Systron Donner 100A Service manual

OPERATION

&

MAINTENANCE

HANDBOOK

CONCORD INSTRUMENT DIVISION

Syrtron

Drtve

r

10

Tel: [phone] TWX: 910-481-9479 . Cable: SYSTRONOONNER

Concord, Caltforn~a 94518 . U.S.A.

MODEL

700A

PULSE GENERATOR

Part

Number

37000

-

690

WARRANTY

Systron-Donner instruments are warranted during a period of one year from date of shipment to
original purchaser to be free from defects in material and workmanship. This warranty does not apply
to vacuum tubes, except as these are warranted by tube manufacturers. The liability of Seller under
this warranty is limited to replacing or repairing any instrument or component thereof which is returned
by Buyer, at his expense, during such period and which has not been subjected to misuse, neglect.
improper installation, repair, alteration, or accident. Seller shall have the right to final determination as

a

to the existence and cause of
damages. This warranty is in lieu of any other warranty, expressed, implied, or statutory; and no
agreement extending or modifying it will be binding upon Seller unless in writing and signed by
authorized officer.

defect. In no event shall Seller

RECEIVING INSPECTION

Every Systron-Donner instrument is carefully inspected and is in perfect working order at the time of
shipment. Each instrument should be checked as soon as received. If the unit is damaged in any way, or

a

fails to operate,

Whenever a Systron-Donner instrument requires service, the nearest Systron-Donner representative
should be contacted; all representatives will provide immediate
necessary.

Please specify both model and serial number in all correspondence concerning Systron-Donner instru­ments. Address all inquiries on operation or applications to your nearest sales representative; or, Sales
Manager, Concord Instrument Division, Systron-Donner Corporation,
California

claim should immediately be filed with the transportation company.

94518.

be

liable for collateral or consequential

a

duly

service or arrange factory returns when

10

Systron Drive, Concord.

-

MODEL

S

OOA

-

-

+

-

-

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Model

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MODEL 1 WA

TITLE PAGE

FRONTISPIECE

TABLE OF CONTENTS

LlST OF SCHEMATICS
LlST OF

l

LLUSTRATIONS

LlST OF TABLES

SECTION

I

SPEC1 FICATIONS

TABLE OF CONTENTS

PAGE

i

iii
v
vi
vi

vii

Repetition Rate

External Trigger
Manual Cycling
Gated Operation
Trigger Outputs
Pulse Mode
Pulse Delay
Pulse Width
Main Pulse Output
Rise and Fall Time

Jitter
Waveform Aberration
Output Protection
Output Mixing
Operating Temperature
Power Required
Physical Characteristics
Accessories Available

SECTION

SECTION

I1 OPERATION

2.1

2.2

2.3

2.4

2.5

Ill

THEORY OF OPERATION

General Information
Controls and Connectors
Functional Verification
Operating Instructions
Definitions

3.1 General Description

3.2 Circuit Description

MODEL 100A

SECTION

SECTION V

Drawing Number

Figure Number

IV

MAINTENANCE

4.1 Preventive Maintenance

4.2 Parts Removal

4.3 Troubleshooting

4.4 Calibration
PARTS LlST

5.1 Abbreviations and Symbols

5.2 Repetition Rate Switch Assembly

5.3

5.4 Pulse Width Switch Assembly

5.5 Front Panel Assembly

5.6 Back Panel Assembly

5.7 Main Circuit Board Assembly

Pulse Delay Switch Assembly

LlST OF SCHEMATICS

Description

Block Diagram

Schematic - Model 100A Pulse Generator

Schematic

LlST OF

-

Model 100A Pulse Generator

-

Power Supply

l

LLUSTRATIONS

Title

PAGE

1

OOA

Model
Model

Front Panel

Model

Back Panel

Networks for Transistor Load

Output Decoupling Circuits

Reverse Voltage Protection
Output Mixing
Output Pulse Characteristics
Waveform Diagrams

Repetition Rate Oscillator
Trigger Multivibrator
External Trigger Amplifier

Accessories

100A Controls and Connectors
l00A Controls and Connectors

Figure Number

Title

Delay

Multivibrator

Output Drivers

Parts Location - Schematic

Top View

Bottom View - Model lOOA

LIST

OF

and

-

Model 100A

TABLES

Amplifiers

37000

MODEL

-

152

lOOA

PAGE

3-11

3-14

4

-5

4

-8

4

-9

Table Number

4-1

Title

Troubleshooting

4

-6

vii

MODEL

l00A

SECTION

I

SPECIFICATIONS

1.1

1

hertz to 10 megahertz in eight decade ranges for either

0.
single or double pulse operation. Effective rates to 20 mega-

hertz may be set up in the double pulse mode.

