HP 415E Service manual

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MODEL

415E

SWR

METER

SERIALS

PREFIXED:

719-

See

Appendix

I

and

II

at

rear

of

manual

for:

a)

415E

Options

01,

02,

and

b)

Serials

Prefixed

530-,

545-

Model

415E

Lists

of

Illustrations

and

Tables

OF

ILLUSTtATi

Number

Title

Page

1-

1

.

Model

415E

SWR

Meter.

1-0

2-

1

.

The

Combining

Case.

2-0

2-2.

Steps

to

Place

Instrument

in

Combining

Case.

2-0

2-3.

Adapter

Frame

Instrument

Combinations.

2-1

2-

4.

Two

Half

Modules

in

Rack

Adapter

.

.

2-2

3-

1

.

Front

Panel

Operating

Controls

and

Connector.

3-2

3-2.

Rear

Panel

Operating

Controls

and

Connectors.

3-2

3-3.

Typical

SWR

Measurement

Setup

...

3-3

3-4.

General

Turn-On

Procedure.

3-4

3-5.

Expanded

Section

of

Figure

3-6

...

3-5

3-6.

Converting

Decibels

to

SWR.

3-6

3-7.

Attenuation

Measurement

Setup

...

3-6

3-8.

Impedance

Measurement

Rules

Summary.

3-7

3-9.

Shift

of

Minimum

with

Load

and

Short

.

3-7

3-10.

Example

for

Use

of

Smith

Chart

...

3-8

3-11.

415E

Noise

Figure

Curves

.3-10

3-12.

Meter

Noise

Correction

Curve

....

3-10

LIST

OF

Number

Title

Page

1-1.

Specifications.

.

.

.

.

1-0

3-1.

Panel

Descriptions.

.

.

.

.

3-3

5-1.

Recommended

Test

Equipment

.

.

.

.

.

.

5-1

5-2.

Performance

Tests.

.

.

.

.

5-3

5-3.

Etched

Circuit

Soldering

Equipment.

.

.

.

.

5-8

Number

Title

Page

4-

1

.

Block

Diagram.

4-1

5-

1

.

Test

Set

Up.

!

.

'!!!!!

5-3

5-2.

Examples

of

Diode

Marking

Methods.

5-9

5-3A.

Switch

Component

Location.5-10

5-3B.

Switch

Component

Location.5-10

5-4.

Transistor

Biasing

and

Operating

Characteristics.5-12

5-5.

Power

Supply

Waveforms

(AC

Operation

Only.5-14

5-6.

Power

Supply

Waveforms

(Initial

Battery

Operation

-

Only).5-15

5-7.

Signal

Flow

Waveforms

(Input

to

Amplifier

Output).5-16

5-8.

Meter

and

Output

Waveforms

....

5-17

5-9.

Schematic

Notes.5-18

5-10.

Circuit

Board

Component

Location.5-19

5-11.

Power

Supply

and

Input

Circuit

.

.

.

.

5-19

5-12.

Output

and

Meter

Circuit.5-21

1-1.

Battery

-

Cover

Assembly.

1-1

I-

2.

Connector

Assembly.

1-1

II-

l.

Circuit

Board

Component

Location-

Instruments

Prefixed

530

.

II-1

Number

Title

Page

5-4.

Out-of-Circuit

Transistor

Resistance

Measurements.

5-12

5-

5.

Ohmmeter

Ranges

for

Transistor

Resistance

Measurements.

5-12

6-

1

.

Reference

Designation

Index.

6-2

6-2.

Replaceable.

6-8

6-3.

Code

List

of

Manufacturers.

6-11

iii

02152-3

Section

I

Model415E

Figure

1-1

and

Table

1-1

Figure

1-1.

Model

415E

SWR

Meter

Table

1-1.

Specifications

Sensitivity:

0.15

pv

rms

at

maximum

bandwidth

(1

pv

rms

on

high

impedance

crystal

input).

Noise:

At

least

7.5

db

below

full

scale

at

rated

sen¬

sitivity

and

maximum

bandwidth

with

input

termi¬

nated

in

optimum

source

impedance

(see

Input).

Noise

figure

less

than

4

db.

Range:

70

db

in

10

and

2

db

steps.

