HP 683C Service manual

3

P

!

OPERATING

AND

SERVICE

MANUAL

MODEL

6a3c

SWEEP OSCILLATOR

SERIALS PREFIXED:

J

110

-

01130-1

Copyright HEWLETT-PACKARD COMPANY

1501

PAGE

MILL

ROAD, PAL0

ALTO,

CALIFORNIA, U.S.A.

1961

Printed:

Om

1961

Model 683C Specifications’

SPECIFICATIONS

FREQUENCY RANGE:

SWEEP RANGE:

RF SWEEP RATE

OF CHANGE:

SWEEP TIME:

POWER OUTPUT:

POWER

SPURIOUS SIGNAL:

OUTPUT CONNECTOR:

VARIATION:

RESIDUAL FM:

MAXIMUM SWR:

SWEEP MODE:

SWEEP OUTPUT:

2 to 4 kmc (gc)

2.1 mc to 2.1 kmc (gc) in 16 mc/sec to 160 kmc (gc)/sec in 9 steps

0.0135 Adjustable; With leveler operating:

leveler

Less than 100 At least 20 db below

2.5 or Type N female Recurrent; externally triggered (20 volts positive with better than 3 volts/psec

rate to time and

+25 volt (approximately) peak sawtooth provided concurrently with swept output for recorder and oscilloscope sweep. Source impedance 10,000 ohms and 20 pf in parallel.

sec

to 135

sec

0

to

at least 30 mw into 50-ohm load

off:

less

than & 3 db over entire frequency range.

kc

peak

less

of

rise); manually triggered. RF Frequency sweep

is

downward from frequency dial setting.

7

steps. Continuous control between steps.

for full band sweep; determined by sweep range and rate.

less

cw

than f 1.5 db over

output

entire

frequency range.

is

.

linear with respect

With

rf

SWEEP WIDTH:

FREQUENCY

DIAL ACCURACY:

RESIDUAL AM:

MODULATION:

POWER:

Accuracy:

greater for other calibrated sweep widths. Linearity: The half-voltage point of the SWEEP OUTPUT occurs within

of mid-frequency.

1%

Greater than 40 db below carrier amplitude Internal

1200 cps. Peak External AM: Direct coupled dc to 300 kc/sec; -20 volts or more reduces

output 25 pf (approximately) in parallel.

External FM: Approximately 150 volts peak-to-peak required to modulate full

frequency range, 10 cps to 60 cps, Frequency deviation and modulating voltage

be decreased with modulating frequencies higher than 60 cps. Input

must impedance; 43K ohms and 100 pf (approximately) in parallel; ac coupled.

External Pulse: pulse length. decay times (approximately) in parallel; ac coupl6d.

115 or 230 volts

AM:

level

10%

for full band sweep.

Square wave modulation continuously adjustable from 400 to

rf

output power

from rated

+

10 volts or greater pulse required: 5 millisecond maximum

Peak

less

f

lvo,

cw

rf

than 1 psec. Input impedance: 390K ohms and 25 pf

50

is

output to zero. Input impedance: 750K ohms and

pulse level within 1 db of

to 60 cps approximately 540 watts

+25%, -15% or

within 1 db of the

&

3

mc, whichever

cw

level.

cw

level. Pulse

rise

is

5%

rf

and

0

1130-

1

DIMENSIONS:

WEIGHT:

Cabinet Mount: 20-9/16 inches wide, 12-3/4 inches high, 18 inches deep Rack Mount: 17-5/8inches wide,

Cabinet Mount: Net 105 lbs, shipping 134 lbs Rack Mount:

Net

105 lbs, shipping 134 lbs

10-1/8

inches high, 16-5/8 inches deep

iii

Table of Contents List of Tables

Model 683C

TABLE

Section Page

I

GENERAL INFORMATION

1.1

.

Description

1.2

.

Instrument Cooling System.

1.3

.

Three-Conductor Power Cable

1.4

.

1.5

1.6

I1

OPERATING INSTRUCTIONS

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

111

THEORY OF OPERATION

3-

3.2

3.3

3.4

3.5

3.6

3.7 . Helix Supply Reference Voltage and

3.8

3.9

230-Volt

.

Rack Mounting Instructions

.

BWOTube Information

.

Contents

.

Installation

.

Turn-On Procedure Using the Sweep Oscillator

.

a CW Signal Source

.

Sweep Operation of the Oscillator

.

Amplitude Modulating the Oscillator Frequency Modulating the Oscillator

.

Application

1

.

Contents

.

Backward-Wave Oscillator Tube

.

RF Leveler and Anode

Reference Circuit

.

Amplitude Modulator

.

Helix Modulator

.

Linear Sweep Generator

Exponential Voltage Generators

.

Regulated Power Supplies

.

Magnet Current Supply (Regulated)

...........

...

. .

Operation

.......

...

.....

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

...........

.......

as

......

.

..........

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

.

.......

......

.........

.....

.

....

1-1 1-1

1-1

1-2 1-2

1-3

2-

1

2-1 2-

1

2-2 2-2 2-2 2-2 2-8

3-

1

3-1

3-3

3-4 3-5

3-5

3-8 3-10 3-11

OF

CONTENTS

Section IV

MAINTENANCE

4.1

.

General

4.2

.

General Precautions

4.3

4.4

4.5

4.6

4.7

4.8

4.10

4.11

4.12

4.13

4.14

4.15

4.16

4.17

4.18

4.19

4.20

4.21

V REPLACEABLE PARTS

5.1

5.2

Air Filter

.

Cabinet Removal

Quick-Check Procedure

.

Maintenance

Required

.

Magnet Supply (Regulated)

-150

.

Helix Supply

Filament Regulated

.

Measurement of Linear SweepTimes 4-9

.

Replacement

.

Calibration Procedure

RF Sweep Linearity

.

Square-Wave Generator RF

.

Voltage Adjustment

.

Servicing the Sweep Circuits Replacing Neon DC Coupling

.

Elements

Positioning Frequency Dial on

.

Potentiometer Shaft

.

Tube Replacement

.

Troubleshooting Procedure

.

Introduction

.

Ordering Information

...........

.....

..........

.......

....

Test

Equipment

.........

...

Volt Regulated Supply

.

..........

......

of

BWO Tube. and

...

.....

....

Leveler and Reference Anode

.....

. .

.........

.....

......

.

.........

.....

.

Page

c

4-1 4-1 4-2 4-2 4-2

4-6 4-6 4-7 4-7 4-9

4-10 4-14 4-15

4-15 4-17

4-19 4-19

4-22 4-22

5-1

iv

Number

1.1

.

Electronic Sweep Oscillators

3.1

.

Condition of

RF Sweep

4

.

1

.

Tube Replacement

4.2

.

Troubleshooting Procedure

5.1

.

Replaceable

Tubes

..

Parts

LIST

OF

TABLES

Title

........

During CW and

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

Chart

..........

.........

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

Page 1-1

3-9 4 . 23

4-24

5-1

01130-1

Model 683C

LIST

OF

ILLUSTRATIONS

List of Illustrations

Number Title Page

1.1

.

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

2.10

3.1

3.2

3.3

3.4

3.5

3.6

3.7

3.8

3.9

Warranty Sheet

Turn-On Procedure and CW Operation

.

Using the Sweep Oscillator

.

as

a

Internal Sweep Modulation

.

Internal Square-Wave Modulation

.

External Pulse Modulation

.

External Amplitude Modulation

.

External Frequency Modulation

.

Allowable External Frequency

.

Suitable Setup for Measuring

.

Input and Output Connector

.

Backward- Wave Oscillator

.

Block Diagram Model 683C

.

RF

.

Adjustable Segments of

.

RF Leveler Circuit

.

Amplitude Modulation EXT

.

Frequency Modulator Waveforms

.

Simplified Schematic

.

Simplified Schematic of

.

CW Signal Source

Modulation Voltage Amplitude vs

Modulation Voltage Frequency Frequency Deviation Limits when

using External FM Characteristics

Tube Construction

Sweep Oscillator

Leveler Detected Waveform

(Leveled and Unleveled Positions)

Compensated Helix Voltage

Exponential Sweepcircuit

...........

.

. .

.

2-2 2-3 2-4 2-5 2-6 2-7

2-8

2-9 2-10

3-1

3-2

3-3

3-3 3-4

3-5

3-6 3-7

3-8

......

...

......

....

...

........

..........

........

..........

....

.........

.

Position

...

of

Sweep Circuit

.....

1-2 2-0

Number

.

4.1

4.2

.

4.3

.

4.4

.

4.5

.

4.6

.

4.7

.

4.8

.

4.9

.

4.10

.

4.11

.

4.12

.

4.13

.

4.14

.

4.15

.

4.16

.

4.17

.

4.18

.

4.19

.

4.20

.

4.21

.

4.22

.

4.23

.

4.24

.

4.25

.

4.26

.

Title

Measuring RF Power Output Checking Frequency Calibration and

General Performance Setup for Measuring Residual AM Measuring Magnet Circuit Ripple Model 683C Top View Sweep Output Voltage Model 683C Bottom View Model 683C Rear View Positioning the BWO Tube at the

Front and Rear of Magnet Calibration Pips on CRO Sweep Example of Calibration Pips on

CRO Sweep Crystal Detector-Attenuator

Response Curve RF

Leveler Circuit Board RF Leveler Calibration Setup Model 683C Right Side View Model 683C Sweep Output Voltage Linearity Troubleshooting Chart Magnet Power Supply

(Current Regulated)

Regulated Primary Power and

Magnet Current Supply

Regulated +300 and -150 Volt PS Frequency Supply and Low Voltage PS

RF Power Leveler and

Amplitude Modulator Amplitude Modulator and Anode Section Exponential and Linear Sweep Gen

Frequency (Helix) Modulator

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

Left

........

.........

Side View

........

.....

.......

...

.......

......

....

......

.....

......

....

.......

...

. .

.....

.

Page 4-2

4-3 4-5 4-7 4-8 4-9 4-12 4-12

4-13 4-14

4-15 4-16

4-18 4-19 4-20 4-21 4-22

4-28

4-30 4-31

4-32 4-33

4-34 4-35 4-36 4-37

01130-1

V

MODEL 683C

ELECTRONIC SWEEP OSCILLATOR

Model 683C

*

This manual specifically describes Model 683C of the

683C sweep oscillators. If, however, the serial number of your instrument

TllO

series, and

in

general describes all

is

prefixed by TO24 or T044, there are parts of themanual which do not apply to your instrument. If your instrument carries one of these serial numbers, information specific to your instrument

is

furnished with this manual. This supplementary material includes schematics, parts list, and replacement paragraphs and illustrations for those items in the manual that do not describe your instrument. The supplementary data

is

indexed; paragraph and figure numbers are the same as those used

in the manual for the corresponding information.

If

it

is

necessary to order replacement parts, consult the supplementary the component always

use

the part number in your supplementary parts list.

is

not listed,

use

the part number given in section V of the manual; otherwise,

parts

list first.

If

vi

01

130-

1

Model 683C

Paragraphs

Section

1-1

to

T

1-3

SECTION

GENERAL INFORMATION

1-1.

DESCRIPTION.

The @ Model 683C Sweep Oscillator

($3

Electronic Sweep Oscillators which

microwave bands as shown in table

Table 1-1. Electronic Sweep Oscillators

($9

Model

682C 683C 684C

H01

686C 686C 687C

Sweep oscillators are used as signal wide variety of laboratory and production tests. They provide a high-level relatively constant-amplitude

signal that can be rapidly changed in frequency. Thus they permit the characteristics of microwave systems

or components to be quickly checked over an entire

band of frequencies. The

@

Model 683C Sweep Oscillator covers the com-

plete

S

wave oscillator (bwo) tube to generate the The bwo tube has several advantages over previously

used klystron type microwave oscillator tubes when used in sweep sources.

The bwo tube output frequency and power level are determined by the values of applied voltage only. There are no cavity or reflector voltages to adjust or track. There lation. Since frequency and power-level adjustments are electronic, all mechanical problems associated with tunable-cavity Hystron-type oscillators are inated. Control of frequency and power level are simple, positive, and straightforward. By

rf

put from the bwo input, power variations of i1.5 db

are realized, power from the bwo full power from the bwo tube output power

which The Model 683C Sweep Oscillator

output can be either internal square-wave source provides square-wave

modulation at any frequency between 400and 12OOcps. The instrument can be externally pulse modulated or

band from 2 to 4 kmc (gc) and

is

no tendency to switch modes of oscil-

leveler circuit, which programs the

With

the

is

adjustable from 0 to a maximum

is

not

less

than 30 milliwatts.

cw

Frequency Range

1.0 to 2.0 kmc (gc)

2.0 to 4.0 kmc (gc)

4.0 to 8.1 kmc (gc)

7.0 to 11.0 kmc (gc)

8.2 to 12.4 kmc (gc)

12.4 to 18.0 kmc (gc)

rf

leveler inoperative, output

kept constant within 6 db, but

or amplitude modulated. An

is

one of several

cover

1-1.

sources

uses

a backward

rf

power out-

is

obtained. The

is

versatile. The

signal.

use

major

for a

elim-

of

an

rf

I

amplitude modulated by at any percentage from oscillator can be externally frequency modulated or swept

in

frequency over any portion or all 4-kmc (gc) range, or taneously amplitude and frequency modulated.

When used for lator, the internal circuitry provides an extremely wide choice of sweeping rates and bandwidth swept. The rate and adjustable in calibrated steps from 16 mc/sec to 160 kmc(gc)/sec. The frequency range swept can be

small as 2.1 mc or as wide as 2.1 kmc (gc), as

as selected by the calibrated seven position QUENCY switch. In addition, there control associated with the which gives continuous adjustment between the fixed

positions The minimum sweep time of the Model 683C

milliseconds. The sweep time combined settings of the RF SWEEP RATE and the

A

FREQUENCY switches. These switches are inter-

locked by a differential gear drive which automatically

prevents any combination which would produce a sweep time

less

The swept

linear with time and, by adjustment of SELECTOR switch, can be made recurrent or single sweeps. Single sweeps are started either by the front-panel pushbutton or by an external positive pulse (rise time greater than In addition, a sawtooth voltage of approximately 25 volts

to supply a linear time base for an oscilloscope or

X-Y

recorder.

1-2.

INSTRUMENT COOLING SYSTEM.

The instrument fan system. The incoming air excessive dust. This filter must be inspected quently to insure that it dirty

filter

excessive heating of the instrument which can cause

early component failure (see figure 4-3).

1-3.

THREE-CONDUCTOR POWER CABLE.

To protect operating personnel, the National Electrical Manufacturers’ Association (NEMA) recommends that the instrument panel and cabinet be grounded. All Hewlett-Packard instruments are equipped with a three-conductor power cable which, an appropriate receptacle, grounds the instrument. The

offset pin

nector

is

its

primary purpose as a sweep oscil-

of

change of frequency

.

than 13.2 milliseconds.

rf

output frequency from the oscillator

is

provided concurrent with each

is

forced-air cooled by a high velocity

may restrict air flow sufficiently to cause

on

the power cable three-prongcon-

the ground pin.

sine

or complex waveforms

0

to

lOC%.

if

desired the 683C can be simul-

A

FREQUENCY switch

3

volts per microsecond).

is

not clogged with dirt.

In addition the

of

the 2- to

is

linear with time

A

is

a VERNIER

is

determined by the

the

SWEEP

set

rf

sweep

filtered to remove

when

plugged into

FRE-

13.2

is

for

fre-

A

0

1

130-

1

1-1

Section Paragraphs

I

1-4

to 1-5

To preserve the protection feature when operating the instrument from a two-contact outlet,

use

a threeprong to two-prong adapter and connect the green pigtail on the adapter to ground.

1-4.

230-VOLT

The @ Model 683C operation, but

OPERATION.

is

usually shipped wired for 115 vac

is

quickly and easily converted to operation from a nominal 230-volt 50/60 cps source. To convert, remove two jumpers between terminals

A2 and A3.

In

addition, remove the jumper

wire

(connecting the two rear terminals of the MAGNET

AMP and

3 minal of the minal of a pink lead attached to either the MAGNET

the

H.

V.

3

AMP.

fuses)

from the rear

H.V.

fuse and reconnect to the side

H.V.

fuse.

This side terminal also has

it.

Do

not change the size of

fuse

or the

H.V.fuse.

ter-

When operating from a 230-volt source, T101, the magnet supply and the fan operate on 115 volts supplied by T1

primary windings which act as a 2:l autotransformer. This additional load load carried by the

sets

the expected reduction in current due to 230-volt

H.V.

is

added to the normal

fuse

and approximately off-

operation.

Model 683C

1-5.

RACK MOUNTING INSTRUCTIONS.

When mounting a rack model instrument, leave at least three inches clearance behind the air intake to insure that the air intake

ment which

proper

is

air

circulation. In addition, be certain

is

not near another piece of equip-

discharging hot air

in

the

vicinity of

the Model 6836 air intake.

The following instructions should be followed for easy

installation of a rack model instrument (683CR)

in

an

equipment rack.

Remove the four

1)

screws

from

the

rear of the

in-

strument cabinet and slide the instrument forward

from the cabinet.

the

2) Mount

empty cabinet four oval head machine side

of

1-3/4

the cabinet

inches from the top and bottom edges of the

in

the

in

the equipment rack with

screws:

two

screws

on each

mounting holes approximately

mounting flanges.

3) Raise the instrument chassis and slide it gently

into the cabinet. Be certain the power cable passes freely through the hole in the rear of the cabinet.

WARRANTY

CLAIM

AND

ADJUSIMINT PROCIDURI

MICROWAVE

INFORMATION

TUBE

WARRANTY CLAIM

Slp.t"re

Title

FORM

9/12/61

Figure

1-1.

Warranty Sheet

1-2 01130-1

Model 683C

4)

Fasten the instrument panel securely to the rack.

5)

Replace the four

(if

desired).

This instrument weighs over If the rack installation tion or rough handling, additional means of support should be provided at the rear of the instrument.

screws

Note

at the rear of the cabinet

100

pounds.

is

subject

to

vibra-

Section

Paragraph 1-6

1-6.

BWO

The bwo tube used in this instrument

and has a shorter guaranteed tional tubes. See the Tube Warranty sheet, figure

for

details. A sheet for your

appendix of this manual. To

useful

suggested that the instrument be turned off when not in use. Wave Oscillator Tube Claims and Adjustment Pro-

cedure sheet in this manual should be read and the

instructions followed carefully.

hours of When replacing the bwo tube, the Backward-

TUBE

service

INFORMATION.

is

very expensive

life

than that of conven-

use

is

increase

obtained from each tube, it

included in the

the number

1-1,

of

is

I

01130-1

Section I1 Figure 2-1

Model 6836

9.

1.

Rotate CATHODE CURRENT control terclockwise to minimum.

2. Rotate CURRENT switch to MAGNET.

3. Rotate AMPL. MOD. SELECTOR switch toOFF.

4. Rotate SWEEP SELECTOR switch to

5. Turn POWER ON. (Thermal time delay relay delays application of high voltage for approxi-

mately 60 seconds after power Reset overload circuits by momentarily turning

POWER

6.

Read magnet current. time delay relay operates,

7.

Rotate CURRENT switch to CATH.

8.

RF LEVELER switch to

2-0 01130-1

OFF

then back “on”.

0.5

to 0.65 amp before

0.7

amp hot.

ON.

Figure 2-1.

full

coun-

OFF.

is

turned on.)

Turn-On Procedure and CW Operation

Set FREQUENCY dial to frequency indicated

on the meter plate.

10. Rotate CATHODE CURRENT control clockwise until meter reads value indicated on meter plate.

11.

Rotate CURRENT switch to HELIX.

12. Read helix current. The meter should read

less

than

3.0

ma. Do not operate instrument

if

helix current exceeds

13.

Rotate CURRENT switch to ANODE.

14. Read anode current. The current should not exceed 2.0 ma.

15.

Rotate CURRENT switch to COL.

16. Read collector current. The collector current should be approximately the difference between the cathode current and the sum of the other electrode currents.

3.0

ma.

Model 683C

Paragraphs 2-1 to 2-3

Section I1

SECTION

OPERATING INSTRUCTIONS

2-1.

CONTENTS.

Section operating the sweep oscillator, instructions for modulating the cations of the instrument.

2-2.

The Model 683C Sweep Oscillator should be placed on a work bench or table with at least 3 inches of clearance at the filter. To avoid seriously restricted air flow, be careful not to let loose pieces of paper, etc. main in the rear area since they can be pulled against the air filter.

The power cable should be used in a NEMA approved standard three-prong grounding receptacle (paragraph 1-3).

Complete installation instruction for rack model struments are given in paragraph 1-5.

2-3.

Good operating practice dictates that you follow ,a given step-by-step procedure when turning on the Model 683C, to protect the bwo tube. This routine will critical circuits to insure normal operation.

Under normal operation no damage can be done by improper setting of front panel controls since builtin high-voltage transformer

in

by momentarily turning off power to the instrument. In addition to the overload protection, internal

driver-adjust controls preset limits on front panel controls to safe values. BWO tube currents aremonitored with built-in metering circuits, which provide a positive check that the bwo tube in

To place the instrument in operation, the steps outlined

in

Additional data on some of the steps are given below under STEPS; before performing the turn-on procedure for the first time, read this supplemental information.

Figure 2-1 shows the front panel controls as briefly describing the steps of the turn-on procedure.

The unnumbered controls and terminals can be oper-

ated in any order desired, depending on the type of

operation selected. Characteristics of the input and

output connectors are given

With the completion of the turn-on procedure the instrument

set

I1

contains instructions for setting up and

rf

output, and a discussion of some appli-

INSTALLATION.

the

rear to insure adequate air flow through

re-

in-

TURN-ON PROCEDURE.

systematically check out proper operation of all

overload protection cuts off primary power to the

if

excessive current flows

the helix circuit. The overload circuits are reset

screw-

is

being operated

a safe manner.

figure 2-1 should be followed in the order given.

well

as

in

figure 2-10.

is

set

up for

on the FREQUENCY dial. Once

cw

operation at the frequency

cw

operation has

II

been established, the oscillator may be adjusted for frequency and for amplitude modulation (paragraphs 2-4 through 2-7).

Until thoroughly familiar with instrument operation, it

is

recommended that you

information which follows. STEPS: The number associated with each paragraph

the turn-on procedure step under discussion. See figure 2-1 for

5. Set POWER to ON. The plastic graticule at the

top of the FREQUENCY dial fan

will

delays application of high voltage to the main cuits approximately 60 seconds after ment are partly energized when the POWER switch turned on, but do not regulate until the time-delay switch has operated and the filaments lator circuits are energized.

6. Read magnet current on the monitor meter. The

current should be 0.5 to 0.65 ampere when turned on and after a

ATE INSTRUMENT IF AFTER WARMUP THE MAGNET CURRENT AND

8.

With RF LEVELER switch to have a power output variation across the band of

i1.5 db or tion the power variation across the band will not

exceed

9.

It

is cathode current at the frequency indicated on the meter plate. The reasons are: a) Only with the

rated cathode current at the frequency specified

will

conditions are not met, the RF LEVELER give the desired leveling action

10.Rotate CATHODE CURRENT control in a clock-

wise

Normal (at least 30 milliwatts) output tained with the value of cathode current stamped on the panel meter. (The maximum

limited by internal adjustments.)

12.Read helix current. The current should be than 3 ma. DO NOT OPERATE THE INSTRUMENT IF THE HELIX CURRENT EXCEEDS 3MA.

An

overload relay prevents excessive helix

rent. To POWER off, then back to ON. Excessive helix current may indicate misalignment of the bwo tube

in

the magnetic field

the

steps not discussed below.

operate.

is

energized. The magnet supply

will

few

minutes operation. DO NOT OPER-

0.725

AMPERE.

less.

3

db.

important that the meter reads the exact

adequate power be produced. b) If the latter

direction and observe the current reading.

reset

refer

to the supplemental

refers

will

glow. The cooling

A

thermal time-delay switch

cir-

the

instru-

circuits

in

the regu-

first

gradually settle to 0.70 ampere

IS

NOT BETWEEN 0.675

ON

the 683C

In the RF LEVELER OFF posi-

(+

1.5 db).

will

current

will

be ob-

less

will

not

is

cur-

the relay, momentarily turn

(see

section IV, Maintenance).

to

is

01130-1

2-

1

I

Section

I1

Paragraphs 2-4 to 2-7

Verify proper operation of the helix power supply by rotating the FREQUENCY dial from 2 to 4 kmc (gc) and noting that there current. (BWO

in

helix voltage.

helix

Thus

as the FREQUENCY dial

range

is

a check that helix voltage

16. The collector

ference

current

between cathode current and

the helix and anode current readings.

is

a variation

in

helix

current varies with a change

a variation

in

helix

is

turned through

is

current

its

changing.)

reading should be the dif-

the

sum of

If

there

is

a large difference between this value of collector current and that shown by the meter, ment

is

not functioning properly

The instrument

ting a 30 milliwatt or more

is

now operating normally and genera-

cw

signal at the frequency

(see

the

instru-

section

IV).

indicated by the FREQUENCY dial.

2-4.

ment is the AMPL. MOD. SELECTOR switch LEVELER to ON.

is

of better than The output power level

USING THE SWEEP OSCILLATOR AS

A CW SIGNAL SOURCE.

Upon completion of the turn-on procedure, the

set

up for cw operation. However, check that

is

OFF; RF

In

cw operation, output frequency

indicated by the FREQUENCY dial to an accuracy

-+

1%.

is

adjustable from at least

instru-

30 milliwatts down to zero by theCATHODE CURRENT control. Monitor the power level near rated value to ratings are not being exceeded. higher than 7 ma helix

current

to 7 ma and check that helix current This

is

a

check

the bwo

is

discussed in paragraph 4-13B.)

the

cathode current when adjusting

insure

If

cathode current

is

required to get rated power, and

is

higher than 3 ma, set cathode

is

less

that tube

focus

is

correct.

that tube

current

than 3 ma.

(Focusing

By the addition of a precision attenuator, the 683C can be used as a signal generator. Figure 2-2 indicates connection of equipment for such a setup. fraction of the power

SWEEP OSCILLATOR

POWER METER

lpw TO lOmw

2-4gc

in

@gyL

the line

THERMISTOR

MOUNT

Ipw

TO

2-

4gc

is

IOmw

A

20-db

coupled to the

DIRECTIONAL

COUPLER

I

-4gc

cdb .5db

Figure 2-2. Using the Sweep Oscillator

as a CW Signal Source

Model 683C

auxiliary arm of The power-monitoring branch iliary arm. Thus the on the 431A Power Meter plus 20 db, and the at the load

is

the

761D Dual Directional Coupler.

is

taken from this aux-

rf

power in the

line

is

the reading

rf

power

the monitored rfpower minus the setting of the attenuator. The accuracy with which the power reaching the load can be monitored in this way

is

limited by the accuracy of theattenuator. Rated accuracies of the other components are shown

2-5.