1.2

operates at
minimum duration of 20 nanoseconds, or 50 hertz to

10 megahertz from
and level controls provide triggering at any point on the
input waveform more than 0.25 volts and less than 5 volts
above or below the average dc level. Input impedance is
greater than 2. 5k ohms. The maximum transient amplitude

which may be applied safely is

1.3

pulse pushbutton provides one cycle of output (single or
double pulse

Repetition Rate

Repetition rate is continuously variable from

External Trigger

The external trigger input is ac coupled, and

0 to 10 megahertz from f0.25 volt pulses with a

1

volt rms sine maves.

+5

volts.

Slope polarity

Manual Cycling

In the single pulse mode, actuating the single

mode).

1.4

ous), synchronously gated, or asynchronously gated. Signal
levels more positive than
the outputs in either gated mode. The maximum level which
may

Gated Operation

The gating mode is selected as nongated (continu-

t2

volts are required to enable

hc

applied safely is 10 volts.

MODEL

1.4.

1

1 OOA SPECIFICATIONS

Synchronous Gating

this mode and is turned on for the duration of an applied gate
pulse.
and synchronized to the gate signal.

1.4.2 Asynchronous Gating

and the rate oscillator operates continuously.
outputs and the reference trigger begin with the first cycle
(internally or externally triggered) after
occurs and stop when the gate pulse subsides. The advanced
trigger is not gated and occurs at the oscillator repetition
rate.

1.5

1.5. 1 Advanced Trigger

minimum amplitude of 1.
is typically 15 nanoseconds in duration.
ternally triggered operations only, the advance trigger
occurs approximately
fore the reference trigger.

1.5.2 Reference Trigger

minimum amplitude of 2.0 volts from a 50 ohm source, and
is typically 15 nanoseconds in duration. When triggered
from an external source, the reference trigger occurs
approximately 30 nanoseconds after the external trigger.

The repetition rate oscillator

Both main outputs and both trigger

The pulse delay circuit is gated in

Trigger

The advanced trigger is a positive pulse with a

The

Outputs

7

volts from a 50 ohm source, and

10% of the repetition rate period be-

reference trigger is a positive pulse with a

i: normally off in

output. are gated

thi: mode,

the

gate pul~e

Available on in-

Main

pul: e

1.6

the pulse mode switch.

Pulse Mode

Single or double pul~e operation is zelected

hy

SPECIFICATIONS MODEL lOOA

1.6. 1 Single Pulse

at the end of the delay period.

1. 6.2 Double Pulse

outputs, the first approximately 40 nanoseconds after the
reference trigger, and the

the pulse delay controls.

One pulse per cycle occurs in the main outputs

Two identical pulses per cycle occur in the main

second at a time determined by

Pulse Delay

40 nanoseconds with respect to the reference trigger, or
60 nanoseconds with respect to an external trigger,
maximum of 10 seconds in seven decade ranges with a

100:l multiplier.
pulse period up to a repetition rate of 1 megahertz, de­creasing to
The reference trigger is counted down when the delay is
greater than the pulse period, with stable countdown ratios
greater than 100: 1 possible; the advance trigger is not
counted down.

1.8

50%

the

35 nanoseconds (40 nanoseconds maximum) to 10 seconds in
seven decade ranges with a

duty cycle is at least

Pulse delay is continuously variable from

up to a

Delay is variable over at least

50% above 4 megahertz and 30% at 10 megahertz.

70% of the

Pulse Width

Pulse width is continuously variable (measured at

point of the leading and trailing edges) from typically

100:l multiplier. The maximum

60% and is typically 7070.

Main

Pulse Output

0. 5 to 10 volts into 50 ohms with simultaneous positive and
negative dc coupled outputs (baselines are at ground). The

source impedance decreases with amplitude and is approxi-

mately 50 ohms at amplitudes less than

Pulse amplitude is continuously variable from

5

volts.