Accuracy:

±0.05

db/10

db

step;

maximum

cumula¬

tive

error

between

any

two

10-db

steps,

±0.10

db;

maximum

cumulative

error

between

any

two

2-db

steps,

±0.05

db.

Linearity:

±0.02

db

on

expand

scales,

determined

by

inherent

meter

resolution

on

normal

scales.

Input:

Unbiased

low

and

high

impedance

crystal

(100

and

5000

ohm

optimum

source

impedance

respec¬

tively);

biased

crystal

(1

v

into

IK);

low

and

high

current

bolometer

(4.5

and

8.7

ma

±3%

into

200

ohms),

positive

bolometer

protection.

Input

connector,

BNC

female.

Input

Frequency:

1000

cps,

adjustable

7%.

Other

frequencies

between

400

and

2500

cps

available

on

special

order.

Bandwidth:

Variable,

15

to

130

cps.

Typically

less

than

0.

5

db

change

in

gain

from

minimum

to

maxi¬

mum

bandwidth.

Recorder

Output:

0

to

IV,

1000

ohms

source

imped¬

ance,

BNC

female.

Amplifier

Output:

0to0.3Vrms

(NORM),

0to0,8rms

(EXPAND)

into

at

least

1

OK

ohms,

dual

banana

jacks.

Meter

Scales:

Calibrated

for

square-law

detectors.

SWR:

1

to

4,

3.2

to

10

(NORM);

1

to

1.24

(EXPAND).

DB:

0

to

10

(NORM);

0

to

2.0

(EXPAND).

Battery:

charge

state.

Meter

Movement:

0.25%

movement,

taut-band

sus¬

pension,

mirror-backed

scale

with

expanded

db

and

swr

scales

greater

than

4-1/4

in.

(108

mm)

long.

Power:

115

or

230

volts

±10%,

50to

400cps,

2watts.

Power

line

frequency

or

multiples

thereof

must

not

be

at

the

tuned

amplifier

frequency.

Optional

re¬

chargeable

battery

provides

up

to

36

hours

contin¬

uous

operation.

Dimensions:

7-25/32

in.

wide,

6-3/32

in.

high,

llin.

deep

from

front

side

rail

(190

x

155

x

279

mm).

Weight:

Net

7-7/8

lb

(3,

5

kg),

9-7/8

lb

(4,

4

kg)

with

battery.

Options:

01.

Rechargeable

battery

installed.

02.

Rear-panel

input

connector

in

parallel

with

the

front-panel

connector.

1-0

02152-2

Model

415E

Section

I

Paragraphs

1-1

to

1-7

SECTION

1

GENERAL

INFORMATION

1-1.

INTRODUCTION.

1-2.

The

Model

415E

SWR

Meter

is

a

high-gain

ampli¬

fier,

tuned

to

an

audio

frequency,

with

a

square-law

calibrated

meter

readout.

The

Model

415E

is

designed

for

use

with

square-law

detectors

in

the

measurement

of

SWR

and

attenuation.

In

addition,

because

of

the

high-sensitivity

and

tuned

amplifier,

it

can

be

used

as

a

null

detector

for

audio

frequency

bridges.

The

Model

415E

is

shown

in

Figure

1-1.

Operating

Specifications

for

the

Model

415E

are

given

in

Table

1-1.

1-3.

The

Model

415E

is

a

tuned

audio

amplifier

de¬

signed

to

operate

at

a

mean

center

frequency

of

1000

cps

(Hz),

adjustable

7%

with

a

variable

bandwidth

of

from

15

to

130

cps

(Hz).

Operating

center

frequency

and

band¬

width

are

both

variable

at

instrument

front

panel.

Tuned

amplifier

gain

is

only

slightly

changed

due

to

any

change

in

bandwidth

and

is

typically

less

than

0.5

ab.

In

addition

to

the

front

panel

meter

readout

provided

by

the

SWR

Meter,

two

rear

panel

outputs

are

also

available:

An

AC

amplifier

output

is

provided

to

allow

using

the

415E

as

a

high-gain

(126

db)

tuned

amplifier;

a

DC

recorder

output

providing

a

convenient

means

of

obtaining

a

permanent

record

of

measurement

data.

Either

or

both

of

these

rear

panel

outputs

can

be

used

without

affecting

instrument

meter

operation

provided

power

line

ground

is

not

connected

to

the

instrument

through

either

rear

panel

connector.

