Tektronix PG 506 User manual

PG 506
CALIBRATION
GENERATOR
(SN B040000
AN D U P)

T~Jckronbc
INSTRUCTION
MANUAL
Tektronix, Inc .
P .O . Box 500
Beaverton, Oregon

97077

Serial
Number
COMMITTED TO
EXCELLENCE
PLEASE
CHECK FOR CHANGE
INFORMATION
AT THE
REAR OF THIS
MANUAL .
PG
506
CALI
BRATION
GENERATOR
(SN 8040000
AID UP)
070-3383-00

First Printing NOV
1980
Product Group 75

Revised
APR
1984

Copyright © 1980 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 panel
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
:
8000000

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

TABLE OF
CONTENTS
Page
LIST OF
ILLUSTRATIONS ................ . . ii
LIST OF TABLES . ... ..................... . .
Section
1 Specification . . ................
1-1
Section 2 Operating
Instructions ........... 2-1
WARNING
THE
FOLLOWING SERVICE INSTRUCTIONS ARE
FOR
USE
BY QUALIFIED PERSONNEL ONLY . T O
AVOID PERSONAL INJURY, DO NOT PERFORM
ANY SERVICING OTHER
THAN THAT
CONTAINED IN
OPERATING INSTRUCTIONS
UNLESS YOU
ARE QUALIFIED TO DO SO .
Section 3 Theory of Operation .............
3-1
Section 4
Calibration Procedure ............ 4-1
Performance Check
.... ....... 4-3
Adjustment Procedure .... ..... 4-12
Section s Maintenance ............. .....
5-1
Section 6
Options ................. . . . . . 6-1
Section ? Replaceable Electrical Parts . . . . ...
7-1
Section 8
Diagrams and Illustrations ......... 8-1
Section 9

Replaceable
Mechanical Parts ...... 9-1
PG 506 (SN 8040000 & up)

PG 506 (SN
8040000 & up)
LIST O F
I LLUSTRATI ONS
Fig .
No .

Page
PG 506 Calibration
Generator ........

vi
2-1

Plug-in installation and
removal ....... 2-2
2-2

PG
506 controls and connectors ......
2-3
2-3

OutputsignalsfromthePG
506Cafibration
Generator ............ .... ......
2-6
2-4

Risetime Berating
graph ...... . ..... 2-7
2-5

Typical
waveforms showing correct
and
incorrect compensation
adjustments ... 2-8
2-6

Typical
lowfrequency response curve . .

2-9
2-7

Distortion of square waves
caused by low
frequency effects .................

2-9
2-8

Typical waveform
showing ringing at front
corner ... .
.... .................
2-9
3-1

DVM timing diagram for a negative
input to
the integrator U460 .... ............
3-4
4-1

Attenuator
connections for current source
4-4
4-2

Typical response curve of
sampling system 4-9
4-3

Typical sampling
oscilloscope response
display ... .
.... . ... ........... .
4-10
4-4

Typical
sampling oscilloscope response
display ...... ........ .
......... 4-10
4-5

Adjustment
locations for the A1 Main
circuit board .... ............ ....
4-13
4-6

Adjustment locations
for the A2
DVM/Period
circuit board . . .........
4-14
4-7

Adjustment
locations for the
A3 Fast Rise
Output circuit board .......... .....
4-16
4-8

Typical response curve
as displayed on the
sampling system
............... . .
4-17
4-9

Typical response curve as displayed on
the
sampling oscilloscope . . ............

4-17
5-1

Pin assignments
for the PG 506 (rear view,
partial) .......
........ . . .......
5-3
5-2

Main interface board (partial)
showing
amplitude and trigger
output cable
connections ............ ....... ..
5-4

LIST OF TABLES
Table
No .

Page
1-1

Electrical
Characteristics . . .........

1-1
1-2

Environmental Characteristics .......

1-3
1-3

Physical Characteristics . . . ........

1-3
2-1

Output Load Vs . Voltage Out ........

2-5
4-1

Test
Equipment Required .... ......

4-1
4-2

Standard Amplitude (into 1 Mfg) Within
0 .25%, fl ~V ............. ......

