Tektronix FG503 User manual

"'vYti-'s"i' :'

.~w .yvue ;*-

~'4r' :?

. . .yam

~!' .4-
.
~
.
:~
. :" .
.`xtiY

.e'~l~l~

BEFORE READING
070-1727-00
PLEASE CHECK FOR CHANGE
INFORMA TION
AT THE REAR OF THIS MANUAL .
THIS MANUAL REPRINTED FEBRUARY
1978
FG
503
FUNCTION
GENERATOR
INSTRUCTION
MANUAL
Tektronix,
Inc .
P
.O .
Box500
Beaverton, Oregon 97005

Serial Number
First Printing
APR 1974
TEKTRONIX° I
Z 1
A
9
,,

TABLE
OF
CONTENTS
SECTION 1

OPERATING INSTRUCTIONS

Page
Introduction

1-1
Instrument Description

1-1
Initial Operation

1-1
Functions Available At Rear Connector

1-2
Operating Considerations

1-2
Output Connections

1-2
Risetime and Falltime

1-2
Impedance Matching

1-2
Basic Operation

1-4
Free-Running Output

1-4
Voltage-Controlled Frequency
(VCF) Output

1-4
Custom Timing Capacitor Selection

1-5
Typical VCF Application

1-6
Electrical Characteristics

1-7
Repackaging for Shipment

1-8
SECTION 2

THEORY OF OPERATION
Introduction

2-1
Triangle Generator

2-1
Sine Shaper

2-1
Output Amplifier

2-2
Power Supplies

2-2
SECTION 3

SERVICE INFORMATION
Symbols and Reference Designators

3-1
Electrical Replaceable Parts List

3-2
Front Panel Controls and Connectors
Calibration Procedure
Services Available
Maintenance
Test Equipment
Parts Location Grid
Rear Interface Connector Assignments
Block Diagram
Generator Loop Schematic
Output Amplifier Schematic
Power Supplies Schematic
Mechanical Replaceable
Parts List
Exploded View
Accessories
CHANGE INFORMATION

FG 503

Section
1-FG 503
OPERATING
INSTRUCTIONS
INTRODUCTION
The
variety of swept and modulated signals available
from the FG 503 make
it especially useful for such
applications as
testing servo-system or amplifier
response,
distortion and stability . It is also useful
for FM
POWER
MODULE
Barrier
7
J +
generation or as a variable beat-frequency
oscillator . The
square wave
trigger output can be used as a source for
The FG
503 Function Generator is designed to operate

TTL logic, or to synchronize an external device such asan
in a TM 500 series power module .
Low distortion sine,

oscilloscope or counter
.
square and
triangle waveforms from 1 Hz to 3 MHz, are
available at the front panel . A +2 .5 V square wave trigger
also is available at the front panel
. Variable do offset of

INITIAL
OPERATION
±5 V is provided .
INSTRUMENT DESCRIPTION
A custom timing switch position
is provided . This
allows
the user
to
install a timing capacitor for custom
tailoring the frequency range of the FG 503 .
A voltage-controlled frequency
(VCF) input controls
the output frequencyfrom an external voltage source . The
output frequency can be swept above or below the
selected frequency, to a maximum
of 1000 :1, depending
on
the polarity and amplitude of the VCF input and the
selected output frequency .
REV . B, MAR . 1976
Top
Groove
Bottom
Groove
Fig . 1-1 . FG 503 InstaIlatlon and
removal .
CAUTION
Turn the Power Module off before inserting the
plug-
in ; otherwise, damage may occur to the plug-in
circuitry .
The FG
503 is calibrated and ready for use when
received . It is designed to operate in any compartment of
the TM 500 series power module . Refer to the power
module instruction manual for line voltage
requirements
andpower module
operation . See Fig . 1-1 for installation-
removal procedure . Check that the FG 503 is fu Ily inserted
in the powermodule . Pull the PWR switch on the power
module . Check
that the green POWER light on the FG 503
is on . The Controls, Connectors and Adjustments foldout
Slot
FG 503
PLUG-IN

Operating
Instructions-FG 503
page in Section 3 gives
acompletedescription of the front

A slot between pins 23 and 24 on the rear connector
panel controls and connectors .

identifies the
FG
503 as amember of the signal source
family . A barrier may be inserted in the corresponding
position of the power module jack, to prevent other than
signal source plug-ins from being used in that compart-
FUNCTIONS AVAILABLE AT REAR CONNECTOR

ment . This protects the plug-in should specialized con-
nections be made to that compartment . Consult the
Refer to the rear connector assignment
illustration in

Building A System section of the power modulemanual
the Service Section of this manual for pin assignments .

for further information .
RISETIME AND FALLTIME
OPERATING
CONSIDERATIONS
OUTPUT CONNECTIONS

introduced will not exceed
1%
.
This error can genera~iy be
ignored . When the rise or falltime of the test device is less
The output of the FG 503 is designed to operate as a

than ten times as'long as the combined risetimes of the
50 S2 voltage source working
into a50 S2 load . At higher

testing system, the actual risetime of the device must be
frequencies, an unterminated or improperly terminated

determined .
This
is
found from the risetime of each
output will cause excessive
aberrations
on
the output

component making up the system . The total risetime
waveform (see Impedance
Matching discussion) . Loads

equals the square
root of the sum of the squares of the
less
than 50 f2 will reduce the waveform amplitude .

individual
risetimes . R,= ~/ (R,) + (Rz) + . . .Conversely,
the risetime of the device under test can be found, from the
same
relationship, if the actual risetimes in the system are
Excessive distortion or aberrations, due to improper

known .
termination, are less likely to occur at the lower frequen-
cies (especially with sine and
triangle waveforms) . To
ensure
waveform purity, observe the following
precautions :
1 . Use good quality 50 S2 coaxial cables and connec-
tors .
2 .