SWEEP OPERATION

OF

THE OSCILLATOR.

After the oscillator has been set up for the

rf

output should

be

set

to the desired power level

in

figure 2-2.

cw

operation

and the FREQUENCY dial set to the proper setting.

Refer

to figure 2-3, for instructions on how to obtain

sweep operation.

2-6.

AMPLITUDE MODULATING THE OSCILLATOR.

The 683C provides facilities for modulation with internally-generated square waves, externally-supplied pulses (683C input, ac coupled), or externally supplied voltages (683C input, dc coupled). Operation at various positions of the switch are described

in

figures 2-5,

2-6, and 2-7.

2-7.

FREQUENCY MODULATING

THE OSCILLATOR.

The oscillator can be frequency-modulated from an external source by placing the SWEEP SELECTOR switch

in

the

EXT. position and applying a modulating voltage to the FREQ. MOD. jack (figure 2-7). The jack

is

ac coupled to an impedance of 43K shunted by

approximately 100 pf. The bwo

rf

output frequency varies with respect to the voltage at the input to the FREQ. MOD. jack from approximately 8.2 mc/volt at 4 kmc (gc) to 23.8 mc/ volt at 2 kmc (gc). The full frequency band (2.1 kmc [gcJ) may be swept (at a rate of between

10

to 60 cps) by applying a voltage of 150 volts peak-to-peak to the FREQ.

MOD.

jack. When sweeping full band,

the FREQUENCY dial should be set at approximately

3.2 kmc (gc). Frequency modulation

is

up and down from the frequency indicated on the FREQUENCY dial. Positive-going voltage applied to the FREQ. MOD. iack increases the freauencv.

is

When the full band

swept, the frequency of the

modulation voltage should be within 10 and 60 cps.

When

the frequency of the modulation voltage

is

higher than 60 cps, the band swept must be reduced to avoid overload of the helix power supply.

The

chart shown

as figure 2-8 shows the maximum voltages which

should be applied to the FREQ. MOD. jack

when

mod-

ulating frequencies above 60 cps are used.

For external frequency modulation of the 683C, consideration must be given to the modulation character-

istics

voltage produces an exponential change of the

of the bwo.

rf

output.

If

A

linear change

in

modulation

in

the frequency

small modulation voltages are used,

2-2

01130-1

Model 683C

COL

CURRENT

HELIX

,wr,

ANODE

RF

SWEEP

RATE

IMC/SECI

Section

Figure 2-3

-0

I1

3A

POWER

H.V.

3A

MAGNET

First turn on instrument and adjust for normal out-

put

under

cw

operation as shown in the turn-on

procedure (figure 2-1).

1.

Rotate the AMPL.

OFF,

or other desired mode.

2. Set FREQUENCY (KMC) dial to (sweep

is

downward from FREQUENCY dial

MOD.

SELECTOR switch to

4

kmc (gc)

setting).

3.

Rotate A FREQUENCY switch to position cor-

responding to number of megacycles to be

swept. Set VERNIER to CAL. For variable segments

4.

Rotate the RF SWEEP RATE switch totheposi-

of A FREQUENCY, rotate out of CAL.

tion corresponding to the rate of sweep desired in mc/sec.

The

A

FREQUENCY switch and the RF SWEEP RATE switch are mechanically interlocked to prevent a combination result in a sweep time of

of

settings that would

less

than 0.0137

second.

5.

Rotate SWEEP SELECTOR switch to RECUR

if

automatically recurring sweeps are desired.

6.

Rotate SWEEP SELECTOR switch to

TRIG.

single sweeps are desired. Sweeps may be started by momentarily pressing MANUAL

TRIGGER button, or by supplying a positive

20-volt pulse to Em. TRIG. jack.

CHARACTERISTICS

-

Direction:

RF sweeps are downward, starting at the quency indicated on the FREQUENCY (KMC) dial.

SWEEP OUTPUT voltage

is

a positive going

20-25 volt sawtooth voltage.

Accuracy:

Frequency band swept sweep. +25%, -15% or greater, for sweep widths

is

within

i3

mc, whichever

less

f

10%

than full band.

for

if

fre-

full

is

O

1130-

~~

Figure 2-3. Internal Sweep Operation

1

2-3

Section

I1

Figure 2-4

Model 683C

RF

LEVELER

CATHODE CURRENT

FREQUENCY

(KMC)

RF SWEEP RATE (MCISECI

SW

5%

VERNIER

First turn on instrument and adjust

for

normal output under cw operation as shown in the turn-on procedure (figure 2-1).

1.

Rotate SWEEP SELECTOR switch to OFF.

2. Rotate AMPL. MOD. SELECTOR switch toINT.

3.

Adjust

INT.

SQ. WAVE FREQUENCY with red

concentric knob.

CHARACTERISTICS

-

Range:

400 to 1200 cps

Figure

2-4.

2-4

Symmetry:

Better than 4v0

Rise and Decay

Time:

Less than 2 microseconds

RF Output:

During "onyy time, established output

4

mc

of

cw

is

zero. RF output frequency

the

cw

frequency.

Note: The AMPL. MOD. SELECTOR and SWEEP SELECTOR switches operate independently. Both may be types

set

in any position at any time. Thus two

of

modulation may be obtained simultaneously.

Internal Square-Wave Modulation

to

60%

rf

output

level. During

is

within 1 db

"off"

time,

is

within

01

of

rf

130-

1

Model 683C

Section

Figure 2-5

I1

First turn on instrument and adjustfor normal output under

procedure (figure 2-1).

1.

Rotate SWEEP SELECTOR switch to OFF.

2. Rotate AMPL. MOD. SELECTOR switch to PULSE.

3.

a) Feed

or

to

b) be applied to the AMPL. MOD. jack.

01130-

1

cw

operation as shown in the turn-on

a

+

10

to

+30

volt signal, 5 milliseconds

less

in width, at frequencies from

300

kc into the AMPL. MOD. jack.

A

square wave

-10

volts

100

or

more can also

Figure 2-5. External Pulse Modulation

cps

CHARACTERISTICS

RF

Output:

During "on" time, established output

4

Note: The AMPL. MOD. SELECTOR and SWEEP

-

SELECTOR switches operate independently. Both may be set in any position

types

is

zero. RF output frequency

mc

of

the cw frequency.

of

modulation may be obtained simultaneously.

-

rf

cw

level. During "off" time,

output

is

within 1 db

at

any time. Thus two

is

of

rf

within

2-5

Section

I1

Figure 2-6

RF

SWEEP RATE (MCISEC)

yI0

5x

Model 683C

CURRENT

HELIX

,udrs

COL

RF

CATHODE CURRENT

OFF

LEVELER

ANODE

3YA

@

31

POWER

n.v.m

MAGNET

16

FS

I601

First turn on instrument and adjust for normal output under procedure (figure 2-

cw

operation as shown

1).

in

the turn-on

lation pulses. However, large internal capacitor in

(example

($9

Model 212A) no external capacitor

if

the signal source has a

series

with the output,

needed.

1.

Rotate SWEEP SELECTOR switch to OFF.

2. Rotate AMPL. MOD. SELECTOR switch to EXT.

CHARACTERISTICS

-

Modulation: Direct coupled, dc to 300 kc

a)

A

modulation voltage of -20 volts applied to

the AMPL. MOD. jack.

3.

Feed modulation voltage

from an external source into AMPL. MOD. jack.

Note:

-

Positive input pulse can be applied providing it is either capacitively coupled or superimposed on a -20 volt bias.

If

capacitively coupled the capacitor

must be sufficiently large and the duty cycle such,

as to maintain a charge (grid bias) between modu-

of

20 volts or more

b)

A

+20 volt signal

is

applied to the AMPL. MOD. jack, providing a -20 volt bias externally.

Automatic Gain Control:

Since the EXT. position itself very

well

is

dc coupled,

to external automatic gain

control.

is

applied

it

applies

Figure 2-6. External Amplitude Modulation

2-6 01

is

130-

1

I

Model 683C

RF

LEVELER

CATHODE CURRENT

FREQUENCY (KMCI

RF SWEEP RAT€ IMCISEC)

VERNIER

Section

Figure 2-7

I1

31

POWER

H.V.3A

MAGNET

@@

First

turn on instrument and adjust

put under

cw

operation as shown in the turn-on

procedure (figure 2-1).

Rotate the AMPL. MOD. SELECTOR

1.

2. Rotate SWEEP SELECTOR switch to EXT.

3.

Feed a signal from an external source into the FREQUENCY MOD. jack.

for

normal out-

to

OFF.

CHARACTERISTICS

-

Modulation:

A

linear change in modulation voltage produces an exponential change in Modulation

is

up and down from the FRE-

rf

output frequency.

QUENCY (KMC) dial setting.

Phase:

Positive-going voltage causes the frequency to increase.

Note: Refer to chart figure 2-8 for upper limit on amplitude of modulating frequencies higher than 60 cps.

As

frequency

of

modulating frequency in-

creases the band swept must be reduced.

Figure

2-7.

01130-1

Note:

The AMPL. MOD. SELECTOR and SWEEP SELECTOR switches operate independently. Both may be

set

in any position at any time. Thus two

types of modulation may be obtained simultaneously.

External Frequency Modulation

2-7

Section 11

Model 683C

Paragraph 2-8

the

bwo will be operating over a small section of the helix voltage-vs-frequency considered a straight

curve

and the

line.

If, however, large modu-

curve

can be

lating voltages are used, the bwo will be operating over a large section of the helix voltage-vs-frequency curve and lating voltage

the

curve

is

large, a shaping

is

exponential. When the modu-

circuit

may be used which provides an exponentially-varying voltage which has a helix the same shape as that

voltage-vs-input-voltage

of

the bwo helix voltage-vs-

curve which

is

frequency curve.

CAUTION

The bwo can be damaged if out of its rated band (2 to possibility of sweeping outside greatest 1) when a wide band age excursions applied to the FREQ. MOD. jack are greater than 150 volts peak-to-peak) and

2)

when the FREQUENCY dial

near one edge of

the

band.

To guard against sweeping outside the band, the arrangement shown used. The output from through an attenuator, two wavemeters, and a crystal detector to the vertical input of an oscilloscope. The modulating voltage applied to the oscilloscope horizontal input. Each wavemeter band. Thus, as

is

tuned for one edge of the

the

meter pip at each end of the oscilloscope trace will define the rated range. and any excursion beyond limits can be ietermined.

2-8.

APPLICATION.

the

683Cis swept

4

kmc [gc]). The

is

swept (volt-

in

figure 2-9 may be

the

683C

band

is

swept, a wave-

the

is

band

is

set

applied

is

5

10

20

50

100

150

MODULATING VOLTAGE (PEAK-TO-PEAK)

RO

Figure 2-8. Allowable External Frequency

Modulation Voltage Amplitude

vs

Modulation Voltage Frequency

reflection or

looked

is

equally valuable for measuring attenuation, gain,

swr

with a reflectometer, but often over-

is

the fact that a reflectometer or ratio meter

and other transfer characteristics over a wide range and

in

rapid fashion. The ratio meter system

is

also good for measuring the magnitude of scattering matrix coefficients when it

is

desired that a transmission-line

network be described in terms of such coefficients. Information regarding this type of measurement using

the 683C

is

found in Hewlett-Packard Journal Sept.Oct. 1957, Volume 9, No. 1-2 (Permanent Record and Oscilloscope Techniques with the Microwave Sweep

One of the valuable uses for a microwave sweep oscil- Oscillator); Hewlett-Packard Journal Dec. 1960, Vollator lies in its ability to permit rapid measurements ume 12, No.

4

(Improved Sweep Frequency Techniques

of microwave device performance over a range of for Broadband Microwave Testing); Application Note

frequencies.

One example

is

the measurement of 42 (Applications of

the

416A Ratio

Meter).

,

2-8

01130-1

Model

683C

7

1/2

AMPERE VARIABLE

TRANSFORMER €QUI PP ED

WITH A VOLTMETER

ACCURATE TO WITHIN

+I

VOLT

@

MODEL 150A OSCILLOSCOPE

C.R.O. VERTICAL SENSITIVITY

0.050

D.C. COUPLED

V/CM

A/B

=

Section

Figure 2-9

I1

SWEEP I-4-KMC

TWO WAVEMETERS

SUCH

AS THE

EXTERNAL SOURCE OF MODULATION VOLTAGE

IO

TO

60

VARIABLE AMPLITUDE CONTROL

OF

IS

CPS WITH

FROM

0-150

MODEL 205AG

RECOMMENDED.

VAC

RO

11130-1

Figure

2-9.

Suitable Setup

for

Measuring Frequency Deviation Limits when using External FM

2-9

Section Figure 2-10

I1

Model 683C

.

RF

OUTPUT

s

1.

PULSE

Ixto AMPL. MOD. jack Input Pulse: maximum length. Impedance: 390K shunted by 25 pf.

EXT.

Input

to AMPL. MOD. jack dc

-20 volts level to zero. Impedance: 750K shunted by 25 pf, with diode CR301

2. FREQ. MOD. Input: Positive pulse, 20 volts Input Impedance: approximately

+

10

or

more reduces

biased off.

100

volts or more; 5 milliseconds

ac coupled; 43K shunted by

pf.

is

ac coupled.

to

300

rf

level from cw

kc;

Frequency Response: Full band may be swept 10

cps

to

to avoid overload chart figure 2-8 for limits at higher modulating frequencies. Sensitivity: 29.2 mc/volt at 2 kmc (gc) and

8.5 mc/volt at

3.

SWEEPOUTPUT Output: 20-25 volts positive-slope sawtooth, concurrent with Internal Impedance:

4. EXT.TRIG. time greater than

Impedance: 10K shunted by

60 cps, input voltage must be reduced

of

4

kmc (gc).

rf

output.

3

volts/psec.

power supplies. Refer to

10K

shunted by 20 pf.

10

pf.

or

more,

rise

2-10

Figure 2-

10.

Input and Output Connector Characteristics

01

130-

1

Model 683C

Paragraphs 3-1 to 3-2

Section

Ill

SECTION

THEORY

3-1.

CONTENTS.

This section explains how the circuits of the sweep oscillator operate. First, the overall operation of the backward-wave osCillator tube the bwo tube characteristics of the tube are understood, an overall picture of the purpose of the various circuits easily understood.

3-2.

BACKWARD-WAVE OSCILLATOR TUBE.

The helix type backward-wave tube (figure 3in

the sweep oscillator the helix type traveling wave tube, Each basically consists of an electron gun, a metallic helix through which the electron beam passes axially, and a collector electrode. The electron gun assembly

.produces a hollow electron beam.

is

used to produce a strong, uniform, axial magnetic field around the bwo tube. This magnetic field focuses the electron beam into a hollow cylinder which

centric with the helix. The tube

tioned

passes down the full length of the tube to the collector

without striking the helix. Briefly, the tube oscillates as follows:

RF energy travels down the helix away from the

lector end at a velocity equal to the speed of light

multiplied by the ratio of the turn-to-turn spacing of the helix divided by the circumference of the helix. This energy causes electric fields to exist along the

is

the heart of the instrument. Once

in

the magnetic field

is

similar

so

is

described, since

the

is

more

1)

used

in

appearance to

in

a bwo tube

An

external solenoid

is

con-

is

accurately posi-

that the electron beam

col-

111

OF

OPERATION

helix. Since the helix cycles will exist along its length which speed up and slow down the electron beam, causingit velocity of the electron beam the effective phase velocity of the helix. When oscillations are taking place, the bunched electron beam advances a quarter of a cycle as it approaches encounters the full decelerating effect of the electric

field. This results maximum amount of kinetic energy to the backward traveling

The helix used

that produces a 100-ohm balanced output.

anced output

the balanced output to a 50-ohm single-ended output at the front panel.

A.

OUTPUT FREQUENCY. The operating frequency

of the bwo ageover a range of approximately 250 to 2000 volts positive with respect to the cathode. frequency the frequency change per volt decreasing as frequency increases. The frequency change per volt

change at the helix varies somewhat from tube to tube,

but

is

2.08 mc/volt at Control of the operating conditions of the bwo thus be-

comes simply one of controlling the potentials supplied

to the tube.

is

quite long, a number of

to

is

slightly faster than

rf

the

collector end of the tube, and thus

in

the electron beam giving up a

rf

wave on the helix.

in

the 683C bwo

is

sent through a balun which converts

is

controlled by changing the helix volt-

vs

helix voltage curve

approximately 0.56 mc/volt at 4 kmc (gc) to

2

kmc (gc).

is

a bifilar wound coil

is

bunch. The

energy along the

The bal-

The bwo output

exponential, with

rf

output

01 130-

Figure 3-1. Backward-Wave Oscillator Tube Construction

3-

1

Section 111

Paragraph 3-2 cont’d

B.

OUTPUT POWER. The power output mined by electron beam density, which

trolled by the cathode-to-anode voltage. The cathode

is

at

ground, and the level of the anode voltage determined control.

C. MODULATION. The oscillator can be amplitude

modulated at any percent from the voltage on the control grid from approximately 0

to

With pulse modulation, grid voltage under the “on” condition condition, and incidental fm

by

the setting of CATHODE CURRENT

0

20 volts negative with respect

is

essentially the same

is

negligible.

AMPL

I

/-----

I

to

as

is

deter-

is

con-

100

by varying

to

the cathode.

under the cw

MOD

SELECTOR

r-------

I

is

Model 6836

D.

FACTORS AFFECTING FREQUENCY. The

quency by the velocity determined by the voltage difference between the cathode and the focus electrode. The frequency lation

netic field flux density. Frequency will change with anode voltage change.

The change in frequency due field With the solenoid used in this instrument, change in frequency of net

is

are

held

the solenoid supply

-7

I

01

of

oscillation

of

the electron beam. This in turn

is

alsoaffected by the anode voltageand the mag-

at

a

is

essentially constant

across

very well regulated

the solenoid winding will cause a change

50

kc. However, the supply

to

very low levels. This effectively eliminates

rate

as

of

the bwo tube

of

approximately

to

changes in the magnetic

at

any operating frequency.

is

to

so

that regulation and ripple

a

source

of frequency change.

determined

350

a

fre-

is

of

oscil-

kc/volt

one-volt

the mag-

.

>I

%

-

w

C301

I\

e.

.,

IEXTIO

Q

ISWEEP

LINEAR

SWEEP

GENE R ATOR GENERATOR

I

t

I

SELECTOR

SOUARE WAVE

GENERATOR

i

I

I--------

I

LEVELER

VOLTAGE

RF

I

“

---c

-

0

LIMITER

0

CATHODE

/

.

ANODE

REFERENCE

CIRCUIT

-1

I

41

EXPONENTIAL COLLECTOR

CURRENT

-

ANODE

I-

I

-W

GRID

1

m

~

3

IY

0

I-

U

-I

J

-

V

v)

0

W

>

4

0

U

a

s

Y

TRIG PULSE

It

GENERATOR

I

3-2

I

Figure 3-2. Block Diagram Model 683C Sweep Oscillator

SWEEP OUTPUT

ED-H-248

01130-1

Model 683C

15OWW

(2I.Td b)

w

=

(20db)

0

@-

IWW

(Odb)

Figure 3-3.

3-3.

RF LEVELER

REFERENCE CIRCUIT.

A.

GENERAL. The leveler circuit

vice which reduces power variations across the band to 1.5 db or plished by programming the anode voltage to compensate for the coarse grain power variation characteristics (figure 3-3) of the bwo tube.

The leveler circuit functions ring sweep modes of operation. tion the leveler circuit compensates for coarse grain power variations throughout the frequency range (2 to 4 kmc [gc]). holds the output power level relatively constant for each selected output frequency. To describe sweep operation, swept anode voltage, the will be discussed with the SWEEP SELECTOR switch

in

the RECUR position and with the

swept. The bwo output frequency and power level are both

voltage controlled. For a linear change in output frequency, an exponential voltage

helix. Simultaneously, the

the

helix exponential (figure 3-4A)

leveler circuit, reshaped, and applied to the bwo

anode (figure 3-2). The anode voltage waveform composed of four variable segments. Segments 1 and

2 (figure 3-4B) are shaped by cathode follower V303A and associated circuitry. Segments 3 and 4 (figure

3-4C) are shaped by inverter amplifier V302A and

associated circuitry. The four segments are combined at the junction of CR302 and CR303 (figure 3-4D). The resultant waveform

erence

to the bwo anode.

B. ANODE WAVEFORM.

differential amplifier modulator V105, and applied through R321 (segment of cathode follower V303A. Potentiometer R321, by varying the amount of signal to V303A. determines the slope of segment

amplifier V302B and cathode follower V303B

the helix voltage

FINE

GRAIN

-+-

Lx

2

1.5db

2KYC 3KWC 4KWC

-FREOUENCY

RF Leveler Detected Waveform

(Leveled and Unleveled Positions)

I

-

AND

ANODE

is

an internal de-

less.

Leveling action

in

both the

In the RECUR posi-

In

cw

operation the

A

voltage proportional to

is

then applied through

A

is

1

voltage proportional to

taken from the cathodes of

1

adj., figure 3-5) to the grid

(see

figure 3-4B). The wave-

leveler

full

is

sent through the

is

cw

and

band being

applied to the

COARSE

GRAIN

POWER VARIATIONS UNLEVELED

2

3db

*-I-

273

accom-

recur-

circuit

is

ref-

Section

Paragraph 3-3

form of segment

is

an exponentially decaying voltage which starts at

+I50 volts.

R324 (segment 2 adj., figure 3-5) diode CR302 opens

(ceases conducting) causing a plateau This plateau diode CR302 remains open for the duration of the sweep.

While segments nential voltage at the cathode of differential amplifier VI05

is

applied to the grid of V302A through the potentiometer R315 (segment 3 adj., figure 3-5). CR303 junction of CR302 and CR303.r At a time determined by the bias on CR303, the positive-going voltage on the plate of V302A causes CR303 to close. The rising voltage at the junction of CR302 and CR303 ment mined by the setting of R315 (segment 3-5). The cathode of V302A follows the negativegoing voltage applied to the grid of V302A. At a time determined by the voltage at thearm of the potentiom-

eter

conduct, effectively decreasing the cathode resistance of V302A and increasing the gain of the circuit. This increased gain accounts for segment

is

open, no output from V303A appears at the

3

(figure 3-4C). The slope of segment

R320 (segment 4 adj., figure 3-5), CR304

i'

2KMC

41

STEP ANGLE

EG-h

VENT

4

SEGMEN

1

(taken from the cathode of V303A)

At

a point determined by

is

segment 2

-

3

/p

1

and 2 are being formed, the expo-

(see

TIME

I

EXPONENTIAL

VOLTAGE CATHODE

OF DIFFERENTIAL

P LATE AU

DETERMINED

BY A324

1

MINED ANGLE

COMPLETE POWER

in

figure 3-4B).

4

-

2

CR302 OPENS

p

BY

DETER- R315

2

the

setting of

the waveform.

3

is

3

adj., figure

(figure 3-4C).

i

SLOPE DETERMINED BY

SEGMENT

/

PRODUCED

BY GRID

LIMITER

R316 OF

V302A

111

Crystal

As

is

seg-

deter-

will

4

KMC

4

I

A

THE POINTS AT WHICH THE

MOVE BOTH HORIZONTALLY AND VERTICALLY.

Figure 3-4. Adjustable Segments of

Compensated Helix Voltage

a

NOTE

SEGMENTS MEET,

6-5-217

01130-1

3-3

Section 111

Paragraph 3-4

The composite waveform (figure 3-4D) at the junction

of CR302 and CR303 is applied to fier

V302B.

reference

ampli-

C. REFERENCE AMPLIFIER V302B AND CATH-

ODE FOLLOWER V303B. Characteristically,

anode voltage

vs

power

level

(30 mw)

is

different

from one tube to another. Thus to obtain the power

level (30 mw) specified by

reference

the purpose of ply a variable dc

anode voltage must be variable. The

the

reference amplifier, V302B,

reference

the

bwo tubemanufacturer,

is

voltage between

to sup-

+55

and

+255 volts at the bwo anode.

Model 683C

D.

RF LEVELER OFF POSITION. When RF LEVELER switch S302 is in the

cathode of Y302B

is

placed at a dc reference by the

OFF

position, the

combined settings of R327, R332, and R335. The purpose of the RF LEVELER OFF position

is

to make available at certain frequencies higher power outputs. Since

rf

leveling action

point, power output is sacrificed to obtain

is

referenced atthelow power

the

desired

leveling action.

3-4.

AMPLITUDE MODULATOR.

Resistor R327

is

a front panel control (CATHODE CURRENT) that varies the bwo output power from 0

to 100%. The waveform at the plate of V302B coupled to which

the

grid of

in

turn applies the complete waveform to the

the

cathode follower V303B

is

dc

bwo anode. Degenerative feedback from the cathode

of V303B

is

applied to the grid of V302B through R330 to reduce drift caused by tube aging andline voltage variations.

i3OOV

(REG)

A

TO

CATHODE

VIOSA

OF

a

B

V302A

R320 20K

Y

RF LEVELER AND

REFERENCE ANODE CIRCUIT

1

Signals for amplitude-modulating the applied to

the

control grid of the bwo tube, through the

rf

power are

amplitude modulator circuit. Voltage from the internal 400- to 1200-cps square-wave generator or signals (pulse, square wave,

sine

wave, or complex wave) from an external source may be used to modulate the

rf

output. Condition of the amplitude modulator

circuit under various types of operation

is

discussed

briefly below.

FILAMENT ARRANGEMENT

PART

OF

et-

i

300

I33231

68

K

!&a24

V/REG)

IOOK

TI01

300

V

c

A0

(REG1

tl5OVIREG)

t-/

3-4

JEGMENT

ADJUST

pam

R321

1

IM@

\e/

3V

(REG1

3V

(REG1

1

CATHODE

FOLLOW

E R

S302

?F

-CR302

vu

BALANCE

Figure 3-5. RF Leveler Circuit

LEVEL.ER

ON

R333 15K

-fx)V

(REG)

"?"

\

ICATHODE

CURRENT]

R331

IOOK

R332

IOOK

..

RO

01130-1

Model 683C

A.

CW

OPERATION.

In

cw operation (AMPL.

MOD.

SELECTOR at OFF) diode CR301 clamps the bwo

control grid to ground. The

mined by the voltage on

rf

output level

the

anode, which

is

adjusted

deter-

by means of the CATHODE CURRENT control.