4-3
4-3

100 V do Range DEFLECTION ERROR
Resolution Tolerances ...... ......

4-5
4-4

10 V do Range DEFLECTION
ERROR
Resolution Tolerances ....... .....

4-5
45

Standard Amplitude into a 50 O Load . .

4-5
46

Fast Rise and High Amplitude Output
Period ..... ..................
.

4-7
5-1

Selected Component Criteria ....... .

5-1
5-2 RelativeSusceptibilitytoStaticDischarge
Damage .... . ..................
5-5
PG 506 (SN 8040000
& up)

PG 506 (SN 8040000
& up)
OPERATORS SAFETY
SUMMARY
The general safety information
in this part ofthe summary

supply conductors
or between either supply
conductor
is for both operating and
servicing personnel . Specific

and
ground . A protective ground
connection by way of the
warnings and
cautions will be found throughout
the

groundingconductor in
the power cord is essential for
manual
where they apply, but may not appear
in this

safe operation
.
summary .
TERMS
This product is grounded through the
grounding conduc
In This
Manual

for of the power cord . To
avoid electrical shock, plug the
power cord into
a properly wired receptacle before
CAUTION statements
identify conditions or practices
that

connecting to
the product input or output terminals .
A
could result indamagetotheequipmentorotherproperty
.

protective ground connection by way of
the grounding
conductor in the power cord is
essential for safe opera
WARNING statements
identify conditions or practices

tion .
that could result
in personal injury or loss of life .
As Marked on
Equipment
CAUTION indicates a personal
injury hazard not im-
mediately accessible
as one reads the marking, or a
hazard to property
including the equipment
itself .
DANGER indicates a personal
injury hazard immediately
accessible as one reads the marking
.
SYMBO LS
To avoid fire hazard, use
only the fuse of correct type,
voltage rating
and current rating as specified in
the parts
In This Manual

list for your product .
This symbol indicates where
applicable
QI

cautionary or other
information is to be
found .
As Marked on
Equipment
DANGER
- High voltage .
Protective ground
(earth) terminal .
ATTENTION - refer to
manual .
Grounding the
Product
Danger Arising From Loss of
Ground
Upon loss
of the protective-ground connection,
all
accessible
conductive parts (including knobs
and con-
trols that may appear to be
insulating) can render an
electric shock .
Use the Proper
Fuse
Refer fuse replacement to
qualified service personnel
.
Do Not Operate in Explosive
Atmospheres
To avoid
explosion, do not operate this
product in an
explosive atmosphere unless
it has been specifically
certified for such
operation .
Do Not Operate
Without Covers (for TM 500
plug-
ins
only)
Power Source To
avoid personal
injury, do not operate this product
This product is intended to operate
from a power source

without covers
or panels installed . Do not apply
power to
that will not apply more
than 250 volts rms between the

the plug-in
via a plug-in extender .

SERVICE SAFETY SUMMARY
FOR
QUALIFIED SERVICE PERSONNEL
ONLY
Refer also to the preceding Operators
Safety Summary .
Do
Not Service Alone

Disconnect power before removing
protective panels,
soldering, or replacing
components .
Do not perform
internal service or adjustment of this
product unless another person capable of rendering first
aid and resuscitation is present .
Power Source
PG 506 (SN 8040000 & up)
This product is intended to
operate from a power source
Use Care When Servicing With Power On

that will not apply more than 250 volts rms between
the
supply conductors or between either
supply conductor
Dangerous voltages
exist at several points in this product .

and ground . A protective
ground connection byway of the
To avoid personal
injury, do not touch exposed connec-

grounding conductor
in the power cord is essential for
lions and components
while power is on .

safe operation
.

