National radio Ncx-500 User manual

NATIONAL

RADIO

COMPANY,

INC.

37

WASHINGTON

ST.,

MELROSE,

MASS.

02176

NCX-500

TRANSCEIVER

SECTION

1

GENERAL

DESCRIPTION

The

NCX-500

ie

a

5

band

high

perform-

ance

transceiver

covering

the

80,

40,

20,

15

and

10

meter

amateur

bands.

Three

modes

of

communication

are

provided:

SSB,

AM,

and

CW.

The

NCX-500

Main

Tuning

Dial

is

cali-

brated

in

7

discrete

bands,

4

covering

the

80,

40,

20

and

15

meter

bands,

and

3

bands

,

covering

the

10

meter

band.

.

This

dial

con~

;

trols

the

VFO

of

both

receiver

and

trans-

>

mitter

portions

of

the

transceiver,

pro-

*

viding

a

high

order

of

stability

and

tuning

accuracy.

~

A

crystal

lattice

bandpass

filter

is

incor-

porated

in

both

the

transmit

and

receiver

sections

of

the

transceiver.

The

bandwidth

is

2.8

KHz

at

the

center

frequency

of

5.2020

MHz

with

a

6:50

db

shape

factor

of

2.2

to

1.

ALC

(automatic

Level

control)

is

incor-

porated

in

the

NCK-500.

Effective

talk

power

is

thereby

increased

and

microphone

gain

and

speech

loudness

are

made

less

critical

by

this

system.

The

10

db

range

of

the

ALC

circuit

in

the

NCX-500

mini-

mizes

“flat

topping"

and

splatter.

The

transceiver

operates

on

LSB

on

the

80

and

40

meter

bands,

and

USB

on

the

20,

15

and

10

meter

amateur

bands.

SECTION

2

INSTALLATION

2.1

The'NCX-500

transceiver

requires

a

suitable

power

supply

with

excellent

regula-

tion

and

filtering,

such

as

the

NCX-B

Power

Supply/Speaker.

Console

or

the

AC-500

Sup-

ply

(supply

only).

Both

of

these

power

units

will

operate

from

either

117

or

234

VAC

and

are

supplied

with

power

cables

to°

directly

connect

to

the

NCX-500.

When

the

AC-~500

Supply

is

used,

an

external

speaker

is

required

(see

paragraph

2.2 for

installa-

tion

detail).

Figure

1

illustrates

the

power

connections

and

power

requirements.

For

use

with

a

12

volt

DC

power

supply

connec-

‘tions

to

the

power

supply

from

the

primary

,

12.6

volt

source,

and

between

the

power

.

eupply

and

transceiver,

should

be

made

in

accordance

with

the

wiring

instructions

“included

with

the

12

volt

DC

power

supply.

During

mobile

operation,

make

certain

that

the

transceiver

VR

tube

remains

lit

at

all

times

and

does

not

extinguish

during

voice

peaks

or

under

full

TUNE

input.

Such

VR

tube

extinction

will

cause

severe

frequency

shift

with

modulation.

Extinction

of

the

VR

tube

usually

results

from

improper

loading

or

from

low

4280

volt

output

from

the

DC

supply.

It

is

important

to

use

a

DC

supply

which

will

provide

rated

power

to

the

trans-

ceiver

and

also

to

provide

adequate

voltage

to

the

DC

supply.

2.2

SPEAKER

INSTALLATION

Two

terminals

on

the

12

terminal

Jones

plug

at

the

rear

of

the

NCX-500

(pins

5

and

7)

are

provided

for

a

pair

of

leads

to

be

brought

out

for

speaker

connection

if

the

NCX-B

Supply

is

not

used

(see

figure

1).

Alternatively,

the

rear-panel

phone

jack

may

be

used

for

a

speaker.

When

the

NCX-500

is

installed

in

an

automobile

for

use

with

the

12

volt

DC

sup-

ply

it

will

usually

be

most

convenient

to

use

the

regular

automobile

broadcast

radio

speaker,

connected

through

a

DPDT

switch

mounted

under

the

dash,

to

allow

a

choice

of

speaker

operation

of

either

the

NCX-500

or

the

broadcast

receiver.

INSTALLATION

DIAGRAMS

Power

Switch

Power

Switch

-100

Volt

Bias

@6

Ma.

12,6

Volt

Heater

baa

Speaker

Ground

Common

Ground

Speaker

#280

Volt

@

200

Ma,

11

1100

Volt

@

450

‘

POWER

CONNECTIONS,

FIGURE

1

WNOW

a

uN

MOUNT

TODASH

wiTH

"10,

12.08

G20

SCREWS.

REMOVE

RUBBER

FEET

FOR

MOBILE

INETALLATION

PTT

BUTTON

MICROPHONE

CONKECTIONS.

FIGURE

3

2.3

MOBILE

MOUNTING

A

mounting

bracket

is

included

with

the

.

NCX-500

transceiver.

For

mobile

opera-

tion,

thia

bracket

should

be

mounted

under

the

automobile

dashboard

with

two

#10,

12,

or

1/4

x

20

screws.

For

maximum

sta-

bility,

these

screws

should

be

located

as

-far

apart

as

possible

in

the

mobile

mounting

bracket.

A

pair

of

large

threaded

knoba

hold

the

transceiver

directly

to

the

bracket.

These

knobs

permit

rapid

installation

or

removal)

of

the

transceiver

from

the

mount.

Mobile

operation

usually

results

in

consider-

*

able

vibration

and

shock.

For

maximum

frequency

stability

of

the

NCX-500

trans-

‘Seiver,

it

ie

important

that

all

mounting

screws

used

to

hold

the

cabinet

to

the

chassis

and.

panel

assembly

be

in

place

and

firmly

tightened.

In

mobile

use,

the

rubber

feet

may

be

removed

from

the

bottom

of

the

NCX-500,

-

(See

figure

2.)

“ee

2.4

MICROPHONE

CONNECTIONS

'

The

microphone

input

of

the

NCX-500

is

equippéd

with

a

three

circuit

jack

providing

.

&

ground

on

the

main

shank

of

the

three

.

circuit

plug.

The

audio

output

of

a

hig!

impedance

ceramic

or

dynamic

(recom-

mended)

microphone

(a

crystal

microphone

may

be

used,

but

is

not

recommended

for

mobile

operation)

should

be

connected

to

the

ring

of

the

three

circuit

jack.

If

the

micro-

phone

is

equipped

with

a

push-to-talk

button,

it

should

be

so

wired

that

the

tip

of

the

microphone

plug

is

connected

to

the

grounded

shank

of

the

plug

when

the

push-

to-talk

button

is

pressed:

The

microphone

push-to-talk

button

is

connected

to

+12

VDC.

Accidental

interchange

of

the

wiring

on

the

microphone

plug

will

result

in

application

of

+12

volts

to

the

micro-

phone

cartridge,

which

may

damage

the

microphone.

The

rhicrophone

input

jack

of

the

NCX-

500

is

equipped

with

a

grounding

contact

so

that

no

modulation

of

the

transceiver

is

pos-

sible

when

the

microphone

plug

is

removed.

Microphone’

connections

are

illustrated

in

figure

3,

We

recommend

the

use

of

a

good

quality,

wide-range

microphone,

since

all

necessary

restriction

of

audio

bandwidth

is

accomplished

in

the

NCX-500

crystal

lattice

filter.

2.5

AUXILIARY

RELAY

CONTROL

TERMINALS

.

A

pair

of

SPST

relay

terminals

rated

at:

3

amperes

current

capacity

are

provided

at

the

rear

of

the

NCX-500

to

allow

control

of

accessory

equipment

such

as

the

NCL-2000

amplifier.

Terminals

are

open

during

receive,

and

closed

during

transmit.

The

NCX-500

is

wired

for

12

volt

negative

ground

mobile

installations.

For

use

on

positive

ground

installa-

tions

the

polarity

of

the

12

volt

diode

D-6

and

the

250

mfd

capacitor

C-147

must

be

reversed,

Failure

to

do

this

will

result

in

damage

to

the

unit.

SECTION

3

OPERATION

3.1

TUNING

PROCEDURE

MIC

GAIN

fully

ccw

(counterclockwise)

3.1.2

RECEIVER

TUNE-UP

(SSB)

¢

Before

attempting

to

operate

the

NCX-500

transceiver,

the

following

preliminary

connections

should

be

made,

A

suitable

antenna

or

dummy

load

presenting

40

to

60

ohms

resis-

tive

load

impedance

should

be

con-

nected

to

the

antenna

terminals,

a

proper

power

cable

should

be

con-

nected

from

the

transceiver,

and

a

microphone

or

key

should

be

con-

nected

to

the

appropriate

input

jacks.

The

function

switch

should

remain

in

the

OFF

position

while

the

con-

nections

are

being

made.

3.1.1

PRELIMINARY

ADJUSTMENTS

Set

front

panel

controls

as

follows:

RF

GAIN

fully

cw

(clockwise)

AUDIO

GAIN.

at

9

o'clock

BAND

and

MAIN

TUNING

to

desired

band

and

frequency

MOX

switch:

OFF

Turn

the

FUNCTION

switch

from

OFF

to

SSB.

Adjust

the

PA

TUNE

and

EXCITER

TUNE

controls

for

maximum

S-Meter

read-

ing

or

background

noise.

This

adjustment

automatically

seta

up

approximate

transmit

tuning

since

these

controls

are

common

for

both

transmitter

and

receiver.

Adjust

AUDIO

GAIN

for

comfortable

listening

level.

3.1.3

TRANSMITTER

TUNE-UP

Do

not

prolong

tune-up

procedures

for

more

than

30

seconds

in

order

to

prevent

unnecessary

overheating

of

components

during

out-of-resonance

conditions,

After

experience

is

gained,

tune-up

may

be

accomplished

in

a

matter

of

a

few

seconds.

