Tektronix AM 502 User manual

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BEFORE READING
070-1582-01
PLEASE
CHECK FOR CHANGE INFORMA TION
AT THE REAR OF THIS MANUAL
.
THIS MANUAL REPRINTED MARCH 1978
TEKTRONIX
A I~ 5®~
DIFFERENTIAL
AlUIPL1FIER
INSTRUCTION
MANUAL
Tektronix, Inc .
P.O . Box 500
Beaverton, Oregon 97077

Serial Number
First Printing MAY 1973

WARRANTY
This Tektronix instrument is
warranted against defective
materials
and
workmanship for one year
. Any questions with respect
to the
warranty should
be taken up
with your Tektronix Field
Engineer or
representative .
All requests for
repairs and replacement
parts should be directed to
the Tektronix
Field Office or
representative in your area .
This will
assure you
the fastest
possible service . Please
include the
instrument type number or part
number and serial
number with all
requests for parts or
service .
Copyright ~~
1973, 1978 by Tektronix,
Inc . All rights reserved :
Contents
of this publication may not be
reproduced in any
form
without
the permission of Tektronix,
lnc :
Products of Tektronix, Inc .
and its subsidiaries
are covered by U .S .
and foreign patents and/or
pending patents
.
TEKTRONIX,
TEK, SCOPE-M08fLE,
TELEQUIPMENT,
and
are registered
trademarks of
Tektronix, Inc . Printed
in U .S :A :
Specification and price
change privileges
are reserved .

REV . B MAR 1978
Page
SECTION
1

OPERATING
INSTRUCTIONS
SECTION
2

SPECIFICATION
AND PERFORMANCE
CHECK

2-1
WARNING
TABLE
OF
CONTENTS
The remaining
portion of this Table of
Contents lists servicing instructions
that
expose personnel
to hazardous voltages .
These instructions are for qualified
service personnel
only .
SECTION 3

ADJUSTMENT

3
- ~
SECTION 4

MAINTENANCE
AND INTERFACING
INFORMATION

4-1
SECTION 5

CIRCUIT DESCRIPTION

5-1
SECTION 6

OPTIONS

6'1
SECTION 7

REPLACEABLE ELECTRICAL
PARTS

7-1
SECTION
8

DIAGRAM
AND CIRCUIT BOARD
ILLUSTRATION

8-1
SECTION 9

REPLACEABLE MECHANICAL
PARTS AND
EXPLODED VIEW

9-~
CHANGE
INFORMATION
AM
502

AM
502 Differential Amplifier plug-in module
.
i!

REV .
B MAR 1978

Description
INTRODUCTION

Installation and Removal
The AM 502
is a dc-coupled differential
amplifier with
excellent common-mode rejection capabilities
and high
gain for
low voltage measurements . The do
offset capabili-
ty
permits nulling up to 1 volt dc, so
that low level, low
frequency signals impressed on
a do level can be
amplified without the
degradation often introduced by ac
input coupling .
High andlow frequency -3 dB points
can
be selected at
the front panel to suit the application
. Signal
inputs and
outputs are available at the rear
connector as
well as at
the front panel . A front panel
lamp indicates
most
overrange conditions of excessive
input signal,
excessive gain, or excessive
offset .
The input circuit
can be represented by approximately
1 megohm to
ground paralleled by
approximately 47
picofarads .
The input impedancecan be raised to
about
200
megohms with the removal of a jumper .
Overload protection is provided
by fuses in series with
the input which open when
large amounts of currentflow
due to
overloading conditions .
A STEP GAIN DC BALANCE
control is provided to
adjust for zero shift as thegain switch
is changed from one
position to another .
The DC
OFFSET COARSE and FINE controls give
offset up
to fi volt do potential difference
at the input
connectors . The amplifier internal
bias is changed to
accomplish the offset . The LF -3dB switch
mustbe in the
DC OFFSET position to actuate these
controls .
The HF -3 dB switch is used
to reduce the upper
bandwidth limit as
necessary to improve the signal-to-
noise
ratio when using the AM 502 in
low-frequency
applications . The LF -3 dB control
increases the lower
bandwidth frequency .
Use of the pre-charging
feature prevents surge
currents, due to
charging the ac coupling capacitor,
from
damaging the circuit under test .
REV . CMAR
1978
Overheating
Section 1-AM 502
OPERATING
INSTRUCTIONS
CAUTION
Turn the power module off
before inserting the plug-
in ; otherwise, damage may occur
to the plug-in
circuitry . Because of the high current
drawn by the
AM 502, it is also
recommended that the power
module be turned
off before removing the AM 502
.
Refer to Fig .
1-1 . Check to see that
the plastic
barriers
on the interconnecting jack of theselected
power
modulecompartment match
the cut-outs in
the AM 502 circuit board edge
connector .
Align the AM 502
chassis with the upper and
lower
guides of the selected
compartment . Push
the module in
and press firmly to
seat the circuit
board in the inter-
connecting
jack .
To remove the AM 502,
pull on the release latch
located
in the lower left `corner,
until the interconnecting
jack
disengages and the
AM 502 will slide out .
Controls and Connectors
Refer to
Fig . 1-2 . Even though the
AM 502 is fully
calibrated
and ready to use, the
functions and actions of
the
controls and connectors should be reviewed before
attempting to use it . Pull the
Power switch on the power
module to apply power to the
AM 502 . The POWER
indicator light indicates when
power is applied to the AM
502 .
OPERATING
CONSIDERATIONS
The AM 502 is
designed to operate at
an ambient
temperature
from 0° to+50°C . However,
when operating
several power supplies in a multi-plug-in
power module,
especially
at low output voltages,
orwhen operating close
to
other heat-producing equipment,
internal temperature
may exceed safe limits and
actuate a thermalcutout in
the
power module . Refer to
the power module instruction
manual for more
complete information .