MODEL IOOA SPECIFICATIONS

1.10

time is typically less than
~naximurn) with the outputs terminated in 50 ohm resistive
loads.

1.11

than
decade on the width and delay ranges with more than
10: 1 coverage).

1.12

aberration are typically less than

k70/0)

connected 50 ohm terminations).

1.13

nation of front panel control settings and will withstand

short circuits to ground of any duration.
is not rated for operation into loads at other than ground
potential.

Rise and Fall Time

Rise time is less than 5 nanoseconds, and fall

7

nanoseconds (10 nanoseconds

Jitter

Repetition rate, delay, and width jitter are less

0.

15%

(typically 0. 1%) on each range (within the highest

Waveform Aberration

Overshoot, preshoot, ringing, and top slope

f5%

(with a maximum

at amplitudes greater than 3 volts (with properly

Output Protection

Output stages will not be damaged by any combi-

The instrument

of

1.14

negligible loss of amplitude. Same or opposite polarity
outputs may be resistor mixed with a resultant loss of
amplitude. Outputs may not be directly coupled together.

Output Mixing

Same polarity outputs may be diode mixed with a

SPECIFICATIONS

1.15 Operating Temperature

MODEL

lOOA

The instrument is designed for operation in

ambient temperatures of 0

1.16

and 50-400 hertz
regulated against line and load changes.

1.17

Dilnensions are 3-112 inches high by 8-112 inches wide and

11 inches deep.
tached line cord and
front panel are brushed aluminum with black etched mark-

ings and trim. The russet brown top, bottom, and side
panels are removable. A tilt-up bracket is provided.
Instruments
unit) or Type 1006 (dual unit) Rack Mounting Sets.

1.18

1. 18. 1 Type 1005 Rack Mounting Set

19 inch wide by 3-112 inch high rack panel, offset to either
side of center.

Power Required

Approximately 15 watts at 105-125/210-230 volts

ac is required.

Physical Characteristics

Instrument weight is approximately 8 pounds.

Each instrument is furnished with an at-

NEMA

may

he

rack mounted by Type 1005 (single

Accessories Available (Figure

This set mounts a single instrument in a standard

0

to 50° C (32O to 122O

All power supplies are

3-prong plug. The cabinet and

F).

1-1)

1.18.2

19 inch wide by 3- 112 inch high rack panel.

1.18.3

termination of 50 ohm coaxial cables for fast-rise pulse
outputs.

Type 1006 Rack Mounting Set

a

This set mounts two instruments in

Type

2003A 50 ohm Termination

This specially designed load provides proper

standard

MODEL

1.

18.4

trigger output (advanced or reference) for applications
requiring a negative synchronous trigger.

lOOA SPECIFICATIONS

2

Type

The 2 101 transformer inverts the poeitive

101 Inverting Transformer

1. 18.5

outputs with approximately 1 volt loss of amplitude.

1.

18.

6

pulse rise and fall times.

1.

18.

7

supplied with each instrument. Additional handbooks are

available at a slight additional charge.

Type 2302 Mixing Unit
The mixing unit combines two same polarity

Type 240 1 Variable Integrator.

This accessory provides a means of varying

Instruction Manual

One operation and maintenance handbook is

Figure

1-1.

Model

lOOA

Accessories.

MODEL l00A

SECTION

II

OPERATION

General Information

CAUTION

The outputs are designed for 50 ohm

resistive loads. An inductive load or
active circuit connected directly to an
output may damage the instrument.

2.4

Refer to paragraph
Instructions) for non-standard load
connection and output mixing
tion.