B.

INTERNAL SQUARE-WAVE OPERATION. With the AMPL.

MOD.

SELECTOR on INT dual triode V301 operates as a symmetrical free-running multivibrator. The frequency mined

by

the charge and discharge time of C302 and

of

the

square wave

is

deter-

series-connected R303 and R302 (INT. SQ. WAVE FREQUENCY control). The symmetry of

is

set by adjusting (with

R3lO)

the

square wave

the dc bias on the

B section of V301. The two adjustments are slightly interdependent. The square-wave amplitude

is

clamped

to ground through crystal diode CR301. Thus the level

of the

rf

output during the “on”portionof the squarewave cycle corresponds to the cw level, set by the CATHODE CURRENT control.

Paragraphs 3-5 to 3-6

Section

OUTPU

r

OF

TO

BWO

’5

R304

GRID

-

RO

Figure 3-6. Amplitude Modulation EXT. Position

Ill

C. PULSE OPERATION. With the AMPL.

SELECTOR switch on PULSE, the AMPL.

jack

is

connected, through capacitor C301, to the grid of the diode CR301

A

section of V301. Dual triode V301,

in

the plate circuit of

its

B

MOD.

with

section,

is

operated as a limiting amplifier to provide constant amplitude pulses to the control grid of the bwo tube.

The

A

section of V301

lower and the

B

Before an externally-supplied pulse section of V301

is through contacts on the AMPL. switch,

is

tied to the control grid of the bwo tube; both

is

operated as a cathode fol-

section as a single-stage amplifier.

is

received,

the

conducting. The B-section plate,

MOD.

SELECTOR

are tied to the anode of diode CR301. With V301B conducting, the bwo tube pulse, coupled by capacitor C301 to theV301Agrid,

is

cut off. The incoming positive

is

coupled to theV301 cathode, and turns off the B section. The B-section plate rises, and

is

clamped

to

ground through diode CR301. Thus during the “on” time of the pulse, the level of the bwo

rf

output corresponds to the

cw level (set by the CATHODE CURRENT control). The PULSE position

is

intended primarily

for

applications where low voltage pulses are available. Pulses of tion for faster pulsing characteristics

D.

volt source

20

volts or more can beused on EXT. posi-

EXTERNAL

MOD.

SELECTOR

is

(see

below).

AM

OPERATION. With the AMPL.

in

the Em. position the 300-

removed (see figure 3-6), eliminating

bias current to diode CR301. Thegridof the bwo tube

is

returned through a 1-megohm resistor R312 to

ground (figure 3-6) which permits application of posi-

tive input pulses provided

they

are either capacitively

coupled or superimposed on an externally supplied

-20

volt bias. The coupling capacitor must be

sufficiently large and the duty cycle such, soas to maintain a charge (grid bias) between modulation pulses.

Generally very fast modulating the bwo tube with a sine wave

the

external modulation facility

rise

time pulse modulation. Amplitude

is

used for

is

also

possible but introduces frequency pulling.

B

3-5.

HELIX MODULATOR.

The helix modulator (figure 4-22) consists of three major sections:

the

linear sweep generator, the helix supply reference voltage generator, and the exponential voltage generator. The linear sweep generator generates:

1)

a precision time interval to start and stop the exponential voltage generator thus determining the time duration of the sweep output voltage concurrent with the sweep. The length of the precision time interval

rf

output sweep, and

2)

a linear

rf

output

is governed by the settings of both the AFREQUENCY and the RF SWEEP RATE controls.

The helix supply reference voltage generator determines the

rf

output frequency for cw operation and the starting frequency for swept operation. The output of the reference voltage generator adjustable by means of the FREQUENCY which controls the setting

in

the cathode circuit of control tube V207A. The

of

variable resistor R236

is

continuously

(KMC)

dial

reference voltage generator determines frequency by supplying the reference voltage for the regulated helix supply and the regulated dc voltage for the exponential voltage generator.

The exponential voltage generator produces an exponentially-varying voltage to drive the bwo helix for internal sweep operation. Since the voltage-vs-time

curve

of the exponential generator

is

essentially

the

same shape as that of the bwo helix voltage-vsfrequency characteristic, the bwo produces a linear

rf

output sweep.

3-6.

LINEAR SWEEP GENERATOR.

The linear sweep generator consists of a Miller feed-

back integrator (V204A) which generates a linear voltage sweep whose slope can be adjusted by changing the charging rate

of

the integrator capacitor ((2207 to C213). The AFREQUENCY (MC) range switch (part of which

is

shown in figures 3-8 and 4-26) changes the values of the integrator resistors (R230 to R232) and capacitors (C207 to (2213) to obtain step changes

01130-1

3-5

Section Figure

111

3-7

Model

683C

:N

I I !

v201

7

(0)

I

:

-1I5V

v201

1

(C)

I

;

-I14V,

'J

I

V208

9

(

rn)

s2-40v

V208

v202

I

7

DIODE

I

-25V.

-1ov'

,-23V

V204

(e)

3-6

8

;

I

t3T0

tt

fpTO

A

.-2.0

14

=

SWEEP TIME

lz1

15

RECOVERY AN0 HOLD-OFF TIME

FREOUENCY

,

NOTES

2.

I

KMC

-

SET RF SWEEP RATE (-bp150A, WITH AC-2tA PROBE, DC COUPLED)

-

SET RF SWEEP RATE

WITH

VOLTMETER

TO

t6OKMC WHEN YEASURING WITH OSCILLOSCOPE

TO

16YC/SEC

(-hp-4lOB,

Figure

OR

3-7.

SOMC/SEC WHEN MEASURlNO

EQUIVALENT, OC

Frequency Modulator

VTVM)

Waveforms

*VARIES

a~~~~~

WITH

f

KMC.

VARIES

4 - I4

SETTING

FOR

WITH

171J

RF

SETTING OF

G- L-

VALUE INDICATED Ar

3.

RF-SWEEP START VOLTAGE. [PARA.

OF

RF

DIAL

103

DIAL.

SET

01

130-

1

Model 683C

Paragraph 3-6 cont’d

Section

I11

Figure 3-8. Simplified Schematic of Sweep Circuit

in slope, while the (MC) switch varies the capacitor-charging voltage to provide slope adjustment between steps. The feedback integrator trigger V201 which shunts the integration circuit to

ground through integrator switch V203B to prevent

sweeping, and releases

The feedback integrator current, and the output by operating the schmitt trigger

4-26) from the output of the integrator. After being unlocked by the schmitt trigger, the integrating cuit charges to a predetermined level established by the sensitivity of the trigger. back voltage causes the trigger to change state. The trigger relocks the integrator circuit and terminates the sweep with a rapid flyback. Trigger tube V201A is

held conducting for a predetermined period of time

by a charge on C205 and supplementary capacitors to allow time for circuit recovery.

discharge, trigger V201 returns to which, in turn, unlocks the integrator circuit can generate another sweep,

When the SWEEP SELECTOR (S202) schmitt trigger V201 R204 and R205 to hold the it does not retrigger, except upon receipt of an externally-generated positive pulse or a pulse provided by the front panel pushbutton (S201, MANUAL TRIGGER). The positive pulse instantaneously raises the voltage

positive-going pulse

B side to conduct which, in turn, cuts off the

With the SWEEP SELECTOR switch set to RECUR,

V201A conducts before a sweep starts because

grid placed there by cathode follower V202A when theprevious sawtooth went positive. In this state, the side plate voltage and B-side grid voltage are down,

on

is

held positive by the charge on capacitor C205

vernier

is

pin 6 (V201) to almost zero volts.

(R229) on the AFREQUENCY

started and stopped by schmitt

it

from ground to start a sweep.

is

made automatically

is

made constant in amplitude

(see

figures 3-8 and

At

this level, the feed-

As

the capacitors

its

original state

is

set to TRIG.,

is

biased by voltage divider

A

side conducting. Thus

is

transferred to pin 2 causing the

A

re-

cir-

so

This

side.

its

A-

it

while the B-side plate voltage

plate voltage up, integrator switch V203B conducts and locks the integrator circuits to ground through

R208. the A-side grid voltage reaches a point where it causes the cut off and the B side to conduct.

At this time, V201 A-side’s plate voltageand B-side’s grid voltage go up, and B-side’s plate voltage goes down, cutting off (opening) integrator switch V203B.

Opening the switch permits the grid of the feedback

integrator and one side of the integrator capacitor (C207 through C213) to charge through one

resistors (R230 to R232) to a negative voltage determined by the setting of R229. negatively, the voltage at the grid of V204A falls

(figure 3-7e). The plate voltage

10 volts for each 0.1 volt the grid falls (100 being approximate gain of this state). The integrator tube (V204A), by virtue of this gain and the degenerative feedback due to the integrator capacitor connected between its plate and grid, has a small grid-voltage change for a large plate voltage change 3-7f). Since the resistor connected to the grid of V204A

is

only changes about 0.7 volt (plate voltage change of approximately sistor V204A, by means of its gain, allows the integrator capacitor to charge to a large voltage while maintaining a nearly constant charging current. The change in voltage across C213 thus

As reaches a level (t2 figure 3-7f) where the voltage coupled through cathode follower V202A to schmitt trigger V201 (t2 figure 3-7a) switches theV201 B-side

plate up, locking the integrator grid to ground and

stopping the integration process. Upon being stopped, the integrator plate voltage drops rapidly from

high positive voltage. The plate voltage through a 63-volt constant-voltage neon lamp and diode clamp (triode V204B connected as a diode) back to the integrator grid. V204B’s cathode drops (figure 3-7g). When V204B’s cathode voltage drops to -1.0 volt, V204B’s plate voltage integrator grid and the circuit stabilizes. During integration, diode V204B tively when integrator switch V203B releases the cuit from ground (figure 3-7e). This removes the clamp negative direction.

The length of time that the schmitt trigger held conducting to allow for circuit recovery mined by the positive charge placed on C205 by V202A. For the longer sweep times, the switch S203, adds additional capacity to C205 to lengthen the discharge time.

The linear sweep voltage from the feedback integrator

pl.ate the SWEEP OUTPUT connector. Two other signals are coupled to the grid of V202B. First, a negative voltage from the plate of V201A

As

the charge on C205 leaks off through R202,

A

side of the schmitt trigger to

returned to -50 volts orgreaterand the grid voltage

80

volts) the current through the

is

nearly constant. Therefore integrator tube

rises

the plate of V204A

As

is

-1.3 volts (due to contact potential). The is

clamped at approximately

is

cut

off

(opened) as

circuit

is

and allows the grid of V204A to go in a

coupled by output cathode follower V202B to

is

up. With the V201B

(ti

figure 3-7a)

of

As

the capacitor charges

rises

approximately

(see

figure

at a linear rate.

rises

during integration, it

is

coupled

the integrator plate drops,

-

1.3

volts

its

plateis carried nega-

A

side

is

deter-

A

FREQUENCY

is

coupled through

the

re-

its

cir-

is

0

1130- 1

3-

7

Section

111

Paragraph 3-7

diode V203A to cut off V202B during thefly-back time and at all times before a sweep starts 3-7j). Second, a dc voltage by R217 which output from 5203

will

give an instantaneous +1.5 volt

when

is

applied and adjusted

schmitt trigger V201 flips and

(see

figure

opens coupling diode V203A removing the negative bias on

the

grid of V202B

(see

figure 3-7k). The instantaneous initial positive output voltage produces a thin section of trace on

the

cathode ray tube which separates the beginning of the main trace from the bright dot, or vertical line, which occurs during circuit recovery time.

Model 683C

3-7.

HELIX SUPPLY REFERENCE VOLTAGE AND

EXPONENTIAL VOLTAGE GENERATORS.

The frequency of the

rf

output of the sweep oscillator is determined by the amplitude of the voltage applied to the bwo helix. The amplitude of the helix voltage

is

varied by varying the to the regulated helix supply (figure 4-22). operation, the

reference

voltage supplied

For

voltage, supplied by the

cw

reference voltage generator, has a constant amplitude, the level being set by means of the FREQUENCY (KMC) dial. For sweep operation, the referencevoltage

is

supplied by the exponential voltage generator.

The amplitude of this voltage starts at a value estab-

lished by the setting of the FREQUENCY (KMC) dial, and then decreases exponentially. The resulting output is

a linear

device. Operation of the

rf

sweep, the bwo beingan exponential-law

reference

and exponential

voltage generators are briefly described below.

A.

REFERENCE VOLTAGE GENERATOR. Basic-

ally, the reference voltage generator (figures 3-9 and 4-26) source of

is

reference

a typical voltage regulator with a

voltage (regulator tube V206), a control tube (V207A) which compares the reference voltage with a sample of the reference voltage generator output, and a

series

regulator (V207B). A signal from the control tube controls conduction through the series regulator of the output to deviate from thedesiredlevel

in

such manner that any tendency

is

com-

pensated for. The output of V207B

switch V205A and applied

is

brought through regulator

1)

to differential amplifier V105 in the regulated helix supply (figure 4-22) and capacitor C215

(in

the

line

to VlOS), and

2)

to the

grid of control tube V207A to provide the sample of

output voltage required by the regulator. Status of

tubes during However, the

cw

operation

reference

is

shown in table 3-1.

voltage generator’s output level can be varied from the front panel providing the means for selecting the frequency of the In addition,

reference

it

is

possible to electronically turn off the

voltage generator and to turn it on again

rf

output.

after precise predetermined time intervals required for sweep operation. The circuit sequences which effect this action are described in subparagraph B.

B. EXPONENTIAL VOLTAGE GENERATOR. Oper-

ation of all the rent for charging the capacitance

the

circuits

exponential voltage generator requires

shown in figures 3-9 and 4-26. Cur-

in

the

rc

circuit

I

[FREOUENCV IXHCI]

I,

Figure 3-9. Simplified Schematic of

Exponential Sweep Circuit

is

of the exponential voltage generator

reference

voltage generator citor( resistor network, and it voltage which Turn-off of the

voltage generator.

is

turned off, the charged capa-

s)

starts to discharge through

is

this exponentially decaying

is

fed to the regulated helix supply.

reference

voltage generator (as

As

supplied by the

soon as the reference

its

corresponding

well as its turn-on after a precise predetermined time) under the control of the linear sweep time generator. The rate at which the capacitor discharges (and thus the rate at which the

rf

frequency

is

changing) determined by the values of capacitance and resistance selected by the RF SWEEP RATE (MC/SEC) switch, S204. The exponential voltage generator when the reference voltage generator on by voltage

the

linear sweep time circuit. How long the

is

permitted to decay

is

thus determined by

the linear sweep time circuit which

is

turned off

is

again turned

is

controlled by

AFREQUENCY (MC) switch S203. Thus the width of band swept (band “distance”) (sweep time x sweep rate)

is

S204. (The though action

In the following discussion of “sweep”

the linear sweep time generator; the term

refers

Operation of the linear sweep time generator

determined by the settings of both S203 and

A

FREQUENCY switch determines time

it

is

calibrated in terms of “distance”.) Circuit

is

discussed in more detail below.

refers

circuit

to the sawtooth voltage produced by

action the term

“rf

sweep”

to the output of the bwo tube (figure 4-21).

is

de-

scribed in paragraph 3-6, and only that part of the

action which

is

pertinent to an understanding of the

exponential voltage generator will be discussed here.

Condition of main tubes at various stages of circuit action

is

shown

in

table 3-1.

With the instrument set for internal sweep operation, the linear sweep time generator

is

producing a sawtooth voltage. While the voltage at the output of feedback integrator V204A schmitt trigger V201 conducting. Feedback from V204A

is

rising, the A section of

is

cut off and the B section

is

returned to the

is

grid of V201A, and when the amplitude of the sawtooth reaches V201 changes state: the

and the B section

the

schmitt trigger upper hysteresis limit,

A

section starts to conduct

cuts

off. Thefeedback also charges

is

3-8

01 130-

1

Model 683C

Table

3-1.

Condition of Tubes During CW and RF Sweep

Section 111

Paragraph 3-7 cont’d

Oper-

ation

State of Circuit

cw

RF Sweep

capacitor C205 in the V201A grid circuit, and this charge holds V201A conducting during the sawtooth dead time.

With V201A conducting there the grid of V207B, supplied through V208A; this holds

series

cut off, the cathode of regulator switch V205A pulled in a negative direction, holding V205A in conduction. In the same manner current through V207B, diode CR204, and V205A establishes the charge on capacitor C215 at a level which corresponds to the setting (KMC) dial.

During the sawtooth dead time, the charge on capacitor C205 leaks off through resistor R202. When the voltage across C205 drops to the schmitt trigger

hysteresis limit, V201 again changes state: V201A

cuts tive signal on the V207B grid, cutting off conduction

through the

switch V205A and 2) closes clamp V205B. With supply voltage removed, capacitor C215 starts

discharge through the resistors selected by the RF

SWEEP RATE switch. Thus the voltage applied

V105 in the regulated helix supply starts to fall exponentially, causing the frequency change at the rate selected by the

switch. The

on the slider of variable linearity adjustment.

In the the amplitude the schmitt trigger upper hysteresis level, and conducting V201A turns on the reference voltage generator. To protect the bwo tube, however, circuitry cluded a level. The clamp V205B, when conducting, holds the plate of V205A at approximately the linear sweep time generator does not turn on the reference voltage generator before the exponential voltage decays to approximately will start to conduct and will clamp the exponentiallydecaying voltage to

Before Exp Gen capacitors charging

RF sweep starts; Ref Volts Gen turned

RF sweep reaches low end:

regulator V207B in conduction. With V201B

off and V201B turns on. This results in a nega-

usual

to

prevent the voltage from decaying to

rf

sweep starts;

off

schmitt trigger trips decaying voltage reaches

-1.1

Cond.

series

or

volt

=

conducting

is

a positive signal on

as

in

of

the FREQUENCY

regulator which 1) opens regulator

of

the

RF

rc

network discharges toward the potential

resistor

case the voltage decay

of

the sawtooth voltage again reaches

-1.1

volts.

R244, the

will

-1.1

V201A

Cond.

c.

0.

Cond.

is

cw

operation,

lower

to to

rf

sweep to

SWEEP RATE

rf

sweep

continue until

is

in-

too

low

-1.1

volts.

volts, V205A

If

V201B

c.

0.

c.

0.

C.

0.

Cond.

V205A Cond.

Cond.

I

Cond.

c.

Cond.

C.

0.

Cond.

Thus the length of time the voltage decayis permitted to continue (unless it reaches mined by how long the V201 (and therefore the reference voltage generator)

is

cut off. This period

amplitude tive value. This total time nents switched into the linear sweep time generator circuit by the AFREQUENCY switch (S203).

The voltage at the center tap established by current distributed through R233, R234, R263, R240, diode CR202, and the section of V201. In diode CR202 R233 and R263 the junction Resistor R263 establishes the voltage at the cathode of

coupling diode V203A at such level that V203A will not close until V201A starts to conduct (when the sawtooth reaches maximum level and the flyback starts).

Tap resistors R234 and R240 change the voltage char-

acteristic that dial calibration frequency end

Diode CR204 tains

a

cathode of V207B and the plate

Front panel controls

RF SWEEP RATE (MC/SEC), S204, are operated through differential gears, and are a combination which would require a sweep time

less

than 0.0135 second

the

A

FREQUENCY selector S203, the switch S204

for

too high a rate

the same manner, the RF SWEEP RATE selector

operate switch S203

set

for too short a sweeptime(toonarrow a frequency

for

band)

0.

C.

Cond. C.

0.

c.

of

the sawtooth to reach

of

the V207A cathode circuit in such manner

is

55-volt difference in potential between the

A

FREQUENCY selector

if

the sweep rate selected.

cut off

0.

-1.1

A

section

is

the time required is

determined by compo-

of

potentiometer R236

cw

operation (V201A conducting),

is

forward-biased and the junction of

is

practically at ground, CR202 clamps

R233 and R263

is

improved (crowding at the low-

is

reduced).

a 55-volt breakdown diode which main-

A

the RF SWEEP RATE selector

for

if

so

of

FREQUENCY (MC), S203, and

is

prevented. Thus, though

is

the control

the sweep band selected. In

the A FREQUENCY switch

C.

Cond. Cond.

-

volts first)

of

schmitt trigger

its

maximum posi-

it cannot go negative.

V205A.

so

arranged that

will

V205B

C.

0.

C.

0.

Cond.

0.

C. Cond.

is

deter-

for

the

is

resistors

of

for

switch

also operate

is

set

will

is

A

0

1130-

1

3-9

Section 111 Paragraph 3-8

Model 683C

3-8.

REGULATED POWER SUPPLIES.

In

addition to the magnet regulated power supply,

are

five

1) the regulated -150 volt supply which

regulated voltages generated in the 683C:

is

not dependent

there

upon any other supply but affects all other supplies,

2) the regulated, +300 volt supply which depends upon

the

-150 volt supply for a

reference

voltage,

3)

the

regulated helix supply which depends upon both the

-150 volt and +300 volt supplies, 4) the collector supply which depends upon the regulated helix supply to determine its output voltage, and 5) a

reference

voltage supply (helix supply reference voltage gen-

erator)

reference

tors are fed by half-wave silicon

in

the frequency modulator, which provides a

for the regulated helix supply. The regula-

rectifiers

powered

from a single power transformer, T101. The sequence of operation upon applying

line

power to

the 683C and the operation of the helix overload relay

are explained on the magnet power supply voltage and

resistance diagram (figure 4-15).

The operation of all the voltage regulators

so

only the operation of the -150 volt regulator

is

similar,

is

explained.

A.

-150 VOLT REGULATED POWER SUPPLY. In

the -150 volt regulated supply (figure4-21), CR105 and CR106 approximately 420 volts to the regulator V107B. Since the output voltage spect to ground the cathode of V107B The grid-to-cathode voltage of V107B class variable resistor which adjusts

are

half-wave rectifiers which supply

is

negative with

is

A

operating conditions, and the tube acts

its

resistance tomain-

series

tube,

re-

grounded.

adjusted to

like

a

tain a constant voltage on the -150 volt bus. Thus at normal

line

voltage, the tube has approximately

270 volts drop from plate to cathode. V108, a glow discharge

constant voltage difference between

reference

tube, maintains a

-

150 volts and the grid of the differential amplifier control tube, V109. The cathode of the triode section

will

maintain a constant 1-volt difference with the grid potential and thus keeps a constant 89-volt difference between the -150 volt bus and the cathode of the pentode section. Voltage divider R147, R148, and R149 provides theproper fraction of the -150 volts for the control grid of the pentode section. R148 adjusts the exact value of the bias

so

that the voltage at the grid of

series

tube V107B is held at the correct value. If the -150 volt bus tries to increase toward -151 volts, the increase

will

also make the control grid (pin

2)

of V109 go in a positive direction with respect to the cathode. (The cathode

is

held at a constant voltage with respect to the -150 volt bus by the reference tube, V108, and the cathode follower triode section in V109.) The positive-going grid (pin 2) causes increased plate current to flow through the pentode section and R146. This causes increased voltage drop across R146 which lowers the grid voltage on V107B. The increased resistance of V107B brings the bus voltage back toward -150 volts. crease, the process

If

-150 volt level tends to de-

the

is

the same but in the reverse

direction.

C123 is a coupling capacitor which couples ac ripple directly to the grid of the control tube which in turn acts to regulate it out of the output as a dc change. This results ripple voltage

in

the regulated output.

in

the same manner

in

very low values of

B. +300 VOLT REGULATED SUPPLY. The300-volt

supply circuit is similar to that of the -150 volt

supply except

it

is

referenced to - 150 volts and includes a ripple compensating voltage divider (R137 and R138) from the unregulated output to ground. The voltage tap-off from the divider of V107A this arrangement

(see

figure 4-22). Compensating action of

is

applied to

described below.

the

screen

grid

C. REGULATED HELIX SUPPLY. Screen voltage for

control tube V103

is

supplied from its unregulated source, through

in

the regulated helix supply also

dividers R115-R119. With this arrangement of the control tube lation for changes

screen

circuit, there

in

line

voltage. Circuit action

is

improved regu-

is

similar to that which occurs with a changing voltage

on

the

grid of the control tube: a change in screen voltage tube in such direction that a change in be compensated for by the sult over the range of 103 to 127 volts line voltage.

results

is

an extremely constant output voltage regulation

in

a change

in

conduction through the

line

series

regulator. The

voltage

will

re-

In addition, ripple voltage in the unregulated source drives the

screen

in

the proper direction to help regulate

ripple out of the output, further reducing the ripple

level. Operation of the regulated helix supply

that of the low voltage supplies. However, it

is

similar to

is

more elaborate due to the extreme range of voltage control necessary, and because modulating voltages must be introduced. The voltage control tubes, (series

regulators), require the single-ended ampli-

VlOl

andV102

fier, V103, driven by a differential amplifier, V105, which serves two other purposes helix waveform applied to the

is

taken at the cathode of V105 and

rf

leveler circuit 2) externally-supplied

1)

the exponential

modulation voltages from the FREQ. MOD. jack are fed to the grid of V105 to vary the helix voltage, thus varying

the

frequency. Since two different helix modulating signals must also be applied to the voltage regulator, and

since

a greater order of regulation

is

necessary for helix operation, two stages of voltage amplification are used to obtain greater gain and bandwidth.

The

reference

is

obtained from the helix supply generator in the frequency modulator, and to one side of differential amplifier V105.

voltage for the regulated helix supply

reference

voltage

is

applied

A

sample voltage from the regulated helix supply output and a calibrating voltage obtained from voltage divider stick R132, R133, R134, and R135 are fed to the other grid of the differential amplifier. The calibrating voltage divider stick contains potentiometers which set the upper and lower helix voltage limits and, in turn, the upper and lower sweep voltages, which produce the controlled exponential decays in the regulated

rf

output frequency limits. The

rf

swept output, are

refer-

ence voltage obtained from the frequency modulator.

.

c

3-10

01 130-

1

Model 683C

Section

Paragraph 3-9

111

The sample voltage from the regulator output through a frequency-compensated divider composed of R122, 154, 150, 151, C114, and R131 through R135, C116, C117. Coupling from the plates of differential amplifier V105 to voltage control tube V103 is

through divider V110, R128, R127 to obtain the correct dc voltage level for these compensated coupling networks and the frequency-compensation network V103 serve to control the gain lator feedback loop impedance of the supply remains constant at over the required frequency range.

The collector supply tor tubes, V102A and ages from a divider powered by the regulated helix voltage. The purpose of the collector

is

to keep the voltage between the collector and helix

within

series to handle the maximum voltage that can occur, which

3-9.