1-4.

INSTRUMENTS

COVERED

BY

MANUAL.

1-5.

This

manual

applies

directly

to

the

Model

415E

SWR

Meters

having

serial

numbers

prefixed

719

(first

three

numbers

of

serial

number).

If

the

serial

prefix

on

your

instrument

is

other

than

719,

there

are

differ¬

ences

between

the

manual

and

your

instrument

which

are

described

in

a

Manual

Changes

sheet

included

with

the

manual.

If

the

manual

changes

sheet

is

missing,

the

information

can

be

supplied

by

your

nearest

Hewlett-

Packard

Sales

and

Service

Office

(see

lists

at

the

rear

of

this

manual).

The

manual

change

sheet

may

also

include

an

"ERRATA”

section

which

describes

manual

correction

information

which

applies

to

the

manual

for

all

instruments

including

instruments

prefixed

719.

1-6.

INSTRUMENT

OPTIONS.

1-7.

This

manual

provides

operating

and

servicing

information

for

the

standard

Model

415E.

In

addition,

operating

and

servicing

information

for

Model

415E

instruments

with

Options

01

and/or

02,

described

be¬

low,

is

also

included.

a.

Option

01:

Factory

installed,

24-volt

recharge¬

able

battery

capable

of

supplying

up

to

36

hours

con¬

tinuous

operation

of

the

Model

415E.

If

not

initially

installed

as

an

option,

the

same

battery

is

available

on

order

from

Hewlett-Packard

(see

Paragraph

2-17).

b.

Option

02:

Additional

input

connector

on

rear

panel

wired

in

parallel

with

the

front

panel

INPUT

con¬

nector.

If

not

initially

installed

as

an

option,

the

con¬

nector

-

cable

assembly

is

available

on

order

from

Hewlett-Packard

(see

Paragraph

2-17).

02152-4

1-1

Section

II

Figures

2-1

and

2-2

Model

415E

Figure

2-1.

The

Combining

Case

[twist

divider

to

vertical

POSITION

INSERT

DIVIDER,

ENGAGING

TABS

IN

TOP

AND

BOTTOM

MOUNTING

SLOTS

©

GING

TOM

-OTS

©

PUSH

IN

TO

LIMIT

©

SLIDE

LATCH

TO

LOCK

DIVIDER

n—.

.

*

/

g”T

asL~"

CE

,L=S===1

\\

=>

aS>

t

™

.

\

PUSH

RETAINER

DOWN

TO

RELEASE

©

TO

SET

RETAINER

BACK

IN

PLACE,

ENGAGE

HOOKS

FIRST

ON

ONE

SIDE

OF

DIVIDER,

THEN

ON

OTHER

®

PUSH

RETAINER

UP

TO

LOCK

Figure

2-2.

Steps

to

Place

Instrument

in

Combining’Case

2-0

02152-1

Model

415E

Section

II

Paragraphs

2-1

to

2-16

SECTION

II

PREPARATION

FOR

USE

2-1.

INCOMING

INSPECTION.

2-2.

This

instrument

was

inspected

both

mechanically

and

electrically

before

shipment.

To

confirm

this,

the

instrument

should

be

inspected

for

physical

damage

in

transit.

Also

check

for

supplied

accessories,

and

test

the

electrical

performance

of

the

instrument,

using

the

procedure

outlined

in

Paragraph

5-3.

If

there

is

damage

or

deficiency,

see

the

warranty

on

the

inside

front

cover

of

this

manual.

2-3.

INSTALLATION.

2-4.

The

Model

415E

is

fully

transistorized;

therefore

no

special

cooling

is

required.

However,

the

instru¬

ment

should

not

be

operated

where

the

ambient

tem¬

perature

exceeds

55

°C

(140°F).

2-5.

RACK

MOUNTING.

2-6.

The

Model

415E

is

a

submodular

unit

that

when

used

alone

can

be

bench

mounted

only.

However,

when

used

in

combination

with

other

submodular

units

it

can

be

bench

and/or

rack

mounted.

The

hp

combining

case

and

adapter

frame

are

designed

specifically

for

this

purpose.

2-7.

COMBINING

CASE.

The

combining

case

is

a

full-module

unit

which

accepts

varying

combinations

of

submodular

units.