PG 506 (SN8040000 &
up)
PG 506 Calibration
Generator

Performance Conditions

Items listed in the Performance
Requirements column
The electrical characteristics are
valid only if the

of the
ElectricalCharacteristicsareverifiedbycompleting
PG 506 has been calibrated at
an ambienttemperature

the Performance Check
in the Service Section of this
between+20°Cand+30°C
and is operating at an ambient

manual
. Items listed in the Supplemental
Information
temperature between 0°Cand
+50°C . Forced air circula-

column are not verified in this manual
. They are either
tion is required
for ambient temperatures above +40°C .

explanatory notes or
performance characteristics for
which no limits are
specified .
Characteristics

Performance
Requirements

Supplemental
Information
Range (Peak-to-Peak)
1 MSl Load

~

200 ~V to 100 V
Accuracy

~

Within 0 .25°/a
t1 ~cV
50 S2 Load

I

100 ~V to 5 V
Accuracy

~

Within 0 .25% t1pV
Period

Approximately 1 ms
(1 kHz square wave,
chopped DC)
Deflection Error Readout
Range

+ and - 7 .5%
Resolution

Within 0 .1%
HIGH
AMPLITUDE OUTPUT
Amplitude (Peak-to-Peak)
Unterminated

I

~6 V to ,60 V
50
! ;2
Load

I

~0 .5 V to ~5 V
REVDEC 198 1
SPECIFICATION
SPECI
FI CATI O N
Table 1-1
ELECTRICAL CHARACTERISTICS
STANDARD AMPLITUDE OUTPUT
Section 1-PG 506 (SN 8040000
& up)
_

Polarity

Positive, measured from a negative
potential to ground .

Specification-PG
506 (SN 8040000
& up)
600 S2
Output Resistance

~

Within 5%
Output Period
1 Ns to 10 ms

~

Within 5%
Variable

Extends output period
to at least 100 ms .
X1 to greater
than X10 range for each
decade
step .
Duty Cycle

I

I
Approximately 50% .
Rise Time
Table 1-1 (cont)
Characteristics

Performance
Requirements

Supplemental Information
Unterminated

~

100 ns
50 S2 Load

~

~10
ns
Leading Edge Aberrations

Within 2% of signal
peak-to-peak
during first 50 ns

amplitude, or 50
mV, whichever is
greater .
Amplitude (Peak-to-Peak)
50 S2 Load

~

<100 mV to >1
V
FAST RISE OUTPUTS
Polarity

Simultaneous
positive and negative .
Positive is
measured from a negative
potential to
ground . Negative is
measured
from a positive
potential to
ground .
Output
Resistance, 50 f2

I

Within
3%

I At either Fast Rise
connector .
Risetime, 50 S2 Load

~

<1 ns
Leading Edge
Aberrations,

Within
2% of signal peak-to-peak
first 10 ns

amplitude, or 10 mV,
whichever is
greater .
Flatness

~

Within 0 .5%
after first 10 ns
Output Period

I

1 ~s to 10 ms

I In decade steps
.
Accuracy

~

Within 5%
Variable

Extends output period
to >100ms . X1 to
greater than X10
range for eachdecade
step .
Duty Cycle

I

I Approximately
50% .
+Trigger
Out
TRIGGER OUTPUT
,1 V peak-to-peak into a 50
S2 load .

Trigger out
function available for
HIGH
Fixed amplitude .

AMPL
and FAST RISE modes .
Output signal
leads HIGH AMPL pulse by
about 18 ns and
leads FAST RISE
pulse by about 8 ns .
REVDEC 198
2

Temperature
Operating
Non-operating
Humidity
Operating
Non-operating
Altitude
Operating
Non-operating
Vibration
Operating and
Non-operating
Shock
Non-operating
Transportation
Characteristics
Characteristics
Maximum Overall Dimensions
Height
Width
Length
Front Panel
Finish
Net Weight
Table 1-2
ENVIRONMENTAL
CHARACTERISTICS
Test to procedures of
MIL-STD-810CMethods 502 .1 and
501 .1 using
Procedure I as specified
in MIL-T-288008 paragraph
4 .5 .5 .1 .3 and
4 .5 .5 .1 .4
.
0° C to +50° C .
-55° C to +75° C .
+50°C to 95% relative
humidity .
+60°C to 95% relative
humidity .
Specification-PG
506(SN 8040000
& up)
Information
Test to
MIL-STD-810C Method 507
.1 Procedure IV, modified as
specified
in MIL-T-288008 paragraph
4 .5 .5 .1 .1 .2 .
Test to
MIL-STD-810C Method 500 .1
Procedure I as specified in
MIL-T-
28800B
paragraph 4 .5 .5 .2 .
To
15,000 feet .
To 50,000 feet .
With the
instrument operating, the vibration
frequency is swept from
10 to 55 to
10 Hz . Vibrate 15 minutes in
each of the three major axes
at 0
.015" total displacement . Hold 10
minutes at any major resonance,
or
if none, at 55 Hz . Total time, 75
minutes .
30 g's
1/2 sine, 11 ms duration, 3 shocks
in each direction along 3
major axes, for a total of 18
shocks .
Qualified under
National Safe Transmit
Committee Test Procedure 1 A,
Category
II .
Table
1-3
PHYSICAL CHARACTERISTICS
4 .969 inches
(12 .621 cm) .
2 .638
inches (6.701 cm) .
12 .088 inches (30
.704 cm) .
Anodized aluminum
.
~2 lbs .
4oz . (1 .02 kg) .
Information