Make all connections
tight and as shortas possible .
The physical and
electrical characteristics of the pulse
transmitting cable determine the characteristic im-
pedance, velocity of propagation, and amount of signal
loss . Signal loss, is related to the frequency ;
therefore, a
few feet of cable can attenuate high frequency
information
in a fast-rise pulse .
It
is
important therefore, to keep these
cables as short as
practical .
3 . Use good quality attenuators,
if it
is
necessary to

When
signal comparison measurements or time
reduce waveform amplitude to sensitive circuits .

difference determinations are made, the two signals from
the test device should travel
through coaxial cables with
identical loss and time delay characteristics .
4 . Use terminators or impedance-matching devices to
avoid reflections when
using long cables (six feet or
more)
.

If there is a do voltage across the output load, theoutput
pulse amplitude
will
be
compressed, or in some cases (if
the voltage exceeds ±10 V), it may short the
output . To
5 . Ensure that attenuators,
terminations, etc . have

prevent
this from occurring, the output must be coupled
adequate power handling capabilities
for the output

through a
do blocking capacitor to the load . The time
waveform .

constant of the coupling capacitor and load
must
be
long
enough to maintain pulse flatness .
IMPEDANCE MATCHING
If the output pulse from the FG 503 is used to measure
the rise or falltime of a device, consider the
risetime

As a pulse travels down a transmission
line, each time it
characteristics of the associated
equipment used . If the

encounters a
mismatch, or different impedance than that
risetime of
the device under test is at least ten times

of
the transmission line, a reflection is generated and sent
greaterthanthecombinedrisetimesoftheFG 503plusthe

back along the line to the source . The amplitude and
monitoring oscilloscope and associated
cables, the error

polarity of the reflections are determined by
the amount of

the encountered impedance in relation to the
characteristic impedance of the cable
.
If the mismatch
impedance is higherthan the line, the reflection will be of
the
same polarity as the applied signal .
If
it is lower, the
reflection will be of opposite polarity .
If the reflected signal returns before the pulse is ended,
it
adds to or subtracts from the amplitude of the pulse . This
distorts the pulse shape
and amplitude .
If the
FG
503
is
driving a high impedance such as the 1 MS2 input im-
pedance (paralleled
by
a stated capacitance) of the
vertical input to anoscilloscope,connectthetransmission
line to
a 50 S2 attenuator, 50 S2 termination, and then the
oscilloscope input . The
attenuator isolates the input
capacitance of the device, and the FG 503 is properly
term i nated .
A simple resistive impedance-matching network, that
provides minimum attenuation, is illustrated in Fig . 1-2 . To
matchimpedance with the illustrated network, the follow-
ing
conditions must exist :
Therefore :
or
(R, +
Zz) Rz
must equal Z,
R~+Zz~
- Rz
R, +

Z`Rz

must
equal Z z .
Z~ +
Rz
Rz = Z~
V
For example, to match a 50 S2 system to a 125 S2 system,
Z, equals 50 S2 and Zz equals 125 f2
.
Therefore :
and
z~
(Low)
Operating Instructions-FG
503
R . =

125(125 - 50) = 96 .8 ohms
125
R z =

50

=

64 .6 ohms .
125-50
m
z~
< zZ
Zz
(High)
Fig . 1-2 . Impedance matching network that provides minimum
attenuation .
When constructing such a device, the environment
surrounding
the components should be designed to
provide a transition between the impedances . The
characteristic impedance of a coaxial device is deter-
minedby the ratio between the outside diameter of the
inner
conductor to the inside diameter of the outer
conductor,
138
D
Zo = ~ IOg~o
RiRz = Z~Zz ; and R,Z~ = Rz(Zz - Zi)

f

d
D is the inside diameter of the outer conductor, d is the
diameter of the inner conductor, and F is the dielectric
constant
(1 in
air) .
R~ =

Zz(Zz -
Zi)
The network shown in Fig . 1-2 provides minimum
attenuation for a purely resistive impedance-matching
device . The attenuation as seen from oneenddoes not
equal that seen from the other end . A signal (E,) applied
and

from the lower impedance source encounters a voltage
attenuation (A,) that is greater than 1
and less than 2, as
follows :
Ez
Zz

Operating Instructions-FG 503
A signal
(Ez)
applied from the higher impedancesource

and
(Zz)
encounters a greater voltage attenuation (Az)
that is
greater than 1 and
less than 2(Zz/Z,) :
Ez R1 R1
Az = - = - + -
+1 .
E,
Rz
Z,
In the
example
of
matching 50 S2 to 125 f2,
96 .8

The illustrated network can be modified, to provide
A,

_

+ 1 = 1 .77

different attenuation ratios, by adding another resistor
125

(less than R,) between Z, and the junction of R, and
Rz .
FREE-RUNNING OUTPUT

MULTIPLIER setting, by applying a0 V to 10 V signal to
the VCF IN connector . It may be necessary to
vary the CAL
control to obtain the full 1000 :1
swept range or the lowest
swept frequency
desired . See Fig . 1-4 for maximum VCF
range for each
MULTIPLIER setting .
Set the AMPLITUDE
control fully clockwise . Notice the
two identical sets of waveforms near the
FUNCTION
selector on the
front panel . The three waveforms in the
lightly shaded area allow use of the OFFSET control
;
the
other three do not . Select the desired waveform
with or
without offset . See
Fig . 1-3
.
Select the desired frequency
with the MULTIPLIER and FREQUENCY
Hz dials . The
output frequency is calibrated when the FREQUENCY
VERNIER control is
in the full clockwise position . Connect
the load to the OUTPUT connector
and adjust the
AMPLITUDE
control for the desired output amplitude .
Fig . 1-3 . Output waveforms
available from the FG 503 .
VOLTAGE-CONTROLLED
FREQUENCY (VCF)
OUTPUT
BASIC OPERATION
96 .8 96 .8
Az =

+

+ 1 = 4 .43 .
64 .6 50
10 3
~

3 kH z

3 MHz
300 Hz

300 kHz
Z
10
30 Hz

30
kHz
W
10'
N
W

3 Hz

3 kHz
2 10 z
¢

1 Hz

300
Hz
Q
10'
W
a
1

1 H
z

30 Hz
' 0 .01
Hz *~ 5 M Hz
C
10_
z
10 - ' 1 10'
10 z 10' 10' 10 3 10 6 10'
When using the offset feature
select the waveform

(

FREQUENCY
Hz
desired in the light shaded
area . Now adjust the OFFSET
control to position
the do level (baseline) of the
output

'C
ust o mized sweep
at least 1000 :1 within this range
waveform above or below
0 V as desired .