Operating Instructions-AM 502
Fig . 1-1 . Plug-in installation and removal .
Input Connections

Probes
Consider the change in the source operating
characteristics due to loading by the signal input cables .
The circuit
at
the input
connectors can be represented by
approximately
1 megohm to ground paralleled by ap-
proximately 47 picofarads . Two feet of 50 ohm coaxial
cable increases the parallel capacitance by
about 60
picofarads, which could be excessive in many situations .
To minimize these effects, use a higher impedance cable
or an attenLator probe .
Bottom
G roove
Input Overloading
Slot
AM 502
(1412)1582-2
Unshielded test leads canbeused to connect the AM

Attenuator probes decrease the
resistive-capacitive
502 to a signal source when a high-level, low-frequency

loading
of
a signal source .
They also
extend the measure-
signal
is
monitored
at a
low impedance point . However,

ment range of the AM 502 to substantially highervoltages .
when any of these factors is missing, it becomes in-

Some measurements require a higher resistance input to
creasingly important to use shielded signal cables . In all

the AM 502, with very little source loading or signal
cases, the signal-transporting leads should be kept as

attenuation . In such situations use a FET probe or the
short as practical .

high-impedance input provision of the AM 502 . Contact
your Tektronix Representative for further
information
on
When making single-ended
input measurements
probes .
(conventional amplifier operation), be sure
to
establish a
common ground connection between the device under
test and the AM 502 . The shield of a coaxial cable is

High Impedance Input
normally used for this purpose . See Fig .1-3 for reference .

To
raise the internal input impedance of the AM 502 to
Push the GND button for the
input not connected to the

about 200 megohms, remove the P40 plug (Fig .3-1) . Make
device under test .

certain the attenuator is in the NORM mode . Signal source
impedance now becomes an important factor
. For exam-
In some cases differential measurements require no

pie, a 100 picoampere gate
current through 10 megohms
common chassis ground connection, and therefore are

produces
a one-millivolt offset . This offset may result in
less susceptible to interference by ground-loop currents .

significant error when small voltages are measured .
When measuring unknown do voltages, push the=100
pushbutton in, and start with the 100 position on the GAIN
switch . Increase the GAIN switch setting and finally
release the =100 pushbutton until a suitable output signal
is
obtained . If the input circuit of the AM 502 is overdriven,
large amounts of current will flow, opening the protective
fuses .
REV . B MAR
1978

STEPGAIN DC BAL Control
Variable Gain
Control con-
tinuously
variable .
When lit, indicates most over-
range conditions .
AC Pushbutton
Selects the input signal (ac or
dc) into the negative side
of the
preamplifier
.
+ Input Connector
BNC connector for the
positive side of
the amplifier .
GND Pushbutton
Grounds
+ amplifier input .
G~ Fund Binding Post
- Input
Connector
BNC connector for the
negative side of the amplifier .
REV . B MAR 1978
Release Latch
Pull
to
remove plug-in .
100 Pushbutton
Divides GAIN switch setting
by 100 .
Ground
- amplifier input .
Fig . 1-2 . AM 502
controls and connectors .
Operating
Instructions-AM 502
DC
OFFSET COURSE and FINE
Controls
Provides internal
offset of
approximately
t1 V to input
signal .
LF -3dB switch must
be in the DC OFFSET
position
for controls to
operate .
When lit, indicates power
is
applied .
HF --3dB Switch
Selects
upper -3dB point of
the amplifier .
LF -3 dB Switch
~ ~ j ~''~

Selects lower -3dB point of
the amplifier and activates DC
OFFSET controls .
OUTPUT Connector
Selects the
input signal (ac or
dc) into
the positive side of the
preamplifier
.
7 582-9

Operating Instructions-AM 502
7-4
Waveforms applied to the (+) and
(-)
input
connectors .