The backward-wave tube requires a powerful axial

magnetic field to hold its hollow electron beam

focus throughout the full length

netic field must be ripple-free and very constant. To this end, the magnet power supply and maintains an exact magnetic field in spite of line voltage variations and temperature variations which

change the dc resistance of the solenoid. To accomplish current regulation, a two-stage differential amplifier senses a voltage which the magnet current and compares it against a stable

reference voltage. The differential amplifier, upon

sensing any change the internal resistance of tubes magnet, and holds the magnet current constant.

V1

(resistances), while ential amplifier which senses any change drop across voltage divider stick R29, R30, R31. V3, operated from its own dc power source, provides a stable dc reference voltage against which the sampled voltage regulators serve to carry a portion

acceptable limits. Two tubes are required

is

about 1800 volts.

MAGNET CURRENT SUPPLY (REGULATED).

and

V2

(figure 4-20) are the

is

compared. Resistors shunting the

in

such a manner that

is

B

in

V4

the

grid of V103. All of

in

the cathode circuit of

in

each step of the

composed of two series regula-

in

series, controlled by volt-

series

of

the helix. The mag-

is

current regulated

is

proportional to

the magnet current, controls

in

series with the

series

and V5

is

a two-state differ-

of

the

is

the

internal

12

regulators

in

the voltage

series

0.7

ampere

fed

regu-

ohms

in

required by have parasitic suppressor resistors while the cathodes have current equalizing resistors.

The dc for the magnet supply age-doubler circuit which operates directly from power line. One in

series with one of the filament windings of T101. This winding voltage going to the silicon rectifier voltage doubler.

When the instrument tion, the voltage doubler from one half of the primary 'of power transformer T1 which motor and the high-voltage transformer are operated from the other half of the transformer to minimize unbalanced load on the two halves of the primary winding.

the

is

poled

is

acting as a,

magnet. Grids of

wire

of the power source

so

that it adds 6 volts to the supply

is

connected for 230-volt opera-

2:

1

the

series regulators

is

obtained from a volt-

is

supplied with 115 volts

autotransformer. The fan

the

connected

the

WARNING

Be extremely careful when working

magnet power-supply section since many tube

socket terminals, filter electrolytic capacitor terminals and cans, etc. are directly connected to the power line. The instrument chassis prong connector.

by a test probe etc. will cause a direct short circuit on currents that will fuses can blow, may severely damage the strument. The magnet supply ground floating and in

This voltage-doubler circuit nate an additional bulky power transformer. The magnet circuitry rest of the instrument, and

is

which are connected to the power line are exposed. The polarities of the grounded and ungrounded power conductors have been carefully controlled. a properly connected three-prong grounded receptacle, polarity will be maintained as intended. For that a three-prong to two-prong adapter not be used with this instrument.

is

grounded through the NEMA three-

An

accidental short caused

the

power line. The high fault

flow,

before the instrument

is

not related to any other ground

the instrument.

is

used to elimi-

is

separate from the

the

such that a minimum number of points

If

the instrument

this

reason, it

is

recommended

in

the

in-

is

parts layout

is

used with

01130-1

3-11/3-12

Model

683C

Paragraphs

Section

4-1

to

IV

4-2

SECTION

MAINTENANCE

4-1.

GENERAL.

This section contains information on the maintenance

and repair of the sweep oscillator.

A

suggested quick-check procedure

fying that the instrument

check

is

made with the instrument in its cabinet. The procedure schedule is set up to verify instrument performance, where incoming quality control checks instrument operation, or where the operator wishes to quickly satisfy himself that the instrument mally and

A

troubleshooting chart systematically follows a logical check sequence through the instrument and indicates which adjustments must be rechecked after repairing any particular circuit.

A

complete adjustment of all The specifications for the sweep oscillator are given

in

the front of this manual. additional data for your convenience in analyzing performance. These tests and data are not to be considered as specifications.

Wherever possible, standard components are used

the manufacture of Hewlett-Packard instruments. Your local Hewlett-Packard sales office

source for special spare or replacement parts; they

maintain a parts stock for your convenience. When

ordering parts, please specify instrument model and serial number plus the component description and stock

number as

Parts (section

Your local Hewlett-Packard sales office also maintains complete facilities and specially trained personnel to assist you with any engineering, application, test, or

repair problem you may have with the instrument.

4-2.

A.

HIGH

tials as high as points in the instrument. The power supplies are all regulated and are capable of delivering relatively high

currents

necessary do not remove

covers most of the high potential circuits. Remember that the instrument chassis

green grounding wire and NEMA three-prong connector. two-prong adapter or by removing the round pin.

B. MAGNET SUPPLY CAUTION. The magnet power

supply the instrument. This supply operates from a voltagedoubler circuit which

is

useful

is

meeting published specifications.

test

procedure

circuits

it

appears in the Table of Replaceable

V).

GENERAL PRECAUTIONS.

VOLTAGES.

for short periods.

Do

not defeat

is

isolated from

is

operating properly. This

where a routine maintenance

is

for optimum performance.

The test procedures give

WARNING:

3200

volts are present at certain

the

is

its

purpose with a three-prong to

the

is

directly connected to the

is

given for veri-

is

operating nor-

included which covers

in

is

a convenient

Operating poten-

Unless

red safety cover which

always grounded by the

chassis and the rest of

absolutely

IV

power line. The cans and/or terminals of all capacitors in the magnet power supply are thuspart of the power system. nected to the ungrounded side of the power line are accidentally shorted to the grounded instrument chassis they may be severly damaged before the blow. Instrument design holds to a minimum the number of exposed parts which are connected to the ungrounded side of the

Silicon rectifiers are used in the magnet supply. Because of the very low forward resistance characteristic of these units, they

if

accidentally short-circuited. Be careful when making voltage measurements not to let the probe slip and short-circuit the voltage-doubler circuit.

Voltage measurements other than ripple measurements in this supply should be made with an insulatedcase voltmeter. Most electronic voltmeters including the

@

Models

connected to the instrument chassis and cabinet which

is

in

turn

the power cable. Accidentally connecting the meter input ground conductor to the ungrounded power con-

ductor

“NEMA” ground on the voltmeter chassis. Low level

ac ripple measurements must be made with caution. See paragraph

C. output cable and connector are replaced as a unit.

Assembling the cable and connector improper assembly may cause a high

Note: The resistance at the

-

zero. This

rf)

to ground. The dc short to protect operating personnel citor that breakdown.

D.

polarized, and selected for correct voltage drop.

Refer

any of these lamps.

E. OSCILLOSCOPE. With the application of a posi-

scope, some oscilloscopes sweep horizontally from left to right, others from right to tions in this manual show the oscilloscope horizontal sweeps going from right to scope the mirror image of the oscilloscope sweep on the illustrations present the proper perspective.

will

RF

OUTPUT CAUTION. Never disassemble the

rf

cable, balun, or connector.

is

placed from the rf connector-center conductor

NEON LAMPS. Neon voltage dividers used as coupling elements in dc coupled circuits are aged,

to paragraph

tive signal at the horizontal input of the oscillo-

is

used with sweeps going from left to right,

If

parts of the circuit which are con-

fuses

line

(black power cord lead).

will

be instantly destroyed

410B

and

400D

have the ground terminal

grounded by the green grounding

short out the power source through the

4-7

for procedure.

The bwo tube

is

wire

difficult, and

swr.

RF

OUPUT connector

is

because a dc short (high impedance to

is

placed in the connector.

in

the event the capa-

is

connected in

series

4-18

for details before replacing

with the bwo helix

left.

The illustra-

left.

Thus

if

an oscillo-

can

in

rf

is

0

11.30-

4-

1

Section

Paragraphs F. BWO CATHODE CURRENT. Frequency calibra-

Therefore to obtain best accuracy:

cathode plate; current.

4-3.

The air filter cabinet. Inspect the filter frequently and clean whenever any appreciable amount of dirt has been picked up. Proper attention

will

Clean filter by washing it in a warm water and detergent solution. Before re-installing, recoat the with a suitable air filter oil to increase its dirtholding ability. heating supply stores or may be obtained through your Hewlett-Packard sales office.

4-4.

The cabinet can be removed from the instrument as follows:

1)

IV

4-3

to

4-5

tion

is

slightly affected by bwo cathode current.

current

2)

AIR FILTER.

result in long tube and component

CABINET REMOVAL.

Remove the back.

value at frequency marked on meter

make all adjustments with rated cathode

is

located at the rear of the instrument

to

maintaining a clean

Air

filter

oil

can be obtained at most

1)

operate with

life.

filter

Model 683C

2)

Tilt the instrument over on strument on a board at least 1-inch thick to avoid crushing the strain feed-through insulator and power cord.

3) Loosen the instrument in the front-panel bezel. These clamp the front panel in the bezel.

4)

Lift the cabinet

5)

To re-install the instrument in the cabinet, perform the above steps in reverse.

4-5.

QUICK-CHECK PROCEDURE.

The following

formance of the sweep oscillator. with the instrument in given in an order which

changes in test setups. The setups shownare recommended because they have the required accuracy and use equipment which components or methods are substituted,

tant

to

select components which have equal accuracy. Otherwise the error introduced by the measuring equipment may make

683C does not meet specifications.

two

setscrews on the bottom of the

off

the instrument.

test

will quickly check the overall per-

is

generally available.

its

back. Rest the in-

All

tests are made

its

cabinet. The tests are

will

provide a minimum of

it

is

or

it

appear that the

screws

If

other

impor-

greater

SWEEP OSCILLATOR

A

@

MODEL

SWEEP OSCILLATOR

683C

WEINSCHEL MODEL

COAXIAL ATTENUATOR

lo?E:Qdb

AT

THERM

MISMATCH LOSS 2-4KMC

210

2-4

KMC

I

STOR MOUNT

f

fs

-0.3db

86

POWER METER

ACCURACY

MODEL 434A POWER METER

ACCURACY

[!I

?5OA

?

5%

OF

00

'

E

ES.

S.

4-2

B

Figure

RG-SA/U CABLE. APPROX.

0.16-0.22

4-1.

Measuring RF Power Output

db/FT.

18"

01

130-

1

Model 683C Section

Paragraph 4-5 cont’d

IV

Figure 4-2. Checking Frequency Calibration and General Performance

OUTPUT POWER ACROSS THE BAND.

A.

1) Set up equipment as shown in figure 4-1A or B.

Note: The power can be severely reduced by use

-

of excessive lengths of cable which are not in good condition; any discontinuities will cause reflections in the system. When the measurement system includes an attenuator it must have

constant attenuation across the band.

2) Turn on equipment and adjust 683C output. (Cathode current at value and at frequency

setting indicated on meter plate;

3) Allow power meter to stabilize.

4) Reduce the 683C power output to minimum with the CATHODE CURRENT control and zero-set the power meter.

When using the or directional coupler, zero the 430C on the watt range. Meter

5) Reset CATHODE CURRENT value at frequency indicated on meter face.

15

minutes for the sweep oscillator and the

@

Model 430C with a 10-db attenuator

If

the @ Model 434A Calorimetric Power

is

used, zero the 434A on the

or

even short lengths

for

rated cw

see

figure 2-1.)

10

0.1

watt range.

milli-

difference between the maximum output level and the minimum output level at any two points in the

rated range should not exceed 6 db with the leveler off.

Note:

-

change measuring equipment. Critical points in the band should be checked with a tunable load in the system. The the system over the 2 to 4 kmc (gc) range.

B. FREQUENCY DIAL CALIBRATION.

1) Connect a wavemeter and detector system to the

sweep oscillator as shown in figure 4-2. Note: The use of three wavemeters

-

not a necessity. When one wavemeter

its

2) Adjust the sweep oscillator for rated (see figure 2-1).

3)

Rotate SWEEP SELECTOR to RECUR. AFRE-

QUENCY to 6.6 and RF SWEEP RATE to 500.

Be certain that an apparent excessive power

is

not in part due to mismatch in the power

@

872A Slide Screw Tuner

setting

for

each frequency check.

is

suitable

is

a convenience,

is

for

used, change

cw

Tune the wavemeters to 2,

3,

and 4 kmc (gc).

tuning

output

6) Rotate the FREQUENCY dial slowly from one end

of

the band to the other and note power change.

The minimum output level at any point across the

band should be not

01

130-1

less

than

30

mw (+14.8 dbm). The

4) Rotate the FREQUENCY dial to the check points

and watch QUENCY dial until the wavemeter pip has moved to the start of the within

for

the wavemeter pip. Turn the FRE-

rf

sweep. Dial reading should agree

1%

of the wavemeter reading.

4-3

Section Paragraph 4-5 cont’d

IV

Model 683C

5) Tune the wavemeter to other frequencies and check the dial reading.

C. SWEPT-FREQUENCY OPERATION.

1)

Set up the equipment as shown in figure 4-2.

Note: Although this procedure can be performed with

-

one wavemeter, considerable time three wavemeters are used.

2) Set sweep oscillator to rated cw output and then rotate SWEEP SELECTOR to RECUR.

3)

RF Sweep Length: a. Rotate the

the RF SWEEP RATE switch to 160K. Be the AFREQLJENCY VERNIER in CAL. position. Set the FREQUENCY dial for 4 kmc (gc).

b. Set the wavemeters to 2,

The 2 kmc (gc) pip should of the sweep trace.

c.

Adjust the horizontal gain of the oscilloscope

until the 2 and 4 kmc (gc) pips are exactly

8 cm apart.

Note:

Therefore a 2.1 kmc (gc) sweep sented by a trace approximately 8.4 cm long.

d. With the low-end wavemeter pip at 8 cm and the

high-end pip at between approximately 7.6 cm and 9.2 cm.

This represents a

(gc) *I%.

A

FREQUENCY switch to 2.1K and

4)

2-4 kmc

c

=

0

cm, sweep length should be

rf

sweep width of 2.1 kmc

is

saved when

is

full clockwise,

3,

and 4 kmc (gc).

occur

near the end

250 mc/cm

will

be repre-

sure

the wavemeters at each step, nd computing the error. For sweeps +25%, -15% or *3 mc, whichever

afrequency dures (with tions of the RF SWEEP RATE switch and with RF SWEEP RATE at 16K through all positions of AFREQUENCY) then the specifications at all other settings.

D.

TRIGGER CHECK.

1)

Set up equipment as shown

that no wavemeters are required.

2)

Rotate

3)

Rotate A FREQUENCY control to 2.1K, with

VERNIER fully

4) Rotate SWEEP SELECTOR to

5)

Push the MANUAL TRIGGER button and observe

rf

sweep display on the cro screen. See specifications

in subparagraphs C3d and C4.

6)

A

positive 20-volt pulse (3 v/psec or time) applied to the EXT. TRIG. jack a sweep.

E. FREQUENCY STABILITY WITH CHANGING

LINE VOLTAGE,

1)

Set .up equipment as shown in figure 4-2 (only one

wavemeter

2) Set the SWEEP RATE switch to

3)

Rotate the SWEEP SELECTOR to RECUR.

less

than full band the specification

is

within specifications for both proce-

A

FREQUENCY at 2.1K through all posi-

A

FREQUENCY switch

RF

SWEEP RATE control to 1.6K.

is

greater.

in

figure 4-2, except

;

clockwise.

TRIG.

will

also initiate

is

required).

A

FREQUENCY switch to 6.6 and

500.

is

less

If

within

rise

the

is

the

RF

.

4) Sweep Linearity: With the center-frequency wavemeter

(gc), the pip should appear at the center of the cro screen at 4 cm i0.2

tion of the center-frequency pip checks the degree of linearity between the exponential curve needed on the

helix of the bwo tube and exponential sweep generated

by the sweep oscillator. coincide at three points, e.g., top, bottom, and

middle, the

5)

A

FREQUENCY Calibration:

Rotate the RF SWEEP RATE switch counterclockwise to each position and observe the position of the wavemeter pips as wavemeter pip at 8 cm and high-end pip at the tolerance

4.1-kmc [gc] sweep) verifies that within specifications at

If

it

is

at the other settings, set the at 16K and rotate the AFREQUENCY switch through each of its positions, measuring the

4-4

curves

desired to check the

cm

(see

figure 4-17).

If

the two exponentials

will

match at all other points.

in

3d and 4, above. With the low-end

(i

10%) referred to 8.4 cm (end of the

is

i0.84 cm. This procedure

A

FREQUENCY switch calibration

its

maximum setting.

AFREQUENCY switch

RF

SWEEPRATE switch

set

for 3 kmc

The posi-

A

frequency with

0

cm,

is

4) Set the power

5)

Adjust sweep width to 10 cm. Thus 1 cm = 0.66 mc.

6) Adjust the most critical frequency.) Tune one of the wavemeters to approximately 2 kmc (gc) centered on the cro. Allow frequency to stabilize for about 2 minutes.

7) Increase the line voltage to 127 volts, wait 2 min-

utes

and note the final drift of the wavemeter pip on

the screen after the frequency drift has stabilized.

Maximum change loscope.

F. MODULATION CHECKS.

1)

Set up equipment as shown in figure 4-2, except

that no wavemeters are required.

2) Adjust the oscilloscope for internal sweep and sync.

Sweep speed should be approximately

3)

Rotate 683C SWEEP SELECTOR to OFF and

AMPL. MOD. SELECTOR to

line

voltage to 103 volts.

rf

output to 2 kmc (gc). (This

so

that a pip

=

2 mc or about 3 cm on the oscil-

INT.

will

0.5

is

the

appear

ms/cm.

01

130-

1

Model 683C

4)

Rotate red knob on AMPL. MOD. SELECTOR, and

observe square-wave symmetry as frequency from

400

to 1200 cps. Symmetry

60%. Verify frequency range by measuring period of

one cycle: 2500

5) Adjust oscilloscope sweep to

6) Rotate

7)

With the oscilloscope dc coupled, note the voltage level with the 683C on 5 cm.

8) Switch AMPL. MOD. SELECTOR to INT. and note the amplitude of the square wave. The amplitude should be within With 5 cm deflection on less

than

G.

RESIDUAL FM. The following simplified

procedure

imum of time and

ever this measurement method all controls are

method for checking residual fm under

is

given in Hewlett-Packard Application Note

note describes a technique which requires considerable

equipment; its operation be obtained from your local Hewlett-Packard sales

office or the Hewlett-Packard Company.

p

sec

=

400

cps and 833

the

AMPL. MOD. SELECTOR switch toOFF.

cw.

1

db or about

cw

0.5

cm.

is

given for your convenience. Amin-

test

equipment

set

as given in the procedure.

use

is

not necessary to verify normal

of

the instrument. Application Note 1 may

is

better than 40 to

p

free

run.

Adjust the deflection to

10%

this difference

is

required. How-

is

valid only

sec

of the

cw

is

varied

=

1200 cps.

cw

level.

will

test

when

conditions

1.

This

be

A

Section

Paragraph 4-5 cont'd

IV

r

1111

IIil~lIH.

..

I1

"

I

0

t

than

6-5-220

is

100

cw

the peak

kc peak;

output.

28F=

.2CM

= =

8F=

4) Observe One-half the distance between the pips residual fm. Residual fm

200

kc

peak-to-peak 3 0.3 cm.

Note: FM

-

frequency end of the band and decreases at higher frequencies.

H.

RESIDUAL AM.

1) Set up equipment as shown

2)

Adjust the sweep oscillator for rated

P-P

.2CM

X

132KC

66KC PEAK

0.66MC

jitter

will

in wavemeter pip at 2 kmc (gc).

is

less

be most pronounced at the low-

in

figure 4-3.

1)

Set up equipment as shown

wavemeter

2) Set output frequency to

3)

Adjust RF SWEEP RATE switch to 500 and FREQUENCY switch to 6.6. Thus with 10 cm deflection on cro,

is

required).

1

cm = 0.66 mc and 0.2 cm = 132 kc.

in

2

kmc (gc).

figure 4-2 (only one

0

3)

Switch AMPL. MOD. SELECTOR

4) Adjust CATHODE CURRENT to get a reading of 15 db on the 400D/H/L Voltmeter (dbo).

5)

Switch back to cw, and rotate the 4OOD/H/L switch

to

the

-50

db position. Read db level (dbl).

to

INT.

v

t

@MODEL

420A/B

CRYSTAL

DETECTOR VOLTMETER

h

MOI

v'400

AC

DEL

D/

VACUUM TUBE

LO

H/

L

-

L.

439

01130-1

Figure 4-3. Setup for Measuring Residual AM

4-5

Section Paragraphs 4-6 to 4-7

IV

Model 683C

6) The residual am

Note: It can be shown that under the specified con-

-

ditions of measurement (steps

factor residual am. (Specified conditions of measurements are that the output voltage be detected by a crystal detector operating

characteristic; readings be taken on an average-

responding voltmeter.)

This 8-db factor accounts for a) the crystal squarelaw characteristic and b) the difference between the

average values and the peak values of a square wave and a

7) Residualamshould be 40 db or more below the

cw

greater than 40 db. For example:

is

required to obtain the correct value of the

sine

wave.

level. Thus the value obtained

dbo (400D reading, step 4) -15 db dbl (400D reading, step 5)

is

equal to (dbo - dbl) + 8 db.

1

through 5), an 8-db

in

the square-law region of

in

step 6 should be

its

*

Residual AM

4-6.

MAINTENANCE TEST EQUIPMENT REQUIRED.

The following test equipment complete adjustment and repair of this instrument.

1) DC vtvm, 122 megohms input impedance, accurate within *3%. vtvm, 200 megohms input impedance, accurate within

*

1%,

such as the @ Model 412A.

2)

@

Model 459A dc resistive voltage divider probe

for

use

input voltage by 100: 1 with a rated accuracy of

The probe input impedance

overall accuracy of 2 or tests. Thus the accuracy of the divider probe should be measured. Rather than trying to calibrate the 410B with the probe, the 410B alone should be accurately calibrated and the percent error introduced by

the probe should be measured. Then readings made with the probe can be modified according to the per-

cent

error of the probe. This error

all ranges of the meter.

3)

AC vtvm, 2 megohms input impedance or more, accuracy *2% of scale.

Transistorized AC VTVM

4) Insulated case rectifier type ac voltmeter (multimeter), The instrument should be calibrated to better than 2% at 6 to 7 volts 60-cycle ac.

5)

@

Model 150A Oscilloscope with 152B Dual Channel Plug-In Amplifier and Model AC-21A Probe. The probe has an input impedance of 10 megohms shunted by 10 pf and has a voltage division ratio of

@

410B dc vtvm

with the 410B vtvm. The probe divides the

3%

full

@

Model 400D/H/L or the @ Model 403A

scale, sensitivity of 0.001

is

5,000

ohms-per-volt or more,

+

8db

43 db

is

recommended for the

is

recommended. A dc

is

12,000 megohms. An

is

desirable for these

is

constant for

recommended.

-f

5%.

full

1O:l.

6) Coaxial attenuator (10 db, 2 to 4 kmc [gq), such as Weinschel Engineering Company's 210-

7) Coaxial wavemeters for the 2 to 4 kmc (gc) range, such as @ Model 536A; three wavemeters are desirable.

8)

@

Model 420A/B Waveguide Crystal Detector.

9)

@

Model 4778 Thermistor Mount.

10)

@

Model 434A Calorimetric Power Meter, Model 430C Microwave Power Meter, @ Model 431A Power Meter.

11)

One variable transformer continuously adjustable

from 100 to 130 volts, 7-1/2'amperes capacity. The output voltage must be monitored with a meter accurate to within

12)

@

4-7.

MAGNET SUPPLY (REGULATED).

A.

EQUIPMENT NEEDED.

1)

An @ Model 403A Transistorized AC VTVM or a 400D ac vtvm can be used. vtvm

is

to two-prong adapter or a

former floating with respect to ground.

2) 7-1/2 ampere variable transformer equipped with voltmeter of

B. MEASUREMENT PROCEDURE.

1)

Set

instrument to heat 15 minutes. Adjust R30for a magnet current of 0.7 ampere as read on front panel meter. (Location of R30

2) Check magnet regulator action by dropping line

voltage to 103 volts. Current should not vary more than 0.025 ampere.

3) Repeat with line voltage at 127 volts.

4) Check ripple voltage (note the WARNINGS below). Connect 403A or 400D voltmeter to upper end of R31 (white See figure 4-4. The twisted to prevent excessive hum pickup. The hum or ripple voltage across the magnet must be

100 millivolts with the

value of the range of 103 to 127 volts.

wire)

1)

When checking ripple voltage, the volt-

meter case must be isolated from ground,

Temporarily disconnect the voltmeter NEMA

ground connector by using a two-prong adapter with the pigtail floating. Place the instru-

ment on an insulated surface. Do not touch the voltmeter cabinet while making this check, as the cabinet point under measurement.

*

2%.

Model 523B or 522B Electronic Counter.

If

the @ Model 400D ac

used,

it

must be equipped with a three-prong

1:

1

115-volt isolating trans-

so

that the instrument case can be made

1%

accuracy.

line

voltage into 683C to 115 volts, and allow

is

shown in figure 4-5.)

and right-hand end of R27 (blue wire).

WARNING

is

at

wires

line

the

to the 400D should be

voltage varied over any

same potential as the

lo.

less

@

than

4-6

01130-1

Model 683C

Section

IV

Paragraphs 4-8 to 4-10

@MOOEL

VACUUM

4000

TUBE

rrT\

VOLTMETER

MAGNET RIPPLE

300MV

MAX

@MODEL

683c

SWEEP OSCILLATOR

MAGNET

P P

LY

POWER

SECTION

Su

Figure 4-4. Measuring Magnet Circuit Ripple

If

excessive ripple

2) that power cord polarity

is

measured, check

is

correct. Measure the voltage between the white-wire end of R31 and ground. Use a multimeter type ac voltmeter with a dc blocking capacitor in one lead; 6.3 volts ac should be measured.

The magnet power supply uses a voltagedoubler circuit directly connected to the power line. When the power cord polarized three-wire outlet that

is

inserted in

is

properly

a

wired, approximately 150 volts dc and 6.3 volts ac appear between electrical ground and the end connected. proximately 122 volts ac as well as the volts dc which

Poor regulation

Tubes Vl,V2,

of

R31 to which the white

If

the line cord

will

be present on the white lead,

will

give a false ripple measurement.

is

almost always due to weak tubes.

V3,

V4, and

is

reversed, ap-

V5

should be replaced in

wires

are

150

that order to locate trouble.

4-8. -150

EQUIPMENT NEEDED.

A.

to

H/L ac vtvm

B.

PROCEDURE.

VOLT

REGULATED SUPPLY.

($3

Model 412A dc vtvm

set voltage level and @ Model 403A or 400D/

to

check ripple.

