GENERAL RADIO COMPANY 1398-A Operating Instructions Manual

OPERATING INSTRUCTIONS

Type

1396-A

PULSE

GENERATOR

Form

1398-0100A

ID-

1032

March,

1966

Copyright

1966

by

General Radio Company

West Concord, Massachusetts,

USA

GENERAL RADIO COMPANY

WEST CONCORD, MASSACHUSETTS, USA

TABLE OF CONTENTS

..............................................

Section 1 INTRODUCTION 1

.................................................

1.1 Purpose 1

.......................................

1.2 General Description 1

1.3 Controls and Connectors

...................................

1

.....................................

1.4 AccessoriesSupplied 1

....................................

1.5 Accessories Available 1

Section 2 INSTALLATION

..............................................

5

2.1 Cooling

.................................................

5

2.2 Power Supply

............................................

5

2.3 Rack Mounting

...........................................

5

.....................................

Section 3 OPERATING PROCEDURE

6

.......................................

3.1 Definition of Terms 6

..................................

3.2 Normal Internal Operation 7

3.3 Normal External Operation

.................................

7

...................................

3.4 PRF vs Pulse Duration

9

..............

3.5 Precautions for Very Long

or

Very Short Pulses

9

......................................

3.6 Rise and Fall Times 10

..............................

3.7 External Load Considerations 10

.....................

3.8 Output Dc Component - Dc Translation 11

.........................

3.9 Locking

on

High Frequency Signals 12

.....................................

3.10 Count-Down Operation 12

....................................

3.1 1 Single-Pulse Operation 12

..................................

3.12 Use

as

a

Delay Generator

12

................................

3.13 Use for Complex Waveforms

13

.................................

Section 4 PRINCIPLES OF OPERATION

14

.................................................

4.1 General 14

........

4.2 Input and PRF Oscillator Circuit - External Operation 14

........

4.3 Input and PRF Oscillator Circuit - Internal Operation 15

...........................

4.4 Output Pulse and Timing Circuits 16

............................................

4.5 Power Supply

19

................................

Section 5 SERVICE AND MAINTENANCE

20

.................................................

5.1 Warranty 20

...................................................

5.2 Service 20

.........................................

5.3 Removal of Cover 20

......................................

5.4 Routine Maintenance 20

....................................

5.5 Trouble-Shooting Notes 21

...............................................

5.6 Waveforms 23

.................................

5.7 Voltages .and Resistances 22

.....................................

5.8 Calibration Procedure 23

...............................................

Parts

Lists

and Schematics

28

SPECIFICATIONS

PULSE REPETITION FREQUENCY
Internally

Generated:

2.5 c/s to 1.2 Mc/s, with calibrated points

in a 1-3 sequence from 10

c/s to 300 kc/s, and 1.2 Mc/s, all + 5%.

Continuous coverage with an uncalibrated control.

Externally Controlled:

Aperiodic, dc to 2.4 Mc/s with 1-V, rms,

input (0.5 V at 1

Mc/s and lower); input impedance at 0.5 V,

rms, approximately 100

kD shunted by 50 pF. Output pulse is

started by negative-going input transition.

OUTPUT-PULSE CHARACTERISTICS

Duralion:

100 ns to 1 s in 7 decade ranges, +5y0 of reading or

+2y0 of full scale or + 35 ns, whichever is greater.

\\

Rise and Fall Times:

Less than 5 ns into 50 or 100

0;

typically

60 ns

+

2 ns/pF external load capacitance into 1 kD (60 V).

Voltage:

Positive and negative 60-mA current pulses available
simultaneously. Dc coupled, dc component negative with respect
to ground. 60 V, peak, into

1-kD internal load impedance for

both negative and positive pulses. Output control has 10 steps

plus continuous adjustment.

Overshoot:

Overshoot and noise in pulse, less than 10yo of ampli-

tude with correct termination.

Ramp-off:

Less than 1

%.

Synchronizing Pulses:

Prepulse:

Positive and negative

8-V,

approx, pulses of 150-ns

duration.

If

positive sync terminals are shorted. negative pulse

can be increased to approximately

50

V.

Sy nc-pulse source impedance:

positive - approx 300 D;
negative - approx 1 kD.

Delay-Sync Pulse:

Consists of a negative-going transition of
approximately 5 V and 100-ns duration, coincident with the late
edge of the main pulse. Duration control reads time between
prepulse and delayed sync pulse. This negative transition is imme­diately followed by a positive transition of approximately 5 V
and 150 ns to reset the input circuits of a following pulse generator.

(See oscillogram.)

Stability:

With external-drive terminals short-circuited, prf jitter

and pulse-duration jitter are each

0.04~0. (Jitter figures may vary

somewhat with range switch settings, magnetic fields, etc.)

Power Required:

105 to 125, 195 to 235, or 210 to 250 V, 50 to

60 c/s, 90 W.

Accessories Available:

TYPE

1217-P2 Single-Pulse Trigger, rack-

adaptor panel.

MECHANICAL DATA

Convertible-Bench Cabinet.

Net

Weight

lb

kg

14Yz 1 7.0

Depth

in

mm

8% 1 210

Width

in

mm

12 1 305

Shipping

Weight

lb

kg

18 1 8.5

Height

in

mm

5% 1 135

INTRODUCTION

INTRODUCTION

1.1

PURPOSE.

The Type 1398-A Pulse Generator is a gen-

eral-purpose pulse source intended primarily for labora-

tory use. The repetition rates of the pulses may be

either internally controlled, at frequencies from

2.5 c/s
to 1.2 Mc/s, or externally controlled at frequencies up
to 2.4

Mc/s.

In addition to the main positive and negative out­put pulses, the instrument also supplies synchronizing
pulses that correspond to the beginning and end of the
main pulse. The early sync pulse ( prepulse )is intended
chiefly for synchronizing an

oscil~oscope while the late

pulse (delay pulse

)

is intended to make the instrument

an accurate time-delay generator.

1.2

GENERAL DESCRIPTION.

The Type 1398-A comprises three main circuit

groups:

(1) A combination input circuit and oscillator that

establishes the repetition rate of the main pulse.

(2) A combination pulse-timing and output circuit
that establishes the duration and amplitude of the
main pulse.

(3) A power supply that provides regulated voltage

for the other two circuit groups.

The repetition frequency, duration, and amplitude
of the main output pulse are adjustable by front-panel
controls. The instrument, which

is

housed in a convert­ible-bench cabinet, may be used as supplied as a
bench instrument or may be quickly and easily adapted
for use in a relay-rack. (Refer to paragraph 2.3.)

1.3

CONTROLS AND CONNECTORS.

See Figure

1-1

and Table

1-1

for the location and

the description of the controls and connectors used on

the Type 1398-A.

1.4

ACCESSORIES SUPPLIED.

One instruction book,form number 1398-0100.
One power cord, part number 4200-9622.

1.5

ACCESSORIES AVAILABLE.

Type 12 17-P2 Single-Pulse Trigger, catalog number
1217-9602. Used to generate single pulses. See Figure
1-2 and paragraph 3.11.4 for further details.

Type

480-P312 Relay-Rack Adaptor Set, catalog

number

0480-9632. Used to rack-mount the Type 1398-A.

Refer to paragraph 2.3 for further details.

,TYPEl398-A PULSE GENERATOR

[ABLE

1-1

S

AND CONN

Function

Sets PRF range. In EXT

DRIVE, it changes prf
oscillator to an aperiodic

input circuit.

Continuous Adjusts prf continuously

rotary control between calibrated switch

positions. When set fully
clockwise, PRF switch is
calibrated. When PRF
switch is set to EXT DRIVE,

flF

control sets triggering

level of pulse generating

circuits.

PULSE DURATION Continuous Sets pulse duration.

rotary dial
(no stop)

Sets pulse duration range

rotary switch in decade steps.

POWER OFF Toggle switch Turns instrument on and off.

OUTPUT PULSE

-

For negative main output

OUTPUT PULSE

+

Jack-top binding For positive main output

AMPLITUDE

Inner Control Continuous Adjusts amplitude

rotary control continuously between

switch positions.

Outer Switch 10-position Sets pulse amplitude

rotary switch

in ten steps from zero

to maximum.

EXT OFFSET Jack-top binding For connection to an

post pair external power supply

10 SYNC DELAYED Jack-top binding For delayed sync pulse.

post pair

Amount of delay

is
controlled by PULSE
DURATION controls.

11

SYNC

-

Jac k-top binding For negative prepulse.
post pair

12 SYNC

+

Jack-top binding For positive prepulse.
post pair

13 EXT DRIVE Jack-top binding For external drive signal.

post pair

12-terminal For use with forthcoming

female connector

Type

1398-P1 DC Component

Control Unit.

-

--

INTRODUCTION

Figure

1-1. Type 1398-A Pulse Generator.

Figure 1-2. Type 1217-P2

Single-Pulse Trigger.

@

TYPE 1398-A PULSE GENERATOR

RUBBER

FOOT

WlNG SCREW

LOCKWASHER

WlNG

Figure 2-1. Rack Mounting: Preparation

of instrument for attachment of wings.

Figure 2-2. Rack Mounting: Wing assembly.

SECTION

2

2.1 COOLING.

It

is

important that the interior of the instrument

be adequately ventilated; therefore make sure the air

holes in the cover, especially those on the right side,
are not blocked.

2.2 POWER SUPPLY.

Connect the pulse generator to a source of power

as indicated by the legend at the input socket at
the rear of the instrument, using the power cord pro­vided. While normally connected for 115-volt operation,
the transformer input circuit

is

so arranged that one
can make the conversion from 115-volt to 215-volt
operation simply by throwing a switch located directly

below the input socket. To do this, unscrew the two
clamp fastners on the back of the instrument and slide

off the dust cover. Flip the

switch over so that the

white indicator

is

on the

195-

235-volt side. The circuit

can also be adapted to accommodate a 230-volt line.

To do this, set the line voltage switch to the

195- to

233-volt position, and remove the two wires from ter-

minal

2L, which

is

on the same panel as the line volt-

age switch, and connect them to terminal 2. For instru-

ments changed to 215-volt or 230-volt operation, name-

plates (Type

LAP166E5 for 215-volt operation, Type

LAP166E2 for 230-volt operation) may be ordered from

General Radio.

2.3

RACK

MOUNTING.

The pulse generator can be rack-mounted by

means of a Type

480-P312 Relay-Rack Adaptor Panel

Set (catalog number

0480-9632). The adaptor panels
are finished in charcoal gray crackle paint to match the
front panel of the instrument and come complete with
the necessary hardware to mount the instrument in the
rack. To make the installation, proceed as follows:

(a.) Remove the rubber feet. Retain the screws.
(b.) Remove and retain the screws that secure the
front panel to the aluminum end frames (see Figure
2-1).
(c.) Remove the spacers between the front panel and
the end frames.
(d.) Install two clips on each wing using lock wash­ers and nuts provided (see Figure 2-2).
(e.)

Attach the wings to the instrument with the front

panel screws removed in step b

(

see Figure 2-3

).

(f.) The assembly

is

now ready co be rack-mounted

in

a

standard 19-inch relay rack.

@

TYPE 1398-A PULSE GENERATOR

SECTION

3

OPERATING PROCEDURJE

3.1

DEFINITION OF TERMS.

main pulse..

...................

.The principal output of the instrument; available at the OUT-

PUT PULSE binding posts.

prepulse..

.....................