The resultant display .
Two signals of
different amplitude .
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Signal (square wave) with an
inter-
fering
line-frequency component is
applied to the (+)input . The interfering
signal (sine wave) is also applied to the
(-) input connector .
Fig .1-3 . Waveforms
showing differential rejection ofa
common-mode signal . Resultant Waveforms show
the difference between
the two signals .
Step Gain DC Balance
1582-5
Output Connections

If this control is misadjusted,
the do output level will
Make output connectionsusing
a bnc to dual binding

shift as the GAIN switch
position is changed . Push both
post connector, or
a coaxial cable with at least onebnc

GND buttons and place the
GAIN switch in the 100
connector
.
To
prevent current limiting in theoutput
stage,

position . Rotate the GAIN
switch from stop to stop while
do not load
the output with less than 250 ohms .
Output

adjusting the STEP
GAIN DC BAL control for nodo
shiftat
current is limited to 20 milliamperes .

the OUTPUT
terminal .
REV . B MAR 1978

DC Offset Coarse and Fine
Use
these controls to offset up to f1 volt do potential
difference at the input connectors . The amplifier internal
bias is changed to accomplish the offset . The
differential
rejection capabilities of the AM 502 are
not affected . The
LF -3dB switch must be in the DCOFFSET
position to
activate these controls .
HF and l-F Bandwidth Reduction
Use the HF-3dB switch to reduce the upper bandwidth
limit, as necessary, to improve the signal-to-noise ratio
when using the AM 502 in low-frequency applications .
The LF -3dB control increases the lower bandwidth
frequency . Use this control to reduce do drift, when
raising the lower bandwidth does
not undesirably reduce
the bandwidth for the signal being measured .
Pre-Charging
Use of this feature prevents
surge currents, due to
charging the
ac coupling
capacitor in the AM 502, from
damaging the circuit under test
. Before connecting the
AM
502 to
a signal containing a do component, push the
AC and GND pushbuttons . Connectthe input to the circuit
under test . Wait about one second for the coupling
capacitor to charge . Release the GND pushbutton, and
the coupling capacitor is charged to the value of the do
voltage to be measured .
Differential Operation
A differential measurement is made by
connecting
each of the two inputs to
selected points in the test circuit .
The input to the amplifier will then be the difference in
voltage of the two selected points . Consideration should
be given to the proper connection
method used between
the AM 502 and the circuit under test
; otherwise improper
measurement results may occur
. See Fig . 1-4 for
reference .
Differential voltage measurements are made by apply-
ing the signals to the +input and -input connectors . Set
the input coupling switches to the same position, AC or
DC, depending on
the measurement being
made .
In
differential
measurements,
only the
voltage
difference
between the two signals is
amplified
. Common mode
signals (common in amplitude, phase, and frequency) are
rejected . See
Fig .
1-3
A, B,
and C
for reference
.
REV . B MAR
1978
(A) Right
circuit
under
test
(B) Wrong
I

I'
___J
circuit
under test
(C) Wrong
I
I

probe shields
I

tied
together
i probe shields
should not be
floating
Operating Instructions-AM 502
U
common ground
I
I

\
I
___J
circuit

probe shields should
under test

not be grounded to
equipment under test
Differential
Amplifier
Differential
Amplifier
I
Differential
`,

Amplifier
(0931)1582-13
Single-ended measurements often yield unsatisfactory

Fig . 1-4 . Connecting a differential amplifier to a signal source .
results because of the interference resulting from
ground-
loop currents between the
AM
502 and
the device under

capacitor,
which
could
limit the low-frequency response .
test . In other cases, it may be
desirable to eliminate a do

The limitations of single-ended measurements are effec-
voltage by
means other than the use of a blocking

tively eliminated by using differential measurements .