Turn

FUNCTION

switch

to

TUNE,

and

adjust

EXCITER

TUNE

control

for

maxi-

mum

meter

reading.

Quickly

adjust

the

PA

TUNE

control

for

minimum

meter

reading

(dip)

indicating

proper

tuning

of

the

Pi

network.

Slowly

rotate

the’

PA

LOAD

control

cw

and

dip

meter

reading

with

the

PA

TUNE

control

until

meter

reads

450

ma.

“Return

the

FUNCTION

switch

to

SSB.

NOTE

If

this

is

the

first

time

that

the

NCX-

500

has

been

placed

in

operation,

the

rear

panel

BIAS

control

should

be

adjusted.

Place

the

NCX-500

in

transmit

with

the

MOX

switch

in

the

*

MOX

position.

The

rear

panel

BIAS

control

should

be

adjusted

until

the

meter

reads

between

50

and

60

ma.

Return

the

NCX-500

to

the

receive

condition

(MOX

switch

OFF).

3.1.4

MOX

OPERATION

The

NCX-500

transceiver

will

now

oper-

ate

in

both

the

transmit

and

receive

modes

using

the

MOX

switch

for

transmit-receive

control.

3.1.5

PTT

OPERATION

Place

the

MOXx

switch

in

the

OFF

posi-

tion,

“Connect

a

suitable

push-to-talk.

switch

as

shown

in

figure

3.

_.

The

NCX-500

will

operate

in

both

the

transmit

and

receive

modes

by

control

from

the

external

push-to-talk

ewitch.

4

3.1.6

SSB

OPERATION

Insert

microphone

in

‘the,

front

panel

MIC

jack.

Turn

the

FUNCTION

ia

to

TUNE,

and

adjust

the

transmitter

as

described

‘in

paragraph

3.1.3.

Turn

the

FUNCTION

Bas

to

SSB.

Place

the

MOX

switch

in

MOX

or

depress

the

microphone

push-to-talk

button.

Advance

the

MIC

GAIN

until

the

meter

-

indicates

voice

peaks

of

200

ma.

The

NCX-500

is

now

adjusted

for

SSB

operation,

3.1.7

CW

OPERATION

Insert

key

plug

in

the

rear

panel

KEY

jack.

Turn

the

FUNCTION

ewitch

to

TUNE

and

adjust

transmitter

as

described

in

paragraph

3.1.3.

Turn

the

FUNCTION

switch

to

CW.

Place

the

MOX

ewitch

in

MOX

and

depress

key.

Rotate

the

rear

panel

CARRIER

INSERTION

control

clockwise

until

the

meter

reads

360

ma.

Do

not

continue

to

rotate

the

CARRIER

INSERTION

control

beyond

the

point

at

which

360

ma.

is

reached.

The

NCX-500

is

now

tuned

for

CW

oper-

ation

and

is

returned

to,the

receive

condition

by

switching

the

MOX

switch

to

OFF,

During

CW

operation,

a

CW

sidetone

signal

is

generated

to

allow

the

operator

to

monitor

the

CW

output.

The

sidetone

signal

is

automatically

generated

when

the

FUNC-

TION

switch

is

in

the

CW

position.

(The

sidetone

signal

can

be

used

for

code

prac-

tice

by

placing

the

MOX

switch

in

the

OFF

position

and

adjusting

the

RF

GAIN

and

AUDIO

GAIN

controls

to

fully

counterclock-

wise

positions.)

3.1.8

AM

OPERATION

Turn

FUNCTION

switch

to

TUNE,

and

adjust

transmitter

as

described

in

paragraph

3.1.3.

Turn

the

FUNCTION

switch

to

AM.

Place

the

MOX

ewitch

in

MOX,

and

rotate

the

CARRIER

INSERTION

control

clockwise

until

the

meter

reads

125

ma.

Advance

the

MIC

GAIN

until

meter

just

flickers

on

voice

peaks.

The

NCX-500

is

now

adjusted

for

AM

operation,

and

the

AM

detector

is

automat-

ically

in

use.

3.2

DETAILED

USE

OF

THE

INDIVIDUAL

CONTROLS.

"

The

operating

instructions

in

paragraph

3.1

of

this

manual

enable

rapid

set-up

of

the

NCX-500

for

SSB,

AM,

or

CW

trans-

mission.

Careful

study

of

the

following

paragraphs

will

help

you

get

the

best

per-

formance

from

your

NCX-500

transceiver.

3.2.1

DIAL

SET

The

dial

of

the

NCX-500

may

be

adjusted

to

exact

frequency

(such

as

a

100

KHz

marker

from

‘the

optional

plug-in

KCU-27

calibrator)

by

tuning

to

the

marker

fre-

quency

with

the

receiver

and

then

by

turning

the

DIAL

SET

control

until

the

fiducial

line

indicates

correct

frequency.

3.2.2

RECEIVE

VERNIER

A

vernier

adjustment

of

the

NCX-500

to

the

received

signal

can

be

made

by

pulling

out

the

REC-VERNIER

knob,

This

control

allows

the

operator

to

fine-tune

to

the

received

frequency

over

a

range

of

+3

KHz

without

shifting

the

transmitter

frequency.

3.2.3

TEE

PA

TUNE

AND

PA

LOAD

CONTROLS

.

Adjustment

of

the

PA

TUNE

and

PA

LOAD

controls

is

interdependent.

For

nor-

mal

tune-up,

the

FUNCTION

switch

is

placed

in

the

TUNE

position,

The

EXCITER

TUNE

control

is

set

for

maximum

meter

indication.

The

PA

TUNE

control

is

then

set for

minimum

indication,

indicating

resonance

of

the

Pi

network,

For

a

normal

40

to

60

ohm

resistive

antenna,

the

PA

LOAD

contro)

should

be

rotated

clockwise

to

increase

the

meter

reading.

As

this

is

done,

there

will

be

some

interaction

with

the

PA

TUNE

control,

and

it

will

be

neces-

sary

to

slightly

adjust

the

PA

TUNE

control

for

minimum

meter

indication.

As

the

PA

LOAD

control

is

advanced,

the

minimum

meter

reading

will

increase.

Proper

load-

ing

for

500

watts

peak

input

occurs

at

450

ma.

This

loading

current

should

not

be

exceeded,

since

the

Pi

network

design

is

such

that

additional

power

input

from

an

1100

volt

supply

will

not

result

in

additional

power

output.

Above

450

ma,

the

efficiency

of

the

NCX-500

final

arnplifier

will

be

im-

paired

and

no

further

output

will

be

obtained.

Proper

operation

of

any

linear

amplifier

depends

on

proper

idling

current

adjustment

and

on

sufficient

drive

for

adequate

peak

plate

current

during

an

off-resonance

condi-

tion.

The

adjustment

of

the

BIAS

setting

of

the

NCX-500

final

amplifier

is

discussed

in

the

operating

instructions.

Assuming

this

setting

has

been

made

for

an

idling

current

between

50

and

60

ma.,

it

should

be

possi-

ble

to

obtain

a

momentary

maximum

off-

resonance

plate

current

in

excess

of

500

ma.

when

the

PA

TUNE

control

is

rotated

away

from

the

point

of

minimum

indicated

cprrent.

If

1100

volts

are

being

properly

supplied

to

the

plate

circuit

of

the

final

amplifier

and

the

EXCITER

TUNE

control

is

properly

adjusted,

this

off-resonance

current

should

exceed

500

ma.

If

this

cur-

rent

cannot

be

achieved,

the

cause

should

be

found.

Typical

causes

may

inciude

any

of

the

following:

improper

BIAS

setting,

improper

EXCITER

TUNE

adjustment,

low

plate

supply

voltage

to

the

final

ampli-

fier

under

full

load

conditions,

low

driver

Bt,

defective

final

amplifier

tubes

or

drive

tube,

or

improper

alignment

of

the

exciter

stages

resulting

in

low

driving

signal.

As

mentioned

above,

low

plate

supply

voltage

to

the

final

amplifier

will

frequentl:

result

in

difficulty

in

obtaining

a

suitable

of

resonance

current.

(The

AC

500

power

su;

ply

is

rated

to

deliver

1100

volts

to

the

fina

amplifier

with

117

volt

AC

input.)

If

the

AC

line

voltage

or

the

mobile

battery

suppl

voltage

is

low,

the

power

supply

output

wil:

be

reduced.

Under

these

conditions,

off-

resonance

plate

current

of

500

ma.

will

probably

not

occur.

This

will

not

impair

the

operation

of

the

NCX-500

transceiver,

provided

that

the

PA

LOAD

contral

is

nat

so

adjusted

as

to

result

in

excessive

loadin

for

the

lower

voltage.

At

no

time

should

tt

PA

LOAD

control

be

advanced

so.

that

the

plate

current

at

the

resonant

dip

exceeds

85%

of

the

off-resonant

plate

current

(whic

is

noted

by

momentarily

detuning

the

PA

TUNE

control).

In

many

instances

an

antenna

load

that

i

outside

the

40

to

60

ohm

range

of

the

Pi

network

will

be

used

with

the

NCX-500.

Antennas

presenting

this

type

of

impedance

should,

if

at

all

possible,

be

adjusted

to

present

a

proper

load

at

the

NCX-500

antenna

terminals,

This

can

be

done

through

the

use

of

matching

networke

and,

in

many

instancee,

by

simply

tailoring

the

length

of

the

antenna

transmission

line

to

modify

its

terminal

impedance.

Generally

speaking,

if

the

NCX-500

exhibits

a

resonant

plate

current

in

the

dij

in

excess

of

450

ma.

with

the

PA

LOAD

control

rotated

to

its

full

counterclockwis¢

position,

the

antenna

load

impedance

is

below

40

ohms.