Description
The
PG 506
Calibration
Generator
is designed to

The Pulse Generator provides three square-wave out-
operate in a TM 500 Series PowerModule . Theinstrument

puts : variable High Amplitude pulses and simultaneous
is a combination Amplitude Calibrator and Square Wave

positive and negative-going Fast Rise, variable-amplitude
Pulse Generator intended for calibration and adjustments

pulses . In the Pulse Generator mode,
the Period
is
of oscilloscope amplifier systems with a 50 f2 or 1
Mil

selectable from 1 ps to 10 ms
in
decade
steps . A variable
input resistance .

control extends the maximum period to at least 100 ms
(for each decade step, the period is variable over a 10 :1
The Amplitude Calibrator function provides either a
+

range) . A positive going pretrigger output isalso provided
do
voltage
or
a 1 kHz square-wave output, as selected by

for
triggering external equipment .
an internal switch . Peak-to-peak amplitudes from 0 .2 mV
to 100 V across a 1 Mfg load and amplitude of 100 mV to
5
V
across a 50 f2 load are available . Output amplitudes
are selected in a 1,2,5 sequence .

Installation and Removal
caurioN
Because errors are often stated as a percentage, an
internal digital differential voltmeter with front-panel light-

Turnthepowermoduleoffbeforeinsertingtheplug-
emitting diode (LED) readout is used to provide a
display

in ; otherwise, damage may occur to the plug-in
equal to oscilloscope vertical or horizontal deflection

circuitry . Because of the high current drawn by the
errors . If the indicated deflection on an oscilloscope

PG 506, it is also recommended that the power
graticule does not agreewith theproper reference line, the

module be turned off before removing
the PG
506 .
output amplitudefrom the PG 506 Amplitude Calibrator

Refer to
Fig . 2-1 . Check to see that the plastic
can
bevaried
untiltheproperalignmentisobtained . Inthis

barriers on the interconnecting jack of the selected
operating mode, the front-panel readoutisadirectdisplay

powermodule
compartment match the cut-outs in
of the oscilloscope deflection error .

the
PG
506 circuit board rear edge connector .
Section 2-PG 506 (SN 8040000 & up)
OPERATING INSTRUCTIONS
INTRODUCTION

A 5 mA Current Loop is provided, which supplies
current (dc or
1 kHz) for calibration of current probes .

Operating Instructions-PG506 (SN 8040000
& up)
CONTROLS AND
CONNECTORS
AMPLITUDE : Selects calibrated output amplitudes
across 1 MS2 or 50 f2 load attached to
AMPL OUT-
PUT (STD) connector .
O
VARIABLE (OUT) : When released,
operates in the
standard
amplitude mode . The deflection error
readout indicates the error in percentages with 0
.1%
resolution .
PERIOD
light : Illuminated when the function switch
is in Fast Rise or High Ampl mode .
© VAR : Extends the period range 10 :1 . The
calibrated
position is counterclockwise .
Top
Groove
\
.i
ll
.\
PLUG-IN
Slot
Fig . 2-1 . Plug-In Installation and removal .
Bottom
Groove
(1431-21)1632-02
+TRIG OUT : Provides a signal source to pretrigger
external equipment .
O
DEFLECTION ERROR
% : A direct display of output
amplitude deflection error .
FAST RISE OUTPUTS : Provides for simultaneous
positive and negative
going square-waves as
selected by the
PERIOD/VAR controls .
Function switch : Determines
whether the instru-
ment is operated
in STD AMPL, HIGH AMPL, or
FAST RISE mode .
PULSE AMPLITUDE
: Controls output amplitude in
the High Amplitude or Fast Rise
modes .
AMPL OUTPUT HIGH or STD : Common
output for
High Amplitude or Standard Amplitude
modes .
1 kHz square-wave
or do for Standard amplitude .
O
PERIOD : Selects the period of eitherthe Fast Rise or