Operating
Instructions-AM
502
DC
Offset Operation
By
using the FINE and COARSEDC OFFSET
controls,
it is
possible to use the AM 502 differentially in a
slide-back
mode, to
observe a small signal whose do
potential
difference may be considerable . The
offset voltage is
continuously adjustable from plus
1 volt to minus 1 volt,
and is internally available
for all of the GAIN switch
positions . The LF -3dB
switch must be in the DC OFFSET
position to activate the
offset circuit .
Common Mode Rejection
Ratio
The ability of the AM 502 to
reject common-mode
signals is indicated by the
common-mode rejection ratio
(cmrr) . For example, assume
that a signal consists of
unwanted 60 hertz
at 10 volts peak-to-peak (common
mode
connected to both inputs), plus adesired
signal at 1
millivolt peak-to-peak (differentially
connected to one
input) . The AM 502 gain is set at 200 .
The output of the AM
502 shows the desired signal at
an amplitude of 0 .2 volt (1
millivolt X 200), and the 60
hertz signal is viewed at an
amplitude of 0 .02 volts .
The cmrr in this application is
100,000 to 1 . This figure
is calculated by multiplying
the
value of the
common-mode signal (10 volt) by thegain of
the amplifier
(200) for a product of 2000 volts .
This product
is
divided by the observed 60 hertz voltage
at the output
(0 .02 volt) and result is the
cmrr, 100,000 to 1 . It would, of
course be impossible to
view the 1 millivolt signal
superimposedon the 60
hertz signal by using single input
methods .
Degradation of Common
Mode Rejection
There are a number
of factors that degrade common-
mode rejection ratio
(cmrr) . The principal requirementfor
maximum rejection is
for the common-mode
signal to
arrive at the input
FET gates at the same phase
and
amplitude . A
difference of only 0 .01% in the
attenuation
ratios of the
input attenuators will reduce
the rejection
ratio to
10,000 to 1 . Also, any difference
in source
impedance will degrade the rejection
ratio . Figures 1-5
and 1-6 show common-mode
rejection degradation due to
differences
in source impedance . The
frequency of the
common-mode signal also affects
the common-mode
rejection ratio . Generally, as the frequency
of the input
signal
increases, the common-mode
rejection ratio is
more
difficult to maintain .
1-fi
source Z
= 10 kfl
v
equal 10 .0-volt
A, 9 .90 volts
_~ _
T
B, 9 .95
volts
A, 9 .9990
volts

'
-r
v
1
T
B, 9 .9995 volts
4t ~-
equal 10-volt
generators B-A= .0005vo1t
source Z
= 5 kf2
$r
1

~i

I - j Differential
Amplifier
generators

,_--
I
B-A=0 .5volt
ApparentCMRR= ~ ~ =200 :1
Differential
source A

-

Amplifier
= 100
fl
source Z
= 50 f2
L I ApparentCMRR=
.000SV
-20°000 :1
1582-6
Fig . 1-5 . Relationship
of test point source
Impedance to the
amplifier input
Impedance and the apparent CMRR
caused by (A)
large difference
between test-point
Impedances and (B) low
impedance
test points .
REV . C MAR 1978

9 meg

I

I

(Apparently
ProbeA

I

~

I Probe
Tolerance CMRR
1
meg
1
meg
~~ I
9 meg I I
ProbeB L__-__J
FIg .1 ~ .
Simplified input circuit and table showing
the change In
apparent CMRR
due to 10X probes that are within
1, 2, and S% of
their attenuation
values (with matched 1 megohm
resistors) .
A +1~° 50 :1
B -1% 50 :1
A +2% 25 :1
B -2°h 25 :1
A
+3% 16 :1
B -3% 16 :1
(0787)15823
Operating Instructions-AM
502
The high frequency cmrr will also
depend upon the
signal source impedance,
since various shunt
capacitances
between the source and the input gate
must
charge
and discharge through that impedance .
Outside influences such as magnetic fields
can also
degrade
the performance, particularly
when low level
signals are involved . Magnetic
interference may be reduc-
ed by using
identical signal transporting leads to the
two
inputs .
Twist the two leads together over as
much of their
length as possible . Low-frequency measurements can be
similarly protected by using ashielded cable
that contains
a
twisted pair of conductors .

Performance Conditions

Items listed in the Performance
Requirements column
The
electrical characteristics are valid
only if the AM

of the Electrical
Characteristicsareverified by completing
502 has
been calibrated at an ambient
temperature

the Performance Check in
this manual . Items listed in the
between +20° C and +30° C and is
operating at an ambient

Supplemental Information column
are not verified in this
temperature between 0° C and +50°
C unless otherwise

manual ; they are either
explanatory notes or performance
noted .