Pulse amplitude, width, delay, and repetition

rate are continuously variable over broad ranges, and pro-

vide an infinite variety of pulse parameter combinations to

satisfy many test requirements.
operation,
flexible external gating and triggering, and countdoun
capabilities extend the
operating convenience is gained through 1000: 1
control and 100: 1 range multiplication of pulse width and
delay. Available accessories provide variable rise and

fall times, reference trigger inversion, low loss output
mixing and minimum distortion load termination.

simultaneous positive and negative outputs,

instrunlent's versatility. Extra

(Operating

inforrna-

Single or double pulse

vernler

Gating capabilities consist of synchronous, asyn-

chronous, and coincidence gating. The output pulse train is

synchronized to the leading edge of an externally applied

gate waveform in the synchronous mode.
nous mode, the output pulse train begins with the first

advance trigger after the gate pulse occurs and continues
until the gate pulse subsides; the output is quiescently off
between gate pulses while the

provides advance trigger outputs.

gated in both modes while the advance trigger is gated in
the synchronous mode only. Coincidence gating is achieved
by application of both a gate signal and an external trigger
pulse so that output pulses occur only when the two are co­incident.

rate oscillator continuously

The reference trigger is

In the asynchro-

MODEL lOOA OPERATION

Frequency division by synchronous countdown is
obtained from either internal or external triggering when
the delay is set greater than the trigger period and the out­put pulse rate is a subharmonic of the trigger rate. The
reference trigger occurs at the subharmonic rate in either
case while the advanced trigger occurs at the oscillator rate

for internal triggering and is turned off for external trig­gering.

2.2

2.2.1

transformer primary and lights the pilot lamp when the

switch is turned

2.2.2

either internal or external triggering and the repetition rate
range for internally triggered operation. The smaller ver­nier knob provides continuously variable control of all

ranges. There are eight decade ranges and the instrument
is set to the rate indicated on the front panel when the
nie r is fully clockwise.

ment to be triggered manually for one cycle of output by the
SINGLE PULSE pushbutton.

permit the instrument to be triggered from an external

source by either a positive or negative going waveform.

(t)

the
instrument for operation from an external source.

Controls

Power Switch

The

Repetition Rate

The REPETITION RATE rotary switch selects

The SINGLE PULSE position permits the instru-

The EXT TRIG

The TRIGGERING LEVEL control determines

or

(-)

amplitude of a signal that will trigger the

and

POWER

ON.

Connectors (Figure

switch connects ac power to the

SLOPE

(t)

and

2-1)

(-)

positions

ver-

A BNC connector is provided for the external

TRIGGER INPUT.

Figure

2-1

b.

Model

IOOA

Controls

and

Connectors.

I

I

I

I

I

OPERATION MODEL lOOA

2.2.

3

Pulse Delay

seven decade ranges and the smaller vernier knob provides

The PULSE DELAY rotary switch selects one of

continuously variable control of each range.

The instru­ment is set to the delay indicated on the front panel when
the vernier is fully clockwise.

The ranges are multiplied

by 100 when the vernier knob is pulled out.
NOTE:

limited to a single range step.
by vernier control causes pulse distortion.

may become unstable because recovery time

Vernier control of pulse delay and width should be

Too much range reduction

Also the outputs

is

longer for

higher ranges.

2.2.4 Pulse Width

The PULSE WIDTH rotary switch selects one of

seven decade ranges and the smaller vernier knob provides

continuously variable control for each range. The instru­ment is set to the width indicated on the front panel when
the vernier is fully clockwise.

The ranges are multiplied

by 100 when the vernier knob is pulled out.

2.2.5 Amplitude

The POSITIVE and NEGATIVE pulse AMPLITUDE

knobs provide continuously variable amplitude control of the

simultaneously occurring main outputs. The baseline for

both outputs is at ground potential.

nectors couple the main outputs to external loads.

The POS OUTPUT and

NEG

OUTPUT

BNC

con-

The
GRD jack provides access to the instrument ground for test
connections.

2.2.

6

Gate Mode

The main outputs are continuous when the GATE
MODE switch is in the NON-GATED position but are inter­rupted and occur in gated bursts, as controlled by an ex-

ternally applied gate signal, when the

switch is in either the

SYNC or the ASYNC position.

MODEL IOOA

In the SYNC position, the repetition rate oscillator

is disabled and the main output pulses occur only during the
pulse interval of an applied gate signal.
pulse of a gated burst is synchronized to the leading edge of
the gate pulse and both trigger outputs are gated.

rate oscillator is disabled in the ASYNC position, and on in-

ternally triggered operations the advance trigger is available
as a clock pulse.

begin with the first rate oscillator pulse after the start of

gate pulse and continue until the gate pulse subsides, for
either internal or external triggering.