Fig . 1-4 . Graph showing
range of frequencies for each MUL-
TIPLIER setting that canbe swept
with a0 to 10 V signal applied to
the
VCF input .
The polarity of
the VCF input signal determines
the
The output frequency of the FG 503
can be swept over a

direction the output frequency
is swept from thefrequen-
frequency

range

of

1000 :1,

depending

on

the

cy set by the MULTIPLIER, FREQUENCY
Hz, and VER-
REV . B, JULY, 197 6

Operating Instructions-FG 503
w
m
NIER controls .
A positive-going voltage raises
the fre-

range of 20 Hz to 20 kHz is desired
. Fig . 1-4showsthat no
quency, while a negative-going voltage
lowers the fre-

fixed multiplier
setting includes the desired
limits . The

n
quency . A voltage that varies
symmetrically about 0 V

value of the capacitor that must be
installed is determined

m
sweeps the output
frequency symmetrically about
the

by the
following formula :

r
center
frequency determined by the
frequency controls .

300
See Fig . 1-5 .

_
Ccus

a
Fmax

O
Z
Since the VCF input
amplitude versus frequency is a
linear relationship,
the frequency output range
may be
determined
from the VCF input amplitude .
Use a fixed do
voltage and frequency counter or other
comparison
method, to accurately determ
ine theoutput frequency and
VCF voltage
relationship . Refer to the test
under the
heading
Response Analysis for a typical
application using
the VCF feature .
CUSTOM
TIMING CAPACITOR
SELECTION

The capacitor selected
must be a low leakage non-
polarized type
within the range of 100 pF to 100
~F and
This feature
allows the user to custom select
a swept

must
have at least a 10 V rating .
Ceramic and mylar
frequency range . For
example, assume a swept frequency

capacitors work well
in this application .
VCF IN
OUTPUT
0
VCF IN
SWEPT FREQUENCY
RANGE
where C~  s is
in ~F, and
Fmax,
in Hz, is the maximum
frequency
required . Apply the formula to the example ;
v
( '
rcus
-5
V
+5
VCF IN

0
-5
OUTPUT
300
20x10'
Fig . 1-5 . Swept frequencyrange
with 10 V signals applied to
VCF IN Connector .
=

0.015
NF .
+5V
C~
w

Operating Instructions-FG 503
Remove the left side cover of the FG
503
.
Refer
to

TYPICAL VCF APPLICATION
Fig . 1-6 for capacitor location . Solder thecapacitor to the
test points located on the left rear side of the circuit board
as shown in Fig . 1-(i . Finally, set the MULTIPLIER control

The

FG 503 is particularly suited for determining
to the C position, and apply the correct voltage to the VCF

response characteristics of circuits
or systems . This
IN connector . Set the
FREQUENCY Hz
and
FREQ
VER-

application utilizes the VCF input of the FG 503 to sweep
NIER dials for the desired swept frequency range .

the
generator over
a
range of frequencies . By applying the
desired waveform from the FG 503 to a device under test,
The calibration marks on
the
FREQUENCY Hz dial are

and sweeping
the
waveform frequency over a selected
not
appropriate for use directly in determining frequency

range, various response characteristics can be observed
in the custom range position
.
It
is
possible however, to

on
a monitoring oscilloscope .
custom calibrate the dial, since the linearity of the
FREQUENCY Hz dial calbration is not changed in the
custom position .
Fig . 1-6 . Custom
timing capacitor location .
Fig . 1-7 . Phase relationships between various OUTPUT
waveforms and the TRIG OUT waveform .
TRIG OUT
Waveform
Squarewave
Triangle
Waveform
Sinewave
The following procedure describes a technique for
determining response characteristics of any frequency
sensitive device that operates within the frequency range
of
the FG 503 . Refer to the Voltage-Controlled Frequency
(VCF) Output discussion for additional information .
1 . Connect the equipment
as shown in
Fig . 1-8 .
2 . Set the MULTIPLIER selector and
FREQUENCY Hz
dial for the desired upper or lower frequency limit
(depending on the direction you may wish to sweep) . See
Fig . 1-4 for VCF ranges and MULTIPLIER
settings .
3 . Apply the desired waveform to the VCF IN connec-
tor .
4
.
Adjust the amplitude of the VCF input waveform for
the desired output frequency range .
5 .
Observe the
response
characteristics
on
the
monitoring
oscilloscope .
The frequency at which a displayed response
characteristic occurs can be determined by first removing
the VCF input waveform,
then
manually adjusting
the
FREQUENCY Hz dial to again obtain the particular
characteristic observed in the
swept
display . Then read
the frequency on the FREQUENCY Hz dial .
REV . C, MAY, 197 7

The electrical characteristics are valid only if the
FG 503 is calibrated at an ambient temperature between
+20° C and +30° C, and operated between 0° C and
+50°C,
unless otherwise
noted .
Sine, square, and triangle .
Usable Range : ,0 .01 Hz to ,5 MHz .
Custom Range : Switch selectable on front panel .
Frequency range determined by user-installed timing
capacitor .
FREQUENCY
RESOLUTION :
REV . B, MAY, 1977
FG 503
VCF
IN O
OUT Q
PU~
DEVICE
UNDER
TEST
Fig . 1-8 . Analyzing circuit or system response .
ELECTRICAL
CHARACTERISTICS
PERFORMANCE CONDITIONS

FREQUENCY STABILITY :
WAVEFORMS :

DIAL ACCURACY :
Operating Instructions-FG
503
OSCILLOSCOPE
~0 .1%of full scaleforl houraftera30minutewarmup,
~0 .5% of full scale for 24 hours . Dial must be on
calibrated portion and ambient temperature mustbe 25° C
±5° C .
Within ±5% of full scale from 1 Hz to 3 MHz .
FREQUENCY RANGE :

DIAL RANGE :
Calibrated Range : 1 Hz to 3 MHz .