Period of the High Amplitude square-wave is set by
High Ampl square-wave signals .

the Period controls .
Current Loop :
A
do
or 1 kHz square-wave 5 mA
current
supply for calibration of current probes . The

Fig . 2-2 . PG 506 controls and connectors .
Operating Instructions-PG 506 (SNB040000 & up)
2-3

Operating Instructions-PG 506 (SN
8040000 & up)
VARIABLE (OUT)
control will vary current through
the loop, but DEFLECTION ERROR
readout is not
directly related to current deviations
. The DEFLEC-
TION ERROR readout
mustbe off or adjusted to
read 0 .0%
for a calibrated output .
Release Latch : Pull to
remove the instrument from
the power module .
WARNING
Dangerous
voltage may be present on the front-
panel BNC connector labeled AMPLOUTPUT
(HIGH or STD) . Before installation, turn
the control
tabled AMPLITUDE (VOLTS
INTO 1 Mfg) fully
counterclockwise (ccw) and the control labeled
PULSE AMPLITUDE to MIN .
Align the upper and lower
groove of the PG 506 chassis
with the upper and
lower guides of the selected compart-
ment
.Push the module in and press firmly to seat
the
circuit board in the interconnecting jack
.
To
remove the PG 506, pull on the release latch
located
in the lower left corner until the
interconnecting jack
disengages and the PG
506 will slide out .
AMPLITUDECALIBRATOR
MODE
Connections and Terminations
To use the PG 506Amplitude
Calibrator system,setthe
mode switch to the
STD AMPL position . Connect the
1 kHz calibrated
amplitude signal at the AMPL OUTPUT
connector to the input of an oscilloscope
through a
coaxial cable that has a 50
f2 characteristic impedance
(RG-58/U) with a maximum
length of 42 inches (shorter
cables can be
used) .
With a
cabletermination of 1 Mfg and the DEFLECTION
ERROR
display off, the 1 kHz signal peak-to-peak
output
amplitude will be equal to the indicated
reading on the
AMPLITUDE switch . If the cable
is terminated into a 50 f2
load, use an output
amplitude in the 10 V to 0 .2 mV range ;
the output amplitude will then be one-half the
indicated
reading on the AMPLITUDE switch
.
Oscilloscope Controls
The deflection
factor (either vertical or horizontal) for
oscilloscopes is the
ratio of the amplitude of the input
signal to the
amount of beam deflection produced on
the
cathode-ray tube (crt), usually stated
as volts per division
of deflection
(Volts/Div) . Calibration procedures for some
oscilloscopes require that the gain be set and the deflec-
tion
accuracy be checked with a probe
(properly compen-
sated) connected between
the PG 506 and the os-
cilloscope input connector
.
For oscilloscope gain adjustments and
checking of
Preliminary Checks

deflection accuracies,
it is always best to set all os-
Make all desired connections to
equipment under test

cilloscope
controls exactly as called out in the
calibration
before applying power to the PG
506 . The power switch is

and performance sections of the oscilloscope
instruction
on the Power Module .
Power application to the PG 506 is

manual . However, it may be found
desirable to set the
indicated by the
PERIOD light turning on, or the light

oscilloscope sweep controls to
a0 .1 ms/div (or faster)
sweep rate and free-run
the sweep when performing
behind the knob
skirt of the AMPLITUDE control switch

vertical deflection
(amplitude) checks and adjustments .
being
lighted .

This
procedure produces two horizontal traces
that are
separated vertically by an amount proportional
to the
The front-panel LED can be tested (888 display) by

Peak-to-peak amplitude of
the 1 kHz square-wave from
setting the
three-position Mode switch to STDAMPL

the PG 506 .
At faster sweep rates, the display becomes
more
readable .
position, then pushing and holding the
VARIABLE knob
concentric with the AMPLITUDE
switch .
Deflection Error Readout
To test
the digital voltmeter system, release
the

When performing
gain adjustments on oscilloscope or
VARIABLE knob to the out position and
rotate the control

amplifier systems, it is mandatory that the
DEFLECTION
in both directions .