1) Connect the 412A voltmeter from chassis to the

-150

volt bus at R129 (150K, white

4-5). Adjust power line voltage

2) Adjust R148

for

exactly

-150

wire;

to

115

volts.

volts dc.

see

figure

3) Drop line voltage to 103 volts andwatchfor change

-150

in

volt level. There should beno visible change.

4) Raise line voltage to 127 volts and watch

for

change in level; there should be no change in the 412A reading.

5)

Connect the from the must be

103

to 127 volts.

Poor

6)

-150

less

regulation and/or ripple are generally caused

@I

Model 400D or 403A ac voltmeter volt bus to chassis. The ripple voltage than 3 mv over a line voltage range

of

by weak tubes. Check by replacing one tube at a

time with a new, good tube

4-9.

+300

This supply uses the

voltage. Therefore the

VOLT

REGULATED SUPPLY.

-150

(V107,

volt bus for a reference

V108, orV109).

volt supply must be working perfectly and be accurately adjusted before the

+300

volt supply

EQUIPMENT NEEDED.

A.

or

400D/H/L meters.

B.

PROCEDURE.

is

adjusted.

($3

Models 412A and403A

1) Connect the 412A from chassis to the 300-volt bus

at V106, pin

1

(red

wire;

see

figure 4-5).

2) Adjust R141 to obtain exactly +300 volts.

3) Check the regulation by slowly varying the line voltage down to 103 volts and up to 127 volts. There should be no visible change on the 412A voltmeter.

Check the ripple voltage with the 403A or 400D

4) voltmeter. The ripple should read

over a line voltage range

-150

5) Recheck then reset

+300

volt supply and reset, if necessary,

volt supply.

of

103

less

to 127 volts.

than 10mv

4-10. HELIX SUPPLY.

A.

EQUIPMENT NEEDED. 410B dc vtvm equipped with

1001

divider probe as described in para-

graph 4-6.

B.

PROCEDURE.

1) Check the helix regulator by measuring the voltage from the meter helix shunt toground. (This measure-

is

will

vary from

is

at the

identified

low-

ment point, on CURRENT switch S103, in figure 4-15.) Typically the voltage +250 volts when the FREQUENCY dial frequency end to +2000 volts when the FREQUENCY dial

is

at the high end.

2) Adjust the FREQUENCY dial until the voltage

1000

volts. Slowly vary the line voltage from

103

is

to

127 volts; there should be no visible change on the

voltmeter.

3) TURN THE SWEEP OSCILLATOR POWER OFF. Disconnect the bwo tube high-voltage connector (figui Series three

100K,

1-watt resistors, and

connect them from the bwo tube side of overload relay

K103

(figure 4-16) to ground. Rotate the FREQUENCY dial to the low end. Rotate the CATHODE CURRENT control full counterclockwise.

a

0

1

130-

1

4-7

Section IV Figure

4-5

Model 683C

VI01

R36

BWO

HIGH-VOLTAGE

CONNECTOR

K

-

\

MEASURE R148 ADJUST

-lSOV (R129) FOR -150VOLTS

MEASURE MAGNET RIPPLE

-

R31 R27

COMMON

TERMINAL TERMINAL

(NOT

GROUNDED)

I

Y

SIGNAL

I

,

R236

R35-

MEASURE t 300V

(RED WIRE, VI061

b

/

c2

IO

ADJUST ADJUST HELIX REGULATOR

,0132

FOR

C207

FOR

I

.0418

FREQUENCY RESPONSE

\

C117

\

R30 ADJUST

MAGNET CURRENT

0

4-8

Figure

4-5.

Model

6836

Top

View

01

130-

1

Model 683C Section

Paragraphs

4-1

1 to 4- 12

IV

4)

Connect a voltmeter across the

Turn

on

the

equipment. There

series

will

be approximately

resistors.

250 volts across the resistors.

5) Slowly rotate the FREQUENCY dial toward the high-frequency end and watch the rising voltage across the resistors.

When

the voltage reaches 1000 to 1100 volts the overload relay should operate and cut off the high-voltage circuits. This corresponds to

the

3.5 ma (approximately) required to operate helix overload relay K103.

if

Pad K103

6)

it operates at too low a current.

50,000-ohm resistor

will

increase the current required

A

to operate K103 by about 10%.

4-11.

FILAMENT REGULATION.

The bwo, helix control circuits, and the sweep generator ment supplies. The regulated filament supply

circuit

are all operated from regulated fila-

circuits

must be adjusted accurately, otherwise associated

tubes and circuits The voltage

will affect the

is

nominally 6.3 volts. When a

make sure that the voltage

will

be affected drastically.

on

the bwo tube filament

life

of the tube. The filament voltage

is

critical and

new

tube

is

installed

adjusted to agree with

the tube manufacturer’s specifications furnished with

the replacement tube. The best way to adjust the bwo tube filament voltage

is

to adjust the

line

voltage to 127 volts and then adjust the value of shunt pad resistors R37, R38, and R39 (figure 4-16)

until

the voltage is near the high safe limit, as specified by the manufacturer. The ballast tube (R36) will then hold filament voltage within 0.1 or

0.2 volt at lower line voltage. Note: must be replaced,

it

must be aged for 24 hours.

If

ballast tube

Aging minimizes filament voltage fluctuation once filament voltage limits have been set.

WARNING

BE CAREFUL WHEN MAKING CONNEC-

TIONS. Very high voltage exists in this area.

Be certain the equipment

nections are made or broken or padding

sistors are changed.

is

off before con-

Use

insulated clips to

re-

avoid accidental short circuits.

When adjusting bwo tube filament voltage, first con-

nect an accurate insulated-case ac voltmeter across

the

bwo filament shunt resistors. These resistors are located under the red safety cover andare identified

in

so

figure 4-16.

that

the

filament voltage does not exceed the

The

padding should be adjusted

optimum value by more than 0.2 volt with the line voltage adjusted to 127 volts. The regulator should not allow the voltage to go more than 0.2 volt below the optimum value at 103 volts. When checking the voltage at the limits, allow the

103 or 127 volts for several minutes

line

voltage to remain at

so

that the ballast tube completely stabilizes. The padding resistors should have sufficient wattage rating. carbon resistors down to 36 ohms and 5-watt wound resistors

if

under 36 ohms, or

Use

use

2-watt

wire-

parallel combinations of 2-watt carbon resistors greater than 36 ohms to get low values.

Quite often, malfunctioning of the sweep generator circuit can be traced to low or high filament voltage.

A

filament voltage change affects tube contact potential due to the change contact potential

in

emission current. Achangein

will

shift the gating point of schmitt

trigger V201 and clamp point of clamp diode V204B.

To

set

the helix control circuit and sweep circuit filament regulator, follow the same procedure as for the bwo filament regulator. Using an insulated-case voltmeter, measure the voltage across shunt resistor

R32

(39 ohms). (R32

resistor board

--

is

located on a long horizontal

see

figure 4-15.) Voltage measured must not exceed 6.4 volts at 127-volt line or 6.1 volts at 103-volt line. Pad R32 as necessary to get proper range.

4-12.

MEASUREMENT OF LINEAR SWEEP TIMES.

A.

EQUIPMENT NEEDED. Counter with facilities

for time interval measurements: or 522B Electronic Counter Model 412A dc vtvm,

($3

Model 150A or 130A/B

is

@

Model 523B

recommended;

($3

oscilloscope.

B. PROCEDURE. Note: Controls specified in the

following instructions assume the use of an

($3

electronic counter.

1)

Measure the - 150 volt and + 300 volt supply voltages and set as described in paragraphs 4-8 and 4-9. Be certain to set the -150 volt supply first.

2) Measure sweep amplitude (at SWEEP OUTPUT jack). Sawtooth should be between 20 and 25 volts

(see

figure 4-6).

first check the regulated filament voltage

If

sawtooth

is

not within these limits,

(see

paragraph 4-11), and then check V202 and the other tubes in

the

linear sweep time circuit.

is

correct and all tubes are good, pad R212 to obtain

If

filament voltage

a sawtooth of between 20 and 25 volts.

3)

Connect the junction of R207 and R208 to the

counter trigger input (START connector).

4) Set counter input switch to COMMON.

5) Set counter TRIGGER SLOPE START switch to

and STOP switch to

‘11

v202

‘

OUTPUT

I

*

(+).

t

12

I

VALUE VARIES

OF

RF-SWEEP

[PARA.

4-14171

WITH

STAUT

t

:3

SETTIING

VOLTAGE.

t

14

20

SWEEP

I

G-S-21)

TO

(-)

25V

AMPL

Figure 4-6. Sweep Output Voltage

01 130-1 4-9

Section Paragraph 4-13

IV

Model 6836

6) Rotate 683C SWEEP SELECTOR switch to RECUR.

7) Rotate AFREQUENCY switch to 2.1K, RF SWEEP

RATE switch to 160K.

8) Set up counter TIME

mal point

9) Set comter START TRIGGER

TRIGGER level to about -3 volts.

lo) The counter should read between 12.7 and 13.7 ms with 6836 line voltage at 115 volts. tions, adjust C207 (figure 4-5) for 13.2 ms sweep time.

11)

Rotate RF SWEEP RATE switch to 50K and read

sweep time. The counter should read 40.0 to 43.6 ms with 683C line voltage at 115 volts. If out of specifications, adjust C210 (figure 4-5) for 41.8 ms.

12) Rotate RF SWEEP RATE to 16K. Read sweep time on counter. The limits are 127 to 137 ms. Check the sweep time with RF SWEEP RATE at 5K. The limits are is

out of specifications, correct the setting of R225 (figure 4-15) of RF SWEEP RATE the sweep times are within the specified limits.

13) Repeat step 12 for sweep rates of 1.6K and

Specifications: 1.27 to 1.37

If

out of specifications, adjust R226 (figure 4-15).

14) Repeat step 12 for sweep rates of 160 and 50.

Specifications: 12.7 to 13.7

If

out of specifications, adjust R227 (figure 4-15).

15)

Measure sweep time with RF SWEEP RATE at

16. Specifications: 127 to 137

adjustment should be required. However, cations are not met, change the valueof R232 slightly. (R232

see

figure 4-15.)

16) Connect the SWEEP OUTPUT to the vertical input

of the oscilloscope. Set the RF SWEEP RATE switch to 160K and AFREQUENCY switch to the oscilloscope controls to display a 20- to 25-volt sawtooth voltage of

17) Measure the sweep starting voltage which

appear as a vertical step at the beginning of the sawtooth

1 and 2 volts.

to obtain approximately 1.5 volts. Final adjustment

is

made when making the

graph 4-14, step 7).

will

400

so

that for both the 16Kand 5K positions

is

a

3.3

megohm resistor on switch S203;

(see

figure 4-6). The step must be between

If

necessary, adjust R217 (figure 4-15)

UNIT

give a 13.2-millisecond reading.

switch

to 436 ms.

so

that the deci-

level

and STOP

If

out of specifica-

If

either sweep time

500.

sec

13-

to 14-ms duration.

rf

sweep adjustments (para-

and 4.0 to 4.36

and 40.0 to 43.6

sec.

Generally no

2.1K.

if

specifi-

sec.

Adjust

will

Handle the old tube as carefully as a new tube when the old tube Follow shipping instructions carefully ance will be made on a tube which reaches the manufacturer. information regarding the cause of bwo tube failure,

if

possible.

A.

REMOVING THE BWO TUBE.

1)

Disconnect power from the instrument and remove

the cabinet.

2) Disconnect the bwo tube multi-conductor highvoltage cable connector (figure 4-5) from receptacle located at the left-hand side of the ment, as seen from the front. Disconnect lead to

bwo control grid.

3) Remove the four transformer (identified in figure 4-15) and type connector to the front panel. Be

screws.

balun transformer.

transformer.

4) With a 8

to 10 inches long, back off the two #10 allen

at

the front and

#lo

allen drivers can be ordered from the HewlettPackard Company. The stock number section

laneous. (These

sule.) The front

accessible from the top and right side of the instrument. Back them off about 1/2 inch. The two rear

screws

the top and side deck. One

a hole near the magnet supply resistor board on top of the instrument, and the other through a hole above XV208 on the side of the instrument. The angle at which the wrenches make contact with the is

indicated in figure 4-9. Looking into the magnet from the rear of the magnet, the Back them off until they are out of contact with the capsule; this

5) Carefully remove the high-voltage cable and connector through the magnet core.

6) Follow the Backward-Wave Oscillator Tube Claims and Adjustment Procedure instructions in this manual. Pack the bwo tube, output cable and balun transformer with connector, as directed, to at the factory.

is

to be returnedfor warranty adjustment.

since

In

screws

is

addition give complete

which hold the balun

careful

Do

not remove the coaxial cable from the

Do

not disassemble

#lo

allen wrench mounted

rear

of the magnet castings. Note:

V,

Table of Replaceable Parts, under miscel-

are not seen

screws

so

bear against the tube cap-

are easily seen and are

easily since they are under

screw

in

is

accessible from

screws

will

be approximately 1/2 inch.

the

capsule from the rear. Feed

insure

no allow-

broken when it

its

to save the

the

a driver handle

is

given in

may be seen.

safe arrival

mating

instru-

N

balun

screws

the

screws

4-13.

Always handle the bwo tube with extreme care. The tube proper handling. The tube never should be removed from

moval and installation instructions before proceeding.

4-10

REPLACEMENT

CALIBRATION PROCEDURE.

is

very expensive and can be damaged by im-

the capsule for any reason! Read all the

OF

BWO TUBE, AND

re-

OF

A

INSTALLATION

B.

1)

Carefully feed the multi-conductor high-voltage connector through the rear of the magnet towards the front panel. The magnet should be backed oilt 1/2 inch catch on the connector.

#lo

NEW BWO TUBE.

allen

screws

at the ends of the

so

as to not

01130-1

.

Model 683C

Section

Paragraph 4-13 cont’d

IV

2) The bwo tube should be installed

of

the capsule figure 4-7) from the bracket which supports the magnet. The output fitting should be pointing downward

to

the left at an angle

3) Adjust the two

is

accurately centered in the magnet hole.

Note: The capsule are1200 apart. One other points are the fully adjusting the two screws the capsule can be firmly supported and accurately centered (see figures 4-8 and 4-9).

4) Install and connect to the front panel the balun transformer with type

5)

Repeat the centering process with the front two

screws

center the capsule by eye with the front However, it before a final electrical adjustment

6) Mount the new current plate (furnished with the

replacement tube) on the meter.

7) Reconnect the high-voltage connector and bwo

grid lead.

8) By eye, recheck the mechanical positioning of the

bwo tube in the rear. allen setscrews the hole.

9) Set front panel controls

CATHODE CURRENT AMPL. MOD. SELECTOR. SWEEP SELECTOR

A

RF SWEEP RATE. CURRENT selector FREQUENCY dial RF LEVELER..

10) Refer to filament regulator adjustment instruc-

tions (para. 4-11). Connect an accurate ac voltmeter with an insulated case to the bwo tube filament circuit.

11) Turn on power to the sweep oscillator and adjust

the line voltage to 127 volts. Carefully watch the bwo filament voltage for 2 minutes. the rated voltage by more than 0.2 volt, immediately turn the instrument off and readjust the value of the padding

12) 127 volts line, reduce the line voltage to

turn

13) Insert

imately 8-inch long handles into the two front posi-

tioning

(see figure 4-9). It

FREQUENCY

resistors

After

off

the instrument.

screws.

Wrap the shafts with insulating tape

shorting out adjacent circuitry.

is

approximately 3-3/8 inches (see

of

about 450(see figure 4-9).

rear

#loallen

is

supported at three points which

is

a spring-loaded ball and the

two

#lo

allen

N

connector.

is

necessary

to

accurately center the capsule in

to

be as

If

necessary, readjust the

as

follows:

.

extreme counterclockwise

..........

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

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

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

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

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

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

(R37, R38, and R39, figure 4-16).

accurately setting the filament voltage at

two

insulated

#lo

allen drivers with approx-

WARNING

so

that the rear

screws

not possible to exactly

sothe capsule

screws.

close

as

is

attempted.

By care-

screws.

possible

#lo

OFF OFF

66

1.6K CATH. 2 KMc

OFF

If

thevoltage exceeds

115

volts and

to

avoid

14) Turn CATHODE CURRENT control to obtain current.

15) Rotate CURRENT selector switch to HELIX and

read the helix current. Adjust the position of the bwo capsule by simultaneously turning the screws. Position the tube for minimum helix current.

16) Rotate CURRENT selector to CATH. Operate CATHODE CURRENT control to increase cathode current to value marked on panel meter. Return CURRENT selector to HELIX, again read the helix current, and position the tube With the final positioning, the helix current must be

less

17) Return CURRENT selector to CATH. Adjust R332 (figure 4-16) to give cathode current with CATHODE CURRENT control set full procedure). Return CATHODE CURRENT control setting which gives rated current.

18) Check frequency calibration.

C. FREQUENCY CALIBRATION.

1) Set up test equipment as in ‘figure 4-2. Note: If desired, one wavemeter may be used instead

ofree.

2) Turn FREQUENCY dial to 2 KMC adjust wavemeter to 2 kmc (gc). R132 (figure 4-15) to make dial setting agree with wavemeter.

3) Turn FREQUENCY dial to 4 kmc (gc) and set wavemeter to 4 bring output frequency into agreement with wavemeter.

4) Repeat these refine the adjustments.

5) Adjust, by padding (figure 4-15),

track.

6) Adjust sweep oscillator to sweep the full band, and

set up the three wavemeters at 2, Check linearity tests, Swept-Frequency Operation, paragraph 4-5C.

If

linearity

graph 4-14, RF Sweep Linearity.

D.

1) Check power output across the band as described

in paragraph 4-SA. Inability to get some frequencies quency when operating into a matched load a defective bwo tube.

Note: Be certain that an apparent excessive power change

measuring equipment. Critical points in the band

should be checked with a tunable load in the system. The tuning the system

on

instrument.

than 3 ma unless .cathode current exceeds 7 ma.

clockwise

is

OUTPUT POWER CHECK,

is

not in part due to mismatch in the power

($3

Model 872A Slide Screw Tuner

(see paragraph 4-16

kmc

(gc). Adjust R135 (figure 4-15) to

two

if

necessary, to make

as

described in proof of performance

not within specifications,

or

excessive power change vs

over the 2

After

two minutes, adjust

1

ma cathode

two

#lo

for

minimum current.

1

ma more than rated

for

adjustment

cw

output, and

If

necessary, adjust

checks at 2 and 4

or

selection, the value of R234

kmc

(gc), and

3.1

kmc (gc)

3,

and 4 kmc (gc).

refer

full

power at is

is

to

suitable

4 kmc (gc) range.

allen

to para-

fre-

due to

to

for

01130-

1

4-11

Section IV Figures

THERMAL TI

DELAY

CR2-

BWP

CRl-

v5 v2

v4

s

102

TUBE

-

4-7

SW

and

I

IT1

v

TI(

Model

4-8

p!

683C

-

I

b

4

1

I.

i

NO

TUBE MAGNET

V5 (12AXll-

v4-

ECC88/6DJ8

v2

-

608

0

CRI

Figure - .7.

Model

683C

Bottom

View

mr

!

L

rr

v3

OA2

VI

6080

CR2

4-12

Figure

4-8.

Model

683C

Rear View

-

913

01130-1

Model

683C

Section

Figure

IV

4-9

01 130-

1

Figure

4-9.

Positioning the

BWO

Tube

at

the Front and Rear

hlr-

of

Magnet

s-Y

IZ

Section

IV

Paragraph

4-

Model 683C

14

4-14.

RF SWEEP LINEARITY.

Allow instrument to operate at least 1/2 hour before

making adjustments.

it

is

Note:

cane

Though

performed with one wavemeter.

not recommended, this procedure

The

use

of

three wavemeters saves considerable time.

1)

Set up test equipment as in figure 4-2.

2)

Set the wavemeters to

3)

Turn RF SWEEP RATE to 50K.

Set the AFREQUENCY switch at 2.1K, and FRE-

4)

QUENCY dial for

5)

Adjust vernier

control of oscilloscope

4.1

kmc (gc).

on

so

2,

3, and 4 kmc (gc).

horizontal input sensitivity

that sweep trace

is

approx-

imately 8.5 cm.

6) With R244 (figure 4-15), adjust sweep linearity in

a

direction which centers the 3 kmc (gc) pip between

the

2-

and 4-kmc (gc) pips

2

kmc (gc) pip moves off the scope

brought back by adjusting

(see

figure 4-10). If the

face

it

rf

sweep length with R246,

can be

located near R244.

error with R244. Do not change the setting of R244 without checking all previously-adjusted positions (by returning RF SWEEP RATE to 50K and repeating steps 6 through

12) Repeat steps 8 through

11).

11

with RF SWEEP

RATE at:

32K (adjust b with R247) 10K (adjust b with R248)

3.2K (adjust b with R249) 1K

(adjust b with R250)

320 (adjust b with R251)

Do not change the setting of R244 without checking all previously-adjusted positions..

Note:

-

sweep rates (160K to 1,6K), it the oscilloscope for a

When RF SWEEP RATE

2-

to 4-kmc (gc) trace of ap-

is

set for the faster

is

practical to adjust

proximately 8 cm and to read linearity (d) directly. For the slower sweep rates (RF SWEEP RATE on the

500

to 16 positions) probably

it

will

bemore practical

to calculate linearity (d) and sweep length (b). Calculation procedure: Record (in cm) the positions

of the 2,

3,

and 4 kmc (gc) pips, and the end of the sweep. Determine linearity and sweep length, and calculate the error.

9

0.2Sb50.81

-4bk

2.OKMC

Figure 4-10. Calibration Pips on

I

II

ICM : 250MC/S

1

d1.P-

.,,

3.0KMC

--I

t-0.2CM: 50MC/S

II

(8

I

CRO

7) Adjust oscilloscope horizontal gain

=

4-kmc (gc) trace

a

=

0.5

cm (adjust with R217, figure 4-15).

b

=

within

8 cm.

0.2

cm to 0.8 cm

(if

not, adjust R246 to bring the 2-kmc (gc) wavemeter pipO.5 cm from the end of the sweep).

c

=

*0.2

cm (adjust R244: since R244 and R246

interact, check that b remains within speci-

fications).

8) Turn RF SWEEP RATE to 160K.

9) Adjust R245 to bring b to

0.2

to 0.8 cm when total sweep length

0.5

cm (specification:

mately 8.5 cm).

--tat-

4.0KMC

G-S-220

Sweep

so

that

is

II

2-

to

approxi-

Example: Linearity and sweep length error

are

calcu-

lated for the sweep shown in figure 4-llA.

Since the rf sweep starts at the high-frequency end, numbering on the graticule horizontal axis

is

from

right to left. For convenience, the 4-kmc (gc) pip

(rather than the start of the sweep at

is

designated 0 cm.

4 kmc (gc) pip

3

kmc (gc) pip

2

kmc (gc) pip

Endof sweep Start of sweep

=

= =

0

4.4 cm

8.4 cm 9 cm

+0.2

cm

4.1

kmc rgc])

Determining linearity (d) error:

Pcf -0.5L

x

g

error

where

Pcf = position of center-frequency pip

=

0.5L

100

(distance in cm from high-end pip)

L = band length in cm (distance between

end pips)

0.5L =-band midpoint in cm

For the sweep shown in figure 4-llA:

Pcf

=

4.4 cm

0.5L

=

4.2 cm

10) Adjust vernier of cro horizontal amplifier to 4-kmc (gc)

2-

11) Check that d (linearity)

linearity d

is

trace

is

exactly 8 cm in length.

is

within

*0.2

not within specifications, correct the

,4-14

so

that

cm. If

Linearity specification: Position of center-frequency pip in cm shall be within

of band midpoint

in

cm.

*5%

Thus the sweep shown in figure 4-llA meets the

linearity specification.

01130-1

Model 683C

Paragraphs 4-15 to 4-16

Section

IV

INCREASE R254/R256

..

I

2.0

KMC

DECREASE R254/R256

I1

I

2.0

KMC

Figure 4-11. Example of Calibration

Pips on CRO Sweep

3.0

KMC

4.0

a-

2.1

KMC

B

KMC

C

s-220

15) Turn RF SWEEP RATE to 16, selecting a value

for

R256 (figure 4-15) to bring bwithin specifications.

See figures 4-llB and 4-llC.

4-15.

A.

as

Procedure:

1) Set SWEEP SELECTOR at OFF, AMPL. MOD. SELECTOR at QUENCY (vernier on AMPL. MOD. SELECTOR full counterclockwise).

2) Connect probe at pin 3, V301.

3) Adjust R310 (identified on figure 4-13) for squarewave symmetry

1200 cps range.

B.

-10

imately 25 C.

SQUARE-WAVE GENERATOR.

ADJUSTING SQUARE-WAVE SYMMETRY. Equip-

ment required: High-frequency oscilloscope, such

$3

150A; oscilloscope probe, such as the AC-21A.

INT.,

of

DIODE CR301. Diode CR301 Leakage current volts. OMeasurements should be made at approx-

40

to

is

and

INT.

SQ. WAVE FRE-

60%,

or

better over the 400 to

is

less

than 10 microamps at

a

silicon diode.

Determining sweep length (b)

La

-

Ld

%

error

where La = actual sweep length in cm

Ld

For

the sweep shown in figure 4-llA:

La Ld

To

obtain Ld,

where

AF = sweep band in kmc (gc) (2.1 kmc[gc])

%error

Sweep length specification:

set

at 2.1K.

Thus the sweep shown in figure 4-11Ameets the sweep length specification.

13) Turn RF SWEEP RATE to

=

3-

=

desired sweep length in cm

=

9.2

cm

=

8.8 cm

use

the expression

B

=

frequency in kmc (gc) between end pips (2 kmc I&])

L

=

distance in cm between end pips (8.4 cm)

=

9J8,

error:

x 100

8.8

x 100 = +4.5%

f

10%

50.

AF

B

x L

with A FREQUENCY

4-16.

The programming and reference anode voltages are supplied by the focusing the bwo in the instrument bwo tube, the reference power level re-established.

A.

procedure. The

152B dual channel amplifier

B. POWER LEVELER CIRCUIT CALIBRATION.

1) Obtaining reference power level:

RF LEVELER AND REFERENCE

ANODE VOLTAGE ADJUSTMENT.

rf

leveler

rf

leveler must be recalibrated and

SPECIAL TEST EQUIPMENT. An oscilloscope with a dual channel amplifier

($3

Model 150A oscilloscope with a

a.

Set up 683C as shown in figure 4-14.

b. 683C front panel control settings:

SWEEP SELECTOR. RF SWEEP RATE.

