OPN
LOLOL
LOLS
LOLS
Before
applying
any
signal
in
excess
of
10
volts
to
the
7A29,
refer
to
Detailed
Operating
Information
given
later
in
this
section
of
the
manual.
The
7A29
front
panel
is
shown
in
Figure
2-1.
A
brief,
functional
description
of
each
control
and
connector
is
included
in
the
illustration.
Refer
to
Detailed
Operating
Information
for
additional
information.
CHECKOUT
PROCEDURE
The
following
procedure
can
be
used
for
incoming
inspection
to
verify
proper
operation,
and
may
also
be
used
by
the
operator
for
instrument
familiarization.
Only
instrument
functions
(not
measurement
quantities
or
specifications)
are
checked
tn
the
procedure;
therefore,
a
minimum
amount
of
test
equipment
is
required.
if
performing
the
Checkout
Procedure
reveals
improper
performance
or
instrument
malfunction,
first
check
the
‚operation
of
associated
equipment;
then
refer
to
qualified
service
personnel
for
repair
or
adjustment
of
the
instrument.
NOTE
Refer
qualified
service
personnel
to
the
Calibration
section
of
this
manual
for
the
procedure
to
check
the
Option
4
VARIABLE
DELAY
control.
BEFORE
YOU
BEGIN:
Refer
to
the
Change
Information
at
the
rear
of
this
manual
for
any
modifications
which
may
affect
this
procedure.
TEST
EQUIPMENT
REQUIRED
The
following
test
equipment
was
used
in
preparing
the
Operators
Checkout
Procedure.
Other
test
equipment
which
meets
these
requirements
may
be
substituted.
When
other
equipment
is
substituted,
the
control
settings
or
setup
may
need
to
be
altered.
1.
7000-series
oscilloscope
mainframe
(e.g.
7104,
7904,
or
7704A).
2.
7B-series
time-base
unit
{e.g.
7810,
7815,
7B80,
or
7B85).
3.
One
bnc
cable:
50-ohm
coaxial,
Tektronix
Part
012-
0057-01.
SETUP
PROCEDURE
1.
With
the
7000-series
oscilloscope
power
switch
in
the
off
position,
connect
the
oscilloscope
to
a
suitable
power
source.
2.
Instal!
the
7A29
in
the
left
vertical
compartment.
3.
Install
the
7B-series
time-base
unit
in
the
B
horizontal
compartment.
4.
Set
the
front-panel
controls
as
follows:
7A29
AMPLIFIER:
VOLTS
DIV
weten
zen
0.1
V
VARIABLE
(Volts/Div)
.................22..
CAL
IN
POSITIONS,
as
ee
ee
te
Midrange
POLARITY
san
este
AN
en
+UP
AC
pre
DO
san
bana
maa
Rina
ates
OFF
Time-Base
Unit:
TANG?
DIV
Gis dnb
cctv
a
gn
pute
Mune
Re
PAN
ARE
1
ms
POSO
os
Na
NN
Pan
ee
Midrange
O
en
PAMA
PANRB
Le
Ra
Xt
Triggering
Mode
a
Sate
AN
Gade
E
anneal
wee
pats
Auto
External
Trigger
In
nee
In
Combi
een
eig
AC
SOUL
UU
ma
Internal
Oscilloscope:
Vertical
Mole
sure
Oia
NE
tale
eer
Left
Horizontal!
Mode
ua
ta
rest
B
B
Trigger
SOUMGs
nie
Vert
Mode
Calibrator
unten
Rasen
4
Y
A
and
B
Intensity................
Counterciockwise
2-1
Operating
Instructions—7A29
BIENEN
POSITION
VARIABLE
|
CAL
IN
}
VOLTS/DIV
VARIABLE
DELAY
{RANGE
+G.bas}
-0
+01
\
Y
MAXIMUM
INPUT
TEV
RMS
50V
PEAK
Tektronix
AMPLIFIER
AC-OFF-DC
(Switch)—Selects
signal
input
coupling
mode.
AC:
The
ac
component
of
the
signal
is
coupled
to
the
amplifier
input
while
the
de
component
is
blocked.
