Hammarlund HX-50 - Tuning Procedures; General and Mode-Specific Tuning

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IIi

TUNING

GENERAL

The

HX-500

Transmitter

has

been

designed

to

give

the

utmost

in

quick

and

easy

operation

for

the

radio

amateur

operator.

All

operating

controls

are

clearly

identified.

The

slide-rule

type

of

dial

is

marked

off

to

indi-

cate

every

10

kilocycle

change

in

frequency

on

each

of

the

eight

direct

reading

bands.

In

addition

to

the

10

kcs

markings,

every

band

contains

two

heavy

dot

markings

and

two

heavy

diamond

shaped

markings.

The

dot

markings

indicate

the

outer

limits

of

each

amateur

band

in

which

authorized

amateur

communi-

cation

is

permitted.

The

diamond

shaped

markings

have

been

included

to

show

at

a

glance

the

outer

limits

of

each

amateur

phone

band.

Since

the

10

meter

band

extends

over

foUF

band

change

positions,

the

markings

are

included

only

on

the

first

and

last

of

the

four

segments.

The

frequency

tuning

knob

and

dial

lock

knob

are

connected

to

the

variable

capacitor

located

on

the

VFO

sub-chassis

by

means

of

a

spring

loaded

gear

drive

mechanism.

Twenty

five

revolutions

of

the

tuning

knob

covers

a

SOO

Kcs

band

segment.

The

major

markings

on

the

frequency

tuning

knob

are

calibrated

to

indicate

1

Kcs

changes

in

frequency

and

are

sub-divided

to

indicate

frequency

changes

of

two

hundred

cycles

between

each

small

division.

To

accurately

set

the

transmitter

to

a

specific

frequency;

for

example

3962.4

Kcs.,

turn

the

tuning

knob

until

the

dial

pointer

indicates

the

nearest

10

Kcs

point

below

the

desired

frequency

e.g.,

3960

Kcs

and

add

two

major

divisions

(2

Kcs)

plus

two

sub-divisions

(400

cycles)

as

indicated

on

the

skirt

of

the

tuning

knob.

The

HX-SOO

dial

drive

mechani~m

has

been

machined

to

extremely

close

tolerances

in

manu-

facturing;

however,

there

will

exist

(as

with

all

gear

driv~s)·

a

very

small

error

between

dial

pointer

indication

and

the

tuning

knob

skirt

calibration

when

knob

markings

are

compared

with

the

pointer

indica-

tion

at

various

points

across

the

band.

There

are

several

other

frequency

determining

elements

which

also

contribute

to

the

dial

inaccuracies

such

as:

VFO

tuning

capacitor

and

crystal

tolerances.

As

shipped

from

the

factory

the

"0"

marking

on

the

knob

skirt

has

been

mechanically

aligned

to

the

high

frequency

end

of

all

bands.

Since

most

amateurs

operate

within

a

limited

portion

of a

particular

band,

the

knob

markings

should

be

indexed

for

the

highest

a

ccuracy

possible

in

the

area

of

operation.

To

correct

for

this

knob

runout,

the

knob may

be

PROCE

URE

turned

when

the

pointer

remains

stationary

with

the

aid

of

the

dial

lock.

The

most

accurate

frequency

calibration

means

readily

available

to

the

amateur

is

the

crystal

calibrator

located

in

the

communica-

tions

receiver.

Zero

beat

the

transmitter

as

outlined

below

to

the

nearest

100

Kcs

check

point,

lock

the

dial

by

turning

the

lock

knob

clockwise,

then

turn

tuning

knob

until

"0"

on

the

knob

coincides

with

the

fiducial.

This

will

require

more force or

torque

than

when di

al

is

free running.

CAUTION

The

HX-SOO

Transmitter

has

been

very

conservatively

designed

to

give

reason-

ably

long

vacuum

tube

life.

However,

the

life

expectancy

of

vacuum

tubes

greatly

depends

upon how much

use

and

abuse

they

get.

All

tuning

adjustments

should

be

made

with

the

RF

output

level

meter

indicating

less

than

-10

db

for

conserva-

tive

operation

(with

the

meter

sensitivity

set

at

its

proper

operating

level).

The

final

setting

of

the

RF

level

control

should

be

the

last

tune-up

adjustment

to

be

made.

INITIA

TUNE-UP ADJUSTMENT

The

Operating

controls

should

be

set

as

follows:

FUNCTION:

DSB

OPERATION:

OFF

AUDIO

LEVEL:

o

DRIVER

TUNE:

Set

to

"5"

BAND

SELECTOR:

Set

to

desired

band

FREQUENCY:

Set

to

desired

frequency

CAUBRATE

LEVEL:

Set

to

"s"

METER

SENSITIVITY:

Set

to

"5"

R.F.

LEVEL:

Set

to

"3"

FINAL

TUNE:

Set

to

middle

of

desired

band

segment

VOX

DELAY:

C

ounterc1ockwise

posi-

tion

FSK-FM-~F:

Set

to

middle

of

range

ANTI-TRIP

SENSITIVITY:

C

ounterc1ockwise

posi-

tion

VOX

SENSITIVITY:

Counterclockwise

posi-

tion

ALC

(REAR

APRON):

Clockwise

position

(OFF)

Page

7

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