Being

a

full-module

unit,

it

can

be

bench

or

rack

mounted

analogous

to

any

full-module

instrument.

An

illustration

of

the

combining

case

is

shown

in

Figure

2-1.

Instructions

for

installing

the

Model

415E

in

a

combining

case

are

given

graphically

in

Figure

2-2.

2-8.

ADAPTER

FRAME.

The

adapter

frame

is

arack

frame

that

accepts

any

combination

of

sub-modular

units.

It

can

be

rack

mounted

only.

An

illustration

of

the

adapter

frame

is

given

in

Figure

2-3.

Instructions

are

given

below:

a.

Place

the

adapter

frame

on

edge

of

bench

as

shown

in

step

1,

Figure

2-4.

b.

Stack

the

sub-modular

units

in

the

frame

as

shown

in

step

2,

Figure

2-4.

Place

the

spacer

clamps

be¬

tween

instruments

as

shown

in

step

3,

Figure

2-4.

c.

Place

spacer

clamps

on

the

two

end

instruments

(see

step

4,

Figure

2-4)

and

push

the

combination

into

the

frame.

d.

Insert

screws

on

either

side

of

frame,

and

tighten

until

sub-modular

instruments

are

tight

in

the

frame.

e.

The

complete

assembly

is

ready

for

rack

mounting.

2-9.

THREE-CONDUCTOR

POWER

CABLE.

2-10.

To

protect

operating

personnel,

the

National

Electrical

Manufacturers’

Association

(NEMA)

rec¬

ommends

that

the

instrument

panel

and

cabinet

be

grounded.

All

Hewlett-Packard

instruments

are

equipped

with

a

three-conductor

power

cable

which,

when

plugged

into

an

appropriate

receptacle,

grounds

the

instrument.

The

offest

pin

on

the

power

cable

three-prong

connector

is

the

ground

wire.

2-11.

To

preserve

the

protection

feature

when

oper¬

ating

the

instrument

from

a

two-contact

outlet,

use

a

three

-prong

to

two-prong

adapter

and

connect

the

green

pigtail

on

the

adapter

to

ground.

2-12,

PRIMARY

POWER

REQUIREMENTS.

2-13.

The

Model

415E

can

be

operated

from

an

AC

or

DC

primary

power

source.

The

AC

source

can

be

either

115

or

230

volts,

50

to

400

cps.

The

DC

source

is

a

24-volt

rechargeable

battery.

The

rechargeable

bat¬

tery

is

supplied

with

option

01

instruments

only.

2-14.

For

operation

from

AC

primary

power,

the

in¬

strument

can

be

easily

converted

from

115-

to

230-

volt

operation.

The

LINE

VOLTAGE

switch,

SI,

a

two-position

slide

switch

located

at

the

rear

of

the

in¬

strument,

selects

the

mode

of

AC

operation.

The

line

voltage

for

which

the

instrument

is

set

to

operate

ap¬

pears

on

the

slider

of

the

switch.

A

1/16-ampere,

250

volt

fuse

is

used

for

both

115-

and

230-volt

operation.

CAUTION

DO

NOT

CHANGE

THE

SETTING

OF

THE

LINE

VOLTAGE

SWITCH

WHEN

THE

IN¬

STRUMENT

IS

OPERATING.

2-15.

INITIAL

BATTERY

CHECK.

2-16.

The

following

applies

to

option

01

instruments

or

instruments

that

have

field

-

installed

batteries.

When

the

battery

is

used

as

the

power

source

for

the

first

time,

perform

the

following

steps:

Figure

2-3.

Adapter

Frame

Instrument

Combinations

02152-1

2-1

Section

II

Paragraphs

2-17

to

2-20

Model

415E

©

ADAPTER

FRAME

Figure

2-4.

Two

Half

Modules

in

Rack

Adapter

a.

Connect

Model

415E

to

AC

source.

Set

POWER

switch

to

CHARGE

and

charge

battery

for

a

minimum

of

16

hours

or

overnight.

Note:

the

battery

can

be

maintained

in

the

charging

state

indefinitely

without

damaging

the

battery.

It

will

assume

its

full

capacity,

1.25

ampere

hour,

and

no

more.

b.

Set

POWER

switch

to

TEST

position,

the

meter

needle

indication

should

be

within

the”BAT.