OFF:
Disconnects
input
signal,
precharges
input
coupling
capacitor,
and
resets
input
protection
system
when
OVERLOAD
tight
is
on.
DC:
Both
ac
and
de
components
of
the
signal
are
coupled
to
the
amplifier
input.
(2)
overtoan
{Indicator}—When
on,
indicates
that
input
signa!
exceeded
the
safe
input
level.
+UP:
A
positive-going
signal
at
the
INPUT
connector
deflects
the
crt
display
upward.
INVERT:
A
positive-going
signa!
at
the
INPUT
connector
defiects
the
crt
display
downward.
©
POLARITY
(Switch)—Provides
a
means
of
inverting
the
display.
(4)
VARIABLE
(Controi)—Provides
continuously
variable
defiection
factors
between
settings
of
the
VOLTS
/DIV
switch.
©
VOLTS/DIV
(Switch}—Selects
calibrated
deflection
factors
from
10
mV/Div
to
1
V/Div;
7
steps
in
a
1-2-5
sequence.
IDENTIFY
(Switch)—Deflects
the
trace
about
0.2
division
for
trace
identification.
In
instruments
with
readout,
also
replaces
readout
with
the
word
“IDENTIFY”.
O)
POSITION
(Control}—-Controls
the
vertical
position
of
the
trace.
GAIN
(Controf)—Screwdriver
adjustment
permits
calibration
of
deflection
factor.
Option
4
VARIABLE
DELAY
(Controtj—Detays
the
signal
up
to
+
and
-
500
picoseconds
by
using
a
calibrated
10
turn
dial
(deleted
on
the
standard
7A29}.
(10)
eur
{Connector}—Provides
a
means
for
connecting
a
signal.
Figure
2-1.
Front-panel
controls,
connectors
and
indicators.
2-2
@
5.
Set
the
oscilloscope’s
power
switch
on
and
allow
at
least
20
minutes
warmup.
AMPLIFIER
FUNCTIONS
1.
Connect
a
bnc
cable
from
the
oscilloscope’s
calibrator
output
connector
to
the
7A29
INPUT
connector.
2.
Rotate
the
B
intensity
control
clockwise
until
the
trace
is
just
visible.
3.
Set
the
7A29
AC-OFF-DC
switch
to
DC.
4.
With
the
POSITION
control,
align
the
display
with
the
center
4
divisions
of
the
graticule
area.
Adjust
the
GAIN
{screwdriver
adjustment)
for
4
divisions
of
display.
5.
With
the
POSITION
control,
align
the
bottom
of
the
displayed
signal
with
the
center
horizontal
graticule
line.
6.
Set
the
AC-OFF-DC
switch
to
AC.
Notice
that
the
displayed
signal
shifts
downward
approximately
2
divisions,
and
that
the
tops
of
the
waveforms
are
tilted.
7.
Set
the
AC-OFF-DC
switch
to
DC.
With
the
POSITION
control,
align
the
trace
with
the
center
and
top-most
graticule
lines.
8.
Set
the
POLARITY
switch
to
the
INVERT
position.
Notice
that
the
displayed
signal
is
now
inverted,
being
|
;
roughly
aligned
with
the
center
and
bottom
graticule
lines.
9.
Set
the
POLARITY
switch
to
the
+UP
position.
10.
Rotate
the
POSITION
control
fully
counterclockwise
and
notice
that
the
displayed
signal
can
be
positioned
off
the
graticule
area
at
the
bottom
of
the
crt.
11.
Set
the
POLARITY
switch
to
INVERT.
12.
Rotate
the
POSITION
control
fully
clockwise,
and
notice
that
the
displayed
signal
can
be
positioned
off
the
graticule
area
at
the
top
of
the
crt.
13.
Return
the
POLARITY
switch
to
the
+UP
position.
Position
the
display
to
the
center
4
divisions
of
the
graticule
area.
14.
Press
to
release
the
VARIABLE
(Volts/Div)
control.
Rotate
the
VARIABLE
(Volts/Div)
control
fully
counterclockwise
and
notice
approximately
1.6
divisions
of
displayed
signal.
Rotate
the
VARIABLE
(Volts/Div)
control
fully
clockwise
and
notice
at
least
4
divisions
of
displayed
signal.