If,

on

the

other

hand,

the

resonant

dip

is

still

less

than

450

ma.

wit:

the

PA

LOAD

control rotated

to

its

full

clockwise

position,

the

antenna

load

imped-

ance

is

above

60

ohms.

It is

possible

to

‘modify

the

Pi

network

output

capacitors

of

‘the

NCX-500

to

take

care

of

some

misload-

ing

in

these

directions.

With

the

PA

housing

removed,

a

group

of

four

mica

capacitors

will

be

seen

just

below

the

BAND

switch

and

connected

between

the

BAND

switch

and

chassis,

These

capacitors,

C-1

(3.5

MHz),

G-2

(7

MHz),

C-3

ti

MHz),

and

G-5

(21

MHz)

are,

respectively,

1000,

470,

220,

and

220

pF;

They

appear

in

parallel

with

the

front

panel

PA

LOAD

control

as

shown

on

the

schematic

diagram,

and

may

be

altered

to

extend

the

range

of

the

Pi

net-

work.

If

the

load

impedance

is

too

low,

the

capacitance

should

be

increased.

A

good

quality

silver

mica

capacitor

may

be

used

for

this

purpose.

It

is

advisable

to

use

as

large

a

case

size

on

these

capacitors

as

can

be

obtained.

There

is

of

course

some

interaction

of

tuning

between

the

PA

LOAD

control

and

the

PA

TUNE

control.

If

load

matching

as

described

in

the

preceding

paragraph

is

attempted,

it

is

possible

that

the

tuning

of

the

PA

TUNE

control

will

be

shifted

toa

point

where

this

control

will

no

longer

cover

the

entire

amateur

band.

In

this

event,

it

will

be

necessary

to

use

external

matching

techniques.

It

is

also

possible

that

the

antenna

line

will

introduce

an

inductive

or

capacitive

component

to

the

NCX-500

antenna

terminals.

In

this

event,

there

may

be

also

a

shift

of

the

PA

TUNE

Control

so

that

it

will

not

tune

over

the

entire

amateur

band.

Again

it

will

be

necessary

to

alter

the

antenna

impedance

by

means

of

an

external

matching

network

or

correction

of

the

antenna

difficulties.

SSB

operation

should

not

be

attempted

unless

the

NCX-500

is

properly

matched

and

loaded

because

severe

distortion

can

result,

as

with

any

improperly

matched

SSB

transmitter.

3.2.4

CARRIER

INSERTION

CONTROL

During

tune-up

(with

the

FUNCTION

switch

in

the

TUNE

position),

the

CARRIER

INSERTION

control

is

inoperative.

Full

carrier

is

automatically

inserted.

In

the

AM

and

CW

pésitions,

the

CARRIER

IN-

SERTION

control

may

be

preset

and

will

vary

the

carrier

level

from

zero

to

full

~

output

as

indicated

by

the

meter.

In

the

SSB

position,

the

CARRIER

INSERTION

control

is

again

inoperative,

and

full

car-

tier

suppression

is

present.

3.2.5

S-METER

ADJUSTMENT

Proper

S-Meter

adjustment

of

the

NCX-

500

is

obtained

by

disconnecting

the

antenna

and

detuning

the

EXCITER

TUNE

control

while

the

NCX-500

is

set

for

SSB

reception,

With

the

RF

GAIN

fully

clockwise

(maxi-

mum

gain),

the

S-Meter

adjustment

on

the

rear

apron

is

rotated

until

the

meter

indicates

between

0

and

|

"S'

units.

Some

“wandering”

of

S-Meter

zero

may

be

experi-

enced

during

warm-up.

3.2.6

THE

MOX

SWITCH

The

MOX

switch

in

the

MOX

(manual)

operation

position

places

the

NCX-500

in

the

transmit

mode,

regardless

of

the

posi-

tion

of

the

FUNCTION

switch.

This

position

is

useful

for

manual

operation

when

the

microphone

is

not

equipped

with

a

PTT

switch

and

is

necessary

for

CW

operation.

3.2.7

MIC

GAIN

CONTROL

For

SSB

operation,

set

up

the

NCX-500

by

proper

tuning

of

the

final

amplifier

and

exciter

stages

(paragraphs

3.1.1

to

3.1.3),

and

advance

the

MIC

GAIN

control

until

the’meter

reads

between

150

and

200

ma.

with

modulation.

Single

sideband

audio

has

a

rapidly

varying

energy

content

and

the

meter

will

rapidly

fluctuate

between

the

50

to

60

ma.

idling

current

and

the

150

to

200

ma.

meter

reading.

Actual

peak

current

is

about

450

ma.

This

fluctuation

will

be

affected

by

the

nature

of

the

speech

content

and

individual

voice

characteristics.

For

AM

operation

with

the

CARRIER

INSERTION

control

set

as

described

in

the

operating

instructions,

there

will

be

a

steady

meter

reading

of

[25

ma.

If

the

MIC

GAIN

control

is

advanced

during

speech,

AM

modulation

of

the

final

amplifier

will

occur.

When

the

MIC

GAIN

control

setting

reaches

a

point

where

the

meter

just

indicates

a

slight

flicker

on

speech

peaks,

modulation

is

100%.

Operation

with

the

MIC

GAIN

control

above

this

point

should

be

avoided,

since

excessive

drive

will

cause

clipping

of

the

modulation

envelope,

resulting

in

unwanted

splatter.

3.2.8

TEN-METER

SEGMENT

SELECTION

If

it

is

desired

to

operate

on

other

than

the

28.5

MHz

to

29.1

MHz

segment,

the

10

meter

band

crystal

(14.6

MHz)

must

be

changed.

Crystals

are

available

from

the

Service

Department

of

the

National

Radio

Gompany,

Inc.

at

a

cost

of

$5.95

each.

The

optional

crystals

are

32,1

MHz

(covering

28.0

MHz

to

28.6

MHz)

and

15,2

MHz

{covering

29.1

MHz

to

29.7

MHz).

For

operation

on

the

29.1

MHz

to

29.7

MHz

seg-

ment

utilizing

the

15.2

MHz

crystal,

the

14.6

MHz

crystal

is

removed

and

replaced

with

the

15.2

MHz

crystal.

For

operation

on

the

28.0

MHz

to

28.6

MHz

segment

the

180

p¥

capacitor

C-73

across

the

10

meter

oscillator

trimmer

must

be

disconnected

at

one

end

and

the

32.)

MHz

crystal

should

be

inserted

in

the

14,6

MHz

socket.

3.2.9

CARRIER

INSERTION

CONTROL

AND

CARRIER

BALANCE

The

carrier

balance

control

R-56

of

the

NCX-500

is

internal

and

has

been

factory

adjusted

for

proper

carrier

suppression.

Readjustment

should

not

be

required

for

normal

SSB

operation.

If

desired,

it

may

be

set

in

the

following

manner:

Allow

the

transceiver

to

warm

up

for

approximately

30

minutes;

then

tune

and

load

as

for

SSB

operation.

Set

the

FUNC-

TION

switch

to

SSB.

Place

the

NCX-500

in

a

transmit

condition

either

by

means

of

the

push-to-talk

button

or

by

the

MOX

switch.

In

either

event,

the

MIC

GAIN

control

should

be

in

fuil

ccw

position

so

that

no

audio

modulation

will

occur.

The

carrier

balance

control

is

then

adjusted

for

mini-

mum

meter

indication,

This

meter

reading

should

be

between

50

and

60

ma.

if

the

BIAS

control

is

properly

adjusted.

When

the

carrier

balance

control

is

properly

set,

it

may

be

left

in

this

position

for

all

subse-

quent

operation.

A

more

precise

indication

of

carrier balance

control

setting

should

be

obtained

either

by

using

an

oscilloscope

connected

to

the

antenna

line

or

by

listening

to

the

suppressed

carrier

ona

separate

receiver.

With

proper

carrier

balance

and

tuning

of

the

transceiver

circuits,

voltage

on

the

antenna

line

should

not

exceed

0.5

volt

peak-to-peak

as

indicated

on

the

oscil-

loscope.

For

AM

operation,

it

is

necessary

to

adjust

the

CARRIER

INSERTION

control

‘

cw

from

zero

until

the

meter

indicates

a

final

amplifier

current

of

125

ma.

Thia

corresponds

to

approximately

135

watts

input

to

the

fina)

amplifier,

thus

assuring

operation

of

the

tubes

within

their

plate

die-

sipation

rating.

For

GW

operation,

it

is

necessary

to

adjust

the

CARRIER

INSERTION

‘control

cw

from

its

zero

setting

until

a

meter

indi-

cation

of

360

ma.

is

obtained.

This

assures

an

input

to

the

final

amplifier

of

approxi-

mately

400

watts

during

key

down

transmit

conditions

of

GW

operation.

Normai

keying

waveforms

approximate

less

than

a

50%

duty

cycle;

that

is;

Tibre

is

full

input

for

less

than

one-half

of

the

time

and

no

power

for

the

remaining

time.

Thus

the

time-

averaged

input

to

the

final

amplifier

assures

conservative

operation.

In

the

SSB

position

the

CARRIER

INSER-

TION

control

is

inoperative

and

full

carrier

suppression

is

obtained

at

alltimes.

When

the

FUNCTION

switch

is

turned

to

AM

or

CW,

the

CARRIER

INSERTION

control

becomes

operative

and

carrier

is

automat-

ically

inserted

according

to

the

preset

posi-

tion

of

the

CARRIER

INSERTION

control.

oo

SECTION

4

THEORY

OF

OPERATION

4.1

GENERAL

The

NCX-500

transceiver,

designed

to

cover

the

80

through

10

meter

amateur

bands,

combines

a

single

conversion

super-

heterodyne

receiver

and

single

sideband

transmitter,

both

employing

a

common

crystal

lattice

filter.