.The positive or negative sync pulse supplied just before the

start of the main pulse; available at the SYNC +and SYNC

-

binding posts.

delayed pulse

...................

The pulse coincident with the end of the main pulse; available

at the DELAYED SYNC binding posts.

internal operation..

.............

The mode where pulse repetition frequency

is

determined by

the pulse generator itself and controlled by the

PRF

controls

on the front panel.

external operation

...............

The mode where pulse repetition frequency

is

determined by

an external signal source; the pulse generator generates

pulses only when triggered by signals applied to the EXT

DRIVE

binding posts.

duty ratio..

....................

.The ratio of pulse aonn time to the total time of the period

established by the prf setting; duty ratio, in percent

=

prf

x

duration x 100.

-

--

OPERATING PROCEDURE

3.2

NORMAL INTERNAL OPERATION.

3.2.1 PRF ADJUSTMENT.

Pulse repetition frequency

is

adjusted by the

PRF controls (1 and 2,

Figure

1-I), over a range of

2.5

c/s to 1.2 Mc/s. The PRF switch

is

calibrated to

indicate prf correctly only when the

AF control

is

fully

clockwise. When the

AF control

is

fully counterclock-

wise, the prf

is

lowered well below the next lower PRF

switch setting. The range of adjustment of the OF con-

trol

is

more than enough to span any one of the ranges
set by the PRF switch and thus affords continuous
coverage of the prf range of

2.5 c/s to 1.2 Mc/s. It

is

important to remember, however, that the only calibrated
frequencies are those indicated by the PRF switch

positions, and that these are accurate only when the

AF

control

is

fully clockwise.

3.2.2 PULSE-DURATION ADJUSTMENT.

Duration of the main pulse

is

adjusted by the

PULSE DURATION controls (3 and 4, Figure 1-1).

The RANGE switch (4) selects one of seven decade

ranges and the range selected

is

covered by the PULSE

DURATION dial (3). This control consists

of a knob

linked by

a

slow-motion drive to a dial that

is

calibrat-

ed from

1

to

11

in tenths of a unit. The overlap beyond

the decade span ensures continuous coverage of all

durations.

3.2.3 AMPLITUDE ADJUSTMENT.

Amplitude of the main pulse

is

adjusted by the
large AMPLITUDE switch, which varies the amplitude
from zero to maximum in ten steps, and by the small

amplitude control (concentric with the switch

)

which
facilitates continuous adjustment between steps. The
positions of the larger switch corresponds to changes in
in output impedance in 100-ohm steps. Thus a setting of
five indicates that the output impedance

is

about 500
ohms. When both controls are fully clockwise, the am­plitude

is

60 volts and the output impedance

is

one

kilohm.

3.2.4 FAMILIARIZATION PROCEDURE.

The best way to become familiar with the pulse

generator

is

to connect it to an oscilloscope and watch

the pulses themselves. The procedure

is

as follows:

a. Connect the OUTPUT PULSE

t

binding post to

the oscilloscope vertical input by means of open

leads or a probe.
b. Connect the SYNC +binding post to the oscillo-

scope sync or trigger input.
c. Connect any of the ground binding posts to the
oscilloscope ground.
d. Be sure that the link across the EXT OFFSET
binding post

is

firmly connected to both posts.

e. Adjust the oscilloscope trigger controls to trigger

on the

%volt, 100-ns, positive prepulse of theType

1398-A.
f. Set the oscilloscope sweep rate controls for a
2-ms/div sweep rate.

g.

Set the oscilloscope vertical gain controls for

about 40

volts/cm sensitivity.

h. Set the PRF switch to

1

kc/s.

i.

Set the AF control fully clockwise.

j.

Set the PULSE DURATION dial to 5.

k. Set the PULSE DURATION RANGE switch to
100

ps-1

ms.

1. Set the AMPLITUDE control fully clockwise.

The oscilloscope should now display a 1-kc

square-wave from the pulse generator. Use the PULSE
DURATION dial to shorten and to lengthen the pulse and
then set the PULSE DURATION RANGE switch to the

next lower range Decrease the prf first

by turning the OF
control counterclockwise and then by setting the PRF
switch to the next lower position. Adjust the oscillo­scope sweep rate control to keep both

thepulse duration
and frequency under observation. To decrease pulse am­plitude, turn the AMPLITUDE control counterclockwise.

If the oscilloscope has a dc-coupled vertical am-

plifier, set it for dc, disconnect the pulse, and estab-

lish the ground reference trace. Now reconnect the pos­itive main pulse and vary its amplitude. Then move the
connector from the

+

OUTPUT PULSE to the - OUT-

PUT PULSE binding post and vary the amplitude again.

Note that the pulse contains a dc component that

is

negative with respect to ground. The positive pulse

starts from

-60 volts and rises to ground during

its

active interval. The negative pulse starts from ground
and

fal!s to -60 volts during its active interval.

If, during any of the above procedures, the pulse

is

defective or the pattern becomes confused, check to
make sure that the pulse duration has not been made
too long for the pulse repetition frequency and that an

oscilloscope with a dc-coupled vertical amplifier

is

used to observe pulses of very long duration.

3.3

NORMAL EXTERNAL OPERATION.

3.3.1 DRIVING-SIGNAL REQUIREMENTS.

The Type 1398-A will produce externally triggered

pulses at frequencies from dc to 2.4

Mc/s. The driving
signal should be applied to the EXT DRIVE terminals,
and should be at least

0.5

volt,rms, up to 500 kc/s and

at least

1

volt,rms, from 500 kc/s to 2.4

MC/S.

Exces-

sive driving voltages at frequencies above

1.5 Mc/s

may overload the triggering circuits. If the unit fails to

trigger, reduce the driving voltage. With optimum driving

voltage the unit will trigger to frequencies typically as
high as 2.5 Mc/s.

@

TYPE

1398-A

PULSE GENERATOR

Figure

3-1.

Typical

sensitivity-vs-frequency

characteristics.

3.3.2

EXTERNAL DRIVE PROCEDURE.

For external operation, set the PRF switch to

EXT DRIVE and apply the external driving

signal to

the EXT DRIVE binding posts. The

AF control now be-

comes a triggering level adjustment; the input circuits

are set for maximum sensitivity when this control is

centered.

The input circuit is dc-coupled, and the pulse
generator will operate from pulses at any low frequency
desired. The input

signal must therefore either be at a
dc potential close to ground or be ac-coupled, with an
external blocking capacitor.

3.3.3

OPERATION WITH OSCILLOSCOPE.

trigger, adjust the AF control until triggering is re­established. When no further adjustment of the

AF

control will re-establish triggering, the triggering
threshold has been reached (this should be at about

0.3 volt, p-to-p, to 1 kc/s

).

A plot of typical sensi-

tivity

is

given in Figure 3.1.

g. Reset the generator amplitude to

1 volt, rms. If

possible, display its output waveform and the Type

1398-A output pulse simultaneously on the oscillo-

scope.

h. Adjust the

AF

control and observe the starting

point of the pulse. Note that the

AF

control adjusts

the phase at which the pulse is formed, and that the

pulse always starts during the negative-going input

To observe external operation on an oscilloscope

transition.

proceed as follows:

a. Set up the equipment to display a

1-kc square

wave, as described in paragraph

3.2.4, a to 1.

b. Set the PRF switch to EXT DRIVE.

c. Connect an adjustable audio-frequency generator
to the EXT DRIVE binding posts and set the gener-

ator to produce a

1-kc signal of at least 1 volt, rms.

d. Center the

AF control (now used as a triggering
level control). The oscilloscope should display a
square wave as described in paragraph

3.2.4.

e. Decrease the frequency of the audio-frequency

generator. Note that the external generator controls
the prf of the Type 1398-A.
f. Reset the audio-frequency generator to

1

kc/s and

reduce its amplitude. When the Type 1398-A fails to

TABLE

3

-

1

DURATION ACCURACY

VS

DUTY RATIO

Duty Ratio Accuracy

0 to 20%

f2%

of full scale with

with DURATION dial at 1 to 4.

k5% of reading

with DURATION dial

at

5 to 10.

135 ns with durations of

0.1 to

0.7~~.

20 to 50% +lo% of reading.

I

Over 50% Inaccurate.

I

OPERATING PROCEDURE

3.4

PRF VS PULSE DURATION.

3.4.1 DUTY RATIO LIMITS DURATION ACCURACY

There is no restriction on the duty ratio of the

Type 1398-A. (Duty ratio is the ratio of the pulse

"

on"
time to the total time of the period established by the
prf setting; duty ratio in percent

=

prf xduration x 100.)
Therefore, the PULSE DURATION controls may be
mistakenly set for a duration longer than the total

period (period

is

the reciprocal of prf

).

The instrument
cannot be damaged by such settings, but the user may
be confused by the resulting oscilloscope display.
Refer to Table 3-1 for duration accuracy versus

duty-

ratio specifications.

3.4.2 DURATION LESS THAN 50% OF PERIOD.

The accuracy of the DURATION control settings

is preserved if the duty ratio is 50% or less

(pulse
duration is 50% or less of total time of period). Table
3-2 lists the 50%-of-period figures for each PRF control
setting.

3.4.3 DURATION GREATER THAN 50% OF PERIOD.

When the pulse occupies more than 50 percent of

the total period, the dial reading of duration is erron-

eous. This effect is due to insufficient recovery time

for the pulse-forming circuits but can

be

circumvented

by the reversal of the OUTPUT PULSE polarity.

For example: A 1-kc,

600 ps positive pulse

is

desired. From Table 3-2 it can be seen that 600

ps

exceed the 500 ps maximum duration given for a

PRF

control setting of 1 kc/s (actual duty ratio 103

x

6

x

10

x

lo2

=

60%). But, from Figure 3-2, it also can be

seen that a positive duration of 600

,US

can be obtained

TABLE 3-2

50%-OF-PERIOD FIGURES

I

50%

of Period (Durations inaccurate

PR

Con'r01

/m

DORATON

controi setti~gs

I

(AF

control fully clockwise)

longer than those listed)

3.4.4 DURATION EQUAL TO PERIOD.

When the DURATION controls call for a pulse
exactly equal to the pulse period, the instrument fails
completely, and both duration and prf are indeterminate.

3.4.5 DURATION GREATER THAN PERIOD.

When the duration is set longer than the pulse

period, the pulse timing circuits will "count down

",

producing one pulse for each 2,3,4,

...

n input periods.
In general, the pulse duration will not be precisely
controllable due to lack of recovery time. However,

such frequency division may be useful in some applica-

tions and it should be remembered that the Type 1398-A
can be used as a frequency divider of arbitrary scale

by such operation.

if connection is made to the -OUTPUT PULSE binding

3.5

~RECAUT~ONS

FOR

VERY

LONG

post rather than to the +OUTPUT PULSE binding post

OR VERY SHORT PULSES.

and if the DURATION controls are set to 400 ps pulse
(total period minus 600 ps). The duty ratio for a 1-kc,

3-50' GENERAL-

400-ps pulse is 40%; therefore the

DURATION

control

When pulses of very long or very short duration

accuracy is preserved.

are to be produced and observed, special attention must

~PERIOD=IOOO~~~

+OUTPUT

PULSE

OV

-

(INACCURATE)

-

60V

j4

1

I

DURATION

CONTROLS

SET

TO

600ps

DURATION

INACCURATE

BECAUSE DUTY

RATIO

EXCEEDS

50%

~PERIOD=~O~~~,

,

-OUTPUT

PULSE

OV-

(

ACCURATE)

-

60V

f'

11598-21

DURATION

CONTROLS

SET

TO

400ps

DURATION

ACCURATE

BECAUSE

DUTY

RATIO

IS

LESS

THAN

50%

Figure

3-2.