characteristics for which no
limits are specified .
Gain
Normal Mode
=100 Mode
Variable
Range
Frequency Response
Direct Coupled
AC Coupled
Bandwidth
HF -3dB
Accu racy
LF -3dB
Accu racy
REV . B MAR
1978
Characteristics
SPECIFICATION
ELECTRICAL
CHARACTERISTICS
Performance Requirements
100 to 100,000
within 2%,
10 steps in 1, 2,
5 sequence .
1 to
1000 within 2% .
do to 1
MHz
2 Hz or less,
at lower
frequency
-3dB point to 1 MHz .
100 Hz to 1 MHz, 9 steps in
1-3 sequence .
+1dB, -2dB
+1dB,
-2dB
SPECIFICATION
AND
PERFORMANCE
CHECK
Table 2-1
0 .1 Hz to 10
kHz 6 steps in
1-10
sequence .
Section 2-AM
502
Supplemental Information
Continuously variable
uncal-
ibrated gain to at least
2 .5 times
the calibrated gain
setting .
With Gain control set to 20K
or less,
selectable HF -3dB
points
are within +1dB, -2dB .
Upper
-3dB point reduces to
500 KHz at 50K gain,
and
250 KHz at 100K
gain .
Reference approximately 5 .0 V
peak-to-peak output at 1 KHz .
Reading range -2dB to -5d8
.
Reading
range -2dB to -5dB .

Specification and Performance
Check-AM 502
2-2
Characteristics

~

Performance Requirements

~

Supplemental Information
Output
Voltage Swing

I

t5 V .
Current

.

I

I

f20 mA
R °

I

I

5 f2 or less
Minimum Load

I

I

250 f2
Impedance
Common
Mode
Normal Mode
Range

t5 V .
Rejection Range

I

100 dB, do to 50 kHz .

I

Direct coupled with inputs
shorted together .
=100 Mode
Range

I

t50
V .
Table 2-1 (Con't)
Rejection Range

I

50
dB, do to 50 kHz .

I

Direct coupled
with
less
than
100
V peak-peak sine-wave input .
DC Offset
Range

(

At least + and - 1 V .
Maximum Safe Input
Voltage
Direct Coupled
Normal Mode

I

I

15 V (dc plus peak ac) to
5 MHz or less .
=100 Mode

I

I

350 V (dc plus peak ac) to
5 MHz or less .
AC Coupled

I

I

350 V (dc plus
peak ac) with
coupling capacitor precharged .
Maximum Input Gate
Current (each input)

I

50 pA at 25°C .
Noise (Tangentially

25 pV or less .

With
25
f2
or
less source
Measured)

I

resistance, from 5 Hz to 1 MHz .
Voltage Drift with
Time
Short Term

I

I

10 pV (peak-to-peak) per hour
Long Term

~

~

20 NV (peak-to-peak) per hour
.
Voltage Drift with

(

(

100
pV per °
C .
Temperature
Input R and C

I

Resistance, 1 Mfg .
Capacitance,
Approximately 47 pF .
REV . B
MAR 1978

Vibration
Shock
Overall Dimensions
(measured at
maximum points)
Height
Width
Length
Net Weight
(Instrument Only)
REV . B
MAR 1978
Characteristics
Tem
peratu re
Operating
Storage
Altitude
Operating
Storage
Operating
and
Non-operating
Operating and
Non-operating
Table
2-2
ENVIRONMENTAL
Specification and Performance Check-AM 502
0° C to +50°
C
Table 2-3
PHYSICAL
CHARACTERISTICS
To
15,000 feet ;
maximun
operating
temperature
decreased
by 1 ° C/1000
feet from 5000
to 15,000 feet
.
To 50,000 feet
.
Information
-40°
C to +75° C
With
the instrument
complete
and
operating, vibration freq-
uency swept from 10
to 55 to
10 Hz at 1 minute
per sweep .
Vibrate 15 minutes
in each of
the three
major axes at 0 .015
inch
total displacement .
Hold
10
minutes at any major
reson
anace, or
in none, at 55
Hz .
Total
time 75 minutes .
30 g's 1/2
sine, 11 ms
duration,
2 shocks
in each
direction along
3
major axes, for a
total of 18
shocks
.
Characteristics

~
Information
5 .0
inches
12 .7
centimeter
2 .5 inches
6 .35 centimeter
11 .8 inches
30 .0
centimeter
1 .8 lbs .
.82
kilograms
2-3

Specification and
Performance Check-AM 502
Introduction

Test Equipment Required
This procedurechecks the electrical characteristics of

The following test equipment, orequivalent, is required
the AM 502 that appear in the Specification section of this

to perform the performance check . Test equipment
manual . If the instrument fails to meet the requirements

characteristics listed are the minimum required to verify
given

in

this

performance

check,

the

calibration

the performance of the equipment under test
. Substitute
procedure should be performed .
This procedure can also

equipment must meet or exceed the stated requirements .
be used by an incoming inspection facility to determine

All test equipment is assumed to be operating within
acceptability of performance .

tolerances .
The electrical
characteristics in Section 2 are valid only
if the AM 502
is
calibrated at an ambient temperature of
+20° C to +30° C and operated at an ambient temperature
of 0°C to +50°C . Forced air circulation is required for
ambient temperature above +40°C .
Special test
devices are used where necessary to
Tolerances that are specified in
this performance check

facilitate
the procedure . Most of these are available from
procedure apply to the instrument under test
and do not

Tektronix,
Inc
.
and can be ordered through your local
include test equipment error .