The pulse delay circuit, rather than the repetition

Main output and reference trigger pulses

The fir st main

0PERP.TION

a

ENABLING GATE INPUT BNC connector.

2.2.7 Pulse Mode

the

PULSE

per cycle occurs at the outputs,
trigger for
~ulses occur when the switch
is delayed approximately 30
trigger, and the second is delayed for
by the delay controls.

2.2.8 Trigger Output

the ADVANCE and REFERENCE trigger outputs to external
instruments.

2.2.9 Power Input

3-prong plug is attached to the back of the instrument.

connects the power transformer primaries for operation
from either a 115 or a 230 volt ac input.

cartridge type fuse mounted on the back

The external gate signal is connected to the

Single or double pulse operation is selected by

MODE switch. In the

a

period set by the delay controls.

The TRIGGER OUTPUT BNC connectors couple

A 6-foot, 3-wire ac line cord with a

The

115/230 selector switch on the back panel

Overload protection is provided by a

SGL

delayed from the reference

is

in the DBL ~o~ition. the first

nano~econds from the reference

position, one pul~e

Two

identical

a

period determined

NEMA

112

ampere

pancl.

OPERATION

MODEL

1

OOA

2.3

of the instrument and an introduction to the

2.3.

1

Functional Verification

The following procedure provides a brief check

CAU

TION

The instrument is designed for resistive
loads only. Reactive loads connected
directly to the output will produce pulse
distortion. Inductive loads may damage
the instrument. Refer to paragraphs

2.4.4

load connections.
Equipment (or equivalent) Required
a.

b.

through

A

general purpose oscilloscope of at least

15 megahertz

NOTE:
adequate for the basic tests outlined here but
a sampling oscilloscope is needed for a full

range check to verify specifications.
axial attenuators for the main pulse and
trigger outputs may also be required because

many sampling oscilloscopes are limited to

inputs below

A 50

2

watts dissipation such as a Datapulse

2003A

2.4.6

The general purpose oscilloscope is

ohm coaxial termination capable of

Power Termination.

for nonstandard

bandpass with triggered sweep.

250

millivolts.

control^.

Co-

NOTE.
for most combinations of control settings

but should be used with care because pulse
output power approaches
duty cycle waveforms at full amplitude.

A

c.

nectors capable of

A

d.

of

A

one watt termination ie adequate

2

watts for high

50

ohm coaxial termination with

1

/

2

watt dissipation.

general purpose signal generator capable

2

volts into

500

ohms (the square wave

BNC

con-

MODEL

IOOA OPERATION

amplitude calibrator of many oscilloscopes
may be adequate).

2.3.2

e. Three

(3-4

feet long) 50 ohm coaxial cables
with BNC connectors, and one BNC Tee con­nector.

Test Connections and Settings

CAU

TION

Check the position of the 1151230 volt

slide switch on the back panel for
agreement with the line voltage before
connecting the power cord.

Connect the instrument to a suitable power

a.

source.

Connect a 50 ohm coaxial cable from the POS

b.

OUTPUT to the oscilloscope input, and term­inate the cable at the oscilloscope using the

(2

50 ohm

watt) coaxial termination and the

BNC Tee connector.

Connect a 50 ohm cable from the REFERENCE

c.

TRIGGER OUTPUT to the oscilloscope trigger
input, and terminate the cable in 50 ohms at
the oscilloscope using the

112 watt termi-

nation.

d.

Set the instrument controls as follows:

Control Setting
POWER switch OFF

REPETITION RATE

range 1.0 MHz

REPETITION RATE

vernier midrange

PULSE DELAY range

1. OpS
PULSE DELAY vernier midrange
PULSE WIDTH range 1.

OpS

PULSE WIDTH vernier fully clockwise

OPERATION

MODEL

POSITIVE AMPLITUDE 5V

NEGATIVE AMPLITUDE 5V

GATE MODE switch NON-GATED
PULSE MODE switch SGL

lOOA

3.

Set the oscilloscope sweep speed to

e.

and the vertical sensitivity to 2V/CM.