15.
Press
the
VARIABLE
{Volts/Div}
control
in.
:
16.
Set
the
AC-OFF-DC
switch
to
the
OFF
position
and
notice
that
no
signal
is
displayed
on
the
crt.
@
Operating
Instructions—7A29
17.
Press
the
IDENTIFY
button.
Notice
that
the
displayed
trace
is
deflected
upward
approximately
0.25
division
and,
in
oscilloscope
mainframes
equipped
with
readout,
notice
that
the
7A29
readout
display
is
replaced
with
the
word
“IDENTIFY”.
18.
Rotate
the
VOLTS/DIV
control
through
each
position
and
note
that
the
7A29
readout
display
corresponds
with
the
front-panel
nomenclature.
Change
the
POLARITY
switch
to
INVERT.
Rotate
the
VOLTS/DIV
control
through
each
position.
Again
note
that
the
7A29
readout
display
corresponds
with
the
front-panel
nomenclature.
Note
additionally
that
a
downward-pointing
arrow
appears
within
the
readout
display.
19.
Press
and
release
the
VARIABLE
(Volts/Div)
control.
Note
that
a
“>”
symbol
appears
in
the
readout
display
between
the
downward
pointing
arrow
and
the
deflection
factor
information.
20.
Change
the
POLARITY
switch
to
+UP.
Note
the
disappearance
of
the
"|"
symbol.
Press
and
latch
the
VARIABLE
(Volts/Div)
control.
Note
the
disappearance
of
the
">"
symbol.
21.
Disconnect
the
bnc
cable
from
the
INPUT
connector
of
the
7A29.
22.
Connect
a
10X
readout-encoded
probe
to
the
INPUT
connector
and
note
the
corresponding
change
in
the
defiection
factor
of
the
displayed
readout.
Repeat
with
100X
probe.
NOTE
Readout
encoding
is
accomplished
by
connecting
a
resistance
from
the
outer
ring
of
the
7A29
INPUT
connector
to
ground.
The
following
gives
the
resistance
value
necessary
to
simulate
a
probe,
and
may
be
used
in
place
of
an
actual
probe.
Function
Resistance
ME
SN
eed
et
eee
Ya
PN
Na Sa
Ka
Open
circuit
O
an
11
KO,
within
596
ADO
Pee
enam
Wiser
6.2
kQ,
within
5%
IDENTIFY
nata
aan
knpa
ale
nb
Ø
ohms
23.
This
completes
the
Operators
Checkout
Procedure.
2-3
Operating
Instructions—7A29
DETAILED
OPERATING
INFORMATION
PROBES
Probes
recommended
for
use
with
the
7A29
are
the
P6056
{10X}
or
P6057
{100X}.
Both
probes
are
compatible
with
50-ohm
systems,
and
will
allow
good
frequency
response.
These
probes
also
contain
trace
IDENTIFY
and
readout
encoding
functions.
If
the
P6201
Probe
is
used,
a
one-megohm
input
impedance
may
be
achieved
(with
some
loss
in
bandwidth).
Consult
your
local
Tektronix
Field
Engineer
or
Representative
for
further
information.
VERTICAL
GAIN
CHECK
AND
ADJUSTMENT
To
check
the
gain
of
the
7A29,
set
the
VOLTS/DIV
switch
to
0.1
Y
and
connect
a
0.4
V,
1
kHz
signal
from
the
oscilloscope
mainframe
calibrator
to
the
7429
INPUT
connector.
NOTE
Oscilloscope
calibrators
typically
have
an
output
impedance
of
either
50
Q
or
450
DO.
The
50-ohm
input
impedance
of
the
7A29
forms
a
voltage
divider
with
the
calibrator
output
impedance,
reducing
the
voltage
to
the
7A29
by
a
precise
factor
of
2
(for
50-ohm
calibrators}
or
10
{for
450-ohm
Calibrators).
Thus
the
4
V
calibrator
output
of
the
7104
and
7904
must
be
selected
for
an
output
voltage
of
0.4
volts.
The
vertical
deflection
should
be
exactly
four
divisions.
If
not,
adjust
the
front-panel
GAIN
adjustment
for
exactly
four
vertical
divisions.