Tektronix Field Office or representative .
Oscilloscope
Description
Power Module
Calibration Gen-
erator
Function Generator
Termination
Attenuator, 10X
(4 required)
Coaxial cable
(2 required)
bnc .
' Requires TM 500-Series power module
2- 4
PERFORMANCECHECK
Table
2-4
LIST OF TEST EQUIPMENT REQUIREMENTS
Performance
Requirements Applications

Example
Bandwidth, do to 2 MHz ;

Used throughout pro-

TEKTRONIX 5110 .
Minimum deflection

cedure to provide

5A13N,
5B10N .
factor, 20 mV/div ;

display .
sweep rate, .2 ms/div
to 1 Ns/div ; accuracy,
within 3% .
Three compartments or

All tests
more .
Amplitude calibration,

Amplifier gain check
5 mV to 10 V
;
accuracy,
f0 .25% into 1
M(2 ;
out-
put, square
wave at
approximately 1 kHz .
Waveforms, sine and

Signal generation
square ; voltage ampl-

for cross neutral-
itude, 10 V p-p ; freq-

ization and high
uency
range, 1 kHz
to

frequency cmrr
50
kHz ; accuracy, with-

check .
i n 3% .
Impedance, 50 f2
;
accur-

Output
termination
acy,
within 2% ; conn-

for signal gen-
ectors, bnc .

erator .
Impedance, 50 f!
;
accura-

Output attenuation
cy, within 2% ; conn-

for signal gen-
ectors, bnc .

erator . Noise check .
Impedance, 50
!Z
;
length,

Provides signal
36 inches ; connectors,

interconnection .
TEKTRONIX TM 503 or
TM 504 .
TEKTRONIX
PG
506
Calibration
Generator .'
TEKTRONIX FG 501
Function Generator
.'
Tektronix Part No .
011-0049-01
Tektronix Part No .
011-0059-02
Tektronix Part No .
012-0057-01
REV . B MAR 1978

Preliminary Procedure

Time Base Plug-In
1 . Ensure that all test equipment and the AM 502 under
test are suitably
adapted to the line voltage to be applied
.

Time/Div

.5 ms
Refer to the
installation section of the power
module

Variable

(cal in)
manual .

Triggering
+ Slope

selected
2 .

Ensure that all test
equipment is suitably adapted to
the applied line voltage .
3 . Install the AM 502
into the power module, and if
applicable, install
the TM 500 series test equipment
into
the test
equipment power module .
4 . Connect the equipment under test and
the test

Amplitude

.5 V
equipment to a suitable line voltage source
. Turn all
equipment on and allow at least
20 minutes for the
equipment to stabilize .
Initial Control Settings
Set the following controls
during warm-up time :

The oscilloscope
vertical
amplifiersystemgain,
the 50-ohm
termination, and 50-ohm
attenuator
are
required to be calibrated within 0 .5%
ac
AM 502

curacy prior
to proceeding with Steps
1 and 2 .
The PG 506
calibration generator
may be used
STEPGAIN DC
BAL

midrange

to set the
system to 0 .5% accuracy .
=100

pushbutton out
DCOFFSET
FINE and COARSE

midrange

1 .
Check Amplifier Gain .
GainAccuracy is within
GAIN

100

2%
CAL

fully
clockwise (cal)

a .
Connect the calibration
generator to the vertical
HF -3dB

1
MHz

amplifier
input, using a 50-ohm
cable .
LF -3dB

DC
OFFSET
+ AC

pushbutton out
+ GND

pushbutton out

b . Set the calibration
generator for a
five-division,
- AC

pushbutton
out

square-wave
display ; set the Deflection
Error control for
- GND

pushbutton in

zero percent
error . Disconnect the
50-ohm cable from the
vertical amplifier input .
Oscilloscope
Intensity, Focus

Set
for well-defined trace
and
normal brightness .
Vertical Amplifier
Specification and Performance
Check-AM 502
Mode

p-p auto
Coupling
ac
Source

internal
Position

Set so trace starts at left
side
of graticule .
Display Mode

main sweep
Magnifier

X1
Calibration Generator
PERFORMANCE
CHECK
PROCEDURE
NOTE
c .
Connect the calibration generator
to the AM 502 +
input
connector through a 50-ohm
termination, and a50-
ohm 10X attenuator, using a
50-ohm cable .
d . Connect
a 50-ohm cable from the
AM 502 OUTPUT
connector
to the vertical amplifier
input connector .
e . Adjust the AM 502 DC OFFSET
controls (FINE and
Volts/Div