Circumvention of

50%

duty-ratio limitation at 1 kc/s

by

reversal

of

OUTPUT PULSE polarity.

@

TYPE 1398-A PULSE GENERATOR

be given to the equipment setup and interconnections.

Bandwidth considerations are fundamental and oscillo-

scopes with the desired frequency response must be

chosen as indicators.

3.5.2 LONG PULSES- LOW-FREQUENCY RESPONSE.

An oscilloscope with a frequency response to dc

is necessary to observe very long pulses. The

low­frequency cutoff of most oscilloscopes that do not have
dc amplifiers

is

about 5 or 10 c/s, and these oscillo-

scopes will exhibit

"

ramp-off effects with pulse dura­tions over 10 milliseconds. (Ramp-off is the slope on
the

flat

top and bottom.) Almost any indicator has

adequate high-frequency response for long-duration

pulses becuase the "flats" are usually of more interest

than are the rapid rise and fallvoltage transitions. The

Type 1398-A uses a direct-coupled output system and

will not cause ramp-off at any duration.

3.6

RISE AND FALL TIMES.

The Type 1398-A has very short rise and fall

times (typically

5 ns ) of output current into the internal

1-kilohm loads and their associated stray capacitances.

The internal stray capacitances are about 40

pF, which

results in open-circuit rise and fall times of about

90 ns

across the internal

1-kilohm load. The rise and fall
times increase linearly with external capacitance and
and decrease linearly with external resistance

-

the

final transition time is about 2.2

RC.

The intrinsic rise

time can therefore be observed only if a resistance of

100 ohms or less is connected across the output binding
posts. With an open-circuit connection, the Type 1398-A
output circuit

is

capacitance-limited, the voltage tran-

sition varies exponentially with time, and no overshoot

is possible. Because of this important feature, the
Type 1398-A can be used to check almost any amplifier
system for overshoot

-

including any oscilloscope whose

input impedance is over

1 kilohm.

3.5.3 SHORT PULSES-HIGH-FREQUENCY RESPONSE.

For further information on rise and fall times,

Faithful reproduction of very short pulses or of

refer

paragraph

3.77

the rapidly changing voltage of the leading or trailing
edge of such a pulse requires wide-bandwidth amplifier

3.7

EXTERNAL LOAD CONSIDERATIONS.

and indicator systems. For example, when a pulse with

The output circuits of the pulse generator are as

a rise time of 0.05

ps

is

displayed

on

an oscilloscope

stable as possible

for

an instrument of such simplicity.

whose amplifier has a rise time of 0.05 fis, the indi-

Some imDortant

Doints

to

remember

are:

cated rise time will be 0.07 ps. For a system with n

(1)

The output tubes act as current sources that

individual components of specified rise time, the

equa-

produce 60-rnA pulses into a parallel combination of

tion for over-all rise time1

is

the AMPLITUDE control resistors and whatever ex­ternal load is

c0nnecte.d to the instrument.

(1)

(2)

The pulses are direct-coupled to the OUTPUT

PULSE binding posts and therefore contain a

nega-

The rise time of an amplifier system, TI, is related to

tive dc component of 60

mA.

the 3-dB bandwidth,

B,

by the equation (2), where the
factor of 0.35 should be used if the overshoot is less
than

10 percent.'

With very short pulses, it is necessary to take care in

the wiring of system components. Short, direct wires
should be used for both signal and ground paths if open

wiring

is

used, and coaxialcables should be terminated
properly. A common sign of an improperly connected
ground or of an inductive loop in the wiring is the pres­ence of high-frequency ringing (damped oscillation) on
the pulse transitions.

'

Valley,

G.

E.,

and

Wallrnan,

Henry,

"Vacuum

Tube Ampli-

fiers,

I'

Radiatiolz

Laboraiory

Series,

Vol

18,

McGraw-Hill,

1948,

p

77.

lbid,

p

80.

OUTPUT

Figure 3-3. Equivalent circuit for Type 1398-A

output system feeding high load impedance.

Figure 3-3 shows an equivalent circuit for the

Type 1398-A output system as it appears when feeding

a high external load impedance

(e.g., a 12-pF, 10-

megohm oscilloscope probe). The pulses from this cir-

cuit will be capacitance-limited by the

50-11s RC time

constant, and a rise time of about

100 ns results

(Figure

3-4c). The appearance of a brief pulse at out-

put settings of 0.6 volt and

6

volts is shown in Figure

3-4 a and b, respectively.

OPERATING PROCEDURE

0.6 volt,

peuk-to-peak, into 10

5

volts, peok-to-peak, into 100

36

volts, peak-to-peak, into 1

ohms; 0.1

ps/cm. ohms; 0.1 ps/cm.

kilohm, 0.1 ,us/cm.

Figure 3-4.

Pulses from circuit of Figure

3-3.

Two important features should be noted from the

above:

(1)

the rise time can be controlled with no ter­mination and maximum output, by the addition of fixed
external capacitance according to the equation

Tr

(ns)

=

2.2

(40 pF

+

C,,,)

(3)

and (2) the ultimate rise time can be realized only by
termination of the instrument either externally by

placing a

50-0 resistor across the output terminals, or

internally by setting the output impedance to 50

0

(

AMPLITUDE switch at 0.1, AMPLITUDE control cen­tered), or both, as shown in Figure 3-5. Here the time
constant of the output circuit

is

about 1.5 ns, and the

fast rise and fall of the current pulse can be observed.

OUTPUT

40-pF

!

lka

INTERNAL?;

0

--I,

-

-

-

mT

Figure 3-5. Equivalent circuit for

achieving ultimate rise time.

In this connection, the transitions will typically be

less than

5 ns. See Figure 3-6 for the typical appearance

of waveforms under

t~rminated conditions.

3.8

OUTPUT DC COMPONENT-DC TRANSLATION.

In certain applications it may be desirable to
remove or to change the dc component of the main out­put pulse. If it is necessary only to remove the dc

component, and if the pulses are fairly short and the

circuit impedances high, the desired result may be ob­tained simply by addition of an external coupling ca­pacitor large enough to prevent ramp-off for the desired

pulse duration. If the above conditions do not hold, or

if it is necessary to introduce dc offset, an external

power supply can be connected to the OFFSET ter-

minal. Such

a

connection will allow the dc component
level to be shifted by as much as 20 volts in either the
positive or the negative direction since the voltage of
power supply is then applied to the plate load resistors

of the output tubes, thus changing their quiescent

-

voltage levels.

The AMPLITUDE control

is

adjusted until a 20-

volt swing is attained

as

measured on

an

oscilloscope.

Then an adjustable positive power supply is connected

to the EXT OFFSET terminal and its voltage

is

adjust-

ed until the dc output of the pulse generator is zero

as

measured on a dc voltmeter. Alternatively, the voltages
needed for the desired offset may be precalculated and

set accordingly. For instance,

if

the duty ratio (refer to

paragraph 3.4.1) is

50%, the required offset voltage

is

+

10 volts for a twenty-volt pulse. A + 10-volt power

supply

is

connected to the EXT OFFSET terminal and,

using only

a

dc voltmeter, the AMPLITUDE control ad-

justed so that the dc level is zero.

NOTE

Do not apply more than

k

20 volts to the

EXT OFFSET terminal, as voltages ex­ceeding this level may damage the output
tubes.

3-volt, 5-,us pulse; 50-ohm

termination.

As in (a), but with

open-cir-

cuit terminotion,60-volt pulse.

Figure 3-6. Typical waveforms under terminated conditions.

@

TYPE 1398-A PULSE GENERATOR

3.9 LOCKING ON HIGH FREQUENCY SIGNALS.

3.9.1 FREQUENCY DIVIDER ACTION.

If an external signal

is

applied to the EXT DRIVE

binding posts and the PRF switch

is

set to one of the

numbered positions, the internal oscillator of the Type

1398-A will lock on the external signal. For instance,

if a 50-kc signal

is

applied at the EXT DRIVE termin-

als

and the PRF

is

set to nearly 10 kc/s the main pulse
of the Type 1398-A can be locked at the external
frequency of 50 kc/s. In other words, the pulse genera­tor

is

operating as a 5-to-l frequency divider and

supplies one output pulse for every five input pulses.

The pulse generator can be phase-locked in this manner
to frequencies well above the maximum prf of the inter­nal oscillator.

3.9.2 OBSERVATION WITH OSCILLOSCOPE.

To observe the above action, connect an oscillo­scope and an audio-frequency generator to the Type
1398-A as described in paragraph 3.3.3. If possible,

observe the waveform of the external generator on the

oscilloscope, together with the Type 1398-A output.
Then proceed as follows

a.

Set the PRF switch to 1 kc/s.

b. Set the

AF control fully clockwise.

c. Set the external generator to

1

kc/s.

d. Set the output amplitude of the external generator
to minimum and then increase it until the Type

1398-A locks

.

e. Set the frequency of the external generator to

2 kc/s, 3 kc/s,

4

kc/s, etc., and each time advance
the signal amplitude to lock the pulse generator. In
this way the pulse generator can be locked at very
high ratios.

3.10 COUNT-DOWN OPERATION.

When the duration

is

set longer than the pulse

period, the pulse timing circuits will "count down

",

producing one pulse for each 2,3,4,

...

n input periods.
In general, the pulse duration will not be precisely
controllable, owing to lack of recovery time.

3.11 SINGLE-PULSE OPERATION.

3.11.1 METHODS.

There are three ways by which one can produce a

single pulse:

(1.) By rotating the

AF control with the PRF switch

set to EXT DRIVE.

(2.) By touching the EXT DRIVE binding post.

(3.) By using the Type

1217-P2Single-Pulse Trigger.

The following three paragraphs explain each

method in detail.

3.1 1.2 ROTATION OF AF CONTROL.

Set the PRF switch to EXT DRIVE and rotate the

AF control about 20 or 30 degrees clockwise from its
center position and then reverse the direction of rota­tion. An output pulse will be produced as the

AF con-

trol

is

moved counterclockwise past the center position.

Very little rotation

is

necessary to reset and to start the

input circuits. Be careful not to touch the EXT DRIVE

binding post because a pulse burst may be produced by

the injected hum.

3.11.3 TOUCHING EXT DRIVE BINDING POST.

Set the PRF switch to EXT DRIVE and set the
AF control near the center of its range. A single pulse
will be produced when the EXT DRIVE binding post

is

touched. This method

is

useful only for very long pulses

because the driving signal

is

a burst of noise or hum.

3.11.4 TYPE 1217-P2 SINGLE-PULSE TRIGGER.

The most convenient way to produce single pulses

is

to use a pushbutton actuating-circuit such as the
Type 1217-P2 Single-Pulse Trigger, shown pictorially
in Figure 1-2 and schematically in Figure 3-7. To use

it, set the PRF switch to EXT DRIVE and set the

AF

control between three-quarters clockwise and fully

clockwise.

100

kn

1.5V DRIVE

f

O.1LJF O.'PF TERMINAL

I

I

NORMALLY OPEN

-

-

Figure

3-7.

Schematic diagrom

of

the

Type 1217-P2 Single-Pulse Trigger.

To produce a main pulse when the switch opens,
connect the negative banana plug of the Type 1217-P2
(arrowhead terminal in Figure 3-7) to the EXT DRIVE
binding post of the Type 1398-A.