A

FREQ.

VERNIER.

RF LEVELER.

AMPL. MOD. SELECTOR.. CURRENT selector CATHODE CURRENT.

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

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

circuit.

is

When either

or

installing a new

is

needed

recommended.

for

..........

......

160KMC/SEC

2.1K MC

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

......

........

CATHODE

max cw

OFF

CAL OFF OFF

re-

this

14) Repeat steps 8 through R254 (figure 4-15) Figures 4-llB and 4-llC show thedirectionof ance correction

sweep.

0 1 130-

1

to

for

1) a short sweep and 2) a long

11,

selecting a value

bring b within specifications.

for

resist-

c.

With Balance Adj. R335 mid-range, adjust Level Adj. R332 (figure 4-13) tocathodecurrent and at frequency indicated on meter face.

d.

Turn

SWEEP SELECTOR to RECUR.

DC

4-

15

Section

Paragraph 4-16 cont’d

IV

e.

Check FREQUENCY dial calibration at 2, 3

4

and

f.

Rotate SWEEP SELECTOR to OFF, FREQUENCY dial to 2 KMC.

kmc (gc).

see

paragraph 4-13C Frequency Calibration.

If

recalibration

is

necessary,

Model 683C

g. Control settings for the

Meter:

POWER RANGE INPUT BIAS CURRENT.

h. Rotate

and zero-set the power meter.

i.

Rotate CATHODE CURRENT control R327

clockwise.

j.

Rotate FREQUENCY dial across the band and check that:

(1)

greater than 30 milliwatts (14.8 dbm). If minimum power cathode current with dc level adj. R332.

(2) Power spread from high to low power point across the band should be power spread current slightly.

k.

Readjust dc level potentiometer R332 clock-

wise

than the specified Record cathode current value at frequency at which minimum power point exists.

2) Determining crystal detector-attenuator power response:

a. Rotate FREQUENCY dial to 2 kmc (gc).

b. Rotate CATHODE CURRENT control clockwise

until 30 milliwatts (14.8 dbm) the power meter.

c.

Rotate 683C SWEEP SELECTOR to RECUR. DO NOT MOVE THE CATHODE CURRENT control.

d. Set the oscilloscope for dc coupling.

e.

Rotate the Ah4PL. MOD. SELECTOR switch to PULSE.

f.

For an pencil at some arbitrary point on the oscilloscope graticule. Set the oscilloscope beam at the

Rotate the AMPL. MOD. SELECTOR toOFF.

g. h. The point at which the oscilloscope electron

beam deflects vertically from the reference line

Place a mark on the oscilloscope graticule as shown in figure 4-12.

Z

...........

the

AMPL. MOD. SELECTOR to PULSE

Minimum power across the band should be

until minimum power point

rf

reference

rf

reference

is

the 30 milliwatt point at 2 kmc (gc).

..........

.

is

less

is

too great, decrease cathode

line

@

Model 431A Power

as needed

Setting needed for zero-set

200 for @ 478A

full

than

30

milliwatts increase

less

than *3 db.

is

30

milliwatts (14.8 dbm).

is

obtained on

draw a line with a grease

(see

figure 4-12).

If

greater

ACROSS THE BAND. THE CURVE

AND ATTENUATOR POWER CHARACTERISTIC.

Figure

i.

j.

3) Segment adjustment procedure: a. With 683C setup as shown

b. 683C settings same as lb except:

4-

12. Crystal Detector- Attenuator Response Curve

Repeat steps a through h at 2.5, 3.0, 3.5,

4.0 kmc (gc).

Note:

-

scope, the oscilloscope HORIZ. POS. control must be rotated to move the power point to a new position The space between positioned plots oscilloscope graticule can be easily polated. With oscillator power output a constant across the band, any indicated power variation crystal detector and attenuator used test setup. introduce appreciable error.

Connect points This

line curve for the particular crystal and attenuator used.

nect a test probe (not shown) from the anode meter shunt of the bwo oscilloscope channel

(1)

frequency recorded in step lk. (2) SWEEP SELECTOR to RECUR. Note: The

should be roughly calibrated. See paragraph

4-14 RF Sweep Linearity steps 1, 2 and through 10.

As

each point

on

the graticule

is

due to the characteristic of the

If

not compensated for, these will

on

will

give a permanent record of the power-

the graph

B.

CATHODE CURRENT set to value and at

RF

SWEEP RATE, 160Kposition,

IS

DUE TO

VS

FREPUENCY

is

plotted on the oscillo-

(see

in

figure 4-14, con-

(see

figure 4-16) to

figure 4-12).

on

the

inter-

in

the

figure 4-12).

8

4-16

01 130-

1

Model 683C

c.

Remove wavemeters from setup.

CAUTION

Be

careful that there are no holes across the band due to either poor impedance mismatches.

rf

connections or

Section 1V

Paragraph

4-

17

d. RF LEVELER switch to

ON.

e. Level the coarse grain power variations (fig-

ure 3-3) on the oscilloscope to the

(1)

Adjust segment

shown (2) Adjust segment 2, R324

shown (3) Adjust segment 3, R315, and segment

R320 (figure 4-13) as shown

in

of

step

the

1.

2.

rf

power output presentation

rf

power-line curve.

1,

R321

(figure

in

4-13) as

step 3. After

4,

making all four adjustments readjust segments

1,

2,

3 and 4 as needed to obtain optimum

leveling action.

Note: There will be interaction between

-

segment

which segment 3

2

and segment 3

rises

since

the height to

is

a function of the

parallel resistance of plate-load resistor R318

of V302A and R232, plus a section of R324.

This interaction makes available a wide range

of

leveler shapes. There will also be a slight

interaction between segment 3 and segment

4

adjustments and dc level R332 adjustment.

f.

Turn SWEEP SELECTOR to OFF.

g. Check power variation across the band. The

power spread across the band should be no more than

f

1.5 db.

If

out of specifications retouch segment potentiometers and dc level adjustment as needed.

\3KMC

ANODE

VOLTAGE

w-3-273

h.

Turn FREQUENCY dial to low power point; RF LEVELER

ON.

With dc level potentiometer

R332 increases cathode current to 1 ma greater

than the value recorded

i.

Replace meter plate with new meter plate,

in

Blj.

if

meter plates do not agree.

j.

With the RF LEVELER

set balance R335 (figure 4-13)

power level

is

greater than 30 mw at low

in

the

OFF position,

so

that

the

power point.

4-17.

SERVICING THE SWEEP CIRCUITS.

A.

VOLTAGES circuit can be very difficult to service

AND

WAVESHAPES. The sweep

if

definite conditions are not established. Figure 3-4 gives typical wave shapes and dc levels of the complete sweeping system. These voltages and wave shapes are the same for any speed

rate

is

high, these wave shapes may be directly observed on a dc-coupled oscilloscope such as an Model 150A with a 10-megohm 10 an @ Model AC-21A. able, it

is

possible to accurately measure the upper

of

sweep.

If

this equipment

If

the sweep

pf

probe such as

is

not avail-

@

01130-1

~KMC

STEP

2.

3.

w-

1-270

4-17

Section Paragraph 4-17 cont'd

IV

TO ANODE BWO

PANEL SWITCH

-

TO FRONT

TEST P

NT FOR COMPLETE

RESHAPED WAVEFORM

Model 683C

-

--

R321 R332 324

SEGMENT

ADJ. ADJ. ADJ. ADJ. ADJ. ADJ. ADJ.

and lower voltage limits by reducing the sweep rate to a very low value and using a vtvm with input impedance, such as an

With the SWEEP SELECTOR schmitt trigger V201 hand half. The voltage conditions

then be those at

manner, by temporarily connecting a jumper from pin 7 of V201 to the -150 volt bus, the schmitt trigger can be locked will then be those at time

Note: - The voltages shown (figures 3-4 and

across the coupling and switching diodes may appear, upon first observation, to be given indicate that the diodes are conducting plate This potential between the plate and cathode of about 0.5 volt. For conduct' when the plate to the cathode. The actual value of this voltage change with cathode temperature. The heaters of critical tubes have regulated heater voltage to vent a shift of sweep time calibration

line voltage.

the wrong level the sweep circuit can be disabled. Paragraph regulation.

B.

(see

I

DC

LEVEL SEGMENT

($53

Model 410B.

in

is

biased to cut off the right-

ti

on the waveforms.

in

the sweeping state. The voltages

t2.

in

is

slightly negative with respect to the cathode.

is

correct. Thermionic diodes develop a contact

this

reason, the diode actually starts to

is

about -0.5 volt with respect

If

the heater voltage

4-11

tells how to adjust the filament

SWEEP OUTPUT SAWTOOTH. The sawtooth voltage at the SWEEP OUTPUT jack (5203)

figures 4-6 and 4-17) and generally will not be

2

Figure

the TRIG. position,

in

4-13.

122

megohms

the circuits will

In

error. The voltages

when

with

changing

is

regulating at

is

linear

33

BALANCE SEGMENT

RF Leveler Circuit Board

a like

4-21)

the

will

pre-

1

R32

out of specifications. Should trouble be experienced, however, the points discussed below are among the possible sources.

Three troubles which may occur could cause a distorted wave shape and thus can be easily detected.

If

V203 (6AL5) or V204 (6AN8) (figure 4-15) fective, the sawtooth will be distorted. The defective tube generally has high heater-cathode leakage which modulates the sawtooth voltage. sawtooth SWEEP OUTPUT voltage on an oscilloscope distortion can easily be detected. Diode CR202 (fig-

ure

4-15) associated with ometer circuit will cause limiting on the sawtooth the diode has a low front-to-back ratio. CR201 (figure 4-15)

will

not follow the grid. The grid will then draw

current which will disable the sweep circuit. Note:

have a forward resistance of less than 100 ohms and a back resistance which The actual resistance values read for diode CR201 or CR202 will vary with meter used. The above typical values are those read on an

is

on the

If

under approximately 20 volts or over approximately 27 volts, the schmitt trigger reliably. This will also cause a nonlinear sweep. this case V201 and/or V202A may be defective.

GllA

diodes

($53

measured on the

the sweep output voltage at 5203

Model 410B vtvm. The forward resistance

RXlK

or higher range.

4

is

in

the

RX1

R315

SEGMENT

the

defective the V202B cathode

good condition typically will

is

greater than

internal voltage of the ohm-

range and the back resistance

is

3

By

observing the

FREQUENCY potenti-

500,000

is

too low or high,

probably not triggering

I

R310

SYMMETRY

very

is

de-

If

diode

ohms.

In

RO

if

4-18

01 130-

1

Section IV Figure

4-15

Si

3

R225 CR201 ADJUST RF SWEEP LENGTH ADJUST RF SWEEP

ADJUST ,132

AND

.418

SEC AND RF SWEEP RATE

I

"TO4

WITH AF SWITCH AT 2.1K LINEARITY WITH

SWITCH AT

500

I60

160K

50K

1.6K

\\\\\

\\

16K

.

AFz2.IK, SWEEP

RATE=50K, R244

INTERACTS WITH R246

5K

Y

Model 683C

R244-

R251

C R202 R234

R256 R254

V20l-

.a!

BALUN:

/

R217

Am

.,,*I

R263 SWEEP R226

ADJUST MANUAL STARTING ADJUST 1.32 ADJUST 13.2 ADJUST LOW ADJUST HIGH FILAMENT

TRIG. LEVEL VOLTAGE AND

LIuIIu3

I

/

4.18

Figure

.

LVL

SEC. AND

4-15.

Model 683C Right Side View

I

V207

I

R2 27

41.8

SEC END, RF BAND END, RF BAND VOLTAGE

\

V208

R132

\

4-20

\

35

\

"''

\R135 AND ADJ.

V206

232

MEASURE

01

130-

1

KI

01

TURN ON

K102

HELIX

OFF

HOLD

RELAY R

\

R37*R387 R39* METER

BWO

TUBE

101

I

FILAMENT (GRAY WIRE) METER

PADS

HELIX SHUNT

I

ANODE SHUNT

I

01130-1

SEGMENT

ADJUST

\

-

R 3'3

I

DC

2

LEVEL R334 BALANCE

ADJUST

Figure

I

SEGMENT

ADJUST ADJUST

4-16.

Model

2

ADJUST

683C

R335

Left

\

R320

SEGMENT

Side

View

SEGMENT 3 R310

4

ADJUST

SYMMETRY

ADJUST

MP-5-911

Section

IV

Paragraphs 4-20 to 4-21

Model 683C

7.2

CM

MAX.

6-5-220

Figure 4-17. Sweep Output Voltage Linearity

3)

Remove the long setscrew on the dial hub (do not touch the short dial counterclockwise until

setscrew;)

and turn the FREQUETY

it

is

stopped by the mechanical stop of the potentiometer rotor. Be careful not to

use

force.

4)

Note the position of the dial with a pencil mark.

5)

The two mechanical stops are

tive location

if

the two pencil marks

in

their proper

are

rela-

3/16 inch

apart, measured on the edge of the dial.

6) To change the relative position of the two marks,

release

7)

the short setscrew on the dial hub.

Hold the potentiometer shaft fixed in

its

counter-

clockwise position and turn the dial to the correct

location with the vernier. Tighten the short setscrew.

4-20.

TUBE REPLACEMENT.

In many cases instrument malfunction can be corrected

by replacing a weak or defective tube. Before changing

the setting of any internal adjustment, check the tubes.

Adjustments that are made in an attempt tocompensate for a defective tube will often complicate the repair problem.

It

is

good practice to check tubes by substitution rather than by using a “tube checker”. The results obtained from the “tube checker” can be misleading.

Before removing a tube, mark it soTthat

is

good it can be returned to the same socket. Re-

if

the tube

place only tubes proved to’ be weak or defective.

Except for the bwo tube, any standard tube with corresponding EIA (JEDEC) characteristics can be used as a replacement. Where variation istics

will

affect circuit performance, an adjustment

is

provided. Table 4-1

which should be performed

4-21.

TROUBLESHOOTING PROCEDURE.

lists

thetests and adjustments

if

The purpose of the troubleshooting chart

4-18)

is

1)

to provide a logical sequence for trouble-

in

tube character-

such tubes are replaced.

(see

figure

shooting the 683C, 2) to isolate trouble to a circuit rather than to a component, and 3) to point out some of the more common troubles which might occur in the stage.

8) Insert the long

chanical stop. The

setscrew

screw

which provides the me-

should hit before the internal stop in the potentiometer, both at full counterclockwise and

B.

POSITIONING FREQUENCY DIAL ON DIAL HUB.

full

clockwise rotation.

The FREQUENCY dial must be properly positioned on the potentiometer shaft for correct frequency calibration. The dial need resetting unless R236

is

set at the factory and should never

is

replaced.

To gain access to the FREQUENCY dial setscrews, loosen the two allen

setscrews

on the large black

knob and slide the knob off the shaft. Connect a low-range ohmmeter between the potentiom-

eter wiper terminal (yellow lead) and the center-tap terminal (green lead). To position the potentiometer wiper at the center tap point, rotate theshaft until the ohmmeter reads a minimum

(less

the FREQUENCY dial until the

than 1 ohm).

3.1

kmc (gc) point

Slip

is

under the cursor. Carefully tighten the setscrews. Recheck the position by rocking the dial each side of the

3.1

kmc (gc) point. The minimum resistance

reading must exactly agree with the 3.1 kmc (gc)

mark. Reposition the dial on the shaft

if

necessary. Remove the ohmmeter and re-install the knob on the dial shaft.

The troubleshooting chart toms, OUTPUT,

as

follows:

1)

2)

NO SWEEP OUTPUT, 3)

JITTER AND/OR FREQUENCY SHIFT, 4) LOW

is

sectionalized by symp-

VERY LOW OR NO RF POWER

RF

SWEEP

RF

POWER OUTPUT AND/OR EXCESSIVE POWER

SPREAD, and

Each section

5)

NO AMPLITUDE MODULATION.

is

divided into

circuit

blocks and trouble

blocks. Circuit block represents a circuit in the

683C; the trouble block represents some common troubles that occur to a circuit block to which it

is

connected. Only those circuits to be checked and

related troubles are included in each section. Arrowed

solid lines indicate circuit relationships and signal direction between circuits. Dotted lines connect circuit blocks to trouble blocks. Where dotted lines

extend from a circuit block in one section to block in another section, such troubles

will

a

trouble

be indicated by the symptoms which head the section in which the trouble block appears. To isolate the trouble causing the symptom, proceed in the order shown in that section.

As

an aid in localizing the trouble within a section,

simplified trouble location procedure

is

included which gives step-by-step procedures for

(see

table 4-2)

trouble isolation within a section.

a

14-22

01

130-

1

Model 683C Section

Table 4-1

4-1.

Table

Tube Replacement Chart

IV

Tube

V104 v201

V204

V207A

V207B

V208

V301

V302 V303

Function

Backward wave oscillator, figure 4-22 Schmitt trigger, linear sweep time

generator, figure 4-26

Feedback integrator, linear sweep time

generator, figure 4-26

Control tube, helix supply reference

voltage generator, figure 4-26

Series regulator, helix supply reference

voltage generator, figure 4-26

Differential amplifier, helix supply

reference voltage generator, figure 4-26

Amplifier/square-wave generator,

amplitude modulator, figure 4-24

RF leveler and reference anode circuit,

figure 4-24

Standard Test or Adjustment

See paragraphs 4-11, 4-13 Adjust sweep time;

Adjust schmitt trigger bias;

Adjust sweep time;

Check FREQUENCY dial settihg;

graph 4-13C

Check calibration adjustment pots (R245-251);

paragraph 4-14, steps

Check calibration adjustment pots (R245-251);

paragraph 4-14, steps

Adjust square-wave symmetry R310;

paragraph 4-15

Adjust R332, paragraph 4-16

see

paragraph 4-12

see

paragraph 4-12

1

through 12

1

through 12

paragraph 4-17C

see

para-

01 130-1

Section

Table 4-2

IV

Model 683C

Table 4-2. Troubleshooting Procedure (Sheet

VERY LOW OR

Step

1.

Low Voltage Power Supply.

-150 Volt Regulated Power Supply.

A.

1)

Check -150 volts.

instructed below.

a. Remove primary power from 683C and meas-

ure

resistance from -I50 volt terminal (any

white

wire)

mately 33K ohms.

b. Check high voltage

c.

Check voltage output across C121; should be approximately 420 volts. Possible trouble, CR105 and CR106.

d. Replace V107, V109, and V108 in that order.

e.

Refer

-150 volt power supply.

to

paragraph 4-8 and calibrate the

No

-150 volts proceed as

to

ground; should be approxi-

fuse

(front panel).

If

not, continue to d.

SECTION

NO

I

RF OUTPUT POWER

B. Magnet Trouble Procedure.

1)

Check magnet

if

there

2) Check voltage from pin 1, 5 of V3 (ground lead of dc vtvm) and pin 2, 5 of VI (positive lead of dc

vtvm); should be approximately +220 volts. Possible trouble CR1 or CR2.

3)

Check voltage from pin 1, 5 of

of dc vtvm) to pin 2, 4,

dc vtvm); should read approximately -150 volts.

Possible trouble, CR3 or V3. Proceed to

4) Replace V4 and V5.

5) Check neon lamps V6 through

6)

Refer

circuit.

Step 3. Filament Circuit (R35).

1

of 4)

fuse

is

no magnet

to paragraph 4-7 to calibrate magnet

(front panel). Check only

current.

.

V3

7

of V3 (positive lead of

(ground lead

V11.

4.

+300 Volt Regulated Power Supply.

B.

Check +300 volts; no +300 volts proceed as instructed below.

a. Remove primary power from 683C and meas-

ure resistance from +300 volt terminal to chassis ground; should be approximately 30K ohms.

b. Apply power to the 683C and measure volt-

age across C119; should be approximately 450 volts. Possible trouble CR103 and CR104.

c.

Replace V106 and V107 in that order.

d.

Refer

+

Step 2. Regulated Magnet Supply.

A.

Magnet Current Check.

1)

Rotate CURRENT selector to MAGNET.

After

2) utes, read front panel meter; should read approxi-

mately 0.7 amp.

(zero to 0.5 amp) proceed as instructed below.

to paragraph 4-9 and calibrate the

300-volt power supply.

the 683C has been in operation for5 min-

If

magnet current

is

very low

1)

Check filament voltage for V103, V105, V107,

V109, V202, V207, V208, and V302. Place an ac

(see

vtvm across R32 view); no 6.3 volts ac, replace R35.

2)

Refer

ment circuit.

Step 4. Filament Circuit (R36). Check filament voltage for V104 by placing an ac

vtvm across parallel combination of R37, R38, R39

(see

replace R36.

Step 5. High Voltage Supply.

Check high voltage between red lead, C103, and chassis ground. Voltage should be approximately 2500 volts. No voltage or very low voltage, check

CRlOl.

Step 6. Collector Supply.

Replace V102.

Step 7. BWO Tube.

Refer to paragraph 4-13, Replacement of BackwardWave Oscillator Tube and Calibration Procedure.

to paragraph 4-11 and calibrate fila-

figure 4-16,

left

figure 4-15, right side

side view); no 6.3 volts ac,

4-24 01 130-

1

Model 683C

Section 1V

Table 4-2 cont’d

Table 4-2. Troubleshooting Procedure (Sheet 2 of 4)

SECTION 11

NO RF SWEEP OUTPUT

Step

1.

Linear Sweep Generator.

A.

Check for 20-25 volt sawtooth at SWEEP OUT-

PUT jack (front panel).

B.

Nosweep.

1)

Rotate SWEEP SELECTOR to RECUR.

2) Rotate

3)

Rotate RF SWEEP MC/SEC to 160K.

4) Connect a jumper between pin 2, V201 and -150 volts (reg.). This will disable the schmitt trigger.

5) Check voltage at plate pin 7, V203; should be approximately -1.8 volts. Possible trouble: V204, V211.

6) Check voltage at cathode, pin 1, V203; should be

approximately +0.06 volt.

7) Check voltage at grid, pin approximately -1.8 volts. Possible trouble:

V204, V211.

8)

Check voltage at cathode pin approximately -1.2 volts. Possible trouble: V204, v211.

9)

Check voltage at plate pin approximately 63 volts, If not, replace V211

neon lamp.

10) Check voltage at grid pin 2, V202; should be approximately -120 volts. If not, check voltage divider stick consisting of R212 and R213.

11)

be approximately -0.35 volt. and/or replace CR201.

12) Remove jumper between pin 2, V201 and -150

volts.

13)

brate sweep

A

FREQ. to 2.1K mc/sec.

If

8

Check voltage at cathode pin

Refer

to paragraphs 4-12 and 4-14 to cali-

circuit.

not, replace V203.

of V204; should be

1

of

V204; should be

6,

V204; should be

8

of

V202; should

If

not, adjust R217

Step 2.

1)

ground. Possible trouble: V206.

2) Rotate SWEEP SELECTOR-to RECUR.

3) Check exponential .waveform with oscilloscope

at pin 2, V105. No exponential sweep, proceed

as instructed below.

4) Rotate SWEEP SELECTOR to OFF.

5)

pin 8, V207 and ground. Rotate FREQUENCY dial; voltage should vary with FREQUENCY dial variation. Possible trouble: R236.

6)

V207 and ground. Rotate FREQUENCY dial; voltage at pin 6 of V207 should follow FREQUENCY dial variation. Possible trouble: V207, V205, CR204.

7)

length.

Step

1) SWEEP SELECTOR to OFF.

2) Connect a dc vtvm, with a range between 200 to 2500 volts, from pins 1, 4, and rotate FREQUENCY dial from 2 to 4 kmc (gc).

Voltage variation should 2200 volts. Possible trouble: V103, V105, V110, C114.

DANGER: before making connections.

3)

QUENCY dial.

Helix Supply

Check +150 volts between pin 1, 5

Connect a dc vtvm (+150 volt range) between

Place dc vtvm (+300 volt range) between pin 6,

Refer

to paragraph 4-14 and calibrate sweep

3.

Regulated Helix Supply.

High voltage; remove primary power

to paragraph 4-13C and calibrate FRE-

Reference

Voltage Generator.

of

V206 and

8

of

VlOl

to ground

be

approximately 350 to

01130-1

4-25

Section

Table 4-2 cont’d

IV

Model 683C

Table 4-2. Troubleshooting Procedure (Sheet 3 of

SECTION I11

RF JITTER AND/OR FREQUENCY SHIFT

Step

1.

Low Voltage Power Supply.

A.

-150 Volt Power Supply.

1) RF Jitter: a. Connect an ac vtvm between ground and

-150 volt terminal (any supply.

b.

If

ripple voltage exceeds 3 millivolts, pos-

sible trouble: V108, V109.

2) Frequency Shift: a. Place a dc vtvm between ground and -150

volt terminal (any white

line

voltage from 103 to 127 volts.

volts varies, replace V107 and V109.

b.

Refer

to paragraph 4-8 and calibrate -150

volt supply.

B.

+300 Volt Supply.

1)

RF

Jitter:

a. Connect an ac vtvm between +300 volts (any

solid red lead) and ground. exceeds 10 millivolts, replace V107 and V109.

b.

Refer

to paragraph 4-9 and calibrate +300

volt supply.

Step 2. Regulated Magnet Supply.

A.

RF Jitter:

1)

Connect a floating ac vtvm with its ground lead

1

and

5

of

at pins side

of

R40.

2) Vary power line voltage from 103 to 127 volts ac and observe ripple voltage on ac vtvm.

V3 and its positive lead to one

white

wire)

and vary power

If

ripplevoltage

in

power

If

-150

4)

2) Vary power ac. Magnet current should not vary more than

*0.25 ampere. Allow time for

to

settle

and current reading

3)

Possible trouble: control tube :V5 or neon

lamps V6 through V11.

4)

Refer

supply. Step 3. Linear Sweep Generator.

A.

RF Jitter:

1)

Connect oscilloscope to SWEEP

SWEEP SELECTOR to RECUR.

2) Check sawtooth displayed on oscilloscope for jitter. V203, V211, V209, V210

B.

RF Frequency Shift: The linear sweep generator should not cause

frequency shift and can be eliminated as apossible

source of trouble. Proceed to next step.

Step 4. Exponential Sweep Generator.

A.

RF Jitter:

1)

683C front panel settings:

SWEEP SELECTOR

AFREQ. SWEEP RATE AMPL. FREQUENCY dial

2) Connect oscilloscope probe from pin and observe exponential waveform. jitter of the exponential sweep, possible trouble: CR204, V206, V207, V208, V209.

MOD.

line

voltage from 103 to 127 volts

the

magnet supply

before the power

to paragraph 4-7 and calibrate magnet

If

jitter

is

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

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

SELECTOR

..........

line

taken.

present, possible trouble:

in

voltage

that order.