3

Main Pulse Output

a. Turn the POWER switch ON. Note that the

a

pilot lamp goes on, and

rectangular pulse
(approximately 5 volts high and 1 micro­second wide with a flat top and near vertical

leading and trailing edges) appears on the
oscilloscope trace.

b. Turn the POSITIVE AMPLITUDE control in

both directions and verify that the amplitude

3

decreases to

volts and increases to 10 volts
uniformly without any noticeable effect on
waveshape.

5

volt position.

the

Return the amplitude control to

c. Disconnect the coaxial cable from the POS

OUTPUT and reconnect the cable to the NEG
OUTPUT.

Note that the negative output looks

like the positive output inverted.

Repeat step

d.

(b)

for the NEGATIVE AMPLI-

TUDE control. Reconnect the POS OUTPUT

to the oscilloscope input.

e. Turn the PULSE WIDTH vernier counter-

clockwise.
the

control and decreases smoothly. Turn

Note that the pulse width follows

the vernier to the fully clockwise position.

0. 2pS/CM

i.

Turn the PULSE DELAY vernier in both

tlirections

control moving

rlght.

po

sltion.

and

Kt,turn

note that the pulse follows the

snloothly to the left and to the

the vernier to the minimum

MODEL lOOA

OPERATION

Turn the REPETITION RATE selector to

g.

1 Hz, the PULSE WIDTH and PULSE DELAY

selectors to 1.0 MS, and all verniers fully
clockwise. Pull the width and delay verniers
out and verify that both pulse width and delay

are approximately 100 milliseconds. Push
the width and delay verniers back in and turn
the PULSE DELAY controls to minimum.

h.

Turn the PULSE WIDTH selector to

and the REPETITION RATE selector to

10 MHz.

pear on the oscilloscope, and that the number
of pulses increases when the REPETITION

RATE vernier is turned clockwise.
Double Pulse Mode

a. Retain the test connections of paragraph

2.3.2 and set the oscilloscope sweep speed

to I.

Set the instrument controls

b.

Control Setting

REPETITION RATE

range

REPETITION RATE

vernier
PULSE DELAY range
PULSE DELAY vernier

PULSE WIDTH range
PULSE WIDTH vernier
POSITIVE AMPLITUDE
NEGATIVE AMPLITUDE
GATE MODE switch
PULSE MODE switch

Note that two or three pulses ap-

OpS/CM.

a? follows

fully clockwise

1

ops
fully counter­clockwise

ops

1.
fully clockwise
5v
any position
NON-GATED
DBL

0.

1pS

c. Turn the PULSE DELAY vernier clockwise

and note that a second pulse appears on the

oscilloscope trace moving smoothly from

left to right,

following the control.

OPERATION MODEL lOOA

2.3.5 Single Pulse Operation
Retain the test connections of paragraph

a.

2.

3.2

and set the oscilloscope sweep speed

to 1.0 MS/CM.
Set the instrument controls as follows:

b.

2.3.

Control

Setting

REPETITION RATE

range
PULSE DELAY range
PULSE DELAY vernier
PULSE WIDTH range
PULSE WIDTH vernier
POSITIVE AMPLITUDE
GATE MODE switch
PULSE MODE switch

Remaining controls

Press the SINGLE PULSE pushbutton and

c.

SINGLE PULSE

1.0

MS

fully clockwise

MS

1.0
midrange
5

v

NON-GATED

SGL
any position

verify that one pulse (only) appears on the

oscilloscope trace each time the button is

actuated.

6

External Triggering

Retain the test connections of the previous

a.

paragraph

(2.

3.5) and set the oscillo?cope

sweep speed to 0.5 MS/CM.

b. Set the instrument controls as follows:

Control

Setting

REPETITION RATE

(i

)

EXT

range

TRIG;

SLOPE

1

PULSE DELAY range

MS

PULSE DELAY vernier lully counter-

c

lockwise

PULSE WIDTII range

I

MS

PU1,SE U IDTH vernier nildranjie

L40DE1, l0OA OPERATION

POSITIVE AMPLITUDE
GATE MODE switch NON-GATED
PULSE MODE switch SGL

Remaining controls any position

c. Connect either the signal generator or the

output of the oscilloscope amplitude calibrator
to the TRIGGER INPUT jack. If the cali­brator is used, set the amplitude to 1.
(the frequency is fixed at 1 kHz). When a
signal generator is used, adjust the frequency
to

1

kHz and set the amplitude to 2 volts.

d. Adjust the TRIGGERING LEVEL control until

several (approximately 5) pulses appear on

the oscilloscope trace. Switch the REPETI-

TION RATE selector to
SLOPE and verify that the pulses do not dis­appear (the trigger input is capacitor coupled).