1 to 30 calibrated, 0 .1 to 1 uncalibrated .
OUTPUT AMPLITUDE :
,20 V p-p open circuit, ,10 V p-p into a 50 S2 load
referenced at 10 kHzand excluding offset .
Variable Amplitude Range : ,20 :1 .
1 part in 10 5 of full scale setting using FREQUENCY

AMPLITUDE FLATNESS :
VERNIER control .

Within 2 db referenced at 10 kHz .

Operating Instructions-FG 503
OFFSET RANGE
:

SQUAREWAVE :
At least ±7 .5 V open
circuit, ,±3 .75 V
into a 50
S2
load .

Risetime : 560 ns .
Peak signal plus offset at least±l5 V open circuit,
~6 V
into
50
S2
load .

Aberrations :53%p-patfullamplitudeintoa50
S21oad .
SINE WAVE DISTORTION :
50
.5% from 1 Hz
to
30 kHz,
G1 .0% from >30 kHz to 300 kHz,
52 .5% from >300 kHz to 3 MHz . Valid for calibrated
frequencies only .
TRIANGLE SYMMETRY :
Within
1%
from 1
Hz
to
100 kHz ; within 5% from
100 kHz to 3 .0 MHz using 10 5 MULTIPLIER setting . Dial
must be on calibrated portion, and ambient temperature
must be 25°C f5°C .
TRIANGLE
LINEARITY
: (From
10% to 90% of the
generated ramp .)
If the Tektronix instrument is to be shipped to a Tektronix

Surround the instrument with polyethylene sheeting to
Service Center for service or repair, attach a tag showing :

protect the finish of the instrument . Obtain a carton of
owner (with address) and the name of an individual at your

corrugated cardboard of
the
correct carton strength
firm that
can be contacted .
Include
complete instrument

and
having inside dimensions of
no
lessthan six
inches
serial number and
a
description of the service required
.

more than the instrument dimensions .

Cushion the
instrument by tightly packing three inches of dunnage
or urethane foam between carton and instrument, on all
sides . Seal carton with shipping tape or industrial
stapler
.
Save and re-use the package in which your instrument was
shipped . If the original packaging is unfit for use or not

The carton test strength for
your instrument is
200
available, repackage the instrument as follows :

pounds .
Within 1% from 1 Hz to
100 kHz .
Within 5°lo from 100 kHz to 3 MHz .

~15 watts .
VOLTAGE CONTROLLEDFREQUENCY INPUT :
Range : A 10 V signal shifts
frequency >1000 :1 where
freq (max) is 530XMULTIPLIER setting
and freq (min) is
;0 .03X MULTIPLIER setting .
Maximum Slew Rate
: Nominally 0 .5 Vlps .
TRIGGER OUTPUT :
,2 .5 V into 600 S2 . Leading
edge coincides with positive
peak of sine and triangle waveforms, and
preceeds leading
edge of square wave nominally by 50 ns .
POWER CONSUMPTION :
REPACKAGINGFOR SHIPMENT
REV . C, MAY, 1977

The lowered voltage (about -9 V) at the junction of
CR127 and CR135 turns CR140 on, and CR135 and CR130
The triangle waveform is
the basic waveform in the

off . This action disconnects the positive
current source
FG 503 . The sine wave is
derived from the triangle

from the timing capacitor and connects the negative
waveform
using
a
five-step approximation .
The square

current source through
CR140, causing the ramp to go in
waveform
is generated by the triangle
generator control

the negative
direction . The ramp goes negative until the
circuitry .

voltage at
pins 3 and 5 of U235A and B, respectively, drops
to about -1 .6 V . At this time the outputs
of U235A and
U235B go low causing the
output of U241C to go high .
Refer to
the simplified block diagram, and the circuit

This action causes
the output of U241 D to go negative,
diagrams in the pullout pages of this manual
along with

turning Q261
off, and the cycle repeats .
the following discussion, for a complete
understanding of
the FG 503 operation .
INTRODUCTION
TRIANGLE
GENERATOR
Operational
amplifier U121, with Q121, form a
positive
constant-current source . Q145 and
Q141 form a negative
constant-current source . These constant
current sources
supply the current (either positive
or negative) to charge
'' r~

the timing capacitor,
generating the triangle waveform
.
Assume that the junction
of CR127 and CR135 is
positive (about
+9 V) with respect to ground . CR127 is
off
and CR135 is conducting . CR140 is off, and
the timing
capacitor is charging from the
positive current source
through CR130 . G~261 is
off . Currentto hold thejunction of
CR127 and
CR135 positive is supplied via VR131, con-
nected to
the +20 V supply .
The ramp, moving in the positive direction, appears
in
the same polarity at the + inputs of U235 . This is
accomplished through the action of source
follower
Q201 A, with its constant current source,
Q201 B . Q211 and
Q221, complementary emitter
followers, drive the ac
compensated attenuator
R226, R227, and C226 .
The voltage at
pin 2
of
U235A rests at about 1 .6 V above
ground . The voltage at pin 6 of
U235B
is about
the same
below ground . Under these
conditions, the output of
U235A and U235B (pin 10)
rests so that the inputs of
U241 C are at the low TTL level .
When the ramp voltage at
pins 3 and 5 of U235A
and U235B respectively reaches
'

about 1 .6
V, the output of these comparators start to go
positive .
When they reach the high TTL level,
pin 10 of
U241 C goes low, causing the output of
U241 D to go high .
This high level couples
through VR261 to the base of
0261, turning 0261 on .
REV
.
B,
OCT . 1974
Section
2-FG 503
THEORY
OF
OPERATION
R123
balances the current between the positive and
negative constant current sources so that the
chargeand
discharge times for
the capacitor are equal .
The frequency of the
triangle waveform is controlled by
two factors : (1) the value of
the timing capacitor, and
(2) the amount of
current available to charge it .
When the FREQUENCY Hz dial is turned in the ccw
direction, the voltage at
pin
5 of
U101A goes positive . This
causes pin 7 of
U101A and pin 2 of U101 B to go positive .
The voltage at pin 2 of U101 B is also controlled by an
external voltage applied to the front panel
VCF IN
connector . Under the above conditions,
pin 1 of U101B
goes negative, causing
pin
6 of
U121 to go negative . This
increases the
current available to charge the ramp

