Moseley Pcl-303/c User manual

--+-

]

1

INSTRUCTION

MANUAL

MODEL

PCL-

303/C

STUDIO·TRANSMITTER

LINK

MOSELEY

A.SSOCIATES,

INC,

Santa

Barbara

Research

Park

III

Castilian

Drive

Goleta,

California

93017

March,

1968

INSTR

UCTION

MANUAL

MODEL

PCL-

303/

C

STUD10-TRANSMITTER

LIKK

Table

of

c.:')ntents

Introduction

Unpacking

and

Initial

Checkout

In

stallation

Antenna

Specification

6

Page

1

3

4

5

6

1)

Transmitter

Operation

6

2)

Transmitter

Circuit

Description

8

3)

Transmitter

Nominal

Performance

Specifications

10

4)

Transmitter

Adjustments

and

Alignments

11

5)

Receiver

Operation

12

6)

Receiver

Circuit

Description

13

7)

Receiver

NOlTlinal

Performance

Specifications

15

8)

Receiver

Adjustments

and

Alignments

16

PCL-

303/

C

3/68

INSTRUCTION

VtANUAL

MODEL

PCL-303JC

STUDIO-TRANSMITTER

LINK

Ir :

t!"

odu

etian

The

\,lodel

PCL-303!C

Composite

Aural

Studio-Transmitter

Link

(STL)

is

a

\\"ide

band

communications

system

designed

ior

the

tran.<;-:ilission

of

a

composite

F\1

stereophonic

signal

between

a

broadcc;.st

studio

and

u

'remotely

located

FM.

tra.T'.srr..itter

.

Rug-

gedly

built,

compact,

and

rated

for

continuous

duty,

the

Model

PCL-303/,C

is

ar..

all

solid-state

unit

emplo")-ing

only

silicon

semi-

conductor

s.

There

are

several

advantages

to

such

a

transrnlssion

technique.

Some

of

these

are:

1.

Only

one

basic

RF

link

is

utilized

to

transmit

the

composite

ster

eo

waveform,

including

the

19

kHz

pilot

subcar:rie:r

as

opposed

to

the

common

practice

of

employing

two

aural

STL

systems

to

convey

the

un...~atrixed

LEFT

and

RIGHT

audio

signal.

This

results

in

an

eqdpment

cost

sa'v-ings.

It

should

also

be

noted

thc.t

a

67

kPz

SeA

subcarrier

can

also

be

applied

to

the

STL.

2.

The

stereo

gener-ator

is

located

at

the

studio

site

'\vhere

adjl.lst!nents.

if

required,

ca::

be

made

away

from

the

strong

RF

fields

fO\;.<1d

near

large

FM

broadcast

transmitters.

These

fields

can

have

de-

lete:=ious

effect

on

the

'

instrunlentation

employed

to

properly

;dign

the

stereophonic

generation

equipment.

The

~{odel

PCL-303/C

Composite

Aural

STL

is

basically

the

same

as

the

Model

PCL-

303

except

that

the

75

u

second

pre

-emphasis

network

and

15

kHz

600~

low-pass

filters

have

been

removed

from

the

transmitte!'

and

receiver

audio

circuits.

The

basic

modulation

response

capability

of

the

direct

FM.

oscillator

elYlployed

in

the

Model

PCL-

303/

C

is

sufficient

to

accept

and

faithfully

tran~.mJ.t

the

frequency

spectru..-n

required

for

FM

stereophonic

broadcasting.

rurthel"-,

-t-he-bandwidth_of_tr...e

10.

7

MHz

1.

F.

amplifier

of

the

com~

posite

system

receiver

has

been

increased

and

adjusted

to

fonow

a

,PCL-

303/

C

3/68

-2-

Gaussian

curve

which

yields

a

linear

phase

ch2.r~cteristic.

The

detected

composite

waveform

in

the

Model

PCL-

303/C

receiver

is

passed

through

a 90

kHz

low-pass

filter

which

cines

not

!:ignif-

ical"'.tly

alter

the

phase

relationship

of

the

composite

sign",l

(does

not

degrade

separation).

The

low-pass

filter

will

attenuate

any

remote

control

or

multip}e~:

subcarriers

place

above

the

co::nposite

signal

to,

2.

negligible

amount.

(Far

in

e.xcess

of

the

requirements

of

FCC

Rule

73.

317(a).