To produce a main pulse when the switch closes,
reverse the double banana plug of the Type 1217-P2 so
the positive banana plug (ground symbol in Figure 3-7

)

is

connected to the EXT DRIVE binding post of the

Type 1398-A.

3.12 USE AS A DELAY GENERATOR.

The delayed sync pulse from the Type 1398-A

can be used to operate the input circuits of a second

Type 1398-A with a minimum of adjustment. The delayed

OPERATING PROCEDURE

pulse consists of a negative-going transition of about

3.13

USE FOR COMPLEX WAVEFORMS.

5 volts and 100-ns duration, followed immediately by a

Since the output circuit of the Type 1398-A

is

positive transition of about 5 volts and 150-ns duration.

essentially a current source feeding a resistive load,

The initial

negative-going transition will trigger the

the outputs of two or more pulse generators can be

input circuits and start the main pulse of

a

following

directly, paralleled to produce complex additive wave-

Type 1398-A. The positive-going transition will then

forms. The output impedance of

n pulse generators so

reset the input circuits of the second Type 1398-A to

paralleled

is

1000/n ohms and the peak voltage

is

still

prepare it for the next delayed pulse. Figure 3-8 shows

60volts. A complexwaveform and the system to produce

connections and timing waveforms of such a system.

it are shown in Figure

3-9.

TYPE 1210-C UNIT TYPE 1398-0, TYPE 1398-A

R-C OSCILLATOR PULSE

GENERATOR# l PULSE G€NERATOR.*2

TYPE

1210-C

TYPE 1398-8

,#I

PREPULSE

TYPE 1398-A

,*

I

MAIN

PULSE(NEG1

I

L

TYPE 1398-A

#

1

DELAYED

PULSE

h

TYPE 1398-A # 2

MA'IN

PULS~

INSa-61

Figure 3-8.

Connection of two Type 1398-A's

as a

delay generator.

TYPE 1398-A$I

TYPE 1398-8 TYPE 1398-A TYPE 1398-A

PULSE

GENERATOR,#I PULSE GENERATORP2 PULSE GENERATOR,#3

TYPE 139&A,X2

V

A

v

0

0 000

o*-

00000 op

-

TYPE 1398-A,X3

Figure 3-9.

System for producing the complex waveform shown.

-a

0

00

0

00

00000

09

-4

0

0000

0--

I

-

-

C

OUTPUT

I

-

-

-

-

@.

TYPE 1398-A

PULSE

GENERATOR

SECTION

4

PRINCIPLES

OF

OPERATION

4.1

GENERAL.

(See

Figure

4-1.)

The Type 1398-A

is

composed of three basic sec-

tions:

(1)

the input and prf oscillator circuit, (2) the

output pulse circuit, and

(3)

the power supply. The

first two sections are shown in block diagram form in

Figure 4-1.

Externally or internally generated positive pulses

from the input and prf oscillator circuit trigger the

output pulse circuit. The output pulse circuit, in
turn, produces positive and negative pulses that ap­pear at the OUTPUT PULSE binding posts.

A

detailed

analysis of each circuit is contained in the following
paragraphs.

4.2

INPUT AND PRF OSCILLATOR CIRCUIT

-

EXTERNAL OPERATION.

4.2.1

GENERAL.

Let us first consider the circuit as an aperiodic

input circuit,

i.e., with the

PRF

switch set to EXT
DRIVE, as shown in Figure 4-2. In this mode, the cir­cuit converts an external signal, applied to the EXT
DRIVE binding posts, to a positive pulse, which ap­pears at the output, pin

6

of V102.

INPUT

AND

pRF-l

(-

OUTPUT PULSE CIRCUIT

FCILLATOR

CIRCUIT

1

-3

-+DELAYED

SYNC

AMPLITUDE

V105

POWER

n

~~sITIvE OUTPUT

STARTQlo3

----C

AMPLIFIER

-$&+C

-NEGATIVE OUTPUT

V106

SYNC

POSITIVE SYNC

AMPLIFIER

VlOlB

Y

SYNC

Figure

4-1.

Block diagram

of

the Type 1398-A Pulse Generator.

PRINCIPLES OF OPERATION

-VOLTAGE AMPLIFIER

.-I(-

SCHMITT

CIRCUIT-

t150V

I'

+150V

+

150V

TO OUTPUT

PULSE

CIRCUIT

Figure

4-2.

Simpl

of the input and

-

150V

4.2.2 SCHMITT CIRCUIT.

V102A and B form a Schmitt trigger circuit.

Whether or not

V102B

is

on (conducting) depends on

the voltage at the grid of

V102A. When V102A's grid

voltage is considerably less then

+

50 volts, V102B

will be on. V102BYs grid voltage

is

set at about +50
volts by R113 and R115. If the grid voltage of V102A
is

raised toward + 50 volts, it will begin to turn on. As
V102A goes on, its plate voltage will begin to fall,
lowering the grid voltage on

V102B and lowering the
common cathode voltage. As the cathode voltage falls,
the plate current of

V102A increases. This regenerative

action will terminate only when

V102B

is

completely

off and

V102A completely on.

To turn

V102B back on, the grid voltage of V102A
must be lowered to a level below that at which the
switching first took place. This voltage hysteresis

effect is shown in Figure 4.3.

WhenV102B switches off,
its rapidly falling plate current produces the triggering
pulse, which is used to initiate the main pulse and
which serves as the pre-pulse for the

SYNC

terminals

after amplification by

VlOlB. This pulse

is

produced

when

V102A is turned on by a positive voltage applied
to its grid. The pre-pulse is therefore produced when a
negative transition occurs at the grid of

VlOlA.

4.2.3 QUIESCENT CONDITIONS.

In the absence of an input signal, the grid of
VlOlA will be at ground potential, and its plate voltage
will be around +60 volts. Whether or not

V102A will

be on will depend upon the setting of

R103, the AF and

trigger-threshold control. When this control is adjusted

ified schematic diagram

prf oscillator circuit.

for maximum trigger sensitivity(centered), the quiescent

voltage at the grid of

V102A will lie in the center of

the hysteresis region. Input signals applied to the EXT

DRIVE terminals are amplified by VlOlA and cause
V102 to switch. The exact phase at which the output

trigger will be formed

is

determined by the setting of
R103. Maximum sensitivity will be obtained when the
amplified signal is centered in the hysteresis region.

A single pulse can be produced (paragraph

3.4.2)

by rotation of the

AF

control through its centered posi­tion. This rotation simply sets and resets the Schmitt
trigger.

4.3

INPUT AND PRF OSCILLATOR CIRCUIT

-

INTERNAL OPERATION.

4.3.1 GENERAL.

In Figure 4-2, the PRF switch

is

shown in the

EXT DRIVE position. When this switch

is

set to any of
the other positions, the voltage amplifier and Schmitt
circuits are converted to

a

prf oscillator.

e

PLATE

HYSTERESIS

L-

----_

11211-18

Figure

4-3.

Diagram showing operation

of internal oscillator.

PRINCIPLES OF OPERATION

tor circuit is applied) V105

is

on (conducting) and

4.4.7 TRIGGER AMPLIFIERS.

about 6OmA flows through the output resistors.

Start-Signal Action

4.4.5 -OUTPUT AMPLIFIER.
Quiescent:

V106

OFF

4103 and 4104 are the trigger amplifiers. Both

are biased off. Since both are npn transistors, a posi-

The

negative output

pulse

starts

from

volts

and

tive pulse applied to their bases will turn them on for

falls to

-6ovolts, Therefore, in the quiescent state,

the duration of the pulse. When a start signal (positive

VlO6

is

off

(not conducting), no current

flows

through,

pulse)

arrives

from

the

and prf circuit,

it

is

its

plate load resistors and the -OUTPUT point rests

applied to the base of

4103. 4103 conducts and pro-

at ground potential

(

0 volts

).

duces a negative pulse at its collector.

4.4.6 MULTIVIBRATOR DRIVER,

OUTPUT AMPLIFIER BIAS.

Quiescent:

QlOl

OFF,

Q102

ON

The plate voltages of the output amplifiers are
controlled by their grid voltages, which, in turn, are
controlled by the bistable driver, which consists of two

npn transistors, QlOl and

4102.

As noted before, V105

is

on in the quiescent state,

which means its grid bias must be low enough to allow

conduction.

V105 and

~106

are self-biased by their

common cathode resistor

R156, through which about

70 milliamperes flow for a 2-volt bias. If QlOl were

on (conducting), current would flow through

R154, and

the voltage drop across

R154 and R156 (V105 bias)

would be sufficiently large to turn off

V105. SinceVlOS

is on, QlOl must be off. When QlOl

is

off, 4102 is on

because the two transistors

.form a bistable multivibrator.

With 4102 on, current flows through

R157 to bias VlO6
off - the quiescent condition described above in para­graph 4.4.5.

1

STOP

I

STAR

1

4.4.8 MULTIVIBRATOR DRIVER SWITCHING.
Start-Signal Action

SWEEP GENERATOR

"3

AND CLAMP

The negative pulse at the collector of 4103

is

coupled to the base of 4102 and causes 4102 to start
to turn off.

4102

is

one half of a multivibrator that con-

sists of

4102 and 4101;

as 4102 starts to turn off,

4101 starts to turn on. This

is

the normal regenerative

action of any multivibrator and the discussion that

follows describes the switching action and the regen-

erative paths of QlOl and 4102.

The negative pulse at the base of

4102 appears

as a positive pulse at the collector of

4102. This pos-

itive pulse

is

coupled through C134to the base of QlOl
and causes QlOl to start to turn on. The positive pulse
at the base of QlOl appears as a negative pulse at the

collector. This negative pulse

is

coupled through C133

and R139 back to the base of 4102, aids the negative

pulse already present from the collector of

4103, and
thus completes the regenerative loop. Upon completion
of the switching action, QlOl

is

on and 4102 is off.

Figure

4-5.

Simplified schematic

diagram of the output-pulse circuit.

@

TYPE 1398-A PULSE GENERATOR

4.4.9 OUTPUT AMPLIFIERS.
Start-Signal Action

As long as

V103A

is

on, C will not charge, and V103B

will be on, holding C's voltage to V.

Since the multivibrator driver has reversed its

state, the

output amplifiers have also reversed their

4.4.1

1

AMPLITUDE COMPARATOR SCHMITT

states. V105

is

now off and the +OUTPUT PULSE

Quiescent:

V104A OFF, V104B ON

voltage is

0 volts, and VlO6 is now on and the

-OUT-

PUT PULSE voltage is

-60 volts instead of

0 volts.
All that remains to convert these dc-voltage steps to
pulses is to return the circuits to their quiescent levels.

4.4.10 SWEEP GENERATOR AND CLAMP,
DURATION CONTROL.

Quiescent:

V103A ON, V103B ON

The stop-signal path returns the circuits to their

quiescent levels. The time required to do this is the
output pulse duration; therefore the PULSE DURATION
controls are located in the stop signal path.

Since the voltage V on its grid is held equal to

or lower than its cathode voltage,

V104A

is

biased off.

Since

V104A and B are a Schmitt circuit, V104B must

be on if

V104A

is

off. V104A will not turn on until the

voltage on its

grid exceeds the voltage on the grid of

V104B set

by

R127 and R129.

4.4.12 SWEEP GENERATOR

AND

CLAMP.

Stop-Signal Action

When

V105 reverts from its quiescent state, it

turns off.