The

final

Pi

network

and

driver

tuning

circuits

of

the

transmitter

also

serve

as

RF

circuite

for

the

receiver.

The

carrier

oscillator

and

VFO

are

com-

mon

to

the

receiver

and

transmitter

circuits

while

the

receiver

first

IF

stage

is

used

as

a

low

level

amplifier

in

the

transmitter

function,

The

use

of

common

filter

and

RF

input

components

results

in

a

sensitive

and

image-iree

selective

receiver

and

in

a

high

quality,

low

distortion

SSB

transmitter.

The

operation

of

the

NCX-500

is

best

understood

by

reference

to

the

block

diagram

figure

4,

and

the

frequency

chart,

figure

5.

BLOCK

DIAGRAM

FIGURE

4

-

DRIVER_{

aad

XMIT

MIXER

aac

PRE

MIX

4.2

THE

TRANSMITTER

The

transmit

signal

path

of

the

NCX-500

is

indicated

on

the

block

diagram

by

a

dashed

line

starting

at

the

mike

jack

and

carrier

oscillator.

The

microphone

input

circuit

is

designed

for

high-impedance

(dynamic

or

crystal)

microphones

and

pro-

vides

a

push-to-talk

microphone

circuit.

©

The

microphone

is

connected

directly

to

the

grid

of

the

pentode

section

of

a

6GH8

(V-7A)

tube

which

operates

as

a

preampli-

fier.

The

signal

is

then

fed

through

the

microphone

gain

control

to

the

triode

sec-

tion

of

the

6GH8

(V-7B)

speech

amplifier.

The

cathode

circuit

of

this

speech

amplifier

is

coupled

to

the

diode

balanced

modulator.

A

12BA6

(V-8)

tube

is

used

for

the

car-

rier

oscillator.

The

carrier

signal

appears

across

a

resistive

plate

load

and

is

fed

to

the

diode

balanced

modulator.

The

ring

balanced

modulator

has

both

a

resistive

balance

adjustment

and

a

capacitive

phase

balance

adjustment.

The

balanced

primary

winding

of

the

output

transformer

is

coupled

to

a

single-ended

winding

which

feeds

the

=

RECEIVE

PATH

AGC

VOLTAGE

«©

-~—~-—

XMIT

PATH

(888)

eoueuen

———

CONTROL

PATHS

=

XMIT

AND

RECEIVE

input

of

the

12BA6

(V-9)

which

functions

as

a

transmit

IF

etage.

The

transmit

IF

stage

feeds

a

double

tuned

output

circuit.

The

secondary

winding

serves

as

an

input

source

for

the

four

pole

crystal

lattice

filter.

The

crystal

lattice

filter

is

terminated

by

the

IF

input

circuit

coupled

to

the

grid

of

the

12BA6

(V-3)

firet

IF

etage.

The

single

tuned

plate

circuit

is

coupled

to

the

grid

of

the

6JD6

(V-12)

transmit

mixer.

The

VFO

uses

a

12BA6

(V-10)

tube

oper-

ating

as

a

grounded

cathode

Hartley

oscil-

later.

The

tank

circuits

of

this

oscillator

use

extremely

stable

capacitors

to

provide

minimum

warm-up

drift

and

maximum

fre-

quency

stability.

Output

is

obtained

from

the

screen

grid

assuring

maximum

stability

with

change

in

output

load.

A

crystal

controlled

band

oscillator

using

the

triode

section

of

a

6GH8

(V-11

A)

provides

crystal

frequencies

of

21.5

MHz,

25.1

MHz,

and

14.6

MHz.

Thies

signal

is

mixed

with

the

VFO

output

in

the

pentode

section

of

the

6GH8

(V-11

B)

resulting

in

an

FREQUENCY

MIXING

CHART

FIGURE

5

BAND

XTAL

OSC.

PREMIX,

«=:

VFO.

OSC,

MIX

CARRIER

OSC.

FREQ:

RESULTANT.

60

NOT

USED

+

8.7

to

9.3

-

5.2003

3.5

MHzto

4.1

MHz

0

Be

ea

87

093

=

5.2003

7.0

MHz

to

7.5

MHz

20

NOT

USED

+

8.7098

+

5.2003

19.9

Mis

to

145

MHz

1s

25.1

-

879.3

+

5.2003

21.0

MHz

to

21.6

MHz

bso

321

_

8.7093

+

5.2003

28.0

MHz

to

29.6

MHz

MIO

146

+

8.71098

+

5.2008

28.5

MHz

to

29.1

MH

H10

182

+

8.71093

+

5.2003

29.1

MHz

to

29.7

MHz

a

injection

signal

for

the

first

receive

and

-tranamit

mixers.

A

single

tuned

circuit

is

used

in

the

output

of

the

pre-mix

circuit

to

provide

for

oscillator

purity.

The

plate

circuit

of

the

transmit

mixer

is

single-tuned

and

feeds

the

grid

of

the

6GK6

(V-13)

driver.

The

single

tuned

plate

circuit

of

the

driver

feeds

the

grid

of

the

final

amplifier.

The

coils

in

the

plate

cir-

cuits

of

the

transmit

mixer,

driver,

and

premixer

are

band

switched

for the

80,

40,

20,

15,

and

10

meter

amateur

bands.

The

tuning

gang

is

tracked

so

that

exciter

tuning

can

be

accomplished

with

only

one

control.

The

gain

of

the

transmit

mixer

and

driver

are

such

that

a

driving

signal

in

excess

of

100

volts

canbe

obtained

at

the

grid

of

the

final

amplifier,

thus

assuring

linear

oper-

ation

of

the

exciter

to

well

above

the

level

necessary

for

proper

drive.

The

final

amplifier

employs

a

matched

pair

of

6LOQ6

(V-14

and

V-15)

tubes

oper-

ating

in

parallel.

A

BIAS

control

on

the

rear.apron

sets

proper

idling

current,

The

plates

of

the

6LQ6

final

amplifier

tubes

are

_

coupled

to

a

high

efficiency

Pi

network.

The

BAND

switch

selects

proper

inductance,

tuning,

and

load

capacitance

to

match

a

40

to

60

ohm

resisfive

load

over

the

entire

80,

40,.20,

15,

and

10

meter

amateur

bands.

The

Pi

network

is

designed

for

continuous

operation

at

a

power

level

of

500

watts

in-

put.

A

small

adjustable

capacitor

coupled

from

the

plate

of

the

6LQ6

final

amplifier

to

the

partially

by-passed

return

of

the

final

grid

circuit

coils

(driver

plate

coils)

pro-

vides

neutralization.

When

the

final

ampli-

fier

is

properly

neturalized,

maximum

out~

put

on

a

matched

antenna

or

accurate

50

ohm

dummy

load

will

occur

at

the

point

of

plate

current

dip

as

indicated

on

the

meter.

An

effective

ALC

(automatic

level

con-

trol)

circuit

is

included,

If

the

final

ampli-

fier

grids

are

overdriven

on

voice

peaks,

the

grids

will

actually

see

a

driving

signal

positive

with

respect

to

the

cathodes,

and

grid

current

will

result.

This

current

will

cause

a

negative

voltage

change

on

the

bias

circuit.

The

resulting

audio

signal

on

the

bias

circuit

ig

capacitively

coupled

to

a

voltage-doubling

rectifier.

This

rectifier

will

provide

a

negative

DC

output

which

is

coupled

to

the

grid

return

of

the

12BA6é

{V-3)

first

IF

amplifier.

When

overdrive

occurs,

the

gain

of

the

first

IF

amplifier

is

reduced,

resulting

in

éea

driving

signal

at

the

final

amplifier.

Charging

takes

place

rapidly

from

the

low-impedance

bias

source

through

the

rectifying

diodes,

but

the

nega-

tive

ALC

voltage

cannot

discharge

through

the

reverse

biased

diodes,

resulting

ina

fast

attack~slow

release

action.

A

gating

diode

prevents

cross

connection

of

the

ALC

and

AGC

circuits

at

the

common

IF

grid

return

point..

The

ALC

circuit

will

provide

automatic

level

control

for

input

signal

variations

of

more

than

10

db,

and

makes

the

setting

of

the.

MIC

GAIN

control

quite

noncritical;

In

addition,

sudden

changes

in

voice

level

or

disturbing

background

noises

are

controlled

without

overdrive

and

distor-

tion

of

the

NCX-500

transmitter

signal.

4.3

THE

RECEIVER

The

receiver

circuits

are

indicated

by

the

double

solid

lines

in

the

block

diagram.

The

receiver

RF

circuits

are

common

to

the

transmitter

RF

circuits.

The

high

impedance

point

of

the

transmitter

Pi

net-

work

is

capacitively

coupled

to

the

grid

of

a

6BZ6

(V-1)

RF

amplifier.

The

transmit

driver

and

RF

amplifier

plates

are

connected

to

the

same

tuned

circuit

insuring

consist-

ency

in

receive

and

transmit

tuning

as

well

as

high

selectivity.

The

output

from

the

RF

amplifier

is

coupled

to

the

signal

grid

of

the

first

receive

mixer,

a

12BE6

(V-2).

The

plate

of

this

mixer

is

coupled

to

the

second-

ary

of

the

transmit

IF

transformer

(T-2)

which

serves

as

the

input

coil

to

the

crystal

lattice

filter.

The

output

of

the

crystal

lattice

filter,

as

in

the

transmitter,

couples

to

the

input

of

a

two

stage

single-tuned

IF

amplifier

operating

at

approximately

5.2

MHz.

The

detector

and

AGC

circuits

are

fed

through

separate

voltage

dividers.