ERROR readout be turned
off in ordertoobtaincalibrated
output amplitudes .
The PG 506 DEFLECTION ERROR
readout
feature finds its greatest use in its ability to
allow
Allow 15 to 20 minutes warmup
time for all equipment

an operator
to verify the oscilloscope deflection
accuracy
before using the PG 506 .

associated with amplifier gain
and input attenuators .

Gain
adjustments for oscilloscope amplifiers are usual-

2 . Reduce

capacitive

and

inductive

loads

to

a
ly made at low levels, for example ;
at a 10 mV/div

minimum . Risetime
degradation occurs with long cable
deflection factor
and a 50 mV signal from the PG 506 . This

lengths .
ratio corresponds to five major graticule divisions of beam
deflection . If the gain of the oscilloscope
amplifier system
is low, the indicated deflection will be
less than five major

3 .

Minimum
risetime and pulse aberrations are ob-
graticule divisions, for
example ; 4 .8 major division . The

tained with
50 O loads and loads must be
capable of
VARIABLE
AMPLITUDE (OUT) control on the PG 506 can

dissipating the power available at any output
connector in
then
be used to increase the output amplitude until the

any operating mode .
total deflection is exactlyfive major divisions .
Atthis point,
the DEFLECTION ERROR readout
will read 4 .0% LOW .
Conversely,
if the oscilloscope amplifier system gain is too

4 . The external equipment is assumed
to have no do
high, the indicated deflection on the crt
will
be
above the

voltage across the load to which the
PG 506 is connected .
proper reference line, for example ; 5 .2 major
divisions .

If a do voltage exists, the output
amplitude from the
Using the VARIABLE AMPLITUDE
control
on
the PG 506

PG 506 will be in error by
the amount of the do offset . To
to reduce the output ampliutde for
exactly five major

prevent dc-offset
errors, couple the PG 506
outputs
divisions of deflection
will produce a DEFLECTION

through a do
blocking capacitor to the load
. The time
ERROR readout of
4 .0% HIGH .

constant of the coupling capacitor and
thetotal resistance
in series must be long enough to
maintain pulse flatness .
For some oscilloscopes
the deflection factor may not
be constant
throughout the full vertical dimensions of
the

High
Amplitude Output
graticule, dueto compression or expansion
nonlinearities .

To use the PG 506 Pulse
Generatorsystem to produce
To check for this type of nonlinearity ;
center a two-

high amplitude
square-waves, set the mode switch to
division display, then position the
display to the top of the

HIGH AMPL
position and connect external equipment
to
graticule .
Measure any deflection errors with the PG 506

the AMPL OUTPUT HIGH connector
. Set the Period
VARIABLE AMPLITUDE control . Next, position
the two-
division displaytothe bottom of
the graticule and measure

controls for the period or
frequency desired . The output
the deflection
errors . These nonlinearities should betaken

amplitude of this
signal can be adjusted with the PULSE
into account when making measurements
with full

AMPLITUDE
control .
graticule deflection, or with the
crt trace positioned
towards thetop or bottom graticule
limits and using small
deflection factors .

This signal can be used to
adjust oscilloscope amplifier
input capacitance, attenuator
compensation networks,
and other
internal frequencycompensation
networks . The
AMPL OUTPUT HIGH signal is
negative with respect to
Current Loop

ground, with its risetime
related to the rising portion (from
One end of the Current Loop is grounded
and ter-

a
negative potential) of the waveform . Refer to Fig .
2-3 .
urinates a precision
voltage divider . The direction of the

The absolute peak-to-peak value of the
square-wave is
arrow is
oriented for conventional current . To obtain a

determined by the load resistance
and the setting of the
calibrated 5
mA from the Current Loop, set the mode

PULSE AMPLITUDE control
. Table 2-1 lists the typical
switch to STDAMPL position and the
AMPLITUDE

amplitudes available
when the PG 506 is terminated into
control switch to the 100 V position
. The DEFLECTION

three
different load resistances .
ERROR readout should
be off, or adjusted to read 0 .0% .
The current signal can be either do or 1 kHz square-wave
current, as selected by an internal switch
.
General
PULSE GENERATOR MODE
In order to ensure
waveform fidelity when using the

T ermination

~

MIN
Pulse
Generator function of the PG 506, the following
precautions should be observed .