Vi03A also turns off because both tubes share

a common bias. When

V103A turns off, capacitor

C

begins to charge to +I50 volts. As it charges, it draws

current through the plate load resistor, R, of

V103A

The duration

is

actually controlled by a sweep

and thus keeps the plate of

V103A from returning im-

generator whose sweep rate can be adjusted by the

mediately to

+I50 volts.

DURATION controls. Before the arrival of a start
pulse all circuits are in their quiescent states.

V105

is

on, and since the grid bias of V105

is

also the grid

bias of

V103A,V103A is also on in the quiescent state.

The diode

V103B

is

connected between C and a

tap on the cathode resistor R125 (the PULSE DURA­TION control) of the Schmitt circuit comprised of

V104A and B. This resistor carries a constant current
(about 15 milliamperes) so that the voltage V at the
tap

is

constant. This positive voltage forms the base

from which the ramp pulse of the sweep generator rises.

Therefore, the voltage at the plate of

V103A
goes positive at a rate determined by the values of C
and R. When this voltage goes more positive than V,

V103B turns off. When the voltage reaches the switching

voltage of the Schmitt trigger-circuit,

V104A turns on

and

V104B turns off. The length of time it takes the
voltage on C to reach this level depends on the base
voltage V: if V is tapped from the top of

R125, the

time

is

short; if V

is

zero (tapped from the bottom),

time

is

long. When V104B turns off, a positive pulse is

applied to the stop-trigger amplifier.

d.

--"

R501

-

--

V501A

t150V REGULATED

-

R504

R505

R506

m

-150V REGULATED

I

I

(-150 REGULATED

Figure

4-6.

Simplified schematic diagram

of the power-supply circuit.

PRINCIPLES OF

OPERATION

4.4.13 STOP-TRIGGER AMPLIFIER.
Stop-Signal Action

The stop-trigger amplifier behaves in the same
fashion as the start trigger amplifier when it receives
a positive pulse,

i.e., it reverses the state of the multi­vibrator, which, in turn, reverses the state of the output
amplifiers. Thus

VlO5 is turned back on,VlO6 is turned
off, all circuits have returned to their quiescent levels,
and the output pulse is terminated.

4.5

POWER

SUPPLY.

(

Figure 4-6).

4.5.1 GENERAL.

Both the positive and negative 150-volt supplies

are highly regulated with conventionalamplifier,

series-

tube, voltage regulators. The negative supply contains

the reference tube and is therefore the primary regulated

voltage source. The positive supply obtains its refer­ence from the negative. The raw dc

s,ource for each
supply is a full-wave bridge rectifier with a capacitor
input filter.

CR501, CR502, CR503, and CR504 provide

+

225 volts with respect to ground to the first half of

V501, the positive series tube. In similar fashion

CR505, CR506, CR507, and CR508 provide an equal dc

and

R513 form a voltage divider establishing the grid

potential of amplifier

tubeV503 at a level very slightly
more negative than the cathode. The plate current of
V503 in

R507 controls the drop across V501. V501 and
V503 are therefore an amplifier with high gain and any
attempt by

V503's grid voltage to change with respect
to its cathodevoltage results in a compensating change
in the voltage drop across

V501. The drop across R.513

and to the top of R512

is

therefore held very constant

and is near 80 volts.

4.5.3 THE POSITIVE VOLTAGE SUPPLY.

The constant -150-volt source established with

V501J3, V503, and V504

is

used as a reference for the

positive supply. The plate current of

V502, the cathode

of which is grounded, in

R501 controls the drop across
V501A. Thus V501A and V502 comprise an amplifier
with high gain. The grid voltage of

v502,only slightly
negative (one volt) with respect to its cathode, is es­tablished by the voltage divider consisting of

R504,

R505, and R506. This divider

is

set so that the portion
of resistance above the tap is equal to that below. For
the grid voltage of V501 to be near zero volts the out-

put voltage at pin 3 of

V501

must

be 150 volts.

voltage which divides across the second section of

V5Ol and the load to ~rovide -150 volts regulatedwith

4.5.4 THE HEATER VOLTAGE SUPPLY.

-

respect to ground.

Two heater busses are used in the Type

1398-A.

4.5.2 THE NEGATIVE VOLTAGE SUPPLY.

The 6.3-volt dc heaters of V101, V102, V104, V501,
and V502 are fed from a common buss at ground poten-

R510 and V503 draw about 10 milliamperes of

tial. The heater supply for

V103,V105,V106, and V501

current in

V504, the voltage reference tube. The drop

is

biased to - 70 volts dc by a divider from - 150 volts

across

V504 is a very constant 80 volts. R511, R512,

comprised of R514, R515, and R518.

@

TYPE

1398-A

PULSE

GENERATOR

SECTION

5

SERVICE AND MAINTENANCE

5.1 WARRANTY.

Before returning an instrument to General Radio

We warrant that each new instrument sold by us

is

free from defects in material and workmanship and
that, properly used, it will perform in full accordance
with applicable specifications for a period of two years
after original shipment. Any instrument or component
that

is

found within the two-year period not to meet
these standards after examination by our factory, sales
engineering office, or authorized repair agency person­nel will be repaired or, at our option, replaced without
charge, except for tubes or batteries that have given
normal service.

5.2

SERVICE.

The two-year warranty stated above attests the
quality of materials and workmanship in our products.
When difficulties do occur, our service engineers will
assist in any way possible. If the difficulty cannot be
eliminated

by

use of the following service instructions,

please write or phone our Service Department (see rear

cover), giving full information of the trouble and of
steps taken to remedy it. Be sure to mention the serial
and type number of the instrument.

for service, please write to our Service Department or
nearest sales engineering office, requesting a Returned
Material Tag. Use of this tag will ensure proper han­dling and identification. For instruments not covered
by the warranty, a purchase order should be forwarded
to avoid unnecessary delay.

5.3

REMOVAL OF COVER.

To open the instrument for access to components,
loosen the large fluted screw at the rear of the right­hand side of the cabinet. Then grasp the panel by the

top and bottom edges with one hand, and with the other
hand slide the aluminum dust cover away from the panel

and off the rear.

All components are easily accessible. See Figures

5-3,

5-4,

and

5-6

for location of components.

5.4

ROUTINE MAINTENANCE.

5.4.1

LUBRICATING

THE

FAN MOTOR.

For long, trouble-free operation, lubricate the fan

motor at least once a year with SAE

20

or

30

premium-

quality oil. There are two lubricating holes, one in

SERVICE AND MAINTENANCE

each of the brass brackets on either side of the motor

laminations.

5.4.2 CLEANING THE AIR FILTER.

To maintain proper cooling efficiency, the air
filter should be cleaned periodically. Local air condi­tions determine how often this

is

necessary. To clean,

release the air filter from its

holder,rap gently to remove

excess dirt, flush from the dirty side with hot soapy

water, rinse, and let dry. Commercially available prep-

arations to increase the filtering efficiency may be
applied but are not necessary.

5.5

TROUBLE-SHOOTING NOTES.

5.5.1 GENERAL.

If the pulse generator

is

inoperative, make the

following simple checks before proceeding further:

a. Check the power line voltage and frequency to
make sure they are as required by the power supply.

b. Check line cord, fuses, and power supply voltage.

If the voltage from pin

3 of V501 to ground

is

not

150 volts or if the voltage from pin

2 of V504 is not

-150 volts, refer to paragraph 5.5.2.

c. See if theprepulse is present at the SYNC binding
posts. If this pulse is present and the main pulse is
defective,refer to paragraph 5.5.2. If the prepulse

is

present and there is no main pulse, refer toparagraph

5.5.3.

If

neither prepulse nor main pulse

is

present,

refer to paragraph 5.5.4. If prepulse

is

absent and

the main pulse is present, refer to paragraph

5.5.7.

5.5.2 INOPERATIVE POWER SUPPLY.
Incorrect voltage.

If

the positive supply voltage

at pin

3 of V501

is regulated but not +I50 volts with

respect to ground, first see if the negative supply volt-

age at pin 4 of

V504 is -150 volts. If this voltage is

regulated but not correct, adjust

R512 so that an ac-

curate voltmeter indicates

+I50 volts from pin 3 of

V501 to ground. If the positive supply voltage adjust­ment drifts, but the negative supply voltage does not,
replace either

R504, R506, or R505. If the negative

supply voltage adjustment drifts, replace

R511, R513,

R510, R512, or V504.

If the voltage drops only at full load, replace
V501, and check the voltage at pins 2 and 5 of V501.
If either of thesevoltages

is

less than 210 volts, check

the corresponding capacitors and diodes.

Unregulated voltage.

The most probable cause of

this trouble is a defectivetube. Remove

V502 and V503
test them, and replace any defective tube. Measure the
voltage at pin 2 of

V503 with respect to ground. If this

is not within

5% of

-66

volts, regardless of the output

load, replace

V504. Measure the resistances to ground

from pin 2, pin 3, pin 5, and pin

6

of V501 and compare

the results with the values in Table

5-1. Replace any

defective resistors or capacitors thus found.

No output supply

voltage.

Check V501. Measure

the regulator input voltage across

C501 and C502.

If

either of these voltages

is

zero, check for a shorted

rectifier diode,

C501, C502, and a blown fuse in the

primary of

T501. If the input voltage

is

normal, check
V502 and V503 for an internal short. Check V504 for a
short. Measure the voltages at key points with a vacuum

tube voltmeter, comparing them with those given in
Table

5-1.

Incorrect

heater

voltage.

If the dc voltage at pin 4
of V103, V105, or VlO6 or pin 3 of V503 is not within
10% of -70 volts, check for a cathode-heater short in

one of those tubes. Check the resistance to ground from
pin

2 of V504 against the value in Table 5-1. Replace

any defective resistors. Check for a short in

C504 or

c505.

5.5.3 DEFECTIVE MAIN PULSE.
Overshoot.

Under normal conditions, with a high
impedance load, overshoot is not possible on any tran­sition. Therefore, check the oscilloscope for overshoot
first.

If

overshoot occurs with a low-impedance termi­nated system, check the system for proper grounding
and make sure that all wiring

is

as short as possible.
Note that some overshoot may be present on negative
pulse transitions as shown in Figure 3.6.

Large imbalance in pulse amplitudes

or

slowly

falling negative-going edge of positive pulse.

These
defects can be caused by weakening of one of the out­put tubes.

Output pulse occasionally fails, and

starts

only

when RANGE switch setting

is

changed.

There are two
possible causes of this difficulty: (1) The ionization
voltage of V107 has drifted sufficiently so that the
automatic restarting circuit no longer functions, or (2)
a tube has developed heater-to-cathode leakage. First
check the voltage from the negative side of

V107 to

ground, using an electronic voltmeter of at least

100

megohms input impedance. The proper voltage is -65

t5 volts behind 5 megohms.

IF

this voltage is correct,

the trouble

is

a defectiveV107, and a newNE-96 should

be installed.

If

the voltage measured is not correct,

check all tubes for heater-to-cathode leakage.

Pulse-duration

errors.

An error indication on only,

one setting of the RANGE switch is an indication that
a time-determining component for that range has drifted
or failed.

@

TYPE

1398-A

PULSE GENERATOR

5.7

VOLTAGES AND RESISTANCES.