1 V

COARSE) until the OVER
RANGE indicator light goes out
.
+ Input

do

Position the crt display
to the center of the
graticule with
Variable

fully clockwise
(cal)

the vertical
amplifier position control .
2-
5

Specification and Performance Check-AM
502
f
. Check - using the AM 502 GAIN and calibration
generator amplitude settings given in Table 2-5,
check the
vertical deflection within the given
limits
.
100
_2_00
500
1K
2K
5K
10K
20K
50
K
100 K
NOTE
g .
Check-repeat parts d and e of this step .
The OVER RANGE
indicator light must remain
off during all switch settings . Adjust fhe DC
OFFSET controls as required
during the check

h .
Disconnectthe50-ohmtermination,lOXattenuator,
procedure .

and cable .
NOTE
Install both plug-in side
covers and insert plug-
in into power
module for checking gain below
5K
setting to minimize noise on the display .
Table
2-5
AMPLIFIERGAIN ACCURACY

b .
Set the
AM
502
=100 pushbutton out ; the +input
and -
input
AC
and GND pushbuttons out, and the GAIN
Calibration

switch to 100 .
AM
502

AM 502

Generator

Vertical
GAIN

HF-3dB

Amplitude

Deflection
Setting

Switch Setting

Setting

in Divisions

c . Set the AM 502 HF -3dB switch to .3 MHz and
the LF
-3dB switch to DC .
1MHz I
1V
1
MHz

.5
V
1
MHz

.2 V
1MHz .1V
1 MHz

50
mV
1 MHz

20
mV
10 kHz

10 mV
10
kHz

5 mV
10 kHz

2 mV
10 kHz

1 mV
4 .9 - 5 .1
4 .9 - 5 .1
4 .9 - 5 .1
4 .9 - .5 .1
4 .9 - 5 .1
4 .9 - 5 .1
4 .9 - 5 .1
4 .9 - 5 .1
4
.9 - 5 .1
4
.9
- 5 .1
2 .
Check +100 Amplifier Gain
Accuracy . Gain
Accuracy is within 2%
a .

Disconnect
all cables and repeat Step 1 parts a, b, c,
and d .
2-6
f . Disconnect the 10X attenuator from the
AM 502 +
input connectorand connect it to the -
input connector .
Push in the+ input GND pushbutton
and push and release
the - input GND pushbutton
.
3 . Check Common Mode
Rejection . Rejection Ratio
is 100 dB, do to 50
kHz
a . Connect a dual-input connector cable between the
AM 502 + input and - input connector
.
d . Set the vertical amplifier deflection factor
for 10
mV/div .
e . Connect a 50-ohm cable
from the function
generator to the center connector of
the dual-input
connector . Set the
function generator for a 10 V, 50 kHz
sine-wave output signal .
f . Check - the crt display for one division of
vertical
deflection or less .
4 . Check =100 Common
Mode Rejection . Rejection
Ratio is 50
dB,
do
to 50 kHz
b . Set the AM 502
GAIN switch to 10Kand the HF -3

a . Disconnect the 50-ohm cable from
the function
dB switch to 1 MHz ; push
in the =100 pushbutton .

generator and connect it to the
calibration generator
output . Press in the =100 pushbutton
.
c . Set the calibration generator amplitude
control
to
0 .5 V . Adjust the AM 502 DCOFFSET
control (FINE and

b . Set the
calibration generator for a 100 volt, square-
COARSE) until the OVER
RANGE indicator lightgoes out .

wave output
signal .
d .

Position the crt display to thecenter of the graticule

c .

Check-crt display
for
3 .1

divisions or

less of
with the vertical amplifier position control .

vertical deflection .
e . Check-the crt display amplitude for 4 .9 to 5 .1

d . Disconnect
the dual-input connector and 50-ohm
divisions . ~

cable
from the AM 502 input connectors .

5 . Check HF -3 dB Bandwidth
. Accuracy is +1 dB,
-2 dB
a . Set the AM 502 HF -3 dB switch to 1 MHz, and the -
input pushbutton to GND .
b .