)

The

Model

PCL-

303/

C

ST

L

consists

of

transmitter

and!'

eceiver

units

each

mounted

on

a

standard

5+"

x 19"

racK:

panel

fitted

with

slideo\1.t

rails.

The

STL

receiver

is

of

the

crystal-controlled,

dot:..ble:

conversion,

superheterodyne

type.

A

relay

is

included

in

the

receiver

to

mute

the

composite

output

should

the

incorni:",!'

car:c"ier

f~ll

below

a g:,'Jen

p:reset

value.

In

addition,

Tel"),

C()l,t~ct",

are

brought

out

on

the

rear

of

the

cha

s

sis

for

use

in

exter:1d

alarm

or

control

circuits.

The

transmitter

incorporates

a

direct

FM

basic

oscillator

to

achieve

flat

response

and

uniformly

low

distortion

ove;-

a

wide

modulating

frequency

range

.

Provisions

are

included

on

the

transmitter

to

multi-

plex

two

subcarriers

for

:!:'e:note

control

and

auxiliary

service.

A

special

extended-life,

quiet

(35

db

SIL),

fan

provide

.s

cooling

for

the

final

power

amplifier

chain.

The

basic

direct

FM

oscillator

is

phase

locked

to

a

temperature-controlled,

lO'J,:-frequency,

reference

crystal

oscillator.

Also

induded

in

the

transmitter

aTe

two

frequency

-

doubler

stages,

one

3-stage

Class

C

RF

powe~

amplifier,

aD-d

a

parametric

muHit>lying

power

diode.

A

3-section

bandj)2.ss

filter

is

inc:)rpo7ated

in

the

STL

transmitter

output

c:'rcuitry.

A

san:rling

diode

is

included

in

this

assembly

to

inciicate

relative

power

c·.1tput

of

the

tra::1srnitter.

All

t!'ansistors

in

the

Model

PCL-303/C,

other

than

the:

serr"icon-

ductors

on

the

AFC

board

'in

~he

transmitter

ar:d

the

one

Ie

cn

the

audio

board

in

the

receiver

I

are

socket

mounted.

Doth

transm,ittcr

and

receiver

units

are

fully

shielded,

It

should

be

appa.rent

that

the

Model

PCL-

303/C

Composite

Aural

sr';"L

can

only

be

used

for

those

types

of

FM

exciters

employing

a

direct

FM

oscillator.

Further,

the

unit

is

designed

basically

to

operate

with

the

Moseley

Model

SCG-3T

Stereo

Generator.

How-

---

eve

-

l'-,-it-i

.s .po.s.

sible_to_ap.ply:

a

signal

from

othe:::

_

stereophor.i::

gen-

erators

meeting

the

requirem.ents

of

FCC

F,ule

73.322

and

the

i.np-ut

level

requirements

of

the

PCL-

303/

C

transmitter

to

obtain

satis-

rectory

results.

PCL-303!C

3/68

.

~

..

-3-

The

followi!1g

spec

:'

~icati

0

r..s

apply

to

the

Model

PCL-

303/

C

Co

rr

.

posite

Aural

S1'

L:

L+R

Frequency

Response

L+

R

Di

s

to

rtion

L+R

SNR

Stereo

SeparC'.tion

Deviation

(or

1

OO~

o

Modulation

Maximum

Available

Composite

Output

Signal

Emission

Symbols

Stereo

only

Stereo

and

67

kHz

SCA

Unpacking

2nd

Initial

Checkout

±O. 5

db

,

SO

Hz

to

15kHz

le

s s

than

0.75%,

50

I-lz

to

15

kHz

65

db

for

150

uv

input

signal

Greater

than

35

db,

50

Hz

to

15

kHz

(assuming

input

stereo

signal

has

separation

in

excess

of

38

db).

±

70kHz;

6

volts

peak-to

-peak

1000

Q

minimum

load

i.mpedance

246F9,

290F9.

2.55

kHz

B.

W.

300

kHz

B.

W.

T}

_e

Model

PCL-303/C

transmitter

and

receiver

should

be

care-

fully

unpacked

a...Ttd

inspected

for

concealed

shipping

damages

upon

receipt

of

the

equipment.

If

the

exterior

of

any

of

the

shipping

cartons

has

visible

damage,

retain

all

boxes

and

spacers

in

case

a

claim

is

to

be

made

against

the

carrier

for

damages.