50
R Load

0 .3 V p-p
1 . Use high
quality 50 O coaxial cable, connectors,
and terminations
(where applicable) . Make all connec
tions as tight and short as possible .

'Approximate amplitudes .
OperatingInstructions-PG
506 (SN 8040000
& up)
Table
2-1
OUTPUT LOAD VS .
VOLTAGE OUT
HIGH
AMPL OUTPU T PULSE AMPLITUDE Control'
600 f2 Load

1
.9
V p-p
1 MS2 Load

3 .8 V p-p
MAX
5 .2 V p-p
32 .5 V p-p
>60 .0 V p-p

Operating Instructions-PG 506 (SN 8040000
& up)
+TRIG
OUT
HIGH
AMPLITUDE
SQUARE WAVE
FAST RISE

REFERENCE EDGE
FAST RISE
OUTPUT
2- 6
REFERENCE
EDGE
REFERENCE EDGE
REFERENCEEDGE
FIXED
AMPLITUDE
___OV
~OV
VARIABLE
Q~ ~
___u___u___u~~la~LE
- OV
VARIABLE
1740-02
Fig . 2-3 . Output signals from the PG 506
Calibration Generator .
the leading edge of a
waveform . The risetime of a
displayed
waveform is illustrated in Fig . 2-4 .
Before measuringthe
risetime of a device under test,
the
combined risetime of the PG 506 output signal
and the
oscilloscope vertical amplifier system
must be known .
Refer to Fig . 2-4 for the
percentage error to be expected
when the two
devices are cascaded . Sweep timing ac-
curacy should
be verified before any risetime measure-
ments are made . Inaccuracies in the
sweep timing and
display reading errors must be
added algebraically to the
percentage
error obtained from computations related to
Fig . 2-4 .
The graph for Fig . 2-4 can be
used as a guideline forthe
following general
conclusions .
1 . Oscilloscopes should
have a vertical system
risetime aboutone-seventh
of thefastest signal applied to
keep system errors to a minimum .
2 . Conversely, if the
signal risetime is at least seven
times
faster than the risetime of the oscilloscope vertical
system, the displayed (observed) waveform
will have a
risetime that is very close to the risetime of
the vertical
system .
Fast Rise Outputs

3 . The displayed
risetime as observed on any os-
cilloscope can never be faster
than the risetime of the
To use the PG 506 Pulse
Generator system to produce

slowest device
in the system .
low amplitude,
fast-rise square-waves, set the mode
swtich to
FAST RISE position and connect external
equipment to the FAST RISE OUTPUTSconnector(s) .Set

Risetime of a displayed waveform is related to total
the PERIOD controls for the period or
frequency desired .

system
bandwidth . A system with limited high-frequency
The output amplitude can be adjusted by
the PULSE

response will produce a displayed risetime that is
slower
AMPLIUTDE control .

than expected . If a fast-step signal
produces a crt display
with little or no overshoot or
ringing, the product of
oscilloscope risetime
and oscilloscope bandwidth should
These

signals

are

usually

used

to

adjust

high-

result
inafactorwhosevalueliesbetween0 .329and0 .350 .
frequency compensation
networks in oscilloscope
amplifier circuits . The adjustments are made for optimum
response

(minimum

aberrations) .