O
generating capacitor
. The negative current is also in-

2
creased through the action of emitter follower Q141
.
at
The waveform
at pin 13 of U241 D (about 15 V above the
base of
Q261) drives gates U241A and B, which
in turn
provide in-phase trigger signals to the
front panel and the
rear interface connector
.
The square
wave is taken from the collector of 0255 .
SINE SHAPER
This circuit, by means of a
five-step approximation
method, develops a sine
wave from the applied triangle
wave .
The circuit is composed of 0320, 0340,
and
associated components . Although they
operate in op-
posite polarity, each half of the sine shaper
functions the
H
rn
s
m
z
0
a
0
z
a " ~
v~
O a
Z C
~7
O~
o
c
c~
a~
rn a

TheoryOf Operation-FG 503
A .
2-2
M
R22a
Z varies with
triangle voltage
Transistor
0320, controlled by the setting of
-
sine
adjustment R311, establishes a fixed current through the
resistive divider chain attached to its emitter . This fixes a
different voltage at the cathode of each diode connected
to the divider chain . When sine-wave operation
is selected,
a triangle wave
is applied
through R224, which forms
part
of a voltage divider, the other half of which is the diodes
and
the 0320 resistor chain . The output waveform is taken
from the junction of R224 and the 0320 resistor chain .
B .
+v
-V
Fig . 2-1 . Simplified sine shaper circuits . Part A shows equivalent circuit . Part B shows a three step approximation (actual circuit
is a five step approximation) . See text .
same, so only the upper half (0320) is
described . See

OUTPUT AMPLIFIER
Fig .
2-1 for a simplified version of the sine shaper
.
This circuit
operates as an inverting operational
amplifier . R~ is R371 and R ; is R369 . The base of 0371 is the
negative input and the base of 0380 is the positive input .
The overall gain
is about four . The selected waveform is
applied to the base of 0355 . This transistor
and 0360
operate as cascaded emitter followers . The waveform is
taken from the emitter of 0360, through the AMPLITUDE
control to the base of 0371 .
0380 and 0371 operate as an
emitter-coupled amplifier with 0376 serving
as
a
constant
current source . R375, in the emitter circuitry, adjusts for
do unbalance in the output amplifier . The base of 0380 is
connected to the OFFSET control when waveform offset
capability is required (S380-5 closed) . This control also
effectively
adjusts do levels in theoutput amplifier . The in-
phase signal is fed from the
col lector of 0380 to the base of
0405 . The out-of-phase signal is fed
from the collector of
0371 to the base of inverter 0400 . The waveform at the
collectors of 0420 and 0405 are in phase . Their collectors
drive complementary emitter-follower
amplifiers 0425
and 0410 . Output and feedback are taken from their
common emitters . C369 compensates R
r
for higher fre-
quency components .
As the applied triangle waveform rises to the voltage at
the cathode of CR327, the diode conducts, changing the
divider ratio and thus the slope of the output waveform .
The slope is changed each time anotherdiode turns on (as
a result of the triangle waveform reaching the turn-on
point of the diode), resulting in a waveform of approximate
sinusoidal shape . As the input falls, the diodes turn off in
succession, until the input waveform reaches zero volts .
The changes in
slope
during this
operation would seem to
bepronounced ; however, the nonlinear characteristics of
the diodes tends to round off the changes . The result is a
close approximation of a pure sine wave at the output .

operational amplifier) of U512 . U512 has a gain of
POWER SUPPLIES
VR517 sets the voltage at pin 3 (+ input of an
REV . B, OCT . 1974

TheoryOf
Operation-FG 503
m
s
approximately
three . The output at
pin 6, therefore, is

action of this circuit
is similar to the +20
V regulator .

<
about 20 V . Emitter follower
Q526 drives the base of the

CR539protectsthissupply,shouldashortto+20
Voccur .

m
series pass transistor .
Should the+20 V load increase, pin

z
2 of U512
(through R522 and R520) goes negative
. This

p
causes
pin 6 to go positive, increasing
current flow and

The +17 V is
referenced to the +20 V . U628, with a gain
restoring
the +20 V to its previous
level . Should the

of about
one, controls Q628, the series pass
transistor for

a
current drawn increase, so
the voltage across R523 is

this supply . Feedback occurs
at pin 2 of U628 . Current
O
sufficient to turn
Q523 on, current limiting
occurs . Q526

limiting in the +20
V supply protects this circuit .

z
reduces
conduction, reducing the current
through the
series
pass transistor to a safe
level . CR536 protects the
+20 V supply, if it shorts
to the minus supply .