TABLE

5-1

VOLTAGES AND RESISTANCES

*

*

* *

*

*

*

***

*

*

*

* *

Dc

Volts

Ohms

--

Dc

Volts

Ohms

--

Dc

Volts

03

Tube Pin

--

to

-

to

Tube Pin

-

-

t

0

-

we

&

to

Ground

Ground

--

Ground Ground Ground Ground

Transistor

Dc

Volts

Ohms

Lead to t o

(Type)

--

-

~ui~lv Ground

Transistor

(

Type

Lead

-

Dc

Volts

to

S~PP

ZY

0.96
0

2.9

*

Depends on ohmmeter polarity and resistance range.

**

All heater voltages

=

6.2

volts

ac.

***

Power supply disconnected, terminals

#I17

and

#I18

(near AMPLITUDE

control) grounded, all transistors removed.

TEST CONDITIONS

This table lists important voltages and resistances in the Type 1398-A.

These voltages, measured by

a

Type 1806-A Electronic Voltmeter ( input resis-

tances

=

100MQ), are accurate to within 25%. R505 and R512 were set for

normal power

supply output = 150 volts dc. Power line = 115 volts, power =82

watts. The Type 1398-A controls were set as follows:

.................................

PRF

1

kc/s

AF

................................

centered

PULSE DURATION

dial

..........................

1

.............

RANGE .0.1

to

1

ps

...................

AMPLITUDE.

10

(fully

cw

)

SERVICE AND MAINTENANCE

Auniform error on all ranges is an indication that

the amplitude comparison circuit

(V104 and associated

components) is defective. For instance,

a

decrease in

resistance of

R127 would make all pulses too long at

all settings of the

PULSE

DURATION controls, while

an increase in this resistance would reverse the effect.

If the output pulse is of fixed, long duration,

independent of the PULSE DURATION controls,

V103B

is

not functioning and a new tube should be inserted.

Another difficulty traceable to a defective

V103

would be excessive duration at the high end of each

range, especially at longer duration ranges. It

is

prob-

able that

V103 is not remaining off, and it should be

replaced.

5.5.4 NO MAlN OUTPUT PULSE, SYNC PULSES
PRESENT.

If no output pulses are present and V107 flashes

continually, check

V103 and V104 and replace if nec-

essary.

If V107

is

not flashing, measure the voltage at

the

+

OUTPUT PULSE binding post. If it

is - 60 volts

with respect to ground, the trouble

is

either a defective

transistor 4102 or

4104 or failure of the start triggering

circuits. Check for the presence of a 15-volt,

0.15-ps
positive trigger pulse at pin 6 of V102. Check L103 for
a short or open circuit.

5.5.5 MAlN AND SYNC PULSES BOTH ABSENT

This indicates trouble in the input circuits. First

check

VlOl and V102. (After replacing V101, center

the

AF control and adjust R107 for optimum sensitivity

with an external signal.) If this fails to pinpoint the

problem, checkvoltages against those given in Table5

1.

5.5.6 INCORRECT FREQUENCIES.

If the frequency error occurs at only one setting

of the PRF switch, the fault

is

one of the timing capa-

citors,

C108 through C117. Replace the appropriate

capacitor.

If all frequencies are in error by about the same

amount with the

OF control fully clockwise, check R102,

R104, R105, and R108.

5.5.7 FAILS TO SYNC ON EXTERNAL SIGNAL.

If the instrument operates normally on internal

operation but will not synchronize on external signals,

check the input network. An extremely high transient

voltage may have caused

CRlOl to short-circuit.

5.5.8 MAlN PULSES PRESENT, NO SYNC PULSES.

5.6

WAVEFORMS.

5.6.1 TEST CONDITIONS.

Figure 5-1 depicts important waveforms in the

Type 1398-A. They were taken with a

10-megohm, 12-pF
probe; the vertical sensitivity listed beside each os­scillogram includes the 10X attenuation of the probe.
The Type 1398-A controls were set as follows (except
where noted

):

PRF

..........................

lookc/s

AF.

...........................

centered

PULSE DURATION dial.

................

1

PULSE DURATION RANGE

.....

.0.1 to

1

ps

.........

AMPLITUDE. 10 (fully clockwise

)

V102,

pin

1,

20

V/cm, 2ps/cm.

V102,

pin

2,

20 V/cm, 2ps/cm.

V101,

pin

7,

10 V/cm, 2ps/cm.

V101,

pin

8,

10 V/cm, 2ps/cm.

V102,

pin

1,

20V/cm, 2ps/crn.
V102,

pin

2,

20

V/cm, 2ps/cm.

V104,

pin

2,

10 V/cm, 2 ~s/cm.
V103,

pin

2,

20 V/cm, 2ps/cm.

V106,

pin

8,

10V/cm, 2ps/cm.

V102,

pin

1,

20

V/cm, 2ps/cm.

Figure

5-

1.

Waveforms.

5.7

VOLTAGES AND RESISTANCES (See Table

5-1).

5.8 CALIBRATION PROCEDURE.

5.8.1 TEST SETUP AND EQUIPMENT
REQUIRED.

General.

A description of the equipment required

for a complete

~alibr~tion of the Type 1398-A Pulse

Check

VlOl and the components associated with

Generator

is

given in the paragraphs that follow. The

VIOlB.

interconnections necessary are shown in Figure 5-2.

@

TYPE

1398-A

PULSE

GENERATOR

(1)

Sine-wave generator.

Capable of 10 kc/s, 0.1 V

into

1~fl

and 2.2Mc/s, 0.5 V into

1~0.

Accuracy

*lo% or better. The Type 1330 Bridge Oscillator or

the Type

1001 Standard-Signal Generator may be used.

(2)

Time-markgenerator.

Capable of 100-ms to 0.1-ps
marks in 5 decade ranges. Accuracy +O.l%or better.
The use of a time-mark generator is optional. When
it is used, time-measurement accuracy

is

dependent
upon the accuracy of the time-mark generator (typi­cally

0.001%) rather than upon the accuracy of the

oscilloscope time-base (typically

3%

).

(3)

Terminated 50-ohm coaxial patch cord.

A coaxial

cable with coaxialfittings on both ends with

a

50-ohm

noninductive resistor on one end. An assembly that

consists of a Type 874-R20A Coaxial Patch Cord, a

Type 874-W50 50-ohm Termination, and anadaptor to
fit the 50-ohm termination to the oscilloscope may

be used. A Type 874-QUP Adaptor fits uhf connectors

and a Type 874-QBPA Adaptor fits BNC connectors.

A Table of

GR874 Connectors

is

included at the end

of this book.

(4)

Oscilloscope.

Capable of measuring 5-11s rise

times and durations of 1.05

s

to 75 ns. Accuracy +1%

or better. Must have sweep delaying provision if time

jitter

.is

to be measured (paragraph 5.8.4).

TIME-MARK
GENERATOR

(optional)

shielded

lead

or coaxial cable

\

TIME-MARK
GENERATOR

(optional)

SINE-WAVE

TYPE 1398-A OSCILLOSCOPE

GENERATOR

PULSE GENERATOR

[

@Terminated 50-ohm coaxial

patch cord or 10-megohm probe.

Figure

5-2.

depending upon measurements

Calibration Test Setup.

to be mode

5.8.2

PRF ACCURACY.

Setup.

Connect the -OUTPUT PULSE coaxial

connectors to the oscilloscope via a terminated 50-ohm

coaxial patch cord. Set the Type

13984 controls as

follows:

AF.

...............

HIGH (fully clockwise

)

PULSE DURATION dial.

................

.1

PULSE DURATION RANGE.

....

.O.1 to

1

ps

.........

AMPLITUDE.

.lo

(fully clockwise

)

PRF switch accuracy.

Check or adjust the pulse

repetition frequency as outlined in Table

5-2. Note

that frequency

is

measured in terms of period length

(

l/prf

).

TABLE 5-2

)R

R

ACCURACY

PRF

Switch Period

l/prf

Setting

*5%

Tolerance

300 kc/s

Adjust C117 for period of

3.33

ps.

Vary AF control over full range;
period must change smoothly and
be greater than 10

ps

when AF

control

is

set fully counterclock-

wise.

1.2

Mc/s

Adjust C140 for period of 850

ps.

5.8.3

PULSE DURATION ACCURACY.

Setup.

Connect the -OUTPUT PULSE coaxial

connector to the oscilloscope via a terminated 50-ohm

coaxial patch cord. Set the Type 1398-A controls as

follows:

AF

................

.HIGH (fully clockwise

)

AMPLITUDE

..........

.10 (fully clockwise

)

PULSE DURATION dial accuracy.

In

each of the

following checks, set the PULSE DURATION dial for
the indicated duration as measured on the oscilloscope
and note the PULSE DURATION dial reading:

-u---u-

-I

I-

DURATION

PULSE DURATION

Maximum

Set PULSE DUPATION dial

RANGESetting

KF

for

measured duration

of

10 to 100

ps

3 kc/s 50 ps

100

ps

to 1 ms 300 c/s 500

ps

1

to 10

ps

30 c/s 5 ms

10 to 100 ms 10 c/s 50 ms

The difference between the lowest and highest

PULSE DURATION dial readings is the error span.
Mechanically position the PULSE DURATION dial
with respect to its associated potentiometer so that a

reading of 5 lies on the center of the error span.

For example:

If

the lowest dial reading was 5.8

and occurred on the 10 to

100ms RANGE and the

SERVICE AND MAINTENANCE

highest dial reading was 6.6 and occurred on the

1 to

lOms RANGE, the error spanis 6.6 -5.8 =0.8.

Set the RANGE switch to 10 to 100ms (the range
where the lowest dial reading was noted

)

and set
the PULSE DURATION dial for a measured dura­tion of

50ms. Loosen the hub set-screw (behind
the PULSE DURATION potentiometer) and posi­tion the dial for a reading of

5 - 0.4 ~4.6. Be

careful not to disturb the setting of the potentio-

meter itself; the measured duration must remain
50 ms. Tighten the setscrew. A dial reading of 5
now lies in the center of the error span (center

of error span

=

error span + 2 or 0.8 + 2 = 0.4).

To be sure a PULSE DURATION dial reading of

5 lies in the center of the error span, set the

RANGE switch to 1 to

l0ms (the range where the

highest dial reading was noted) and set the
PULSE DURATION dial for a measured duration
of

5 ms. If the dial has been positioned correctly

it will read 5

+

0.4 = 5.4.

PULSE DURATION RANGE accuracy.

Check or
adjust the PULSE DURATION RANGE accuracy as
outlined in Table 5-3.

5.8.4

OUTPUT-PULSE CHARACTERISTICS.

Setup.

The characteristics and specifications for

both the

+

and the -OUTPUT PULSE waveforms are
the same except for polarity. Connect the appropriate
OUTPUT PULSE binding posts to the oscilloscope
via a terminated 50-ohm cable. Set the Type 1398-A

controls as follows:

AF.

...............

HIGH (fully clockwise

)

PRF

.............................

1.2 MC

................

PULSE DURATION dial. 5

....

PULSE DURATION RANGE.

.O.1

to

1

ps

.........

AMPLITUDE. 10 (fully clockwise

)

Amplitude.

Equal to or greater than 3volts, p-to-p.

Rise time.

5ns or faster as measured between the

10 and

90% points. Be sure any rise-time limitations of
the oscilloscope are taken into account (refer to para­graph

3.5.3 for further rise-time details

).