The

product

detector

employs‘one

triode

of

the

12AX7

(V-5)

tube

with

the

signal

from

one

IF

volt-

age

divider

fed

to

the

grid.

A

BFO

signal

is.

coupled

from

the

crystal

controlled

12BA6

(V-8)

carrier

oscillator

to

the

cathode

of

the

product

detector,

and

the

resulting

audio

signal

is

obtained

across

a

resistive

load

in

the

plate

circuit.

For

AM

operation,

the

cathode

of

the

product

detector

is

grounded

to

permit

operation

as

a

grid

leak

detector.

The

output

from

the

detector

is

coupled

to

the

audio

gain

control,

and

then

to

the

grid

of

the

remaining

triode

section

of

the

12AX7

(V-5

B)

tube

functioning

as

a

grid-

leak

biased,

first

audio

amplifier.

The

plate

circuit

is

coupled

to

the

grid

of

the

6AQ5

(V-6)

audio

output

stage.

The

audio

output

stage

feeds

the

output

transformer

with

a

3.2

ohm

secondary.

This

output

sig-

nal

is

available

on

the

speaker

output

pins

of

the

power

plug

or

at

the

phone

jack.

The

low

impedance

nature

of

the

phone

jack

feed

permits

use

of

either

high

or

low-impedance

phones.

A

secondary

feed

is

obtained

from

the

plate

circuit

of

the

last

IF

amplifier

and

is

fed

to

a

voltage

-doubling

AGC

rectifier

(D-4

and

D-5).

The

low-impedance

driving

source

provides

a

rapid

charge

of

the

AGC

bus.

When

the

signal

disappears,

the

nega-

tive

AGC

bus

cannot

discharge

through

the

diodes,

which

provides

a

long

release

time,

thus

giving

the

AGC

a

very

effective,

fast

attack-slow

release

action.

The

AGC

is

fed

to

the

grid

of

the

6GH8

(V-7

B)

S-Meter

amplifier.

AGC

voltage

is

connected

to

the

grid

return

of

the

RF

stage,

through

the

gating

diode

(D-3)

to

the

first

IF

stage,

and

to

the

second

IF

stage

for

control

of

receiver

gain.

.

4.4

THE

FUNCTION

SWITCH

The

following

paragraphs

describe

the

operation

of

the

various

switching

circuits

with

the

FUNCTION

switch

in

all

possible

positions,

4.4.1

FUNCTION

SWITCH

OFF

In

this

position

the

FUNCTION

switch

interrupts

the

primary

power,

either

directly

in

case

of

the

NCK

AC

500

power

“

supply

or

through

a

remote

relay

in

the

case!

of

a

12

volt

DC

supply.

4.4.2

FUNCTION

SWITCH

IN

SSB

POSI-

TION

In

this

position

the

following

circuits

are

setup:

The

product

detector

and

the

micro-

phone

amplifier

are

connected

into

the

cir-

cuit.

The

key

jack

is

disconnected

to

pre-

vent

accidental

keying.

The

CARRIER

INSERTION

control

is

disconnected,

and

a

negative

bias

is

applied

to

the

12BA6

(V-9)}

transmit

IF

stage

to

reduce

gain.

With

the

MOX

switch

in

the

OFF

position,

the

push-

to-talk

contact

is

connected

across

the

relay

line.

When

the

push-to-talk

contact

is

pushed,

the

relay

line

is

grounded,

closing

the

relay.

With

the

MOX

switch

in

the

MOX

position,

the

relay

line

is

grounded

directly.

Switching

occurs

as

with

push-to-talk

oper-

ation.

Returning

the

MOX

switch

to

OFF

will

turn

the

transmitter

off

and

put

the

equipment

in

the

receive

mode.

4.4.3

FUNCTION

SWITCH

IN

AM

POSITION

The

AM

position

of

the

FUNCTION

switch

applies

bias

to

the

carrier

oscillator

during

receive

conditions

to

silence

the

BFO

signal.

The

product

detector

cathode

is

grounded

during

recéive

periods

to

convert

the

detector

to

a

grid

leak

AM

detector.

In

this

position,

the

carrier

insertion

control

is

connected,

and

bias

is

removed

from

the

12BA6

(V-9)

transmit

IF

stage,

providing

full

carrier

insertion

from

60

to

450

ma.

PTT

and

MOX

functions

now

operate

in

the

same

manner

as

described

under

SSB.

4.4.4

FUNCTION

SWITCH

IN

CW

POSITION

In

this

position

the

function

switch

will

ground

the

plate

of

the

microphorie

preampli-

fier

to

prevent

accidental

modulation

and

MHz,

27.9

MHz,

29.2

MHz.

will

connect

the

KEY

jack

to

the

transmitter

1.

Connects

the

S-Meter

to

the

cathode

bias

line.

The

product

detector

is

con-

of

the

S-Meter

amplifier

tube

during

nected.

The

CARRIER

INSERTION

control

receive

periods,

and

grounds

the

S-

is

still

connected

as

described

in

the

AM

Meter

so

that

it

will

function

as

a

position.

plate

current

indicator

during

trane-

mit

periods.

4.4.5

FUNCTION

SWITCH

IN

TUNE

2.

Closes

the

external

relay

terminale

‘POSITION

during

receive

periods.

;

In

thie

position

the

FUNCTION

switch

3.

Switches

the

220V

B+

to

various

will

ground

the

relay

line,

placing

the

receiver

stages

during

receive

transmitter

into

operation

as

described

periods

and

to

various

transmitter

under

SSB-PTT

Operation.

The

MOX,

stages

during

transmit

periods.

PTT,

and

key

circuits

are

disabled

and

.

have

no

influence

on

the

tuning

procedure.

4.

Removes

bias

from

various

receiver

The

center

arm

of

the

CARRIER

INSER-

stages

during

receive

periods

and

TION

control

is

switched

to

the

top

of

the

removes

bias

from

various

transmit

control,

providing

an

unbalanced

condition.

stages

during

transmit

stages.

Trans-

The

bias

on

V-10

is

still

at

zero.

This

pro-

mitter

bias

is

not

removed

when

the

vides

appropriate

drive

for

tune-up.

FUNCTION

switch

is

placed

in

the

CW

<e

position,

allowing

the

key

to

function

through

this

pole

and

provide

grid

4.5

RELAY

OPERATION

block

keying.

In'the

foregoing

discussion,

the

exact

5.

Grounds

the

RF

Gain

control

bus

nature

of

the

relay

switching

was

not

de-

during

transmit

periods

to

remove

scribed.

The

six-pole

double

throw

relay

RF

Gain

control

from

the

first

IF

is

actuated

by

completing

the

ground

side

amplifier

which

is

used

as

a

trans-

of

the

12

VDC

Relay

Bus.

The

NCX-500

is

mitter

amplifier.

placed

in

a

transmit

condition

when

the

relay

is

energized.

6.

Connects

the

product

detector

cathode

.

return

during

receive

periods

and

The

six

poles

of

the

relay

are

used

in

grounds

the

AGC

circuit

during

trans-

the

following

manner,

reading

from

left

to

mit

periods

to

prevent

accidental

right

on

the

schematic

diagram:

charge

of

the

AGC

bus.

SECTION

5

TEST

AND

ALIGNMENT

NOTE

2.

Vacuum

tube

voltmeter

(VTVM).

Test

and

alignment

of

the

NCX-500

3,

Standard

audio

output

meter.

transceiver

should

only

be

performed

by

competent,

qualified

personnel.

4,

High

frequency

oscilloscope

covering

the

range

from

DC

to

30

MHz

with

a

maximum

sensitivity

of

50

mv

per

5.1

EQUIPMENT

REQUIRED

centimeter

or

eee

and

a

low

Fi

ity

i

be

(Tektronix

type

1,

Signal

generator

providing

output

at

capacity

input

pro!

ses

the

following

frequencies:

3.5

MHz,

oto

Series

hag

type

L

preamplifier

4.1

MHz,

5.2

MHz,

9.0

MHz,

12.5

bea

ara

Miley

BSL

Mis

22-8

ener

20-3

5.

50

ohm

dummy

load

with

calibrated

output

meter

covering

the

frequency

range

from

3.5

to

30

MHz.

(A

high

{frequency

vacuum

tube

voltmeter

with

a

100

volt

full

scale

range

may

be

substituted

for the

calibrated

out-

put

power

meter.)

6.

Power

supply

capable

of

supplying

+1100

volts

at

450

ma.,

+280

volts

at

200

ma.,

and

-100

volts

at

10

ma.

7.

1000

Hz

audio

generator

with

an

out-

put

level

of

10

mv.

8.

High

quality

microphone

equipped

with

push-to-talk

button.

9.

Transmitting

key.

10.

Suitable

alignment

tools

for

adjust-

,’

©

ment

of

coils

and

capacitors,

ll,

xcu-

27

¢rystal

calibrator,

Power

Connections:

Disconnect

the

1100

volt

output

of

the

power

supply.

The

heater

wire

connecting

the

two

6LQ6

sockets

should

be

removed.

5.2

MHZ

IF

ALIGNMENT

Turn

the

FUNCTION

switch

to

AM.

Set

the

RF

GAIN

and

AUDIO

GAIN

controls

to

maximum,

‘fully

cw.

Connect

the

audio

output

meter

to

the

speaker

leads.

This

may

be

conveniently

done

by

plugging

the

meter

into

the

phone

jack.

Conneot

the

signal

generator

through

a

1000

pF

capacitor

to

the

grid

(pin

#7)

of

the

12BE6

(V-2)

receive

mixer

tube

socket.

Set

the

signal

generator

output

to

approxi-

©

mately

5.2

MHz

with

audio

modulation

at

30%.

Audio

output

should

be

audible.