The

top

shield

cover

of

the

STL

transmitter

should

be

removed

60

that

the

shipping

spacers

which

have

been

used

to

secu::-e

the

various

shock-

rnoe.nted

subassemblies

can

be

removed.

It

is

2.lso

recoITunended

that

the

receiver

top

shield

cover

be

removed

to

confinn

that

the

muting

relay

and

all

transistors

are

properly

seated

in

their

sQckets.

':'his

visual

inspection

will

also

acquaint

the

user

with

the

location

of

the

key

components

in

the

equipment.

CA

DT

ION

~

Do

not

attempt

any

tuning

adjustments

on

the

_

r_e

.c_

e.i,y_e

_'f

---.9

r

tra

~

itt

~ r

at

this

time.

All

tuned

circuits

\\

have

been

pre-aligned

at

the

factory

and-

ShOUra--not

o

;o

e

------

---.:

'\

adjusted

unless

proper

test

equipment

is

availa.ble

and

\

then

only

after

reading

the

Tuning

and

Alignment

Procedure

outlined

elsewhere

in

this

m.anual.

:':"

-'

CL-

303/

C.

rev.

8/68

-

4-

If

a

10

watt

50

n

RF

term.ination

is

available.

with

or

without

a

calibrated

wattmete

r.

the

ST

L

transmitter

can

be

bench

"heck-

ed

.

Vdth

the

R F

load

con~ected

to

the

Ot~t::)Ut

of

the

ST

L

trans-

mittel'

and

the

line

cord

plugged

into

a

sour

ce

of

117

\'

AC.

50-

60

Yz

power,

the

frolOt-panel

RADIATE

switch

can

be

turned

on.

The

:R

F

\.vti.ttmeter.

if

used,

will

imi!1ediately

indic?te

between

5

watt;:;

and

7

watts

of

output

power

.

If

a

wattm.eter

i:::

not

avail-

able,

the

R F

output

m.eter

on

the

front

panel

of

the

PCL-

303/

C

will

indicate

between

SO

and

55

divisions.

Tl

;

1e

receiver

can

be

?Iaced

on

an

adjacent

bench,

and

aiter

the

po:wer

;:>1'.1g

ha.s

been

connected

to

the

power

source,

the

p~wer

switch

can

be

turned

on.

It

may

be

nece

s

sary

to

carefully

in-

~

e

rt

a

small

wire

hto

the

Type:'

';

R F

iq:ut

£i

tting

0"

the

rear

of

th~

'

receiver

chassis

to

minimize

multipathing

effects.

Do

not

attempt

to

adj;J.st

the

input

or

output

cavities

of

the

STL

receiver

and

tranE~itteT

under

these

test

conditi~ns.

These

a!"e

p",elimin-

ary

tests

and

should

be

conducted

to

heccme

fam.iliar

with

the

basic

operation

cf

the

system.

An

audio

test

si~nal

of

approximately

1.5

volts

peak-to-peak

rr.ay

be

applied

to

the

Type

ENe

modulation

input

connector

on

the

rear

of

the

STL

transmitter

for

t~e

initial

t:-a:1srnitter

check.

This

sif;na!

can

be

derived

from

a

standard

audio

oscillato:7

or

Model

SCG-3T

FM

stereo

generator.

An

OS-

cillis

cope

or

VTVM

should

be

connected

to

the

type

F)!C

out?ut

connector

located

en

the

rear

of

the

STL

receiver

if

Tr\easu;eme~ts

are

to

be

made

.

Bear

in

mind

that

multip.2thing

conditions

can

exist

uncle.!'

tl'.ese

i:litial

checks

ai.d

will

affect

the

meas~rements

made.

Si:-:ce

the

STL

transmitter

does

not

employ

any

pre-em.phasis

it

is

not

necessary

to

Teduce

the

amplitucie

of

the

l:-lput

signal

source

whe!l

n!.aki::.g

ireo'-!ency

response

measurements.

(This

of

co~r

se,

"'"

iii

not

be

true

if

t!ie

test

signal

source

is

deYi

ved

from

a

stereo

generato::'.)

Should

any

!najo!"

malfunctiorL

be

noted.

it

is

recommended

that

the

engbeering

dep2.rtrner..t

of

\1oseley

As::oc-

iate

5,

~nc.

be

cor.taded.

In

stallation

The

Model

PCL-

303/

C

transmitter

and

receiver

can

be

mounted

in

a

standard

19

11

wide

rack

using

the

slides

provided.