The -17 V supply is
referenced to +17 V at pin 2 of
U640 . The gain of
U640 is about one . Q640 serves as the
series pass transistor
for this supply . Feedback occurs
U566
is an operational amplifier with
a gain of about

through R633
. Current limit for this supply is
the +20 V
one .
The reference voltage is the
+20 V applied at pin 2 .

supply
.
The output, at pin 6 (-20 V),
drives emitter follower Q569 .
Q569 drives the series
pass transistor located in
the power
module .
Current limiting takes place in
conjunction with

The regulatory
action of the +17 V and -17 V supplies
Q566 and
R567 . Feedback occurs through
R564 . The

is similar to that
in the 20 V supplies .

as
a~
1
0
O~
Z C
~7
O~
n
v~
c~
a~
m
a
O~
A~
O~
~i
>~
O
Z
A
2

I

SYMBOLS AND
REFERENCE
DESIGNATORS
Electrical components
shownon the diagrams are in
the following units unless noted
otherwise :
Capacitors =

Values one or greater are
in picofarads (pF~ .
Values less than one are
in microfarads
(taF~ .
Resistors =

Ohms
(W
Symbols
used on the diagrams
are based on ANSI Y32 .2 -
1970 .
Logic symbology is based
on MIL-STD-8068
in terms of positive logic . Logic symbols
depict the logic function
performed
and
may differ from
the manufacturer's data .
The following special
symbols are used on the
diagrams :
pI
0 circuit k~oa>c~
External Screwdriver
adjustment .
External control or connector .
Clockwise control rotation
in direction of arrow .
Refer to diagram number
indicated in diamond .
Refer to wavetorm
number indicated in hexagon .
Connection soldered to
circuit board .
--
Blue tint encloses
components located on circuit board
.
Section
3- FG 503
SERVICE
INFORMATION
a
Connection made to
circuit board with interconnecting
pin .

REV . B OCT .
1974
REPLACEABLE
ELECTRICAL
PARTS
PARTS ORDERING INFORMATION
Replacement
parts are available from orthrough your local Tektronix, Inc . Field Office
or representative .
Changes to Tektronix instruments are sometimes made to accommodate improved
components as they become available, and to give you the benefit of the latest circuit
improvements developed in our engineering department . It is therefore important,
when
ordering parts, to include the following information in your order : Part number, instrument
type or number, serial number, and modification number if applicable .
If a part you have ordered has been replaced with a new or
improved part, your local
Tektronix, Inc . Field Office or representative
will
contact you
concerning any change in part
number .
Change
information, if any, is located at the rear of this manual .
SPECIAL
NOTES AND SYMBOLS
X000

Part first added at this serial number
OOX

Part removed
after this serial number
ITEM NAME
In the
Parts List, an Item Name is separated from the description by a colon ( :) .
Because of space
limitations, an Item Name may sometimes appear as incomplete . For
further
Item Name identification, the U .S . Federal Cataloging Handbook H6-1 can be
utilized where possible .
ACTR ACTUATOR

PLSTC PLASTIC
ASSY ASSEMBLY

QTZ QUARTZ
CAP CAPACITOR

RECP RECEPTACLE
CER CERAMIC

RES RESISTOR
CKT

CIRCUIT

RF

RADIO FREQUENCY
COMP COMPOSITION

SEL SELECTED
CONN
CONNECTOR

SEMICOND SEMICONDUCTOR
ELCTLT ELECTROLYTIC

SENS SENSITIVE
ELEC ELECTRICAL

VAR VARLABLE
INCAND INCANDESCENT

WW

WIRE\'VOUND
LED

LIGHT EMITTJNG DIODE

XFMR

TRANSFORMER
NONWIR

NON WIREWOUND

XTAL

CRYSTAL
ABBREVIATIONS

Replaceable
Electrical Parts-FG 503
CROSS
INDEX-MFR . CODE NUMBER TO MANUFACTURER
Mfr . Code

Manufacturer

Address

City, State, Zip
01121

ALLEN-BRADLEY
COMPANY

1201 2ND
STREET SOUTH

MILWAUKEE, WI
53204
01295

TEXAS INSTRUMENTS,
INC ., SEMICONDUCTOR
GROUP

P O BOX
5012, 13500 N CENTRAL
EXPRESSWAY

DALLAS, TX 75222
04713

MOTOROLA,
INC ., SEMICONDUCTORPROD . DIV .

5005 E MCDOWELL RD,PO BOX
20923 PHOENIX, AZ 85036
05091

TRI-ORDINATE CORPORATION

343 SNYDERAVENUE

BERKELEY HEIGHTS,
NJ 07922
07910

TELEDYNE SEMICONDUCTOR

12515 CHADRON AVE .

HAWTHORNE, CA
90250
15801

FENWALELECTRONICS, DIV . OF
KIDDE WALTER
AND CO ., INC .

63 FOUNTAIN ST .

FRAMINGHAM, MA
01701
56289

SPRAGUE ELECTRICCO .

NORTH ADAMS,
MA 01247
71744

CHICAGOMINIATURE LAMP WORKS

4433 RAVENSWOOD AVE .

CHICAGO, IL
60640
72982

ERIE TECHNOLOGICAL
PRODUCTS, INC .

644 W . 12TH ST .

ERIE, PA
16512
73138

BECKMAN INSTRUMENTS, INC .,
HELIPOT DIV .

2500 HARBORBLVD
.

FULLERTON, CA
92634
75042

TRW ELECTRONIC COMPONENTS,
IRC FIXED
RESISTORS, PHILADELPHIA
DIVISION

401 N . BROAD ST
.

PHILADELPHIA,
PA 19108
80009

TEKTRONIX, INC .

P O BOX500

BEAVERTON, OR 97077
80031

ELECTRA-MIDLANDCORP .,
MEPCO DIV .

22 COLUMBIA
ROAD

MORRISTOWN,
NJ 07960
81483

INTERNATIONAL
RECTIFIER CORP .

9220
SUNSETBLVD .

LOS ANGELES, CA 90069
90201

MALLORYCAPACITOR
CO ., DIV . OF
P . R . MALLORY AND
CO ., INC .

3029 E WASHINGTON STREET
P O SOX372

INDIANAPOLIS, IN 46206
91637

DALEELECTRONICS,
INC .

P .
O . BOX 609

COLUMBUS, NE 68601
98291

SEALECTRO CORP .

225 HOYT

MAMARONECK, NY 10544
3-3
REV . D JAN .
1978

Replaceable Mechanical
Parts-FG 503
Tektronix

Serial/Model No
.

Mfr
Ckt No .

Part No .