Adjust

the

signal

generator

frequency

to

match

the

center

frequency

of

the

band

pass

filter

as

indicated

by

maximum

output,

Tune

the

elugs

of

the

Ist

and

2nd

IF

coils

L-23,

L-24,

L-25

and

the

bottom

slug

of

T2

(transmitter

IF)

for

maximum

output,

being

careful

to

avoid

overload

of

the

recéiving

channel.

The

signal

generator

output

should

be

reduced

throughout

the

alignment

procedure

so

that

the

output

meter

reading

does

not

exceed

0.5

watt.

After

all

coils

are

tuned

and

peaked

the

out-

put

level

of

the

audio

meter

should

read

0.5

watt

with

20

pv

input

from

signal

generator.

Disconnect

the

signal

generator

and

output

neter,

5.3

CARRIER

OSCILLATOR

AND

BALANCED

MODULATOR

ALIGNMENT

Place

the

FUNCTION

switch

in

TUNE

position,

Connect

the

oscilloscope

to

junc-

tion

of

F-1,

C-98,

and

C-99

(output

of

the

5.2

MHz

crystal

filter),

Tune

the

top

slugs

of

Tl

and

T2

transmitter

IF

transformer

for

maximum

output

on

the

oscilloscope.

Adjust

the

carrier

oscillator

trimmer

(C-

146)

until

the

indicated

signal

level

is

0.4

volt

peak-to-peak

as

indicated

on

the

oscil-

-

lescope.

Disconnect

the

oscilloscope

from

circuit.

5.4

VFO

ALIGNMENT

Place

the

FUNCTION

switch

in

the

SSB

position,

Set

the

BAND

switch

to

3.5

MHz.

Place

the

MOX

switch

in

the

OFF

position.

Connect

the

high

frequency

signal

generator

to

antenna

jack.

Set

the

generator

output

to

3.5

MHz,

and

tune

the

main

tuning

dial

to

3.5

MHz.

Tune

the

VFO

coil

slug

(L-20)

for

zero

beat.

Now

tune

the

main

tuning

dial

to

4.1

MHz,

and

set

the

generator

to

hear

a

signal

at

the

4.1

MHz

dial

setting.

Check

for

zero

beat.

If

zero

beat

occurs

higher

than

4.1

MHz,

adjust

the

VFO

trim-

mer

capacitor

(C-86)

for

more

capacity.

If

zero

beat

occurs

lower

than

4.1

MHz,

adjust

the

VFO

trimmer

capacitor

(C-86)

for

less

capacity.

Now

return

the

VFO

dial

to

3.5

MHz,

and

set

the

signal

generator

to

3.5

MHz;

repeat

this

procedure

until

the

3.5

MHz

beat

note

occurs

at

the

3.5

MHz

dial

setting

and

the

4,1

MHz

beat

note

occurs

at

the

4.1

MHz

dial

setting,

or

until

desired

accuracy

is

achieved.

5.6

PRE-MIX

AND

DRIVER

ALIGNMENT

Connect

the

signal

generator

output

to

the

grid

(pin

#2)

of

the

premixer

on

6GH8

(v-11)

through

a

1000

pF

capacitor.

Remove

the

12BA6

{V-10)

VFO

tube;

then

remove

the

14.6

MHz,

25.1

MHz,

and

21.5

MHz

crystals

from

the

sockets

of

the

crystal

oscillator.

Connect

the

oscilloscope

to

the

grids

of

the

6GJ5

(V-14

and

V-15)

final

‘

amplifier

tubes.

Set

the

FUNCTION

switch

to

the

TUNE

position

and

the

BAND

switch

to

the 3.5

MHz

position,

Set

the

signal

generator

to

9.0

MHz,

and

turnthe

EX-

CITER

TUNE

knob

to

#5

on

panel.

Adjust

the

pre-mix

trimmer

(C-62),

the

mixer

coil

(L-11),

and

driver

coil

(L-5)

for

maximum

indication

on

the

oscilloscope.

This

output

should

exceed

200

volts

peak-to-peak.

“+10

Meter

Band:

~

FOR

EACH

BAND

REPEAT

THE

PROS.

ESS

USED

ON

THE

80

METER

BAND:

oe

40

Meter

Band:

es

a

Set

the

signal

generator

to

12.5

MHz.

Then

turn

thé

EXCITER

TUNE

knob

to

#8

on

panel."

Adjust

the

pre-mix

trim-

mer

(C-57),

the

mixer

coil

(L-12),

and

the

driver

coil

(L-6)

for

more

than

200

volts

on

final

grids.

5

"20

Meter

Band:

”

ay

7

Set

signal

géherater

to

9.0

MHz.

Then

turn

the

EXCITER’

TUNE

knob

to

#3

on

“J

panel.

Adjust

the:mixer

coil.

(L-13)

and

the

driver

coil

(L-7}

for

more

than

200

volta

on

final

grids.

.

y

Set

signal

generator

to

29.2

MHz,

and

tune

the

trap

(C-152)

to,

minimum

signal.

Set

signal

generator

to

27.9:.MHz,

and

tune

the

trap

(C-15!)'for

minimum

indi-

cation,

Set

the

EXCITER

TUNE

knob

to

#2

on

the

panel..

Now

set

the

signal

generator

to

22,8

MHz

and

align

the

pre-

mix

coil

(L-16),

the

mixer

coil

{L-15),

and

the

driver

coil

(L-9)

for

maximum

indicated

output

on

oscilloscope.

Set

signal

generator

to

24.5

MHz,

and

turn

the

EXCITER

TUNE

knob

to

#7

on

anel,

Adjust

the

pre-mix

trimmer

'‘C-60)

for

maximum

reading

on

oscillo-

scope.

Repeat

this

procedure

until

proper

tracking

is

achieved.

The

indi-

cated

output

on

oscilloscope

at

both

fre-

quencies

should

read

150

volts

peak-to-

peak.

15

Meter

Band:

.

Set

signal

generator

to

16,1

MHz,

Then

turn

the

EXCITER

TUNE

knob

to

#7

on

nel,

Adjust

the

pre-mix

trimmer

'G-59),

the

mixer

coil

(L-14),

and

the

driver

coil

(L-8)

for

maximum

indicated

output

of

200

volts

peak-to-peak.

Remove

the

signal

generator

and

replace

the

VFO

tube

12BA6

(V-10)

and

the

crystals

in

their

proper

sockets,

This

completes

the

adjustment

of

the

mixer

and

driver

stages

with

the

exception

that

a

slight

mis-

alignment

now

exists

in

the

driver

coil,

due

to

the

presence

of

the

oscilloscope

.

probe

during

and

measurements,

This

error

will

be

cor-

rected

during

testing

of

the

fina]

amplifier

stages

to

be

described

later.

13

5.6

CRYSTAL

OSCILLATOR

ALIGNMENT

Connect

the

oscilloscope

probe

to

the

grid

(pin

#2)

of

the

6GH8

fv

B)

premixer

tube.

Turn

the

BAND

switch

to

7.0

MHz.

Set

the

FUNCTION

switch

to

the

SSB

posi-

tion,

The

21.5

MHz

crystal

oscillator

now

supplies

the

signal,

Tune

the

21.5

MHz

.,

crystal

trimmer

(C-78)

to

maximum

indi-

cation

ofi

oscilloscope.

When

this

point

is

reached,

add

slightly

more

capacity

to

reduce

the

output

reading

to

80%

of

the

maximum

reading.

Set

the

BAND

switch

to

21:0

MHz.

This

position

uses

the

25.1

MHz

crystal;

tune

the

25.1

MHz

crystal

trimmer

(c-76)

to

maximum

indication

on

the

oscil-

loscope.

Then

reduce

the

output

reading

to

80%

of

the

maximum

reading.

Now

set

the

BAND

ewitch

to

28.0

MHz

where

the

14.6

MHz

crystal

is

now

used.

Te

the

14.6

MHz

crystal

trimmer

(C-74)

to

2

volts

peak-

to-

peak

at

this

point.

a

5.7

FINAL

AMPLIFIER

PRELIMINARY

ADJUSTMENTS

*

e

9

Although

the

NCX-500

does

not

reqiire

any

alignment

of

the

final

amplifier,

it

is

necessary

at

this

time

to

check

for

proper

_

operation

at

the

high

and

low

ends

of

all

bands.

In

addition,

it

is

necessary

to

make

final

adjustments

on

the

driver

plate

coils

*

and

on

the

neutralizing

capacitor,

.These

checks

should

be

made

in

following

sequence:

Reconnect

the

1100

volts

in-power

supply.

Connect

heater

wire

between

the

6LQ6

sock-

ets,

Place

the

FUNCTION

switch

in

TUNE

position

and

allow

30

seconds

for

warm-up

of

final

tubes.

8

Up

to

this

point

there

has

been

no

power

applied

to

the

final

amplifier.

All

circuits

which

have

been

opera-

ting

and

which

have

been

tested

are

low

level,

comparatively

low

voltage

circuits.

From

here

on,

voltages

and

currents

are

present

which

are

particularly

dangerous

to

personnel,

to

the

test

equipment,

and

the

unit

under

test.

It is

essential

to

be

sure

that

no

piece

of

test

equipment

is

misconnected

to

the

NCX-500,

and

that

it

not

be

placed

into

a

transmit-

ting

condition

without

proper

tuning,

since

damage

may

rapidly

result.

In

a

number

of

the

following

teste,

the

transmitter

will

be

operated

at

full

power

output.

It

is

important

that

the

unit

be

returned

to

a

receiving

condition

if

misindications

are

ob-

tained,

if

the

test

is

not

completed

within

a

period

of

30

seconds,

or

if

the

unit

is

not

tuned

up

within

a

period

of

30

seconds.