CHARGED”

area

(see

Figure

3-1).

2-17.

INSTALLING

BATTERY

AND

INPUT

CONNECTOR.

2-18.

Available

from

Hewlett-Packard

are

parts

re¬

quired

for

modifying

any

Model

415E

to

correspond

to

those

instruments

with

Option

01

and/or

Option

02.

A

rechargeable

Battery

Installation

Kit,

hp

Part

Number

00415-606,

contains

the

battery

and

necessary

hard¬

ware

for

installation

(corresponds

to

Option

01).

In¬

stallation

instructions

are

detailed

in

Appendix

at

rear

of

this

manual.

To

obtain

the

parts

required

for

an

input

connector

on

the

rear

panel

(corresponding

to

Option

02),

order

by

hp

Part

Number

as

found

in

Table

6-1

(listed

under

Option

02).

Instructions

for

instal¬

lation

of

this

additional

connector

are

detailed

in

Ap¬

pendix

at

rear

of

this

manual.

2-19.

REPACKAGING

FOR

SHIPMENT.

2-20.

When

returning

an

instrument

to

the

Hewlett-

Packard

Company,

use

the

original

packing

material

(if

foam

type)

if

available

or

contact

an

authorized

hp

Sales

Office

for

assistance.

If

this

is

not

possible,

first

protect

the

instrument

surfaces

by

wrapping

in

heavy

Kraft

paper

or

with

sheets

of

cardboard

flat

against

the

instrument.

Then

protect

the

instrument

on

all

sides

(use

approximately

4

inches

of

packing

material

designed

specifically

for

package

cushioning),

pack

in

a

durable

container,

mark

container

clearly

for

proper

handling,

and

insure

adequately

before

shipping.

Note

When

an

instrument

is

being

returned

to

the

Hewlett-Packard

Company

for

service

or

re¬

pair,

attach

a

tag

to

the

instrument

specifying

the

owner

and

desired

action.

All

correspon¬

dence

should

identify

the

instrument

by

model

number

and

the

full

(eight-digit)

serial

number.

2-2

02152-1

Model

451E

Section

III

Paragraphs

3-1

to

3-14

SECTION

I!!

OPERATING

INSTRUCTIONS

3-1.

INTRODUCTION,

3-2.

This

section

contains

information

and

procedures

for

operation

of

the

Model

415E

(from

either

AC

or

bat¬

tery

power

source)

in

making

swr

and

attenuation

measurements.

Also

included

is

information

on

slotted

line

techniques,

instruction

in

the

use

of

a

Smith

Chart

for

plotting

load

impedance,

and

discussion

of

Model

415E

noise

performance

with

various

source

imped¬

ances

and

noise

effect

on

meter

indication.

3-3.

FRONT

AND

REAR

PANEL

FIXTURES.

3-4.

Figures

3-1

and

3-2

identify

by

number

the

front

and

rear

panel

fixtures

of

the

Model

415E.

The

des¬

criptions

in

Table

3-1

are

keyed

by

number

(1-12

for

front,

13-18

for

rear)

to

the

figures.

Further

infor¬

mation

regarding

the

various

settings

and

uses

of

the

controls,

indicators,

connections,

and

adjustments

is

included

in

the

procedures

of

this

section.

Information

on

battery

is

found

in

Paragraph

3-6.

3-5.

GENERAL

OPERATING

AND

MEASUREMENT

CONSIDERATIONS.

3-6.

BATTERY

OPERATION.

3-7.

The

Model

415E

may

be

operated

from

a

battery

instead

of

the

115

or

230

volt

AC

supply

(see

Paragraph

2-

13).

Battery

operation

requires

some

slightly

dif¬

ferent

procedures

to

prolong

battery

life

and

to

ensure

proper

results.

The

rechargeable

nickel

-

cadmium

battery

is

factory

installed

if

ordered

as

Option

01

(see

Paragraph

1-7).

The

same

battery

may

be

ordered

and

installed

later.

To

obtain

this,

order

hp

Stock

Number

00415-606,

Rechargeable

Battery

Installation

Kit.

3-

8.

INITIAL

BATTERY

USE.

When

the

Model

415E

is

to

be

battery

operated

for

the

first

time,

perform

the

following

steps:

a.