The

risetime

and

The
following steps describe the procedure
tofollowin
amplitude specifications for
the FAST RISE outputs apply

determining the risetime of a device under
test .
only when they are terminated into a 50 f2 load .
Larger
amplitudes (greater than 1 V peak-to-peak)
can be ob-

1 .
Connect the appropriate output signal from the
tained from these output connectors under
unterminated
conditions, but the risetime specification
is no longer

PG 506 to
the oscilloscope vertical input withashort50
f2
applicable .

coaxial cable terminated into a 50
S2
load
.
GENERAL
INFORMATION

2 . Set the oscilloscope controls to display
theleading
edge of the waveform .
Risetime measurements should be
Risetime Considerations

made over the
largest part of the graticule area possible .
When the fastest sweep rate is relatively slow
compared
The PG 506 can
be used in conjunction with an

with the vertical system risetime (or the scale
is small),
oscilloscope
to determine the risetime of a device under

measurements become confined to
small sections of the
test . Risetime is normally measured (unless
otherwise

graticule, and the probability of
display reading errors
specified) between the 10% and 90%
amplitude levels on

becomes greater .

Fg . 2-4
. Risetime
derating graph
.
OperatingInstructions-PG
506
(SN
8040000 & up)
3 . Measure the time duration between the 10% and

the device under test to
the oscilloscope vertical input .
90% amplitude levels . This is
the
combined
risetime of the

Terminate the device under test in its characteristics
PG
506 and the oscilloscope
(T«)
.

impedance for optimum performance .
4 .

Disconnect the coaxial cable and 50
S2 termination

6 .

Set the oscilloscope controls to display the leading
from the
oscilloscope
.

edge of the displayed waveform and measure
the time
duration between the 10% and 90%
amplitude levels (over
the same graticule area,
if possible) . This is the total
5 . Connect the coaxial cable from the PG 506 to the

system risetime
(T~s)
.
input of the device under test and connect the output of
2- 7

Operating
Instructions-PG506 (SN
8040000 & up)
7 .

Calculate the risetimeof
the device under test
(dut)

F, . (3
dB)

_

159 X 10 - '
using the following
formula :

RC
T*
(dut)

_

(Trs)
z
-
(Tm)z
Checking Amplifier
Response
,~z
The square-wave
output signals from
the PG 506 can
be used to
check the response
of active or passive
sys-
tems .
Because the
characteristics of apulse
from the
PG 506 is known
(see ELECTRICAL
CHARACTERIS-
TICS),
distortion of the waveform
beyond these limits
is
due to the
device under test .
The
compensation of an
ac-voltage divider, such as
used
in theinput attenuator of
an oscilloscope or a
passive
attenuator probe,
can be checked by
observing its
response
when a square-wave
signal is applied .
Correct
response
is shown by
optimum square
corner on the
displayed waveform .
If the waveform has
overshoot,
rolloff, or front-corner roundi
ng, the system
is not correct-
ly compensated .
Figure 2-5 shows
typical waveforms
illustrating
correct and incorrect
compensation ad-
justments .
When performing
these compensation
checks,
the
repetition rate of
the applied square-wave
signal
should be at least 3 to 4
decades above the
low-frequency
cutoff point (frequency
where the
equivalent sine-wave
amplitude is 30%
down) .

A .
Overshoot and top not flat .
The low end cut-off
frequency(due to RC
coupling) for
an amplifier can be
approximated very
closely by usingthe
following procedure .
1 . Apply
a square-wave at
a repetition rate that is
not
affected
by the low-frequency
limit .
2 . Slowly
reduce the square-wave
frequency and
adjust
the oscilloscope
(amplifer) controls to
display a
signal similar to
Fig . 2-6 .
3 .
Determine the ratio between
theamplitudelevels,V,
and
V z . Note that V, and Vz are
peakvaluesabovethezero-
volt reference level .
4 . The
equivalent RC product
can be determined by
using the following
formula ; where F e is
the applied
frequency for agiven
ratio of V,/Vz
(greater than unity) .
1
1

F
a I n V,/Vz
= RC (for
square-waves only)
5 . Using the RC
product obtained in step
4, calculate
the low-end
cut-off frequency .

compensation
adjustments .
For example ;
if the applied frequency,
F a , is 10 Hz and the
amplitude
values shown in Fig . 2-6are used,the
lower cut-
off
frequency is calculated to
be about 1 .6 Hz .
Figure
2-7 illustrates other
waveform distortion effects
that may be observed if
amplifier circuits are not
properly
compensated for low
frequencies .
B . Correct
compensation (square corner, flat
topl .
C . Ralloff
and top not flat .
1740-04
Fg . 2-5 . Typical
waveforms showing
correct and incorrect