Setthe vertical amplifier deflection factor to
1 V/div,
and the time-base sweep rate to
1
ms/div
.
c . Set the function generator controls for a 50 mV, 1
kHz sine-wave output signal . (Use appropriate attenuation
to eliminate input overdrive condition
.)
d .
Connect a
50-ohm
cable from the function
generator to the AM 502 + input connector . Adjust the
vertical deflection amplitude for a five-division display .
e . Set the function
generator output frequency to 1
MHz .
f
.
Check-the
amplitude of the crt display for 3 .15 to
3 .85
divisions .
NOTE
The specification in
part f of this step must be
met before proceeding
with part g of this step .
g . Check-the remaining settings of the HF -3 dB
switch, using Table 2-6 as reference .
(Change time-base
sweep rate as needed for
lower frequencies .)
.3 MHz
.1 MHz
30 kHz
10
kHz
3 kHz
1 kHz
.3 kHz
.1 kHz
Table 2-6
AM 502

Function

Vertical
HF-3 dB

Generator

Deflection
Switch Setting

Output Frequency

in Divisions
300
kHz
100 kHz
30
kHz
10 kHz
3 kHz
1 kHz
300 Hz
100 Hz
3 .15 - 3 .85
3 .15
-
3 .85
3 .15 - 3 .85
3 .15 - 3 .85
3 .15 - 3 .85
3 .15 - 3 .85
3 .15 - 3 .85
3 .15 - 3 .85
Specification and Performance
Check-AM 502
6 . Check LF -3 dB Bandwidth . Accuracy is +1 dB,
-2 dB
a . Check-the settings of the LF -3dB switch, using
Table 2-7 as reference . Adjust the time-base
sweep
rate to
obtain an appropriate display .
Table
2-7
LF -3 dB BANDWIDTH ACCURACY
AM 502

Function

Vertical
HF-3dB

Generator

Deflection
Switch Setting

Output Frequency

in Divisions
10 kHz

10 kHz

3 .15 - 3 .85
1 kHz

1
kHz

3
.15 - 3 .85
.1 kHz

.1 kHz

3 .15 - 3 .85
10 Hz

10 Hz

3 .15 - 3 .85
1 Hz

1 Hz

3 .15 - 3 .85
NOTE
The components used in the .1 Hz position are
also used in the other
positions of the switch ;
therefore, the tolerance of the .1 Hz position is
checked .
b .

Press
in the AM 502 + input AC pushbutton . Set the
function generator controls for a2 kHz output
signal .
c . Check-the amplitude of
the crt display for 3 .15 to
3 .85 divisions .
d .
Disconnect the 50-ohm cable from the AM 502 +
HF-3dB BANDWIDTH ACCURACY

input
connector and connect it to the -input connector .
e . Press in the AM 502
+
input
GND pushbutton and-
input AC pushbutton . Press to
release the -input GND
pushbutton .
f . Check-the amplitude of the crt display for 3 .15 to
3 .85 divisions .
g . Set the
LF
-3 dB
switch to the DC OFFSET position .
Press in the
AM 502 - input GND pushbutton .
h . Disconnect the 50-ohm cable from the AM 502 -
i . Set the HF-3dB switch to 1
MHz .

input connector .
2- 7

Specification
and Performance Check-AM
502
7 . Check
Overall Noise (Tangentially Measured)
a .
Set the AM 502 GAIN control to 100K
; press in to
release the + input AC and GND
pushbutton, and the -
input AC pushbutton .
. :~ , . .
b . Set the vertical
amplifier deflection factorto 5V/div .
Set the time-base
sweep rate to 10 ~s/div, and the
trigger
source
switch to external .
c . Connect
a 50-ohm termination to the AM 502
+
input connector ;
connect four series-connected
10X
attenuators to
the 50-ohm termination .
d . Connect a 50-ohm cable
from the calibration
generator fast-rise output
connector to the end of the
attenuator
string . Set the pulse duration control
for 1 ms .
e . Adjust the AM 502 DC OFFSET
controls (FINE and
COARSE) until the OVER RANGE indicator
light goes out .
f . Adjust the
calibration generator pulse amplitude
control and observe two noise bands as
shown in Fig . 2-1 A
(remove one attenuator if necessary, to
produce the
desired display) .
g . Decrease the calibration generator
pulse amplitude
until the noise bands just merge . See
Fig . 2-1 B .
h .
Remove three of the attenuators and connect the
signal through the 50-ohm attenuator (including
the 50-
ohm termination), to the
vertical amplifier input and
measure the pulse
amplitude . Calculate the tangentially
measured display noise as
follows :
Signal level (measured in part h)
Noise (in NV) =

Attenuation Removed
Typical figures are :
i saa-22
Fig . 2-1 . Typical display of
(A) two noise bands and (B)
noise
bands merged .
i . Disconnect all cables and equipment
.
12 mV
=
12 x 10~ - 12 uV of noise

This completes the
Performance Check of the AM 502
10 -
Differential Amplifier .