Switch

the

Model

415E

POWER

switch

to

BAT-

TERY/TEST

position

and

note

meter

pointer

indication:

A

meter

pointer

indication

in

the

"BAT.

CHARGED"

area

indicates

the

internally

battery

properly

charged

and

ready

for

use:

A

meter

pointer

indication

to

the

left

of

the

"BAT.

CHARGED"

area

means

that

the

battery

must

be

charged

as

described

below.

b.

Connect

the

Model

415E

to

AC

power

source.

Set

POWER

switch

to

BATTERY/CHARGE

and

charge

the

battery

for

a

minimum

of

16

hours

or

overnight.

c.

After

at

least

16

hours

of

recharge

time,

switch

POWER

switch

to

BATTERY/TEST

position

and

check

battery

charge.

If

the

battery

charge

indication

is

still

unsatisfactory,

see

Paragraph

5-35.

3-9.

OPTIMUM

BATTERY

USAGE.

It

is

recommended

that

the

Model

415E

be

operated

by

the

battery

for

up

to

8

hours,

followed

by

16

hours

of

recharge.

If

con¬

tinuous

battery

operation

is

required

for

more

than

8

hours,

the

recharge

time

should

be

double

the

oper¬

ating

time.

Continuous

battery

operation

is

possible

for

up

to

36

hours

but

this

must

be

followed

by

a

pro¬

longed

recharge

period.

3-10.

BATTERY

STORAGE.

Storage

of

the

battery

at

or

below

room

temperature

is

best.

Extended

storage

at

high

temperatures

will

reduce

the

cell

charge

but

not

damage

the

battery

if

the

storage

temperature

is

less

than

140°F.

It

is

suggested

that

the

battery

be

charged

after

removal

from

storage

and

before

using

the

Model

415E

for

battery

operation.

3-11.

GROUNDLOOP

CURRENTS

.

3-12.

The

415E

SWR

Meter

audio

amplifier

has

high

sensitivity

to

low

level

signals.

To

reduce

ground

loop

currents,

the

415E

grounds

are

isolated

by

a

46.4

ohm

resistor.

Ground

loops

occur

when

instruments

are

connected

to415E

outputs

and

grounded

through

power

cords

or

rack

mountings.

Ground

loops

can

be

min¬

imized

in

the

following

ways:

a.

Connect

the

415E

to

instruments

with

floating-

inputs;

b.

Connect

the

415E

to

instruments

with

high

input

impedance;

Connect

only

the

signal

wire

between

in¬

strument

and

the

415E;

c.

Operation

at

higher

signal

levels;

d.

An

Adapter

on

the

power

cord

to

float

the

instru¬

ment

ground

where

not

prohibited

by

safety

regulations.

3-

13

.

BANDWIDTH

AND

FREQUENCY

SELECTION.

3-14.

Two

front

panel

adjustments

are

provided

to

op¬

timize

operation

of

the

Model

415E

tuned

amplifier.

The

FREQ

(frequency)

control

allows

a

total

variation

of

7%

of

the

center

tuned

frequency.

When

more

than

one

Model

415E

is

included

in

the

same

measurement

setup,

the

variable

tuned

frequency

is

used

to

set

all

the

instruments

to

the

exact

frequency

modulating

the

source.

The

high

sensitivity

and

narrow

bandwidth

of

the

amplifier

make

the

Model

415E

valuable

as

a

meter-indicating

null

detector

for

audio

frequency

bridges.

The

BANDWIDTH

adjustment

varies

the

tuned

filter

bandwidth

from

15

to

130

cps.

A

narrow

band¬

width

is

best

for

low

level

signals

as

this

improves

the

signal

to

noise

ratio.

A

wide

bandwidth

would

find

more

use

in

fast

sweep

rate

measurements.

02152-4

3-1

Section

HI

Figures

3-1

and

3-2

Model

415E

4I5E-A-9

Figure

3-1.

Front

Panel

Operating

Controls

and

Connector

Figure

3-2.

Rear

Panel

Operating

Controls

and

Connectors

3-2

02152-1

Model

415E

Section

in

Paragraphs

3-15

to

3-21

Table

3-1.

Panel

Descriptions

1.

Selects

desired

415E

power

source:BATTERY/

CHARGE

position

allows

internal

battery

re¬

charge

when

power

cord

is

connected

to

AC

line,

2.