INPUT
COUPLING
The
AC-OFF-DC
switch
allows
a
choice
of
input
coupling
methods.
The
type
of
display
desired
and
the
applied
signal
will
determine
the
coupling
to
use.
The
DC
coupling
position
can
be
used
for
most
applications.
For
signals
with
frequencies
below
about
1
kHz
the
DC
coupling
position
is
necessary
to
avoid
signal
attenuation.
In
the
AC
coupling
position
the
de
component
of
the
signal
is
blocked
by
a
2
microfarad
capacitor
in
the
input
circuit.
The
AC
coupling
position
provides
the
best
display
of
signals
with
a
dc
component
much
larger
than
the
ac
component.
2-4
In
the
OFF
position
of
the
input
coupling
switch,
the
signal
path
of
the
amplifier
is
interrupted
so
that
there
is
no
displayed
signal.
However,
a
signal
connected
to
the
“~~
INPUT
connector
will
be
loaded
by
approximately
390
|
kilohms
dc,
or
by
195
kilohms
ac.
At
extremely
high
frequencies
a
small
portion
of
the
input
signal
will
still
be
displayed.
For
example,
the
signal
attenuation
in
the
OFF
position
is
about
32
dB
at
1
gigahertz.
The
OVERLOAD
protection
feature
of
the
7A29
activates
when
a
signal
capable
of
causing
damage
{to
7A29
internal
circuitry)
is
applied
to
the
INPUT
connector.
To
reset
the
7A29,
turn
the
AC-OFF-DC
switch
to
the
OFF
position
and
remove
the
cause
of
overloading.
The
7A29
is
then
ready
for
normal
operation.
The
7A29
is
capable
of
withstanding
short
term
overloads
in
excess
of
its
continuous
rating
of
10
V
rms.
Thus,
it
is
possible
to
apply
50
V
peak
(the
same
as
50
V
rms
for
a
single
pulse}
for
20
ms,
or
a
20
V
rms
signal
for
125
ms.
The
7A29
integrates
the
rms
input
power
and
disconnects
the
signal
before
damage
can
occur.
Generally
speaking,
the
7A29
will
protect
itself
from
excessive
(damaging)
signals;
however,
there
are
exceptions.
Continuous
wave
or
pulsed
radio
frequency
signals
above
100
MHz
are
not
sensed
by
the
input
protection
circuitry
and
may
cause
damage
to
the
input
attenuator
if
in
excess
of
the
10
V
rms,
50
V
peak,
rating.
The
relay
contacts
which
disconnect
the
7A29
from
«~~
excessive
voltages
may
themselves
be
damaged
by
|
arcing.
lf
the
contacts
open
with
a
signal
greater
than
50
V
applied
to
the
INPUT,
the
contacts
may
be
permanently
damaged.
The
ac
coupling
capacitor
used
in
the
AC
position
of
the
AC-OFF-DC
switch
is
rated
at
100
V
dc.
Since
the
input
protection
circuitry
is
located
after
the
ac
coupling
Capacitor,
application
of
up
to
100
V
dc
to
the
INPUT
is
possible
in
the
AC
coupled
mode.
However,
in
order
to
avoid
a
fast-rise
pulse
being
sent
to
the
7A29
from
a
signal
in
excess
of
50
V
dc,
turn
the
AC-OFF-DC
switch
to
OFF
before
connecting
such
a
signal
to
the
7A29
INPUT.
In
the
OFF
position,
the
ac
coupling
capacitor
is
safely
precharged
to
the
average
dc
voltage.
Figure
1-2
in
section
1
shows
the
maximum
rms
amplitude
which
may
safely
be
applied
to
the
7A29
INPUT.
Figure
1-2
also
corresponds
approximately
to
the
rms
voltage
the
7A29
will
accept
without
automatically
disconnecting
itself.
A
complex
pulse,
whose
rms
value
is
equal
to
the
amount
shown
in
Figure
1-2,
is
safe
if it
is
also
less
than
50
V
peak.
For
example,
a
30
V
rms
sinusoid
may
be
applied
for
up
‘to
55
ms,
but
a
36
V
rms
sinusoid
may
not
be
applied
because
the
peak
voltage
exceeds
50
V.