...........

is

changed

OUTPUT

RECUR

2.1 kmc (gc)

..........

4.0 kmc (gc)

5,

If

there

jack;

160K

OFF

V205

is

,.

B.

If

ripple voltage exceeds 100 millivolts, possible

3) trouble: V5, V6 through

Note:

-

V

a 470K resistor across each neon while watching the ripple indication indication on ac vtvm dips the faulty neonlamp has been isolated and should be replaced.

4)

power supply. B.

1)

4-26 01130-1

In

the

case of the neon lamps V6 through

11,

the faulty neon lamp can be isolated by shunting

Refer

Rotate CURRENT selector to MAGNET.

to paragraph 4-7 and calibrate magnet

Frequency Shift:

V11.

of

the ac vtvm. When ripple

Frequency Shift:

The exponential sweep generator should not cause momentary frequency shifts; thus the circuit can be eliminated as a possible frequency shift trouble. Proceed to next step.

Step 5. Regulated Helix Supply.

A.

RF Jitter:

1)

Front panel control settings same as

4A1.

2) Place oscilloscope probe at pin 1, V105 and observe exponential waveform on oscilloscope. there is jitter of the exponential sweep, possible trouble: V105, V103, V110, LlOl

in

step

that order.

If

.

Model 683C

Section

Table 4-2 cont’d

IV

Table 4-2. Troubleshooting Procedure (Sheet

SECTION

LOW POWER OUTPUT AND/OR EXCESSIVE POWER SPREAD

1.

Step

A.

1)

30 milliwatts at 4-16 and calibrate

A.

B.

applying an external signal where appropriate. there the AMPL. MOD. SELECTOR, possible trouble: D. No PULSE modulation, all other modulation CR301, V301. Refer to paragraph 4-15 and cali- positions operating normally. Possible

brate circuit.

Reference Anode Circuit. 2) Replace bwo tube;

Low Power. Connect an oscilloscope to the output

Adjust dc level adj. R332 to obtain minimum of Vary segment

low

power point. See paragraph should vary as its adjustment

rf

leveler circuit. possible trouble: CR302, CR303, CR304.

SECTION

AMPLITUDE MODULATION

Set the SWEEP SELECTOR to Rotate MOD. SELECTOR to

lating positions. INT., PULSE and EXT.,

is

no modulation output

for

OFF.

all

three modu-

If

positions of

IV

B.

Excessive Power Spread.

cathode follower V303B and observe waveform.

V

C. Rotate AMPL. MOD. SELECTOR

no square-wave output. Possible trouble:

V301, C302, S301.

trouble: S301.

4

of 4)

refer

to paragraph 4-13.

1,

2, 3, 4 adjusts. Each segment

is

varied.

to

If

not,

INT.;

of

0

1130-

I

Section Figure 4-18

IV

Model 683C

HEATER

VOLTAGE FOR VIOI. V102.V104

BALLAST TUBE R35

BALLAST TUBE R36

HIGH VOLTAGE (REGULATED) POWER SUPPLY SEE PARA.4-7

+

COLLECTOR

SUPPLY

I

ADJUST R332 REFERENCE

REPLACE BWO

ADJUST

SEGMENT

ADJUSTS

CR302, CR303

CR304

LOW POWER OUTPUT AND/OR

EXCESSIVE POWER SPREAD

-

__

SECTION

NOTES:

SECTION CIRCUIT RELATIONSHIP

AND SIGNAL FLOW CIRCUIT BLOCK

ANODE

CIRCUIT

V302B AND

V303B

RF LEVELER V302A AND

V303A

4.

0

----

-

I

CIRCUIT BLOCK AND TROUBLE BLOCK

CONNECTIONS. ORDERED SEQUENCE

FOR TROUBLE SHOOTING.

I

TROUBLE BLOCK

COLLECTOR

El

A.

I

-

HEATER VOLTAGE FOR ALL TUBES CRI

OTHER THAN VIOI,

V102,

VI04

BACKWARD WAVE OSCILLATOR TUBE

SEE PARA.

eem

ANODE GRID

-

V103, VI10 C114, R122 OUTPUT

R150, R151,

I

"154

VlIO, LlOl

I

L--.

El

1

HELIX POWER SEE FIG.

4-13

1

!

SECTION

NO RF SWEEP CR202

REGULATED

SUPPLY

I

v209,

v210,

V211, V203

SECTION

VERY LOW OR NO

8

CR2

SUPPLY

I

A

-

2.

-

CR204

I

V207

I

SWEEP

4-10

v211,

v201

CR201.CR209

!O

LINEAR SWEEP

GENERATOR

SEE PARA.

4-17

I

V210, CR204 V108, VI09

SECTION

RF JITTER AND/OR FREQUENCY SHIFT

3.

I

!I

1:

1; I

I

I I

I

111

1 Ill

I

ADJUST R30

.7AMF! ADJUST

j

I1

'I

II

11

II

II !I

POWER OUTPUT

HIGH VOLTAGE CR103

AMPLIFIER AND SQUARE WAVE

GENERATOR

SECTION

NO AMPLITUDE

MODULATION

(INTERNAL OR

EXTERNAL)

(t300) VI07

VI06

I

CR301

1.

-

CR106

-

VI09

lo

5.

8

4-28

Figure 4-18. Troubleshooting

Chart

01130-1

Model 683C

t

SCHEMATIC DIAGRAM NOTES

1.

Heavy box indicates front-panel engraving.

2.

Resistance values otherwise specified.

in

ohms, inductance

in

microhenries, and capacitance in picofarads unless

Schematic Diagram Notes

V

and R Diagram Notes

Section

IV

3. Relays shown

4.

(*)

Indicates a padded resistor, electrical value adjusted at factory. Average value shown.

1.

Voltage values shown with an

tube aging or normal differences between instruments. Resistance values may vary considerably from those shown when the circuit contains potentiometers, crystal diodes, or electrolytic capacitors.

2.

A

solid

terminals; a dotted line between terminals indicates a connection inside

resistance are given at only one/of the two joined terminals.

3.

Unless otherwise specified, dd and resistance measurements made with an @ Model

(122

megohms input impedance), common lead connected to chassis.

measured

4. AC voltage, except ripple measurements, made with multimeter of

&2%

accuracy. Ripple measurements made with

sensitivity, Instrument operating under

5.

meter panel.

in

de-energized position.

VOLTAGE AND RESISTANCE DIAGRAM NOTES

(*)

are for guidance. Values may vary from those shown, due to

line

between socket terminals indicates a connection external to the tube between the

the

tube.

410B

DC

voltages over

with

an @ Model 459A,

10

megohms input impedance).

cw

1OO:l

multiplier probe of

@

conditions at 3 kmc (gc). CATHODE current at value marked on

12,000

Model 400D AC-VTVM

megohms input resistance.

5000

ohms-per-volt sensitivity

(0.OOlV

Voltage and

VT-VOM

1000

fs

volts

max

6. Resistance measurements made with all controls full counterclockwise and FREQUENCY dial

3

kmc (gc).

at

0

1130-1

4-29

J

I

I I

-N

vu

II

U

W

Lz

P

0

2

E

n

0

Y

0

Y

U

t

3

v)

A:

'0

8

d

N

.A

M

a,

aJ

x

3

'u

i

z

n

0

z

0

I-

Y

c

2

n

0)

m

E

g,

Y,

a

.3

aJ

3

0,

VI

m

P)

3

V

x

aJ

1

.3

%

N

M

a,

Y

3

5

al

M

:

M

BWO MAGNET CURRENT REGULATOR

.

c2

600UF

v1

6080 6080

SERIES REGULATOR SERIES REGULATOR

25

R6

100

v3

OA2

REFERENCE TUBE

2s

RT

100

6DJ8/ECC88

DIFFERENTIAL

v2

v4

AMPLIFIER

n

V"?

R12*

15

R13*

I5

RIO

RII

100

220K

V9*

VlO*

Vll*

I

v5

12AX7

DIFFERENTIAL

AMPLIFIER

CONTROL TUBE

1

?22

1.23

6B0K l8OK

RIB

390K

19

30

K

TJ;

'I-

-C6 :47&F

0.00

LI

BWO

MAGNET

-

.7

AMP

AOJUST.

@

R31 390K

R30 5001

R29 15M

*FOR

230V

50-60s

I.

REMOVE STRAPS ON TI BETWEEN

AI

AN0 A3 AN0 BETWEEN A2 AN0 14.

2.

ADO STRAP ON

3

REMOVE JUMPER FROM A TO

4

INSTALL JUMPER

OPERATION:

I

TI

BETWEEN A3 AND A2.

FROM

A

TO

PRIMARY POWER AND

-.

8

c

5

.

V201 V203 V204 >V205

TUBE

HEATER DETAIL

--+v104

5

3

-'-----

ID1

rHROUGH

SI03

TO CATHODE,

TERMINAL

v4

SEE REGULATED

POWER SUPPLIES

F

REFERENCE DESIGNATORS

ON

THIS DIAGRAM

CR1I

TO

CR1

Ge-

GERMANIUM

SIISELENIUM KIOI TO K103

Si

-SILICON

&OE TI

+ELECTRON FLOW

IP

I

W

c.

*

NOTE: NE2 LAMP AGED AN0 SELECTED TO

DROP. BLUE PAINT

I

k:

SI01

i;ol

ON

POSlTlM LEAD.

TO

R43

I

a

SI02

8

TlOl

"I1

57

TO

61

VOLTS

50

CD

e

Section IV

Figure 4-21

VI09

(6U8)

-150V SUPPLY CONTROL TUBE

'rgy

6.3

VAC

ov

0

-

62V

54K

-24V

I6OK

-24V H

160K

SCP

6'8

4

3-*

9

I

PI

GP

I

-63V

Gt

30K

DV

0

-150

NOTES:

X

RESIDUAL VOLTAGE, VARIES WIDELY.

0

READING VARIES WIDELY BECAUSE ELECTROLYTIC C

*

HIGH-LOW AS FREOUENCY RANGE. DIAL

R148

VOLT ADJUST

119.

IS

TURNED THROUGH

OF

VI07

-15OV SUPPLY

SERIES REGULATOR

I2

K

VOLT ADJUST

MEASUGE t300V

AT

VI06 FIN

(6U8)

I

IRED

Model 683C

5lOK

1l5K

WIRE1

+50V

39K

CR3

-

I

VI03

(7239)

HELIX SUPPLY

CONTROL TUBE

NC

+2200

-24V

160K

TO

240V*

2.4M

+O.IV

6.3VAC

I

I-----

1

VI05

HELIX SUPPLY MODULATOR

I

(12AT7)

VI06

+3OOV SUPPLY

SERIES REGULATOR

\

VI08

-15OV

t37v

/BOK

+

21ov

+39

v

9.944 LD- E

REFERENCE TUBE

(1284)

(5651)

SUPPLY

-

269

4-32

Figure 4-21. Regulated

+300

and

-150

Volt Power Supplies

01130-1

TI04

SECMIOARIES

RU)(

f--RECULATED HELIX SUPPLY

-

->,

,--COLLECTOR SUPPLY-,

m

W

n

IZ75VAC

c

ELECTRON

FLOW

FROM

SZOPfbl

7U

FREDUENCl

fSJ

WHEN

MODULATING EXTERNALLY

VI10

TO

VI02

FlLAMENrfPlNS

4851

BACKWARD-

OSCl

TEERMINAL

DMPL MOOULATOR

WAVE

LLATOR

C

*

TI01

REF

AM)

WLTAGES

M05f5)

IN

MODULATOR

SWEEP

FROM

FREOUEhCl

e

-

m

JNWT

Of

Rf

6 - +300V

V106

SERIES REGULATOR

REGULATED SUPPLY

-

-\

R142

270K

PI41

50K

b300VGC

R140

l2OK

4GJ.

f------

82K

R175

C

TO

VlOb.

3

-

150

V

REGULATED SUPPLY

+zrovoc

SERIES REGULATOR

VI078

'12

6U8

-

- -

-

3

cnA.xsl.5

LEVELER

+3W

GRDUNO

VOC

IREG.1

-

420VDC

I

REFERENCE DESIGN4TORS

TU15

DllGR4M

ON

ClOl

TO

C124

CRlOl

TO

CR136

TO171.174J75

VlOt

TO

VI10

I

E:,

LMdlSSIGNEG

RIZI,

1l4.l5S-t51.l59-165.R136

CIG7,

CII9.

1

NOTES

SEE

PRIMARY

FIOS,

4ND P4RT

CN

POSITIVE

POWER

FIOZ,

BlOl,

WlOl

*NE2 L4MP 4GED 4NG

P4lNT

KIOI,

OF

TlOl.

SELECTEE

LE4D

8

MAGNET

K102,

K103.

FOR

CURRENT

5101.

61

TO

SUPPLY

65Y

GWG.

5102,

DROP, RED

FOR

(D

a

0

Section Figure

IV

4-23

VI02

BWO

(6350)

COLLECTOR SERIES

REGULATORS

Model

VtoI

V

IO4

(212

-

BACKWARD WAVE OSCILLATOR HELIX SERIES REGULATOR

150)

(6293)

683C

2900V*

I

L

___-_-

CRlOl

---

ov

25

/'

CONTROL GRID

1(

TO GND = 2K

'I

II II

11

-

I

I I

I,

I

__

-

t300

TO l8OOV*

I

.I

-

_

----I

NOTES:

X

RESIDUAL VOLTAGE, VARIES WIDELY.

*TYPICAL VALUES AS FREO DIAL

TURNED HI-LOW RANGE.

0

TYPICAL VALUE, VARIES WIDELY.

CONDITIONS FOR MEASUREMENT:

I.

SWEEP

2.

3.

4.

SELECTOR

FREOUENCY DIAL \AT 4.0KMC RF POWER LEVELER ON

AMPLITUDE

MOD

"OFF"

IS

SEGMENT I ADJ. INT SQUARE-WAVE SYMMETRY

DC LEVEL ADJ.

V303

CATHODE FOLLOWER

ov

0

Qt125v

3.8K

ot12ov

8.8K

t300V

2.2K

(6DJEIECG88)

I

//

/

+

.3v

2.2K

tl50VO

Z2K

+150VO 0+9.2V

6.2K

t72V

8.5K

i72v

6.5K

Figure

4-23.

I

V302

I

REFERENCE AMPLIFIER

I

9K

(6DJ8IECC88)

8

INVERTER

\

t48V

0

5.4K

t28VQ

9.3K

t28VQ

4.4K 3.5K

-22V'c

6.fK 8.8K

-22v

6.

IK

*

ov

0

-98V

-

-98V

m

\\

98V

\

RF Power Leveler and Amplitude Modulator

V

AMPLIFIER SQUARE-WAVE

\

4-34

301

(6DJ B/ECC88

GENERATOR

1

ov

0

01130-1

Model

683C

Section

Figure

IV

4-24

0

i

I

I I

I

I I

I

I I

I I+,

I

I I

I

I I

I

EGMENl 1DJUST

321

dm

‘IREGJ

r-

---

--

-

f

3WV

--

IREGI

I

RF

REFERENCE ANODE CIRCUIT

V303A

1

6DJ8KCC88

z

CATHODE

’---

FOLLOWER

k;zz

t

1-

REO/

---------_-_-____-_____

t3OOVIREGI

SEGMENT

2

4OJUST

-t-

1

LEVELER

$300

AND

V/REGJ

250K

R335

-1SOVIREG)

47K

FILAMENT ARRANGEMENT

1

P4RTOF

I

t3OOV

R330

220K

I-

IR€G)

- - - - -

R334

68K

cwrpur

-GRIO

TUBE

BWO

ro

-

-7

I I

I

01130-1

-150

R313*

750K

-.

\

0

[INT

SO

WAVE FREOUENCY 400-1200CPS]

AMPL MODULATION AND ANODE SECTION

Figure

4-24.

Amplitude Modulator and Anode Section

VDC

/REG)+

C303

01

pF

I

I I

PRINTED CIRCUIT BOARD

...

680K

0

PDJUST

SOUIRE-W4YE

SYMMETW

REFERENCE DESIGNITORS

C301- C304

CR301-CR304

R301-313.315-327.329-

5301. S302 V301- V303

4-35

Section Figure

IV

4-25

v201

(6

SCHMITT TRIGGER FEEDBACK INTEGRATOR 8 CLAMPING DIODE

DJBIECC

88)

0.92V

1.2Ai

V204

(6AN8)

1

HELIX

Model

V

207

(6 D J

8/

ECC

REFERENCE SUPPLY

88)

683C

,

8h

-

-65V

50K

I'

I/

6.5M

IO

K

3OK

I

R249 ADJUST 1.6K SWEEP

DI

R245 ADJIJST 180K SWEEP

246

I

STANCE

DISTANCE

ADJUST 50K SWEEP DISTANCE

R250 ADJU5T

DISTANCE

500

ADJUST 16K

SWEEP DISTANCE

ADJUST SWEEP DISTANCE

8

ADJUST

SWEEP DISTANCE

.4

ADJUST SWEEP LINEARITY

SWEEP

160

5K

I

1

I

+

300V

30K

V205

DIODE SWITCH

I.

35M

-IV

I.

5K

(6AL51

8.

I

+I

+40V

CLAMP

oov

,

I

_____

J

I

t

4-36

SCHMITT TRIGGER

BIAS ADJUST

R217

ADJUST SWEEP

STARTING

VOLTAGE

V203

INTEGRATOR SWITCH

DIODE COUPLER

05

76

-0.16V

l.5K

p2

LD-E-26I

I

-

I

(6AL5)

Figure

L

-

R226 ADJUST

~225

ADJUST

SEC.

8.

-46V

/OK

ov

-

-0

4-25.

R135 ADJUST HIGH FREQ.

L

_--------

R132 ADJUST LOW FREQ. CALIB.

-

- - -

1.32

SEC.

,418

-65V

CALI BRAT ION

--

+I50

I

41.8

8

13.2

SEC.

-

1

8.

I

4.18

I

e

.132

I

v

202

(

6DJB/ECC88)

CATHODE FOLLOWERS DIFFERENTIAL AMPLIFIER

-22v

-0.4v

I

NOTE:

X

I

7

(

\

I.lK

Exponential and Linear Sweep Generators

NC

RESIDUAL

READING VARIABLE

;N

VOLTAGE, VARIES WIDELY.

CIRCUIT.

V208

(6U8)

DUE

TO

DIODE

400K

01

130-

1

L

a=

0

+

U

CL

W

=z

W

L

W W

3

Ln

x

-

2

Y

I

2

5

I--

==

W

z

0

a

x

W

0

3

0

WARRANTY CLAIM AND ADJUSTMENT PROCEDURE

for microwave tubes supplied by the

HEWLETT-PACKARD COMPANY

for

use

in @ instruments

the

Microwave tubes supplied by for

use

in

@

instruments are actually warranted by the tube manufacturer and not

Hewlett-Packard Company, either as original or replacement,

by

@.

However, @ will process warranty claims for you, and will promptly pass on all allowances granted by the tube manufacturer.

In

the event that your tube

to repair and return

the

is

found to be repairable, the tube manufacturer reserves the right

tube in lieu of issuing pro-rata credit.

For your convenience, warranty claims for all microwave tubes supplied by the Hewlett-Packard Company may be made on and

return

this form, along

Please be processing of your claim.

sure

each space on the form

-

this

single form; merely

with

the defective tube, to your @ engineering representative, or to

is

filled in--lack of complete information may delay

fill

out the information on the

reverse

side

@.

Each tube manufacturer has his own warranty policy. Copies of individual Conditions of Warranty are available from your

engineering representative

@

or

from

the

Hewlett-Packard

Company.

SHIPPING INSTRUCTIONS

The

following

instructions are included to aid you in preventing damage

your tube carefully

Carefully wrap tube

1.

--

no allowance can be made on broken tubes.

in

1/4

inch thick “kimpack”, cotton batting, or other soft padding

in

transit. Package

material. Wrap the above in heavy kraft paper.

2.

Pack

in

3.

4.

Surround

a rigid container which

the

tube with at least 2 inches of shock absorbing material.

is

at least 4 inches larger than the tube in each dimension.

Be certain that the

packing is tight all around the tube.

Tubes returned from outside the continental United States should be packed in a wooden box.

5.

6.

Mark

container FRAGILE and ship prepaid via ship via Parcel Post or Air Parcel Post more apt to be damaged

when

shipped by

Air

Freight or Railway Express.

since

experience has shown that fragile items are

these

means.

Tubes returned to the Hewlett-Packard Company should be addressed to:

OR

CUSTOMER

Hewlett-Packard Company

395

Page

Palo

Alto,

SERVICE

Mill

Road

California,

U.S.A.

(In Western Europe)

Hewlett-Packard Rue du Vieux Billard Geneva, Swikerland

S.A.

No.

1

Do

not

01 153-

1

IMPORTANT:

MICROWAVE TUBE WARRANTY CLAIM

Please answer of your claim.

INFORMATION FORM

all

questions fully

--

insufficient information may delay processing

FROM: (Tube Owner)

Company

Address

Tube type

Tube serial No.

Tube mfr.

Use

in @ Model

Instrument serial no.

is

Tube

Date tube received

Original

(

)

or Replacement

Date

FOR FURTHER INFORMATION CONTACT:

Name

Title

Company

Address

Tube purchased from

On

P.

0.

number

(

)

Hours

use

per day (average)

Date first tested

Date placed in service

of

Date

failure SYMPTOMS: (Please describe conditions prior

tube’s defect,

Were

there other

if

known)

circuit

to

and at time

component failures at time

in

Number of days

Total hours filament operation

of

failure? Which ones?

Signature

Title

service

failure, along with description

of

9/12/61

1-

Model 683C

Paragraphs 5-1 to

Section

V

5-2

SECTION

REPLACEABLE PARTS

5

-1.

I

NTR 0 DUCT

This section contains information for ordering

placement parts for the Model 683C Sweep Oscillator.

Table

5-

1 order of their reference designators. Detailed information on a part used more than once in the instrument applying to the part. Other applying to the same part nator. Miscellaneous parts are included at the end of the list. Detailed information includes the following:

1)

Reference

2)

Full description of the part.

3) Manufacturer of the part list of manufacturers

4)

Hewlett-Packard stock number.

5)

Total quantity used

lists

is

listed opposite the first

ION

replaceable parts

refer

designator.

in

appendix.

in

the instrument (TQcolumn).

in

alpha-numerical

reference

to the initial desig-

in

a five-digit code:

designator

designators

re-

see

V

5-2.

ORDERING INFORMATION.

To order a replacement part, address order or inquiry either to your authorized Hewlett-Packard sales rep-

resentative or to

CUSTOMER SERVICE Hewlett-Packard Company 395 Page Mill Road Palo Alto, California

or,

in

Western Europe, to

Hewlett-Packard Rue du Vieux Billard Geneva, Switzerland

Specify the following information for each part:

1)

Model and complete serial number of instrument.

2)

Hewlett-Packard stock number.

3) Circuit

4)

Description.

reference

designator.

S.

A.

I

No.

1

6)

Recommended spare quantity for complete main-

tenance during one year of isolated service (RS col).

Table 5-1. Replaceable Parts

Ckt Ref.

BlOl

c1,2

c3,4

c5

C6

c7

Fan Motor Fan Blade Capacitor: fixed, electrolytic,

600

pf,

Capacitor: fixed, electrolytic,

20 pf, 450vdcw

Capacitor: fixed, paper,

0.22 pf

Capacitor: fixed, paper,

0.47

Capacitor: fixed, mica,

0.001 pf

Description

200 vdcw

*

lo%, 400 vdcw

pf

*lo%,

*

lo%,

200 vdcw

500 vdcw

To order a part not listed in table 5-1, give description

of the part and include its function and location.

-

Mfr

06812 06812 56289

56289

76433

@

Stock

No.

3140-0011 3 160-0015

0180-0046

0180-0011

0160-0018

0160-0015

0140-0003

rQ

-

1

2

1

RS

C8

01130-1

Capacitor: fixed, mica,

680 pf

*lo%,

500 vdcw

00853

0140-0007

1

-

5-

1

Section Table 5-1

V

Ckt Ref.

Table 5-1. Replaceable Parts (Cont’d)

Description

Mfr

*

($3

Stock No.

-

‘Q*

-

RSC

-

Model 683C

c9 thru ClOO

ClOl

C102,103

C104

C 105

C106

C 107 C108 thri

c112 C113

C114

C115

C116

C117

Not assigned

Capacitor: fixed, paper,

6800 pf

Capacitor: fixed, paper,

3

Capacitor: fixed, electrolytic,

3 sections, 10 pf/section, 450 vdcw

Capacitor: fixed, mylar,

0.22

Capacitor: fixed, mica,

560 pf Not assigned Same

Capacitor: fixed, electrolytic,

50

Capacitor: fixed, ceramic,

100 pf

Capacitor: fixed, mica,

100 pf

Capacitor: fixed, paper,

0.001 pf

Capacitor: variable, mica,

50-380 pf, 175 vdcw

pf

as

pf

f

+

2Wo

pf

*lo%,

ClOl

-

10%

*

+lo%,

lo%,

5000 vdcw

-lo%,

2000 VdCW

+

lo%,

200 vdcw

500 vdcw

+20Wo, 50 vdcw

5%, 4000 vdcw

500 vdcw

*lo%,

600 vdcw

56289

00853

37942

56289

00853

37942

91418

00853

562 89

72 136

Oleo-0045

01

6

0-

0083

0180-0016

0170-0038

0140-0044

0180-0029

01 5 0-0049

0140-0054

0160-0006

0131-0001

e

2

1

3

1

2

1

C118 c119

c120

c121

c

122

C123,12r C125 thr

c2

00

c201

5 -2

Not assigned Capacitor: fixed, electrolylic,

40

elf,

450vdcw

Capacitor: fixed, paper,

/A

*

lWo,

0.1

Same

as

C119

Capacitor: fixed, paper,

0.01

pf

Same

as

C105

Not assigned

Capacitor: fixed, mylar,

4700 pf

400 VdCW

*20%, 400 vdcw

*

lWo,

400 vdcw

*

See introduction to this section

56289

844

11

0180-0024

0160-0013

0160-0054

0

170- 002

1

2

1

3

1

c

-

01130-1

Model 683C

Table 5-1. Replaceable Parts (Cont'd)

Section

Table 5-1

V

Ckt Ref.