Otherwise,

serious

and

permanent

damage

may

occur

in

the

final

output

circuit.

Disconnect

all

previously

used

test

equipment

from

the

NCX-500,

Attach

the

50

ohm

dummy

load

and

calibrated

output

meter

to

the

antenna

connector,

Set

the

BAND

switch

to

28.0

MHz.

Set

the

main

tuning

dial

to

28.8

MHz.

Now

turn

the

FUNCTION

switch

to

TUNE

and

rapidly

peak

the

EXCITER

TUNE

for

maximum

meter

reading

on

the

combination

S-Meter

and

cathode

current

meter.

Adjust

the

10

meter

drive

plate

coil

(L-9)

for

maximum

meter

reading

while

slowly

rocking

the

EXCITER

TUNE

control.

This

will

cor-

rect

for

the

presence

of

the

oscilloscope

probe

in

the

Now

rotate

the

PA

TUNE

control

and

observe

whether

a

dip

occurs

in

plate

current

reading.

Note

the

power

output

recorded

by

the

power

output

meter.

This

power

output

should

exceed

150

watts

at

all

frequencies,

provided

that

the

PA

LOAD

control

is

adjusted

so

that

the

final

amplifier

draws

450

ma.

With

the

PA

TUNE

control

set

for

a

plate

current

dip,

the

PA

LOAD

con-

trol

is

slowly

rotated

in

a

clockwise

direc-

tion.

As

the

PA

LOAD

control

is

adyanced,

it

will

be

necessary

to

slightly

retune

the

PA

TUNE

control

to

stay

in

the

dip.

Con-

tinue

this

process

until

the

minimum

read-

ing

in

the

dip

corresponds

to

450

ma.

on

the

meter.

5.8

NEUTRALIZING

CAPACITOR

With

the

FUNCTION

switch

in

the

TUNE

position,

rotate

the

PA

TUNE

control

to

either

side

of

the

resonant

point

and

observe

the

plate

current

meter.

It

is

necessary

that

the

off

resonance

current

exceed

500

ma.

Having

noted

the

off

resonance

plate

current,

retune

the

PA

TUNE

control

to

the

plate

current

dip

at

450

ma,

and

observe

the

power

output.

It

should

exceed

150

watts.

Carefully

rotate

the

PA

TUNE

con-

trol

to

either

side

of

the

dip

and

observe

whether

the

power

output

rises

or

falls.

With

proper

setting

of

the

neutralizing

capacitor,

the

power

output

should

fall

on

either

side

of

the

dip.

If

the

power

output

rises

as

the

PA

TUNE

control

is

tuned

away

from

the

dip,

it

will

be

necessary

to

adjust

the

neutralizing

capacitor.

This

can

be

quickly

done

on

a

trial

and

error

basis

by

rotating

the

neutralizing

capacitor

and

observing

whether

maximum

power

output

occure

at

the

plate

current

dip.

As

proper

neutralization

is

achieved,

maximum

power

output

will'occur

at

minimum

plate

current.

Return

the

FUNCTION

switch

to

CW.

5.9

FINAL

AMPLIFIER

PRELIMINARY

ADJUSTMENT

(80-15

METERS)

Set

the

BAND

ewitch

to

21.0

MHz

and

the

main

tuning

dial

to

21,250

MHz.

-Turn

the

FUNCTION

switch

to

TUNE

and

rapidly

peak

the

EXCITER

TUNE

for

maximum

meter

reading.

Adjust

the

15

meter

driver

plate

coil

(L-8)

for

maximum

meter

reading

while

slowly

rocking

the

EXCITER

TUNE

control,

This

will

correct

for

the

presence

of

the

oscilloscope

probe

in

Now

rotate

the

PA

TUNE

control

and

observe whether

a

dip

appears

in

the

read-

ing.

Advance

the

PA

LOAD

ina

clockwise

direction,

and

slightly

retune

the

PA

TUNE

control

to

stay

in

dip.

Continue

this

proc-

ees

until

the

minimum

meter

reading

in

the

dip

corresponds

to

450

ma.

The

power

out~-

put

should

exceed

150

watts

and

proper

neu-

tralization

should

be

observed.

Repeat

this

procedure

at

the

following

BAND

switch

and

tuning

settings,

in

each

case

adjusting

the

proper

driver

coil

for

maximum

meter

indication

while

rocking

the

EXCITER

TUNE

control.

BAND

MAIN

DRIVER

SWITCH

TUNING

DIAL

GOIL

14.0

MHz

14,2

MHz

L-7

7.0

MHz

7,2

MHz

L-6

3.5

MHz

3.7

MHz

L-5

5.10

CARRIER

SUPPRESSION,

SIDEBAND

SUPPRESSION,

MODULATION

AND

ALC

CHECKS

Connect

the

audio

generator

to

the

MIC

jack

and

supply

10

mv

of

audio

signal

to

the

NCX-500.

Rotate

the

FUNCTION

switch

to

the

TUNE

position.

Connect

the

high-fre-

quency

oscilloscope

to

the

antenna

line

WAVEFORMS:

FIGURE

6

D

(CLIPPED?

C

(correct)

E

(Poor

cusps)

which

is

connected

to

the

dummy

load,

Tune

the

final

amplifier

for

maximum

out-

put

at

450

ma,

input

as

described

in

the

A

level

well

in

excess

of

200

volts

peak-to-peak

should

be

noted

on

the

oscilloscope,

Turn

the

FUNCTION

switch

to

the

SSB

position.

Place

the

MOX

switch

in

the

MOX

position,

and

set

the

carrier

balance

control

for

minimum

indi-

cation

on

the

oscilloscope

which

should

correspond

to

minimum

indication

on

the

meter.

Adjust

the

BIAS

control

for

60

ma,

on

the

meter.

The

level

remaining

on

the

oscilloscope

should

not

exceed

0.5

volt

peak-to-peak,

‘thus

insuring

carrier

sup-

pression

better

than

50

db.

If

necessary,

carefully

adjust

the

balanced

modulator

phase

trimmer

(C-6)

for

minimum

indica-

tion

while

rocking

the

carrier

balance

con-

trol

through

minimum

until

the

required

0.5

volt

level

is

obtained.

Now

rotate

the

MIC

GAIN

control

slowly

in

a

clockwise

direction.

A

signal

should

again

appear

on

the

oscilloscope.

The

MIC

GAIN

should

be

advanced

until

the

cathode

current

meter

reads

450

ma.

Output

at

the

scope

should

be

120-180

volts.

The

waveform

at’

[

ai

this

point

should

appear

as

indicated

in

figure

6A.

It is

necessary

to

note

the

level

of

ripple

on

the

waveform

to

total

waveform

level.

The

ripple

should

not

exceed

1/30

of

the

‘total

waveform,

This

indicates

that

the

unwanted

sideband

suppression

with

a

1000

cycle

tone

is

in

excess

of

30

db,

the

limit

of

this

measuring

technique.

It

is

important

to

note

the

difference

between

carrier

balance

and

unwanted

side~

band

suppression

in

the

ment.

If

the

carrier

balance

control

is

rotated

slightly,

the

waveform

of

figure

6A

will

be

altered

to

the

waveform

of

figure

6B.

If

this

waveform

is

present

while

attempting

to

make

the

sideband

suppression

measure-

ment,

the

carrier

balance

contro)

should

be

slightly

adjusted

to

compensate

and

return

the

picture

to

that

of

figure

6A.

Place

the

FUNCTION

switch

in

the

AM

position.

Now

further

advance

the

MIC

GAIN

until

the

meter

just

reaches

450

ma,

as

set

by

the

procedure.

Note

the

oscilloscope

level.

Slowly

advance

the

CARRIER

INSERTION

control

cw

from

the

minimum

setting,

As

this

occurs,

the

waveform

will

begin

to

develop

large

cusps

and

peaks

which

will

tend

to

exceed

the

noted

oscilloscope

level.

Slowly

reduce

the

MIC

GAIN

to

keep

the

peaks

at

the

predetermined

level

by

carefully

adjusting

both

the

MIC

GAIN

and

the

CARRIER

INSERTION

control.

It

should

be

possible

to

obtain

a

picture

ae

illustrated

in

figure

6C.

It

is

important

that

the

peaks

of

this

figure

be

at

exactly

the

level

determined

with

the

balanced

carrier

at

450

ma.

of

cathode

current.

This

is

a

two-tone

test

and

is

useful

in

indicating

distortion

in

the

transmitter

channel

and

performance

of

the

modulating

circuits.

The

waveform

which

is

observed

should

have

a

clean

sharp

cusp

and

should

have

a

sine

wave

envelope.

There

should

be

no

flattening

of

the

peaks

and

no

broadening

of

the

cusps.

Typical

incorrect

waveforms

are

indicated

in

figures

6D

and

6E.

5.11

ALC

AUTOMATIC

LEVEL

CONTROL

Advance

the

MIC

GAIN

control

to

maxi-

mum

and

readjust

the

CARRIER

INSER-

TION

control.for

sharp

cusps.

The

final

amplifier

should

now

be

overdriven

and

ALG

voltage

should

result.

The

oscillo-

scope

waveform

should

remain

as

shown

in

figure

6C,

Check

the

ALC

output

at

the

junction

of

D-1,

G-25,

R-6,

and

R-29.

There

should

be

approximately

5

volts

at

this

point.

i

The

rear

ALC

jack

may

now

be

checked

by

applying

-10

volts

at

the

ALC

input

jack.

The

oscilloscope

display

amplitude

should

decrease

indicating

proper

external

control.

Press

the

MOX

switch

to

OFF,

The

set

is

now

ready

for

push-to-talk

operation.