The
7A29
INPUT
may
be
connected
to
a
50
V
power
supply
for
up
to
20
ms
because
the
rms
and
peak
values
of
the
resulting
pulse
are
both
50
V.
VOLTS/DIV
SWITCH
The
amount
of
deflection
produced
by
a
signal
is
A
determined
by
the
signal
amplitude,
the
attenuation
factor
of
the
probe,
and
the
setting
of
the
VOLTS/DIV
switch.
Calibrated
deflection
factors
represented
by
the
VOLTS/DIV
switch
apply
only:
(1)
When
the
probe
attenuation
is
X1
or
when
the
input
signal
is
appreciably
above
1
kHz
with
AC
coupling
(the
dc
blocking
capacitor
attenuates
signals
below
1
kHz)
and
(2)
when
the
VARIABLE
(Volts/Div}
control
is
in
the
CAL
IN
position,
POLARITY
SWITCH
The
POLARITY
switch
provides
a
means
of
inverting
the
displayed
signal.
With
the
POLARITY
switch
set
to
+UP,
a
positive-going
signal
at
the
INPUT
produces
an
upward
deflection
on
the
crt
display.
With
the
POLARITY
switch
set
to
INVERT,
a
positive-going
signal
will
produce
a
downward
deflection
on
the
crt
display.
TRACE
IDENTIFICATION
AND
READOUT
FUNCTIONS
When
the
IDENTIFY
button
is
pressed,
the
trace
is
deflected
upward
about
0.3
divisions
to
identify
the
7A29
trace.
This
feature
is
particularly
useful
when
multiple
traces
are
dis-
played
on
the
cri.
In
oscilloscope
mainframes
with
readout,
~.
the
IDENTIFY
button
also
replaces
the
7A29's
deflection
“
factor
readout
display
with
the
word
“IDENTIFY”.
The
7A29
is
equipped
with
probe
encoding
circuitry
that,
when
used
with
a
coded
probe,
corrects
the
deflection
factor
readout.
VARIABLE
DELAY
(OPTION
4)
The
option
VARIABLE
DELAY
line
provides
a
means
for
delaying
the
signal
applied
to
the
INPUT
connector
up
to
+500
picoseconds
relative
to
another
7A29,
a
7A19,
or
7A19
Option
4.
When
the
Option
4
instrument
is
used
with
a
standard
7A29
(which
has
a
fixed
delay)
the
REV
JUN
1981
Operating
Instructions—7A29
VARIABLE
DELAY
control
can
be
used
to
match
the
signal
delay
time
of
both
units.
MATCHING
DELAY
TIMES
USING
TWO
7A29
UNITS,
ONE
HAVING
VARIABLE
DELAY
(OPTION
4)
In
some
applications
it
is
necessary
to
view
the
time
relationship
of
two
signals,
one
with
respect
to
the
other.
With
high
speed
signals,
the
delay
times
of
the
probes
and
amplifiers
can
distort
the
true
time
relationship
of
the
two
signals.
By
using
the
VARIABLE
DELAY
(Option
4),
the
delay
times
between
the
two
units
can
be
matched
to
within
a
few
picoseconds,
thus
giving
a
true
time
relationship
of
the
signals
being
viewed.
For
matching
delay
times
of
two
7429
units
with
probes,
proceed
as
follows:
1.
Install
the
standard
7A29
in
the
left
vertical
plug-in
compartment
of
the
ascilloscope.
2.
install
the
7A29
Option
4
in
the
right
vertical
plug-in
compartment.
3.
Connect
both
7A29
INPUT
connectors
to
one
of
the
signal
sources
and
adjust
the
time-base
unit
for
the
fastest
convenient
sweep
available.
4.
Set
the
oscilloscope’s
trigger
source
switch
to
Left
Vert,
and
verticial
mode
switch
to
Alternate.
5.
Set
both
7A29
units
to
the
same
deflection
factor
settings.
6.
Center
both
displays
vertically.
7.
Adjust
the
front-panel
VARIABLE
DELAY
knob
so
that
the
two
displays
are
superimposed.
The
delay
times
of
both
units
and
the
associated
cables
(or
probes}
are
now
matched,
2-5
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2
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