~

c2

02

C2 03

C2 04

C205

C206

C207

C208

C2

09

c2

10

Description

Capacitor: fixed, ceramic,

2000 pf i20%, 1000 vdcw

Capacitor: fixed, mylar,

0.1

pf

i5%, 200 vdcw

Capacitor: fixed, mylar,

1

If

*5%, 200 vdcw

Capacitor: fixed, mylar,

0.01 pf

Capacitor: fixed, mica,

10 pf

Capacitor: variable, mica,

170-780 pf, 175 vdcw

Capacitor: fixed, mica,

270 pf *lo%, 500 vdcw

Capacitor: fixed, mica,

390 pf

Same

as

i

lWo,

*lo%,

C207

5%, 400 vdcw

500 VdCw

500 vdcw

Mfr

91418

84411

844

11

84411

76433

72136

00853

76433

*

@

Stock No.

0

150-0023

0170-0019

0170-0018

01 70-0017

0140-0002

0131-0003

0140-0015

0140-0030

rQ

*

1

5

3

4

1

2

1

RS*

1

2

1

c211

c2

12 C2 13 C214,211 C2 16

C2 17

thri

C2 19 c220 c22

1

c222

C223

C224

C225

thri

C3

00

Same

as

C205

Same

as

C203

Same

as

C204

Same

as

C205

Capacitor: fixed, mylar,

10

pf

i5%, 200 vdcw

Same

as

C203

Not assigned Same

as

C116

Capacitor:

68 pf i5%, 500 vdcw

Capacitor: fixed, mylar,

0.1 Same Not assigned

as

pf

C204

fixed,

i2W0,

mica,

100 vdcw

72928

00853

56289

05 170-002

0140-0082

0170-0055

1

C301

01130-1

Same

as

C122

*

See introduction to this section

-

5-3

1

Section

Table 5-1

V

Model 683C

Ckt Ref.

c3 02

C3

03

C304

CR1,2 CR3 CR4 thru

CRlOO CRlOl CR102

thru

CR106

CR107 thru CR200

Table 5-1. Replaceable

~

Description

Capacitor: fixed, paper,

1500 pf Same Capacitor: fixed, ceramic,

0.05 Diode, silicon: 1N1566A Diode, selenium Not assigned

Diode, selenium Diode, silicon: RCA

Not assigned

f

lo%, 600 vdcw

as

C122

p3

*20%, 400 vdcw

Mfr

56289

04713 77638

0089 02 73 5

Parts

*

1

(Cont'd)

@

Stock No.

0160-0012

0150-0052

1901 -0006 1883-0005

1883 -0006 1901 -0029

-

TQ,

-

1

2

1

7

-

RS*

-

1

2

.1

1

7

CR201 thru CR2 03

CR2 04 CR205

thru CR3

00

CR301 CR3 02,

3 03 CR3 04

DS

1

F1

thru

FlOO

F101,102

J1

thru

JlOO

Diode, germanium

Diode, silicon Not assigned

Diode, silicon Same

as

CR102

Diode, germanium: 1N90

Lamp, incandescent: 0.15 amp,

6-8V, #47

Not assigned

Fuse: 3 amp, 3 AG

115V or 230V operation

Not assigned

73 2 93

28480

73 2 93 24455

75915

1910-001

G-31G-56A

G-29E -2

1910-0004

2

140-0009

2110-0003

1

3

1

2

JlOl

5 -4

RF output: part of

component not separately replaceable

BWO

tube assembly;

*See introduction to this section

-

01130-1

Model 683C

Ckt Ref.

~~ ~

Description

Table 5-1. Replaceable

Mfr

Parts

*

(Cont'd)

($3

Stock

No.

-

I'Q

-

RS*

Section

Table 5-1

V

5102 thru

52

00

5201 thru

52

03

5204 thru J300

5301 K1

thru

KlOO K101,102

K103

L1

L2

thru

LlOO LlOl

M1 thru MlOO

Not assigned

Connector, female: BNC

Not assigned

Same

as

5201

Not assigned

Relay armature: DPDT, 1.5 amp

Delayed Turn-On Relay; Helix Overload Holdoff Relay

Relay armature: SPDT,

Helix Overload Relay BWO Magnet Not assigned

Inductor: 118 mh Not assigned

2

amps

91737

70119

77342

28480

98405

1250-0001

0490-0008

0490-0019

9 16 1-0007

9 140-0006

4

1

2

1

MlOl

R1,2

R3

R4,5

R6,7 R8,9 R10 R11

R12, 13

R14 thru R17

Meter

Resistor: fixed, wirewound,

9 ohms

Resistor: fixed, composition,

100 ohms

Resistor: fixed, composition,

47 ohms Same Same Same Resistor: fixed, composition,

220,000 ohms Resistor: fixed, wirewound,

15 ohms Optimum value selected Average value shown.

Resistor: fixed, wirewound,

1000 ohms *5%,

Optimum value selected at factory.

Average value shown.

as

f

*lo%,

R3 R4

R3

*

lo%,

*

lo%,

+

lo%,

5

W

1/2

W

2

W

lo%, 1/2

20

W

40

W

at

factory

*

See introduction to this section

28480

35434

01121

35434

943 10

1120-0063 0813-0016

0687-1011

0693-4701

0687-2241

0819-0012

0818-0014

1

4

1

4

1

2

5

4

1

2

1

4

1

-

01130-1

5-5

Section Table 5-1

V

de 5-1. Replaceable Parts (Cont'd)

Ta

Model 683C

Ckt Ref.

R18,19

R2

0

R2

1

R22

R23

R2 4 R2 5

R2 6

R2

7

R28

Description

Resistor: fixed, composition,

390,000 ohms

Same

as

R4

Resistor: fixed, wirewound,

10,000 ohms

Resistor: fixed, composition,

680,000 ohms

Resistor: fixed, composition,

180,000 ohms

Same

as

R22

Same

as

R23 Optimum value selected Average value shown.

Resistor: fixed, composition,

33,000

Resistor: 0.073 ohms, Shunt Resistor: fixed, wirewound,

14 ohms

ohms

i

lo%,

&

lo%,

*

lo%, 5 W

i

lo%,

i

lo%,

i

lo%,

10

W

1/2

at

w

W

factory.

"A"

Mfr

01121

83777

01121

01:21

28480 35434

*

@

Stock

~

0687-3941

0813-0007

0687-6841

0687- 1841

0687-3331

686A-26A 0816-0019

No.

rQ

*

4

2

4

3

1

2

RS*

1

1 1

R2 9

R3

R3 R3 2

R3 3

R34 R3 5 R3

R3

0

1

6

7

Re

si

stor: fixed, composition,

15 megohms

Resistor: variable, composition,

linear

1/5

W

Same

as

R18

Resistor: fixed, composition,

39 ohms Optimum value selected Average value shown.

Resistor

Same

Tube,

Resistor

:

1

megohm

as

R23

ballast: #15-4 ballast: glass, octal base,

#

12

-4

:

56 ohms Optimum value selected Average value shown.

f

lo%,

1/2

taper,

fixed, composition,

500,000 ohms *30%,

*lo%, 2 W

ilO%,

fixed, composition,

i

lo%,

1/2

W

2

W

at

factory.

at

factory.

01121

71450

01

12

01121

70563 70563

01121

1

0687-1561

2100-0181

0693 -3901

0687-105

0852 -0008 0852-0001

0693 -5601

1

2

1

3

LO

1

5-6

*

See introduction to this section

-

01 130-

1

Model 683C

Ckt Ref.

R3 8

Table 5-1. Replaceable Parts (Cont'd)

Description

Resistor: fixed, composition,

100 ohms Optimum value selected Average value shown.

f

lo%,

2

W

at

factory.

Mfr

01121

*

@

Stock No.

0693-1011

-

rQ

'

-

1

RS*

1

Section

Table 5-1

V

R3 9

R40

R41,42 R43 R44 thru

RlOO RlOl

R102

R103

R104

RlO5

Same

as

R28 Optimum value selected Average value shown.

Resistor: fixed, composition,

2.7 ohms

Optimum value selected Average value

Same

as

Thermistor

Not assigned

Resistor: fixed, wirewound,

7500 ohms

Resistor: fixed, composition,

100 ohms

Resistor: fixed, composition,

2200 ohms

Resistor: fixed, composition,

100,000 ohms

Same

as

R1

R102

*lo%,

shown.

f.

lo%,

i

lo%,

*

lo%,

*

lo%,

1

W

10

W

1

W

at

1

W

factory.

01121

24446

35434

01121

0699 -0005

0839-0006

08 16

-

0007

0690-1011

0690-222

0690-1041

1

3

1

2

1

R106 thru R108

R109,llO

Rlll

R112

R113 R114 R115

R116 thrc R119

01130-1

Resistor: fixed, composition,

1.8 megohms

Resistor: fixed, composition,

820,000 ohms

Resistor: fixed, composition,

220 ohms

Resistor: fixed, composition,

1800 ohms

Same

as

R102 Not assigned Resistor: fixed, composition,

39,000 ohms Optimum value seiected at factory. Average value shou-n.

Resistor: fixed, composition,

470,000 ohms

*lo%,

i

lo%,

+

lo%,

+lo%,

+

lo%,

i

lo%,

1/2

2

W

1

W

1/2

W

2

W

*

See introduction to

01121

this

0693-1851

0690-8241

0687-2211

0687- 182

0687-3931

0693-4741

section

3

1

2

1

2

8

-

5-7

Section

V

Table 5-1

Ckt Ref.

R120

Table 5-1. Replaceable Parts (Cont'd)

~~

Description

Resistor: fixed, composition,

f

lo%,

1

10 ohms

W

Mfr

01121

*

@

Stock No.

0690-1001

-

RS*

rQ*

-

1

Model 683C

1

R121 R122

R 123 R124, 125 R126 R127,128

R129,130

R131

R132

R133

R134

Not assigned

Resistor: fixed, metal film,

450,000 ohms

f

5%,

1

W

Resistor: 7.15 ohms, Shunt "B" Resistor: 50 ohms, Shunt "C"

Same

as

R123

Resistor: fixed, composition,

1.5 megohms

f

lo%,

1/2

W

Resistor: fixed, composition,

150,000 ohms

f

lo%,

1/2

W

Resistor: fixed, composition,

2200 ohms *lo%, 1/2

W

Resistor: variable, composition,

linear taper, 3 megohms f26, 2

Resistor: fixed, composition,

330,000 ohms

f

lo%, 1 W

Resistor: fixed, composition,

68,000 ohms

f

lo%,

1

W

15309

28480 28480

01121

71450

01121

0761-0002

686A-2 6B 686A-26C

0687-155

0687- 1541

0687-2221

2

100-0046

0690-3341

0690-683

2

1

2

1

2

'1

2

5

1

4

1

2

1

R135

R136 R137

R138

R139 R140

R141

R 142

R 143 R 144

Resistor: variable, composition,

linear

taper,

500,000 ohms

f

Not assigned

Resistor: fixed, composition,

15,000 ohms

f

lo%,

1/2

W

Resistor: fixed, composition,

180,000 ohms

Same

as

R33

f

lo%,

2

W

Resistor: fixed, composition,

120,000 ohms

f

lo%,

1/2

W

Resistor: variable, composition,

50,000 ohms *30%, 1/4

W

Resistor: fixed, composition,

270,000 ohms

Same

as

R26

f

lo%,

1/2

W

Resistor: fixed, composition,

47,000 ohms

f

lo%,

1/2

W

lo%,

1

01121

2

W

01121

71450

01121

2100-0043

0687-153

0693-1841

0687- 1241

2 100-0094

0687-2741

0687-4731

1

3

1

2

1

2

1

2

1

2

1

5-8

*See introduction to this section

01 130-

1

Model 683C

Ckt Ref.

R145

R146

R147

Table 5-1. Replaceable Parts (Cont'd)

Description

Resistor: fixed, wirewound,

20,000 ohms

Resistor: fixed, composition,

470,000 ohms

Resistor: fixed, composition,

100,000 ohms

f

lo%,

i

f

10

lo%,

W

1/2

W

Mfr

35434

01121

*

@

Stock

No.

0816-0018

0687-4741

0687- 1041

-

rQ'

-

1

3

5

-

RS*

-

1

2

Section

Table 5-1

V

R148 R149

R150

R151

R152

R153

R154

R155 thri

R157

R158

R159 thri R165

R166

Same

as

R141

Resistor: fixed, composition,

56,000 ohms

Resistor: fixed, deposited carbon,

600,000 ohms i 5%,

Same

as

R122

Resistor: fixed, composition,

10 megohms

Resistor: fixed, composition,

22

megohms

Same

as

R150

Not assigned

Resistor: fixed, composition,

150,000 ohms

Not assigned

Resistor: fixed, composition,

47 ohms

i

lo%,

i

lo%,

i

lo%,

1/2

*lo%,

f

lo%,

1

W

1/2

1

W

2

W

01121

19701

01121

0687-5631

0730-0095

0687-1061

0687 -22 6

0693 -1541

0690-4701

1

2

1

3

1

2

1

R167,16E R169 R170,173 R172,172 R174

R175

R176 thri R2

00

R201

01130-1

Same

as

R116

Same

as

R166

Same

as

R116

Not assigned

Resistor: fixed, composition,

47,000 ohms

Resistor: fixed, composition,

82,000 ohms

Not assigned

Same

as

R153

f

lo%,

f

lo%,

1

W

1

W

*

See introduction to this section

01121

0690-473

0690-823

1

2

1

-

5-9

Section Table 5-1

V

Ckt Ref.

R2 02

Table 5-1. Replaceable Parts (Cont'd)

Description

Resistor: fixed, composition,

8.2 megohms

*lo%,

1/2

W

Mfr

01121

*

@

Stock

No.

0687-82 51

Model 683C

-

RS*

1

R2 03 R2 04 R2

06

R206 R207

R208

R2 09

R2 10

R211

R2

12

Same

as

R30 Same as R33 Resistor: fixed, composition,

3.3 megohms

Same

as

R137

Resistor: fixed, composition,

6800 ohms

Resistor: fixed, composition,

1500 ohms

Resistor: fixed, composition,

27,000

Resistor: fixed, metal film,

600,000 ohms

Resistor: fixed, deposited carbon,

1.5 megohms

Resistor: fixed, deposited carbon,

265,000 ohms Optimum value selected Average value shown.

ohms

i

lo%,

f

lo%, 1/2

f

lo%,

i5%, 1/2

f

1/2%,

f

1%,

i

1%,

1/2

W

1/2

W

at

factory.

12

01

01121

65092

19701

1

0687-33 51

0687-682

0687- 152

0686-2735

0757-0016

0727-0282

072

7

-

022 9

2

1

2

1

c

.

R2 13

R2 14 R2 15 R2

16

R2 17

R2

18

R2 19 R220 R22

1

R222 R223,224

Resistor: fixed, deposited carbon,

1.75 megohms

Same

as

R147

Same

as

R33

Resistor: fixed, composition,

150,000 ohms

Resistor: variable, composition,

linear

taper,

Resistor: fixed, composition,

560,000 ohms

Same

as

R22

Same

as

R147

Same

as

R142

Same

as

R140

Resistor: fixed, composition,

10,000

ohms

i

1%,

1/2

W

f

lo%,

1

W

1

megohm *300/0, 0.2

f

lo%,

1/2

W

f

lo%,

1/2

w

*

See introduction to this section

W

19701

01121

71450

01121

0727-0284

OC90-1541

2100-0080

0687

-

564

0687-1031

1

2

1

4

1

-

1

3

1

-

1

5-10 01130-1

Model 683C

Ckt Ref.

R225 thru R227

R228

R229

R230

R23

1

Table 5-1. Replaceable

Description

Resistor

Resistor: fixed, composition,

Resistor: variable, composition,

Resistor: fixed, deposited carbon,

:

variable , composition,

linear

27,000 ohms

linear

4.9 megohms

taper,

15.7 megohms

50,000 ohms f2W0, 1/4

f

lo%,

1/2

W

5 megohms +20%, 1/4

f

1%,

1/2

W

f

1%,

1

W

U

Mfr

71450

01121

71450

19701

95236

Parts

*

(Cont'd)

($3

Stock

No.

2

100-0141

0687-2731

2100-0066

0727 -0299

0730-0146

-

rQ'

-

3

1

RS*

1

Section

Table 5-1

V

R232

R233

R234

R235 R236

R237 R238 R239 R240

R241

Same

as

R205 Optimum value selected Average value shown.

Resistor: fixed, composition,

12,000 ohms

Resistor: fixed, deposited carbon,

200,000 ohms Optimum value selected Average value shown.

as

Same Resistor: variable, wirewound,

Same

Same Same

Resistor: fixed, deposited carbon,

Same

R21

linear taper, 100,000 ohms

as

R127

as

R33

as

R18

144,000 ohms

as

R208

Optimum value selected Average value shown.

f

lo%,

f

1%,

f

1%, 1

1/2

W

at

factory.

W

W.

at

factory.

f

at

factory.

5%, 8

W

01121

19701

99957

19701

0687-1231

0727-0221

2 100-0042

073 0-0074

1

R242

R2 43

R244

R245 R246

~

11130-1

Same

as

R33

Resistor: fixed, composition,

270,000 ohms

Resistor: variable, composition,

linear

Same Resistor: variable, composition,

linear

1/4

as

taper,

W

R217

taper,

f

lo%,

1

W

200,000 ohms *30%,

3 megohms f30%, 1/4

*

See introduction to

W

01121

71450

this

0690-2741

2100-0164

2100-0165

section

1

2

1

-

5-11

Section

Table

Ckt Ref.

R247

R248

R249 R250

V

5-1

Table 5-1. Replaceable Parts (Cont'd)

Description

Resistor: variable, composition,

linear taper, 10 megohms *30%, 1/4

Same

as

R217

Same

as

R246

Same

as

R247

W

Mfr

71450

*

@

Stock

2100-0040

No.

-

rQ

-

2

Model 683C

RS*

1

R251 R252 R253 R2 54

R255

R256

R257 R258 R253

R260

R261,262

Same

as

R217

Same

as

R146

Same

as

R127

Same

as

R127 Optimum value selected Average value shown.

Resistor: fixed, composition,

5.6 megohms

Resistor: fixed, composition,

4.7 megohms Optimum value selected Average value shown.

Same

as

R147

Same

as

R13

Resistor: fixed, deposited carbon,

46.74 megohms

Resistor: fixed, composition,

130,000 ohms

Resistor: fixed, composition,

39,000

ohms

1

f

lo%,

f

lo%,

f

5%, 1/2

f

1076, 1/2

1%,

1/2

2

at

factory.

W

at

factory.

W

w

01121

01

12

19701

01121

1

0687-5651

0687-475

0733-0011

0686-1345

0687-3931

1

2

1

R2 63

R2 64 R265 thru

R3

00

R301

R3

02

R3

03

R3 04

5-12

Resistor: fixed, composition,

200,000 ohms

Same

as

R146

Not assigned

as

Same Resistor: variable, composition,

Resistor : fixed, composition,

Same

R153

3.5 megohms f20%, 1/4

100,000 ohms

as

R103

f

5%, 1/2

f

5%, 1/2

W

*

See introduction to this section

01121

71450

01121

0686-2045

2 100-0162

0686-1045

-

1

2

1

i

-

01130-1

Model 683C

Ckt Ref.

R305 R3

06

R307

R3 08

R3 09

R3 10

R311

R3 12

Table 5-1. Replaceable Parts (Cont'd)

Description

Same

as

R216

Resistor: fixed, composition,

2.2 megohms

Resistor: fixed, composition,

1.2 megohms

Resistor: fixed, composition,

12,000 ohms

Resistor: fixed, composition,

680,000 ohms

Resistor: variable, composition,

linear taper, 1 megohm *30%, 1/4

Resistor: fixed, composition,

1.5 megohms f10%,

as

Same

R33

f

lo%,

1

W

1

W

1

W

1

W

1

W

Mfr

01121

71450

01121

*

($3

Stock

No.

0690-2251

0690-1251

0690-123

0690-6841

2 100-0096

0690-1551

Section

Table 5-1

-

RS*

rQ'

-

1

rl

1

3

1

V

R3 13

R3 14 R3 15 R3 16 R3 17 R3 18

R3 19 R320

R321 R322 R323

Resistor: fixed, composition,

750,000 ohms f5%, Optimum value selected

Average value shown. Not assigned Same

as

R310

Same

as

R33

Same

as

R223

Same

as

R175 Optimum value selected Average value shown.

Same

as

R26

Resistor: variable, composition,

20,000 ohms f20%,

Same

as

R310

Same

as

R129

Resistor: fixed, composition,

68,000 ohms

f

lo%,

1/2

1/4

1/2

W

at

factory.

at

factory.

W

01121

71450

01121

0686-7545

2100-0093

0687-6831

1

2

1

R324

R325 R326

01130-1

Resistor: variable, composition,

100,000 ohms f30%, 1/4

Same

as

R144

Same

as

R303

W

*

See introduction to this section

71450

2

100-0095

2

1

-

5-13

Section Table 5-1

V

Ckt Ref.

Table 5-1. Replaceable Parts (Cont'd)

Description

Mfr

*

@

Stock No.

-

rQr

-

RS*

-

Model 683C

R327

R328 R329 R330

R33

1

R332 R333 R334

R335

R336 R337 R338,339 R340

Part of S302; component not separately

replaceable Not assigned Same

as

R22

Resistor

Same Same

Same

Resistor: fixed, composition,

Resistor: variable, composition,

Same Same Same Same

:

220,000 ohms

68,000 ohms

linear

fixed, composition,

as

R147

as

R324

as

R137

taper,

as

R323

as

R11

as

R33

as

R129

f

lo%,

2

W

i

lo%,

2

W

250,000 ohms i30%

01

12

01121

71450

1

0693-2241

0693-683

2 100-0144

1

R341,342 S1 thru

SlOO SlOl s102 S103 S104 thru

s200 s201

s2

02 S203 S2 04 S205 thru

S3

00

S301

Same

as

R11

Not assigned

Switch, toggle: SPST Switch, Thermal Delay: SPST Switch, rotary: 2 section, 5 position Not assigned

Switch, push SPDT (manual trigger) Switch, rotary: (sweep selector) Switch, rotary Switch, rotary Not assigned

Amplitude Mod. Switch Assembly

04009 70563 71590

823 89 78854 76854 76854

28480

3 101 -003

0490-0019

3100-0161

3101-0004 3100-0163 3 100-0160 3100-0162

682C

-

19A

1

0

1

5-14

*

See introduction to this section

-

01 130-

1

Model 683C

,

Ckt Ref.

Description

Table 5-1. Replaceable Parts (Cont'd)

($9

Stock

Mfr

*

No.

-

rQJ

-

RSS

-

Section V

Table 5-1

I'

S3 02

T1

T2 thru TlOO

TlOl

v1,2

v3

v4 v5 V6 thru

v11

v12 thru VlOO

VlOl v102 V103

RF

Leveler Switch Assembly

"ransformer, power

Not assigned

Transformer, power

Tube, electron: 6080

Tube, electron:

Tube,

electron: 6DJ8/ECC88 Tube, electron: 12AX7 Lamp, neon: selected, aged and tested

NE2 (blue)

Not assigned

Tube, electron: 6293

Tube,

electron: 6350 Tube, electron: 7239

OA2

28480 28480

2 8480

8013 80131 8013 8013 28480

80131 3013 8013

1

1 1

682C-19B 9100-0086

9100-0085 1932-0010 1940-0004 1932-0022 1932 -003 G-84B

-0007

1923 1932 -0013 1923 -0045

1

2

7

0

1

8

1

V104 V105 V106 V107 V108 v109

VllO

Vlll thru v2

00

v201,202 V2

03 V204 V205

V2

06 V2

07

Tube, electron: BWO Tube, electron: 12AT7

Tube, electron: 12B4A

Tube, electron: 6U8

Tube,

electron: 5651

Same

as

V107

Lamp, neon: selected, aged and tested

NE2 (red)

Not assigned

Same

as

V4

Tube,

electron: 6AL5

Tube,

electron: 6AN8

Same

as

V203

Same

as

V3

Same

as

V4

05783 8013 8013 8013 8013

28480

80131 8013

1 1 1

1

195 1-001

1932-0027 192 1-0010 1933-0004 1940-0001

G-84E

1930-0013 1933-0001

1

3

1

2

1

01130-1

*

See introduction to this section

-

5-15

Section

Table 5-1

V

Table 5-1. Replaceable

Parts

Model 683C

(Cont'd)

Ckt Ref.

V208 V209,210 v211 V2 12 thri

V3

00

V301

thrL

V3 03

w1

thru

WlOO WlOl

Description

Same

as

V107

Same

as

V6

Same

as

VllO

Not assigned

Same

as

V4

Not assigned

Cable, power

MISCELLANEOUS

Ceramic plate cap: 3/8 in. Ceramic plate cap: 1/4

in.

Mfr

70903

76487 76487

*

@

Stock No.

8120-0015

1401-0006 1401-0007

RS*

1

Cronac spring

Filter,

Fuse holder

Fuse holder Knob: CATHODE CURRENT Knob, bar: CURRENT, SWEEP

Knob, bar: ANODE MOD. SELECTOR,

Knob: FREQUENCY DIAL

Knob: FREQUENCY VERNIER

Knob, red: INT SQUARE WAVE

Lampholder

Precalibrated Dial Assembly

Socket (BWO supply)

Tube

air

SELECTOR, RF SWEEP RATE

A

FREQUENCY (MC)

FREQUENCY, VERNIER

socket: (V105)

A

FREQUENCY (MC)

ooooc

82866 75915 75915 28480 28480

28480

28480 28480

28480

95263 28480 OOOOL 71785

1460-0005

3 150-0005

1400-0056 1400-0084 G-74K

G-74N

G-74Q

G-74Z

G-74F

G-74AV

1450-0008

683 A-40A

125 1-0044 1200-0003

1

0

1

3

0

2

0

1

0

2

1

0

1 1

1

5-16

*

See introduction to this section

-

01130-1

Model

683C

Section

Table

V

5-1

Ckt Ref.

5-1.

Tube

Table

Description

socket:

V4, V5, V102, V104, V106, V107, V109, V201, V202, V204, V301 V303

Tube

socket:

V3, V103, V108, V203, V205, V208

Tube

socket:

R35, R36, V1, V2, VlOl

Tube

Clamp

Tube

Clamp

Window, dial

Replaceable Parts (Cont'd)

Mfr

*

71785

thru

91662

71785

91506 91506 28480

@I

Stock

No.

1200-0008

1200-0009

1200-0020

1400-0019 1400-0033 G-99K

rQ

*

14

6

5

5 2

1

RS*

1

:1

0 0

0

01130-1

*

See introduction to this section

5-17

HP 683C Service manual

Specifications and Main Features

Frequently Asked Questions

User Manual