Eff

Dscont

Name & Description

Code

Mfr Part Number
A1

670-3302-00

BO10100 B022971

CKT BOARD ASSY :MAIN

80009 670-3302-00
A1

670-3302-01

8022972 B023160

CKT BOARD ASSY :MAIN

80009 670-3302-01
A1

670-3302-02

B023161

CKT BOARD ASSY :MAIN

80009 670-3302-02
C120

283-0111-00

CAP .,FXD,CER DI :O .lUF,208,50V

72982 8121-NOSSZSU104M
C201

283-0003-00

CAP .,FXD,CER DI :O .OlUF,+BO-208,150V

72982 855-558ZSU-1032
C226 281-0205-00

CAP .,VAR,PLSTC :4-65PF,100V

80009 281-0205-00
C227

281-0627-00
XB020000

CAP .,FXD,CER DI :1PF,+/-0
.25PF,SOOV

72982 301-OOOCOK0109C
C230

283-0003-00

HO10100B019999

CAP .,FXD,CER DI :O
.OlUF,+80-208,150V

72982 855-558ZSU-1032
C230
281-0540-00 B020000 CAP .,FXD,CER
DI :SIPF,5~,500V

72982 301-OOOU2JOS10J
C231

283-0003-00

8010100B019999

CAP .,FXD,CER DI :O .OlUF,+80-208,150V

72982 855-558ZSU-1032
C231

281-0540-00

B020000

CAP .,FXD,CER DI
:51PF,58,SOOV

72982 301-OOOU2JOS10J
C246

283-0067-00 XB022972 B023161X
CAP .,FXD,CER DI :o .001UF,10~,200V

72982 835-S15B102K
C261

283-0003-00

CAP .,FXD,CER DI :O .OlUF,+80-20~,150V

72982 855-558ZSU-1032
C270 1
cz71,
2

r
C273I
(((
C275

295-0164-00

CAP .,SET MTCHD
:lOUF,lUF,O.lUF,O .OlUF,

80009 295-0164-00
C2761

950PF,MTCHD 0 .75$
C277

7
C278

281-0629-00

CAP .,FXD,CER DI :33PF,58,600V

72982
308-OOOCOG0330J

C
C279

281-0540-00

CAP
.,FXD,CER DI :SIPF,58,500V

72982 301-OOOU2JO510J
f .
C280 281-0205-00

CAP .,VAR,PLSTC:4-65PF,100V

80009 281-0205-00
C313 290-0572-00

CAP .,FXD,ELCTLT :O .lUF,208,50V

56289 196D104XOOSOHAI
n
C315 290-0572-00

CAP .,FXD,ELCTLT :O .lUF,208,50V

56289 196D104XOOSOBAI
C369
281-0202-00

CAP .,VAR,PLSTC :1 .5-S .5PF,100V

80031 2222-808-11558
C380

283-0003-00

CAP .,FXD,CER DI :O
.OlUF,+80-20~,150V

72982 855-558ZSU-1032
C405

281-0629-00

CAP .,FXD,CER
DI :33PF,58,600V

72982 308-OOOCOG0330J
'

C406 290-0517-00

CAP .,FXD,ELCTLT :6 .SUF,208,35V

56289 196D685X0035KA1
C415

283-0108-00

CAP .,FXD,CER DI :220PF,10$,200V

56289

27 X13
C420

281-0629-00

CAP .,FXD,CER DI :33PF,5$,600V

72982 308-OOOCOG0330J
C425
290-0517-00

CAP .,FXD,ELCTLT :6 .BUF,208,35V

56289
196D685X0035KA1

Q
C536
290-0559-00

CAP
.,FXD,ELCTLT :22UF,208,35V

90201 TDC226M035WLG

Z
C539
290-0559-00

CAP .,FXD,ELCTLT :22UF,208,35V

90201 TDC226M035WLG
C625 290-0559-00

CAP .,FXD,ELCTLT
:22UF,208,35V

90201 TDC226M035WLG
C633

283-0003-00

CAP .,FXD,CER DI :O
.OlUF,+80-20+t,150V

72982 855-558ZSU-1032
CR127

152-0141-02

SEMICOND
DEVICE :SILICON,30V,150MA

07910
1N4152
CR130

152-0141-02

SEMICOND DEVICE:SILICON,30V,150MA

07910 1N4152
CR135

152-0141-02

SEMICOND DEVICE :SILICON,30V,150MA

07910 1N4152
CR140

152-0141-02

SEMICOND DEVICE :SILICON,30V,150MA

07910 1N4152
CR313

152-0141-02

SEMICOND DEVICE :SILICON,30V,150MA

07910 1N4152
CR315

152-0141-02

SEMICOND DEVICE :SILICON,30V,150MA

07910 1N4152
CR321

152-0141-02

SEMICOND DEVICE :SILICON,30V,150MA

07910 1N4152
CR323

152-0141-02

SEMICOND DEVICE :SILICON,30V,150MA

07910 1N4152
CR324

152-0141-02

SEMICOND DEVICE :SILICON,30V,150MA

07910 1N4152
CR325

152-0141-02

SEMICOND DEVICE
:SILICON,30V,150MA

07910 1N4152
CR327

152-0141-02

SEMICOND
DEVICE :SILICON,30V,150MA

07910 1N4152
CR341

152-0141-02

SEMICOND DEVICE
:SILICON,30V,150MA

07910 1N4152
CR343

152-0141-02

SEMICOND
DEVICE :SILICON,30V,150MA

07910 1N4152
CR344

152-0141-02

SEMICOND
DEVICE :SILICON,30V,150MA

07910 1N4152
CR345

152-0141-02

SEMICOND
DEVICE :SILICON,30V,150MA

07910 1N4152
CR347

152-0141-02

SEMICOND DEVICE :SILICON,30V,150MA

07910 1N4152
CR410

152-0141-02

SEMICOND DEVICE:SILICON,30V,150MA

07910 1N4152
lOptional Timing
Capacitor .
2 Individual
timing capacitors in this
assembly must be ordered by the
9-digit part number,
lettersuffix
and tolerance printed on the
timing capacitor to be replaced .
The letter
suffix
and the tolerance should
be the same for all of the
timing capacitors in the assem-
bly .
EXAMPLE :

285-XXXX-XX F-
REV . D JAN . 1978
3- 4
d

Replaceable Electrical
Parts-FG 503
Tektronix

Serial/Model No .