16

If

all

of

the

tests

are

met

satisfactorily,

it

can

be

assumed

that

the

transmitter

section

is

working

properly,

although

it

is

of

some

value

to

check

the

dynamic

operation

of

the

transmitter

on

the

microphone.

To

do

thia,

return

the

MIC

GAIN

to

zero

and

place

the

FUNCTION

switch

in

the

SSB

position.

Now

remove

the

audio

generator

from

the

MIC

jack

and

replace

‘it

with

the

test

microphone,

Press

the

push-to-talk

switch

and

speak

normally

into

microphone.

Slowly

advance

MIC

GAIN

control

until

peaks

of

the

result-

ing

signal

reach

the

amplitude

used

for

the

test.

Aft

this

point

the

meter

will

be

fluctuating

rapidly

with

the

speech

content.

The

meter

should

generally

average

around

200

ma.

of

current

and

the

output

waveform

should

appear

as

illus-

trated

in

figure

6F.

5.12

CW

CHECK

Place

the

FUNCTION

switch

in

the

CW

position.

Plug

the

key

in

the

key

jack.

Load

the

transmitter

as

in

Press

the

MOX

switch

to

MOX.

With

key

down,

rotate

the

CARRIER

INSERTION

control

until

meter

reads

360

ma.

Now

key

the

transmitter

and

check

the

pattern

of

RF

on

the

oscilloscope.

A

correct

pattern

should

look

like

the

figure

6G.

Remove

the

oscilloscope.

5.13

RECEIVER

IF

TRAP

ALIGNMENT

Connect

the

signal

generator

to

antenna

ts.

Set

the

signal

generator

to

5.2

MHz

‘center

frequency

of

the

bandpass

filter).

Adjust

the

IF

trap.capacitor

(6-91)

for

minimum

output,

ed

;

SECTION

6

PARTS

LIST

ALL

READILY

AVAILABLE

RESISTORS

AND

CAPACITORS:

ARE

OMITTED

FROM

THE

FOLLOWING

PARTS

LIST,

BUT

ARE

COMPLETELY

IDENTIFIED

ON

THE

SCHEMATIC:

PART

NUMBER

PART

SYMBOL

DESCRIPTION

NUMBER

SYMBOL,

_

DESCRIPTION

SOGKETS

AND

JACKS

TUBES

AND

DIODES

(Cont)

Socket

Crystal

A-50799

pis

Diode

1N711

Socket

Novar

‘A-50802

D1,

Diode

Solitron

Socket

7

B-27669-3

D16

TW30

Socket

Octal

B-27674-1

C¥-1

Varactor

PSI-V956E

Socket

9

B-27669-3

a

Jack,

Microphone,

3

ckt,

A-50793-2

COILS

AND

CHOKES

“a2

Jack,

Key,

2

ckt.

A-50793-1

33

Jack,

aht.

phones,

2

ckt.

A-50793-3

Li

Antenna

Choke

C-50523-3

u4

Connector,

Antenna

A-51479

L2

Pi

Network

B~51518-2

35

Plug

Power

A-50791

13

100

ph

Choke

C-50527-4

36

Tack,

External

ALC

In

A-11998

14

PA

Choke

A-51529

J7

Strip

Term.--Relay

C-19458-6

Ls

80

Meter

Driver

B-50755

L6

40

Meter

Driver

B-50757-2

MISCELLANEOUS

ELECTRICAL

L7

20

Meter

Driver

B-§0759-2

Ls

15

Meter

Driver

B-51515-2

M

Meter

A=52039

Lg

10

Meter

Driver

B-51517-2

Ki

Relay

6PDT

62.32

A-52038.

L10

220

ph

Choke

A-50206-1

Fl

Filter

Band

Pass

A-52004

Lil

80

Meter

Mixer

B-50756

5.2

MHz

Li2

40

Meter

Mixer

B-50758

XL

.

Grystal

5.2003

MHz

B-50769

Li3

20

Meter Mixer

B-50760-2

x2

Crystal

14,6000

MHz

B-52042-3

Lia

15

Meter

Mixer

B-51514-2

x3

Crystal

25.1000

MHz

B-52042-2

Lis

~

10

Meter

Mixer

B-51516-2

x4

Crystal

21.5000

MHz

B-52042-1

L16

Pre-Mix

Coll

B-51514

Panel

Lamp

Socket

Assy.

B-52051

Li?

80

Meter

Pre-Mix

B-52053

Panel

Lamp

NPL-47

LB

Oscillator

Coil

B-52047

:

119,

220

ph

Choke,

‘A-50206-1

TUBES

AND

DIODES

L22,

130

.

L20

VFO

Coil

B-52037

v1

6BZ6

L21*

4.7

ph

Choke

RF

G-50750-21

V2

12BE6

126,

3.3

ph

Choke

%-50750-19

v3,

V4,

12BA6

L27

.

va,

V9,

128,

Choke,

Parasitic

B-51545

v10

a

129

v5

12Ax7

L31

68

ph

Choke

C-50750-35

v6

6AQ5

:

v7,

Vil.

6GHB

SWITCHES

vib

6ID6

v.3

2

6GK6

SI-A,B

PA

Band.Switch

Wafer

A-51523

vi4,

VI5*

>

6LA6

$1-C,D

Driver

Wafer

A-51525

v6

OA2

S1-E,

F

Mixer

Wafer

A-51521

Dl,

D2,

Diode

1N484

A-51672

$1-G,

H

“Band

Switch

and

Detent

|

B-52003

D3, D4,

S2

Function

Switch

B-52002

DS

$3

Rocker

MOX-ON

A-52004

Dé

Diode

A-51294-1

s5

Receive Vernier

D7,

D8,

Diode

1N542

Gentralab

Model

2

with

D9,

DIO

DPDT

Slide

Switch

Dil

Diode

Solitron

3R130B

KNOBS

.

DIZ,

Diode

1N457A

: :

p13

Main

Tuning

A-52045-3

Knob

Pointer

A-52045~1

Knob

Round

A-52069

*V14

and

V15

are

matched

6LQ6

tubes

which

are

available

from

the

Service

Dept.

of

National

Radio

Company,

Inc.

17

PART

SYMBOL

DESCRIPTION

-

NUMBER

SYMBOL

SHAFTS,

COUPLINGS,

DRIVE

TRAIN

Shaft,

Band

Switch

B-50854

cs7,

Shaft,

PA

Load

B-50818-3

cs9,

Shaft,

PA

Tune

B-50818-1

C60,

Shaft,

Exciter

Tune

B-50818-9

C62,

Set

Screws

SS6-RG-3X

cisl,

Coupling,

Rigid

A-12611

C152

Coupling,

“Link

B-25000

c74,

Bushing,

Panel

A-50840

C75,

Palnuts

3/8~32

:

B-19332-8

c7s

a6

COVERS

coL

Cover,

VFO

B-52007

146

Cover,

PA

C-50815-4

Front

Panel

Aasy.

C-52009-2

Gabinet

Ghai

Cover

D-52011

Cabinet

Bottom

Pan

c-52010

Hanger

Bracket

C-50836-2

rors

Hanger

Screws

A-50835

ley

Rubber

Feet

A-52041

c40

Bezel

B-50809

cas

cul

FPOTENTIOMETERS

AND

CONTROLS

Ch2

R3

Biag

B-50541-1

R43

Audio

Gain

B-50768-4

C13,

R52

MIC

Gain

Cal,

ON-OFF

B-50986-1

Cl4

R56

Carrier

Balance

A-51847

cB

RA?

Carrier

Insertion

B-50541-1

.73

RF

Gain

B-50768-3

|

C83

abl

S-Meter

B-50541-10

RET

Receive

Vernier

10

K

cas

Linear

C123

RESISTORS

C165,

Rl

3.2

ohms

2

W

43%

B-17436-10

|

C166

R2

650

ohms

1/2

W

22%

_

RC20-

C169

BF651G

R78

2.2K10Wtl0%

B-17436-24

R79

750

ohms

10

W

£10%

B-17436-16

R86,R89

39K,

2

W,

210%

ay

TRIMMERS

T2

73

C6,

C9

Piston

1-8,0

pF

A-51997

L423,

Ci7

APC

Air,

B-50364

24,

Neutralize

4-

15.0

pF

L2s

NOTE

DESCRIPTION

‘TRIMMERS

(Cont)

Trimmer

U

Bracket

Mtd@

1.5

-20

pF

Trimmer

U

Bracket

Mtd

1.5

-

20

pF

-Ceramicon

5-25

pF

NPO

Mica,

7-100

pF

Ceramicon

5-25

pF

NPO

CAPACITORS

Gang:

VFO

Tune

Ceramic

75

pF

500

V

25%

Ceramic

51

pF

500

V

5%.

Ceramic

500

pF

3

KV

45%

Geramic

150

pF

500

V

5

Ceramic

330

pF

#180"

PPM

+1%

Ceramic

150

pF

-

750

PPM

Electrolytic

40-40-20

20Mfd

.02

mfd

50

W

VDG

Erie

855-000-X5J0-2032

.003

mfd,

500

V

Erie

811-000-XR5F332K

TRANSFORMERS

Balanced

Modulatox

Transmit

IF

Audio

Output

IF

Transformers

5.2

MHz

The

parts

listed

above

are

shown

in

figure

7.

PART

NUMBER

B-51304-7

B-51304.2

B-19783-4

A-52049

A-19783-2

C-50788

G-50789

C-51011-2

C-52005

A-50849-3

A-50849-2

A-50849-5

A-50849-10

A-52062

A-52063

°

C~19458-8

B-51821

B-50764

B-19435-4

B-50766

TOP

VIEW

FIGURE

7

©

g

T2(TOP

CORE

PRI.)

TI(TOP

CORE

SEC.)

BOTTOM

VIEW

FIGURE

7

19

National Radio NCX-500 User manual

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