Hammarlund FM50A - Page 8

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2.

(a)

Connect

micro-ammeter

from

J105

pin

2

to

ground.

(position

2

of

recommended

test

meter)

(b)

Adjust

top

and

bottom

of

T102

and

T103

for

maximum

indication.

(c) As

each

adjustment

is

brought

into

resonance,

the

output

of

the

signal

generator

should

be

decreased

so

as

to

produce

a

meter

reading

between

25 and 75

micro-

amperes.

This

precaution

is

necessary

so

as

to

eliminate

the

possibility

of

overload

which

will

result

in

false

peak

indications.

3. (a)

Connect

a

10.7

MC

signal

to

pin

1

of

V102A.

(b)

Leave

micro-ammeter

connected

to

pin

2 of J105.

(position

2 of

recommended

test

meter)

(c)

Adjust

L106, L107

and

L108

for

maximum

indication

observing

step

2(c)

above.

4. (a)

Connect

micro-ammeter

from

pin

1 of

J105

to

ground.

(position

1 of

recommended

test

meter)

(b)

Adjust

L103

(oscillator)

for

maximum

indication.

5. (a)

Connect

signal

generator

on

signal

frequency

to

antenna

terminal,

J102.

(b)

Connect

micro-ammeter

from

J102

pin

2

to

ground.

(position

2

of

recommended

test

meter)

(c)

Adjust

T101, ZF101 and L105

for

maximum

indication

observing

precaution

outlined

in

step

2(c).

6. (a) With

an

input

signal

of

approximately.

5

microvolt,

touch

up T101,

ZF101,

LI05,

LI06,

LI07,

LI08,

TI02,

TI03

for

maximum

quieting.

This

will

approximate

the

same

resonance

points

as

maximum

1st

limiter

grid

current

indication.

7.

(a)

Adjust

L109

for

maximum

hiss

level

keeping

the

front

panel

volume

control

below

the

overload

point.

(b) With

an

on-channel

frequency

modulated

signal

applied

to

the

input

of

the

receiver,

readjust

LI09

for

maximum

recovered

audio.

8. (a)

Loosely

couple

an

accurate

10.7

MC

signal

to

the

grid

of

V102A

(Pin

1)

and

adjust

LI03

for

an

aural

zero

beat

indication

in

the

loud

speaker

with

an

on

frequency

signal

applied

to

the

antenna

input

terminal

J102.

(b)

With

the

same

unmodulated

input

signal

follow

step

6(a).

(c)

Adjust

the

FM

detector

coil

LI09

as

outlined

in

steps

7(a) and 7(b).

In

lieu

of

this

technique

the

modulation

of

an

"on-frequency"

base

station

or

mobile

transmitter

may

be

used.

In

this

instance

LI09

should

be

adjusted

for

maximum

audio

consistent

with

lowest

distortion.

It

is

highly

recommended

that

the

service

technician

make

a few

practice

runs

on

a

normal

operating

unit.

With a

little

practice

the

alignment

may

be

accomplished

in

less

time

than

that

required

to

read

the

procedure

outlined

above.

RECEIVER

ALIGNMENT

PROCEDURE.

FIELD

SERVICE

The

"Complete

Receiver

Alignment

Procedure"

will

rarely

be

required

in

the

field

how-

ever

it

should

be

reviewed

in

order

to

become

thoroughly

familiar

with

the

receiver

section

of

the

unit.

Receiver

field

alignment

should

be

accomplished

as

follows.

9. (a) With

an

input

signal

(unmodulated)

strong

enough

to

produce

approximately

20

db

quieting

of

the

thermal

noise

(hiss)

adjust

LI08

to

zero

the

first

oscillator

with

the

incoming

signal

as

outlined

in

step

8(a).

-8-

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