2.3.7 External Gating
a. Retain the test connections of the previous

paragraph
of the amplitude calibrator (or the signal
generator) to the ENABLING GATE INPUT
and trigger the oscilloscope from the gate

signal.

0.5

Set the oscilloscope sweep speed to

MS/CM.

5V

(-)

EXT TRIG

(2.

3.6) except connect the output

0

volt

b. Set the instrument controls as follows:

Control

REPETITION RATE

range

REPETITION RATE

vernier

PULSE

PULSE DELAY vernier
PULSE WIDTH range

PULSE WIDTH vernier

DELAY range

Setting

0.1 MHz
fully counter-

clockwise

0.1

MS
fully counter
clockwise

0.

I

MS

midrange

-

OPERATION

MODEL

lOOA

POSITIVE AMPLITUDE
GATE MODE switch
PULSE MODE switch SGL

Remaining controls any position

Verify that the pulses occur in gated bursts.

c.

Turn the GATE MODE switch to the
GATED position and note that the pulse output
is continuous.
and note that the output is gated but unstable.

NOTE:
asynchronous mode because the instrument

repetition rate oscillator operates continu-

ously and is not synchronized to the gate

signal nor the oscilloscope.

2.4

2.4.

the other output may cause
can be conveniently avoided by reducing the amplitude of the
idle output to a low voltage so that the output is terminated
in 50 ohms by the attenuator.

2.4.2

Operating Instructions

1

Idle Output
When only one output

Output Termination

The output appears unstable in the

Switch to the ASYNC position

is

ringing of the output in use. This

being used, radiation from

5V
SYNC

NON-

Fifty ohms is used for the output impedance be­cause of the wide use and availability of 50 ohm cables,
connectors, and accessories. To get clean wave shapes

with fast transition times, both the interconnecting cable
and the load termination must have an impedance of 50 ohms.

The terminating impedance must not vary more than

instrument specifications are to be met. Proper loading is

conveniently obtained by using a Datapulse
Termination which also eliminates the need to limit pulse

amplitude and duty cycle.

2003A Power

k50/0 if

MODEL 100A

OPERATION

Output Cabling
When the pulse generator is connected to a load

that is several feet away, clean waveforms with low dis-

tortion are maintained by using a 50 ohm coaxial cable termi­nated in 50 ohms at the load rather than at the instrument.

Terminating at the pulse generator, using clip leads, or
using coaxial cable with the wrong characteristic impedance
will have the same pulse distorting effect as terminating in
the wrong impedance.

2.4.4 Nonlinear Loads
Operating directly into nonlinear devices

~uch as
transistors and diodes that exhibit high impedance in one dir­ection and low impedance in the other causes waveform dis­tortion. This can be prevented by terminating the pulse gen­erator in a network that reflects uniform loading in both dir­ections. Two methods for driving the base of a transistor,
or operating into a diode (the base-emitter junction of a

transistor resembles a diode) are illustrated in Figure 2-2.
In the resistor coupled network, transistor

QL is biased off
between pulses and is turned on during the pulse interval;
while in the capacitor coupled circuit,

QL is quiescently on

and is turned off by the applied pulse.

R1, R2, and Rj and capaci-

tor

C1

depend primarily on the transistor characteristics in

both circuits.

Values for resistors

R1

is calculated from the equations given in
the figure to provide proper termination for the pulse gener­ator (50 ohms) and prevent ringing.

C2, in the capacitor
coupled network, depends on pulse width and repetition rate,
and is determined by the given equations. For a PNP tran-

sistor, the polarity of the input pulse, the applied voltage,

In

and the diode are reversed.

both networks, load mismatch

and waveform distortion are more pronounced at fast rise

and fall times.

2.4.5 Output

An

Decoupling

emitter follower may be used to decouple the
output from a nonlinear load when the passive networks of
Figure 2-2 are unsuitable. The circuits of Figure 2-3 are

useful, for example, when more power

i~

required than can