90%

FALLTIME

IHDLC

5-3

PULSE DURATION RANGE ACCURACY

PULSE

DURATION

Maximum

RANGE

Dial

--

PRF

Duration

Limits

looms to

Is

1

10 c/s

95 to 105 ms ( 52% of full scale

)

10 to 100ms

1

30

C/S

9.5 to 10.5 ms ( 52% of full scale

)

1 to 10ms

1

300 c/s 0.95 to 1.05ms

(rt2%

of full scale)

1OOpstolms 1 3 kc/s 95 to 105

ps

(

f2% of full scale

)

10 to 100ps 1 30 kc/s

9.5 to 10.5

ps

(

+2% of full scale

)

1

to 10p

1

300 kc/s

0.9 to 1.05

ps

(

+2% of full scale

)

0.1 to 1

ps

1

1.2 Mc/s

65

to 13511s (f35ns)

lOOmstols

5 10 d/s 475 to 525 ms ( +5% of reading)

10 to 100ms

5 10 c/s 47.5 to 52.5 ms ( 55% of reading)

1

to lOms

5 30

C/S

4.75 to 5.25 ms ( f5% of reading)

100pstolms

5

300 c/s 475 to 525

ps

(+5% of reading

10 to

100ps

5

3 kc/s

47.5 to 52.5

ps

(

+5% of reading

)

1

to

lops

5 30 kc/s

4.75 to 5.25

ps

(+5% of reading)

0.1 to

1

JLS

5 300 kc/s 465 to 535 ns ( 135 ns

)

lOOmstols

10 10 c/s 0.95 to 1.05 s (55% of reading)

10 to

100ms

10 10 c/s

95

to 105 ms (55% of reading)

1

to 10ms

10 30

C/S

9.5 to 10.5ms (+5% of reading)

100ps to lms

10 300 c/s 0.95 to 1.05 ms ( 55% of reading

)

10 to 100ps

10 3 kc/s 95 to 105

ps

(

f

5% of reading

)

1

to 10p

10 30 kc/s 9.5 to 10.5

ps

(

5%

of reading)

0.1 to

1ps

10 300 kc/s

Adjust C141 for duration of 1

ps

25

@

TYPE

1398-A

PULSE

GENERATOR

Overshoot and ringing.

Not greater than 10% of

amplitude.

5

10%

Jitter-oscilloscope limitation.

The amount of jitter

present in the oscilloscope must be taken into account

when duration and period jitter are measured. Typical

.

.

jitter for most delaying sweep oscilloscopes

is

0.02%
of the amount of delay. To determine actual jitter, con­nect

a

stable time-mark signal to the oscilloscope,

set

the oscilloscope for the amount of delay required,

and measure any jitter that may be present. If the

time-

mark signal is stable, any jitter present is due to the

oscilloscope.

Duration jitter.

Less than or equal to 0.04%. Set

the Type 1398-A controls as follows:

A.

..........................

centered

PRF

..............................

30c/s

PULSE DURATION dial

................

10

PULSE DURATION RANGE.

.....

1 to 10 ms

.........

AMPLITUDE .10 (fully clockwise

)

input of the oscilloscope via a 10-megohm, 12-pF probe.
Set the Type 1398-A controls as follows:

AF

................

HIGH (fully clockwise

)

............................

PRF 1.2 Mc/s

................

PULSE DURATION dial

..5

....

PULSE DURATION RANGE.

.O.1

to 1 ps

.........

AMPLITUDE .10 (fully clockwise

)

+SYNC output.

The characteristics and specifi-

cations for both the

+

and the - SYNC outputs are the

same, except

f

or polarity. Amplitude: Equal to or greater

than

8volts, peak-to-peak. Duration: Equal to or less

than 0.2

ps.

DELAYED SYNC output.

Amplitude: Equal to or

greaterthan

gvolts, peak-to-peak. Duration: Equal to or

less than 0.3

ps.

DELAYING SWEEP

INTENSIFIED BY

,

5.8.6

EXTERNAL DRIVE.

PRF

jitter.

Less than or equal to 0.04%. Set the

Type 1398-A controls as follows:

LF..

..............

HIGH (fully clockwise)

PRF.

............................

100 c/s

................

PUISE DURATION dial.

.1

....

PULSE DURATION RANGE.

0.1 to

1

ps

Setup.

Connect a sine-wave generator to the EXT

DRIVE binding posts. Set the generator for an output

of

l0kc/s, 0.1V, rms. Set the Type 1398-A controls as

follows:

............................

AF. .centered

........................

PRF. EXT DRIVE

................

PULSE DURATION dial.

-1

...

PULSE DURATION RANGE.

.0.1 to

1

ps

.........

AMPLITUDE. 10 (fully clockwise

)

AMPLITUDE 10 (fully clockwise

)

R107

adjustment.

Connect a 10-megohm probe from

the oscilloscope to

V102, pin 1. Adjust R107 for a sym-

loms4--.

metrical square wave.

DELAYING SWEEP

_TV"\_

DELAYED

SIFIED

SWEEP

BY

2.2-Mc

sensitivity.

Set the generator for an output

of' 2.2

Mc/s, 0.5

V,

rms. Set the AF control for a trigger-

'.--'

ed oscilloscope display. After the

AF

control has been

/r7

set for a triggered display, it must be within 30 degrees

,I

of center. To check

if

the display is actually triggered,

-I

disconnect the sine-wave generator; if the display was

JITTER' 5 0.04%

(4~s)

triggered, the display will disappear. Reconnect the

5.8.5

SYNC-OUTPUT CHARACTERISTICS.

generator.

Setup.

Connect the OUTPUT PULSE binding posts

Trigger pulling.

Vary the PULSE DURATION dial

to the external trigger input of .the oscilloscope and con-

from 1 to

6;

the pulse repetition frequency must remain

nect the appropriate SYNC binding post to the vertical 2-2 Mc/s.

AINTENANCE

\

Rlla

C115 C116 R125 C120

C123

Figure

5-3.

Top

interior view.

F102

FlOl

C

5

03

r

8%~

R505 R512

v1b7

ETCHED

CIRCUIT

ASSEMBLY

**

Figure

5-4.

Bottom interior view.

PARTS LIST

REF NO

ClOO
ClOl
C102

C103
C104

C105
C106

C107
C108
C109
CllO
Clll
C112
C113
C114
C115
C116
C117

C118
C119
C120

RlOO
RlOl
R102
R103

R108
R109
RllO
Rlll

DESCRIPTION

CAPACITORS

Trimmer, 8-50 pF
Ceramic, 51 pF 25% 500

V

Ceramic, 68 pF

&lo%

500

V

Ceramic, 0.01 pF t80-20% 500

V

Ceramic, 0.01 pF t80-20% 500

V

Ceramic, 0.01 pF +80-20% 500

V

Ceramic, 100 pF 210% 500

V

Ceramic, 22 pF 210% 500

V

Plastic, 0.909 pF f2% 100

V

Plastic, 0.301 pF *2% 200

V

Plastic, 0.0909 pF 22% 100

V

Plastic, 0.0301 pF 22% 200

V

Mica, 0.00887 pF 21% 300

V

Mica, 0.00301 pF 22% 500

V

Mica, 825 pF 22% 300

V

Mica, 499 pF 21% 300

V

Mica, 100 pF 21% 500

V

Trimmer, 3-12 pF 500

V

Ceramic, 0.001 pF 210% 500

V

Ceramic, 0.001 pF f10% 500

V

Trimmer, 3 -12 pF 500

V

Trimmer, 750 pF "10% 500

V
Trimmer, 5-20 pF
Mica, 976 pF

f1%

300

V

Mica, 0.01 pF 22% 300

V

Plastic, 0.1 pF 22% 200

V

Plastic, 1 pF 22% 100

V

Ceramic, 82 pF 25% 500

V

Ceramic, 0.022 pF +80-20% 500

V

Ceramic, 0.022 pF +80-20% 500

V

Mica, 43 pF 25% 500

V

Ceramic, 4.7 pF 210% 500

V

Ceramic, 4.7 pF 210% 500

V

Ceramic, 6.8 pF f 10% 500

V

Ceramic, 0.01 pF +80-20% 500

V

Ceramic, 0.001 pF 210% 500

V

Ceramic, 15 pF 210% 500

V

Ceramic, 0.001 pF 210% 500

V

Ceramic, 100 pF 210%
Ceramic, 100 pF 210%
Ceramic, 150 pF 22% 500

V

Ceramic, 150 pF f2% 500

V

Electrolytic, 50 pF 300

V

Electrolytic, 50 pF 300

V

Electrolytic, 60 pF 300

V

Electrolytic, 50 pF 300

V

Electrolytic, 50 pF 300

V

Plastic, 0.1 pF 210% 200

V

Ceramic, 0.022 pF +80-20% 500

V

Plastic, 0.1 pF +10% 200

V

Ceramic, 0.022 pF 4-80-20% 500

V

RESISTORS

Composition,

1

MD

f5% 1/2

W

Composition, 33

k0

i57c 1/2

W
Film, 33.2

kD

21% 112

W
Potentiometer, composition
250

kO

f10% 112 W (AF)

Film, 32.4

kQ

f1%

1/4

W

Composition, 3

kD

25% 1/2

W

Con~position, 2

MR

*5% 1/2

W
Potentiometer, composition
500

D

220%

Film, 57.6

kD

21% 112

W

Composition,

1

k0

+5% 1/2

W

Composition,

1

kD

25% 1/2

W

Composition, 22

kD

25% 1/2

W

PART NO

REF NO DESCRIPTION

RESISTORS

(cont)

Composition, 3

kD

25% 1 W

Film, 100

kO

fl%

1/4

W

Composition, 3.3

kc1

25% 1 W

Film, 51.1

k0

21% 1/4

W

Film, 150

k0

21%

1/4

W

Composition, 330 D f5% 112

W

Composition, 56

kD

25% 112

W

Film, 270

k0

21%

114

W

Film, 2.74 M62 +1% 2

W

Composition, 56 W 25% 112

W

Composition,

1

kW

25% 1/2

W

Composition, 1.2

kW

25% 112

W

Composition, 1.2

kD

25% 1/2

W

Potentiometer, wire-wound

5

kO

22% (PULSE DURATION)

Composition, 1.5

k0

25% 1/2

W

Film, 191

kD

21% 114

W

Composition, 180 D 25% 1/2

W

Film, 100

kD

+l%

1/4

W

Composition, 130 D f 5% 1/2

W

Composition, 2

kW

25% 1/2

W
Potentiometer, ganged, wire-wound
120

D

210% (AMPLITUDE)

Composition, 100

D

25% 1/2

W

Composition, 100

D

5%

1/2

W

Composition, 100 D 25% 112

W

Composition, 100 D 25% 1/2

W

Composition, 100 D 25% 1/2

W

Composition, 100 D "5% 1/2

W

Composition, 100 D 25% 1/2

W

Composition, 100 D 25% 1/2

W

Composition, 100 D 25% 1/2

W
Potentiometer, ganged, wire-wound
120

D

210% (AMPLITUDE)