Mfr
Ckt
No .

Part No .

Eff

Dscont

Name & Description

Code

Mfr Part Number
CR420 152-0141-02
CR531 152-0141-02
CR533 152-0141-02
CR536 152-0066-00
CR539
152-0066-00
SEMICONDDEVICE :SILICON,30V,150MA

07910 1N4152
SEMICONDDEVICE :SILICON,30V,150MA

07910 1N4152
SEMICONDDEVICE :SILICON,30V,150MA

07910 1N4152
SEMICONDDEVICE :SILICON,400V,750MA

80009 152-0066-00
SEMICONDDEVICE :SILICON,400V,750MA

80009 152-0066-00
CR633

152-0141-02

SEMICOND
DEVICE:SILICON,30V,150MA

07910 1N4152
CR634

152-0141-02

SEMICOND DEVICE:SILICON,30V,150MA

07910 1N4152
DS528 150-0109-00

LAMP,INCAND :18V,26MA

71744 CM7220
J118 131-0955-00

CONNECTOR,RCPT, :BNC,FEMALE,W/HARDWARE

05091 31-279
J244 131-0955-00

CONNECTOR,RCPT, :BNC,FEMALE,W/HARDWARE

05091 31-279
J415

131-0255-00

JACK,TIP :FOR 0 .08
DIA

98291 SKT-0404
Q121A,B 151-0261-00

TRANSISTOR ;SILICON,PNP,DUAL

80009
151-0261-00
Q141 151-0190-00

TRANSISTOR :SILICON,NPN

80009
151-0190-00
Q145A,B 151-0232-00

TRANSISTOR ;SILICON,NPN,DUAL

80009 151-0232-00
Q201A,B 151-1054-00

TRANSISTOR
:SILICON,JFE,N-CHANNEL,DUAL

80009 151-1054-00
Q211 151-0188-00

TRANSISTOR :SILICON,PNP

01295 2N3906
Q221 151-0190-00

TRANSISTOR :SILICON,NPN

80009 151-0190-00
Q252 151-0103-00

TRANSISTOR :SILICON,NPN

04713
2N2219A
Q255 151-0190-00

TRANSISTOR :SILICON,NPIS

80009
151-0190-00
Q261 151-0190-00

TRANSISTOR :SILICON;NPN

80009 151-0190-00
Q320 151-0190-00

TRANSISTOR :SILICON,NPN

80009 151-0190-00
Q340 151-0188-00

TRANSISTOR :SILICON,PNP

01295 2N3906
Q355 151-0190-00

TRANSISTOR :SILICON,NPN

80009 151-0190-00
Q360 151-0188-00

TRANSISTOR :SILICON,PNP

01295 2N3906
Q371 151-0190-00

TRANSISTOR
:SILICON,NPN

80009 151-0190-00
Q376
151-0190-00

TRANSISTOR
:SILICON,NPN

80009 151-0190-00
Q380 151-0190-00

TRANSISTOR :SILICON,NPN

80009 151-0190-00
Q400 151-0188-00

TRANSISTOR :SILICON,PNP

01295 2N3906
Q405 151-0188-00

TRANSISTOR :SILICON,PNP

01295 2N3906
Q410 151-0439-00

TRANSISTOR :SILICON,NPN

80009 151-0439-00
Q420 151-0190-00

TRANSISTOR :SILICON,NPN

80009
151-0190-00
Q425
151-0440-00

TRANSISTOR :SILICON,PNP

80009 151-0440-00
Q523 151-0190-00

TRANSISTOR :SILICON,NPN

80009 151-0190-00
Q526 151-0190-00

TRANSISTOR :SILICON,NPN

80009 151-0190-00
Q566 151-0188-00

TRANSISTOR :SILICON,PNP

01295 2N3906
Q569
151-0188-00

TRANSISTOR :SILICON,PNP

01295 2N3906
Q628 151-0103-00

TRANSISTOR :SILICON,NPN

04713 2N2219A
Q640 151-0134-00

TRANSISTOR :SILICON,PNP

80009
151-0134-00
8100

311-1770-00

RES .,VAR,WW ;IOK OHM,2W

80009 311-1770-00
8101

311-1559-00

RES .,VAR,NONWIR aOK OHM,20$,O .SOW

73138

91A-10001M
8103

315-0512-00

RES .,FXD,CMPSN :5 .1K OHM,S$,0 .25W

01121 CB5125
8105

311-0169-00

RES .,VAR,NONWIR :100 OHM,20$,O .SOW

01121 W-7564B
8107

315-0100-00

RES .,FXD,CMPSN :10 OHM,5~,0 .25W

01121 CB1005
8109

321-0289-00

RES .,FXD,FILM aOK OHM,1+k,0 .125W

91637

MFF1816G10001F
8111

315-0332-00

RES .,FXD,CMPSN :3 .3K OHM,S$,0 .25W

01121 CB3325
8113

321-0289-00

RES .,FXD,FILM :lOK OHM,1~,0 .125W

91637 MFF1816G10001F
8114

321-0288-00

RES .,FXD,FILM :9
.76K OHM,1~,0 .125W

91637 MFF1816G97600F
R115

321-0240-00

RES .,FXD,FILM :3 .09K OHM,18,0 .125W

91637 MFF1816G30900F
R116

311-1567-00

RES .,VAR,NONWIR :100 OHM,20$,0 .50W

73138 91A-100ROM
8118

321-0297-00

RES .,FXD,FILM ;12 .1K OHM,1~,0 .125W

91637 MFF1816G12101F
8120

315-0102-00

RES .,FXD,CMPSN :IK OHM,S$,0 .25W

01121 CB1025
3- 5
REV . D JAN . 1978