Indicator

lights

when

power

switch

is

in

LINE/

ON

or

BATTERY/CHARGE

position.

3.

Female

BNC

INPUT

connector.

4.

Set

input

of

Model

415E

for

use

with

a

bolom¬

eter

or

crystal

detector

mount.

See

Paragraph

3-53.

5.

Adjustment

allows

center

frequency

variation

by

70

cps.

6.

Attenuator

adjusts

gain

in

10

db

steps.

7.

Allows

full

scale

expansion

of

any

2.0

db

portion

of

the

10-db

scale.

8.

Changes

bandwidth

from

15

to

130

cps.

9.

Allows

initial

meter

reference

setting

with

a

control

range

of

at

least

10-db.

10.

Provides

fine

adjustment

of

GAIN

control

meter

settings.

11.

Mechanical

zero

adjustment

allows

exact

sett¬

ing

of

meter

needle

to

2.0

db

calibration

mark.

12.

With

POWER

switch

set

to

BATTERY/TEST,

a

meter

needle

indication

within

the

’’BATTERY

CHARGE”

area

on

the

meter

face

(indicated

by

12A)

shows

that

internal

battery

is

charged

suf¬

ficiently

for

proper

415E

operation;

if

needle

indicator

is

to

left

(area

12B)

of

"BATTERY

CHARGED”

area,

then

battery

is

not

charged

sufficiently

for

proper

instrument

operation

(option

01

-

ONLY).

13.

Additional

input

connector

(wired

in

parallel

with

front

panel

connector);

supplied

as

Option

02

for

415E

only

upon

request.

14.

DC

output

for

recorder

use

(0

to

1

volt

into

open

circuit

or

1000

ohms).

15.

AC

output

for

use

as

tuned

amplifier

output.

16.

Three-conductor

AC

power

cord

receptacle

(NEMA-type).

17.

Contains

power

line

fuse.

18.

Slide

switch

to

allow

115-

or

230-volt

AC

operation.

3-15.

SWR

MEASUREMENT

EQUIPMENT

AND

TECHNIQUES.

3-16.

EQUIPMENT

.

3-17.

A

typical

setup

of

equipment

used

in

SWR

meas¬

urements

is

shown

in

Figure

3-3.

The

signal

source

is

usually

square-wave

modulated

at

1000

cps

since

other

modulating

waveforms

often

cause

undesirable

fre¬

quency

modulation

of

the

source.

Harmonics

from

the

source

sometimes

cause

trouble

and

can

be

eliminated

with

a

low-pass

filter.

3-18.

The

detector

should

be

a

square-law

device

(out¬

put

voltage

proportional

to

RF

power

input)

such

as

a

barretter

or

a

crystal

diode

operated

at

low

signal

levels.

The

meter

of

the

415E

is

calibrated

for

square-

law

detectors.

Crystal

diodes

are

normally

more

sen¬

sitive

than

barretters

but

barretters

are

square-law

over

a

wider

dynamic

range.

Both

types

of

detector

normally

maintain

accurate

square-law

response

up

to

at

least

full

scale

deflection

with

the

RANGE-DB

switch

set

to

30

position

and

coarse

GAIN

at

maximum.

(1

mv

RMS

sine

wave

or

2.2

mv

peak-to-peak

square

wave

causes

full

scale

deflection

on

HIGH

XTAL

IMPED

position.

On

other

positions

of

INPUT

switch,

0.15

mv

RMS

sine

wave

or

0.33

mv

peak-to-peak

square

wave

causes

full

scale

deflection.)

Above

this

level

these

detectors

should

be

individually

checked

for

departure

from

square-law

behaviour

or

manufacturer’s

data

should

be

consulted.

02152-3

3-19.

A

short

circuit

termination

is

useful

in

establish¬

ing

reference

positions

along

the

transmission

line

and

is

measuring

transmission

line

wavelengths.

3-20.

SLOTTED

LINE

PROBE

PENETRATION

.

3-21.

A

general

rule

in

slotted

line

measurement

is

to

use

minimum

probe

penetration

that

still

picks

up

ad¬

equate

signal

to

measure.

The

probe

couples

to

the

Figure

3-3.

Typical

SWR

Measurement

Setup

3-3