Composition, 100

D

25% 112

W
Composition, 100 D 25% 1/2

W

Composition, 100 0 25% 1/2

W
Composition, 100 D i5% 1/2

W
Composition, 100 D 25% 1/2

W
Composition, 100 D 25% 1/2

W
Composition, 100 D 25% 1/2

W
Composition, 100 D 25% 1/2

W
Composition, 100 D 25% 1/2

W

Potentiometer, composition

lo

kD

220%

Composition, 200

D

25% 1 W

Composition, 100 D 25% 112

W

Composition, 5.6

kW

25% 1/4

W

Composition, 27 D 25%

112

W

Composition, 100 D 25% 1/2

W

Composition, 200 D "5% 2

W

Composition, 5.6

kD

+5% 114

W

Composition, 12 D 25% 1/4

W

Composition, 5.6

kW

25% 1/4

W

Composition, 100

kD

25% 1/4

W

Composition, 12 D 25% 1/4

W

Composition, 100

kW

25% 1/4

W

Composition, 5.6

kD

25% 1/4

W

Composition, 100

kfi

25% 1/2

W

Composition, 100

kD

25% 112

W

Composition, 4.7

kD

25% 1/2

W

Composition, 200 D *5% 1/2

W

Composition, 2.2

kD

25% 1/2

W

Composition,

1

k0

210% 112

W

Composition, 68 D 25% 1/2

W

Composition, 56

k0

+5% 1/2

W

Composition, 33

kD

25% 1/2

W

:d

in

laboratory

PART NO

PARTS LIST

(cont)

REF NO DESCRIPTION

RESISTORS

(cont)

Composition, 51 Q t5% 114

W

Composition, 51 Q 25% 1/4

W

Composition, 1 MQ 25% 1/2 W
Composition, 51

kQ +5% 1/2 W

Composition, 13

kQ 55% 1/2 W

Film, 150

kQ

51%

1/2 W
Potentiometer, wire-wound
20

kQ 510%
Film, 150 kQ +1% 112 W
Composition,

1

MQ

5%

112 W

Composition, 62

kQ 25% 1/2 W

Composition, 10

k0 25% 1/2 W

Composition, 27

kQ 25% 112 W

Film, 13.3

kQ

21%

1/2

W

Potentiometer, wire-wound
20

kQ 210%

Film, 26.1 kQ

51%

1/2 W

Composition, 24

kQ 25% 1/2

W

Composition, 27 kQ f5% 1/2

W

Composition,

11

Q 25% 1/2 W

Composition, 5.1

MQ 55% 1/2 W

Composition, 82

kO

5%

1/2 W

Composition, 100

Q 510% 1 W

LlOl

Choke, Metal, 120 pH 510%

L102

Choke, Metal, 82 pH

51058,
L103 Choke, Metal, 150 pH 210%
L104

Choke, Metal, 27 pH

+lo%
L105

Choke, Metal, 56 pH 210%

L106

Choke, Metal, 0.22

pH +20%

L107

Choke, Metal, 0.1

pH

?lo%

CIRCUIT-BOARD ASSEMBLIES

Power Supply Board Assembly

Etched Circuit Assembly

MISCELLANEOUS

CRlOl DIODE, Type 1N625
CR102 DIODE, Type lN118A
CR103 DIODE, Type lN118A
CR104 DIODE,

Type

1N3604
CR105 DIODE, Type lN3604
CR501

through DIODE, Type IN3254

CR508

PART NO REF NO DESCRIPTION PART NO

F501
F502
FClOl

FC102
FC103
JlOl
J102
J103
5104
Jl05
J106
J107
Jl08

PO9
JllO

Jlll
Jll2
J113
J114
M501
P501
PL501
QlOl
through
4104
SlOl
S102

MISCELLANEOUS

(cont)

FUSE, 215

V,

0.5 A, Slo-Blo

5330-1000

FUSE, 115

V, 1 A,

Slo-Blo

5330-1400
FERRITE CORE 5000-1250
FERRITE CORE 5000-1255

FERRITE CORE 5000-1255
BINDING POST, (EXT DRIVE)

4060-0100
BINDING POST, (EXT DRIVE ground) 4060-0100
BINDING POST, (SYNC

+)

4060-0100
BINDING POST, (SYNC

+

ground) 4060-1800

BINDING POST, (SYNC

-

)

4060-0100
BINDING POST, (SYNC

-

ground) 4060-1800
BINDING POST, (DELAYED SYNC) 4060-0100
BINDING POST, (DELAYED SYNC)
ground) 4060-1800
BINDING POST, (EXT OFFSET) 4060-0100
BINDING POST, (EXT OFFSET
ground) 4060 -1800

CONNECTOR, Coaxial (OUTPUT

+)

0874-4552

JACK, (OUTPUT

+

ground)

0874-6690

CONNECTOR, Coaxial (OUTPUT

+)

0874-4552

JACK, (OUTPUT

-

ground) 0874-6690
MOTOR 5760-1200
PILOT LIGHT, Type 1784 5600-1001
PLUG, Power 4240-0600

TRANSISTOR, Type

2N2369

SWITCH, Rotary wafer (PRF)
SWITCH, Rotary wafer
(PULSE DURATION)
SWITCH, Rotary wafer
(AMPLITUDE)

SWITCH, Toggle (POWER)

SWITCH, Slide

SOCKET

TRANSFORMER, Power
TUBE, Type

6DJ8
TUBE, Type 6DJ8
TUBE, Type 6DJ8
TUBE, Type 6922
TUBE, Type 8233

TUBE, Type 8233
TUBE, Type NE-96
TUBE, Type 6080
TUBE, Type

6AG5
TUBE, Type 6AH6
TUBE, Type 5651

Figure

5-6.

Power Supply etched-board layout (P/N

1389-2750.).

NOTE: The number on the foil side is not the part number for the complete assembly.

Rotary switch sections are shown as viewed from the panel end of the
shaft.

The first digit of the contact number refers to the section. The

section nearest the panel is

1,

the next section back is

2,

etc. The next

two digits refer to the contact. Contact 01 is the first position clockwise

from

a

strut screw (usually the screw above the locating key), and the

other contacts are numbered sequentially

(02,

03,

04,

etc.), proceeding

clockwise around the section.

A

suffix F or R indicates that the contact

is on the front or rear of the section, respectively.

PULSE

DURATION

RANGE

2

I

IOOJ

1

SEC

/NSUL

ATED

DUMMY

TFRMINAL

AMPLITUDE

4.

5.

.

6.

3

7

I

9

:/-.

0

lo'

A.7:/08

SYNC

DELAYED SYNC

0000000000

EXT

DRIVE

BOTKIM

VIEW

OIOI

THRU

PI04

A.T,J/S

BR

-

f

150V

REG

A.TN7

GN

W

-158V

REG

$CIO75

.

dd2141

.

-

MV

WH-GFRD

4-&

-

/SOV,?EG

9

AT-ANCHOR TERMINAL

m

VALUE

MAY

w

SELECTED

BY

La8

REG

4.7: N8

LOW

ICALIBRATEDI

Figure

5-7.

Schematic Diagram

of

the Type

1398-A

Pulse Generator.

NOTE UNLESS SPECIFIED

1

POSITION OF ROTARY SWITCHES

IN

OHMS

SHOWN COUNrERCLOCKWlSE

K-1000

OHMS M 1 MEGOHM

2

CONTACT NUMBERING OF SWITCHES

~#~A~&!$~~~

YESESAND

EXPLAINED ON SEPARATE SHEET
SUPPLIED IN INSTRUCTION BOOK

THAN ONE IN MICROFARADS

3

REFER TO SERVICE NOTES IN INSTRUC

'

0

TlON BOOK FOR VOLTAGES

8

@

SCREWDRIVER CONTROL

APPEARING ON DIAGRAM

9

AT =ANCHOR TERMINAL

4

RESISTORS

112

WATT

10 TP =TEST POINT

WH-YE-BK

Wlf-150 VREGISO5@1, #I

PL 501
INPUT

105-/25v

OR

195-235v

4.r

b

1-158 V REG/A7-/I7

50-6Oc

5/3

OFF

POWER

WH-BR-BK

FOR

210 -250 VOLTS REMOVE CONNECTION

FROM

A.T

PL

AND

CONNECT TO

A.K

2

(-158

V REG/

AT

/I

7

b

I-7OVl

A.%

141

V/O.? V105 V106 V503

Figure

5-8.

Schematic Diagram of the Type

1398-A

Pulse Generator Power Supply.

L suffix indicates locking Type 874 Connector.

TYPE

874

COAXIAL COMPONENTS

m

FOR COMPLETE DETAILS, REFER TO THE GENERAL RADIO CATALOG.

Example: To connect Type 874 to
a type N jack, order Type

874-QNP.

CONNECTOR ASSEMBLY TOOLS

TYPE 874- FUNCTION

Tool Kit
Crimping Tool

Crimping Tool

rp"

P

a

I

2

"

,

TYPE 874

A2
A3
DZOL, D50L
EL, EL-L
F185L
F500L
FlOOOL
F2000L
F4000L
FBL

G10, GlOL
G20, G20L
GAL
JR

L10, LlOL
L20, L20L
L30, L30L
LAL
LKIOL, LKZOL

LR

'

LTL

CONNECTOR

TYPE

874-A2
RG-8A/U
RG-9B/U
RG-lOA/U
RG-87A/U
RG-116/U
RG-156/U
RG-165/U
RG-166/U
RG-213/U
RG-214/U
RG-215/U
RG-225/U
RG-227/U
RG-11A/U
RG-lZA/U
RG-13A/U
RG-63B/U
RG-79B/U
RG-89/U
RG-144/U
RG-146/U
RG-149/U
RG-216/U
874-A3
RG-29/U
RG-55/U
(Series)

RG-58/U

(Series)
RG-141A/U
RG-142A/U
RG-159/U
RG-223/U
RG-59/U
RG-62/U
(Series)

RG-71B/U

RG-14O/U
RG-21O/U
RG-174/U

RG-188/U

RG-316/U

RG-161/U
RG-187/U
RG-179/U

Example: Fora lockingcableconnector

for

RG-8A/U,

order Type

874-CLBA.

874

CABLE

CABLE

LOCKING

-CLA

-CUA

-CL58A

-CL62A

-CL174A

2

2

_I

0

OTHERCOAXIAL

50 0 cable (low loss)
50

0

cable
20-, 50-cm adjustable stubs
90' ell

185-Mc/s low-pass fllter

500-Mc/s low-pass f~lter

1000-Mc/s low-pass filter
2000-Mc/s low-pass filter
4000-Mc/s low-pass filter
bias insertion unit

3-,

6-,

lo-, and 20-,-j~

attenuators
adjustable attenuator

rotary joint

coupling capacitor

lo-, 20-, and 30-cm

rig~d air lines

33-58 cm adjustable line

constant-Z adjustable lines

radiating line

trombone

constant-Z line

I

m

u

J

m

u

-

a

%

TYPE

CABLE

-CA

-C8A

-C58A

-C62A

-C174A

CONNECTORS

PANEL

FLANGED

-PBA

-PB8A

-PB58A

-PB62A

-PB174A

2

2

0

Z

q

'

r

gz

ELEMENTS

TYPE

874-

ML
MB
MR, MRL
R20A, R2OLA
R22A, R22LA
R33, R34
T, TL
TPD,

TmL
U
UBL
VCL

VI

VQ,

VQL

VR, VRL

wloo

W200
WSOB, W50BL
WN, WN3
WO, W03
X
XL

Y
Z

PANEL

LOCKING

-PLA

-PL8A

-PL58A

-PL62A

-PL174A

component mount
coupl~ng probe
mixer-rectifier
patch cord, double shield
patch cord, double shield
patch cord, single shield
tee
power divider
U-line section
balun
variable capacitor
voltmeter indicator
voltmeter detector
voltmeter

rectif~er
100-52 termination
200-Cl termination
50-0 termination
short-circuit terminations
open-circuit

termmations
insertion unit
series inductor
cliplock
stand

PANEL

,",","liF:D

-PRLA

-PRUA

-PRL58A

-PRL62A

-PRL174A