For

rnaximun'l

stability,

the

rear

of

these

slides

should

be

conne

cted

to

the

rear

rails

(or

to

the

cabinet

walls)

with

the

br2.ckets

provided.

The

ex-

ternal

connections

wniCn

must

-

be

maa

e-

ior---b'(Jth-unit's

irrdud·e-the

-

-----

3-wire

power

cord.

RF

input

and

output

cables,

unbalanced

shielded

PCL-

303/C

3/68

-

)-

composite

program.

linC's,

Clnd

if

used,

signal

leads

for

lnultiplex

subcarriers.

The'

transmitter

should

be

installed

in

such

a

man-

ner

as

to

aDo

·w

air

to

freely

circulate

around

the

equipment

.

Transmission

line

considerations

will

determine

to

some

extent

the

placement

oi

the

equipment.

A 5

lengthy

tr<:.nsmi

s

sion

line

wi

11

btroduce

undesirable

amounts

of

attc:nuation

of

the

transmitter

out-

put,

it

is

always

good

practice

to

place

the

STL

transmitter

as

close

as

possible

to

the

antenna.

If

a

long

length

of

transmission

line

is

required,

\:se

the

lowest

loss

line

possible

consistent

with

mechanical

Gnd

economical

considerations

. ':Lhe

same

precautions

shou

Id

.

be

follo"ved

in

locating

the

receiver.

Because

of

the

usc

of

slide

mounting

:rails,

it

is

p:referable

to

use

a

short

length

of

RG-

8A/D

d:Hl.xial

cable

to

connect

the

RF

H

tting

on

the

rear

of

the

STL

transmitter

or

receiver

to

the

actual

transrnissiOT!

line

so

that

the

units

can

be

easily

pulled

out

for'

inspection

and

pushed

back

into

the

racks.

In

all

case.s

constant

impedance

RF

fittings

shoulr:

be

used,

such

as

a

Type

N

connector,

on

the

tran

smi

s

sion

line.

Assuming

that

the

initial

checks

as

outlined

in

the

p:-evious

section

have

been

made,

the

STL

transmitter

and

receiver

may

now

be

turn

·

ed

on

.

CAU7IOl

\:: .Be

sure

the

transmission

line

and

antenna

have

been

properly

connected

to

the

PCL~

303/C

transmitter

output

.

When

the

RADIATE

is

turned

on,

the

R F

output

meter

of

the

trans-

mitter

should

indicate

between

50

and

55

divisions

. A

reading

dif-

[cr~nt

from

this

value

\lsually

indicateD

the

presence

of

a

high

\,SWR

The

complete

tu..,c-up

p-:-oced'ure

is

described

la.ter

in

this

~anual.

When

the

PCL-303/

C

transmitter

pow

e

::-

co:;:d

is

cO:J.nccted

to

the

?=in:.a!'y

power

li:-,e

SOUl·

ce,

operating

voltages

<'..l'e

applied

to

the

b~sic

osci1l2.tor,

::rystal

()

ve

:-',

,

AFC

network,

ar..d

low-level

fre~-

uency

multiplier

stages.

The

front

panel

l~p

glows

"

....

her..

the

transmitter

is

cC'nnected

to

the

po\ver

line.

':'u!"ning

the

front

pan-

el

switch

to

the

2.

~ADIA':.'E

position

applies

voltn

i2

e

to

the

high

f:re~

-...:ency

power

amplifier

chain

as

well

as

the

c~olir,g

fan.

The

RF

~\!tput

m.eter

on

the

f:ront

panel

provides

and

indication

of

c;:.rder

radiation.

Thi

s

t

'

~rn

-

on

procedure

prevc:::nts

the

ST

L

transmitter

from

yadiating

an

ofi-hequency

signal

prior

to

the

capture

of

the

basic

oscillator

by

t,

he

AFC

circuitry,

Antcnn2.

T h e

Type

PR-4S0

Scala

.P.ntenna

is

normally

r~coTnmended

for

use

\vith

the

Model

PCL-303/C

S'l'L

.

The

reflecting

screen

is

a

PCL-303jC

3/68

-6-

parabol.ic

section

in

onc

plane

and

provides

a

gc.in

of

17.5

cib

over

a

rderencc

dipole

antenna.

Its

physical

ap~rtuTe

is

67"

x

36".

The

anodized

driven

clement

is

located

at

the

focus

u{

the

par-

c:.boloid

and

is

prctuelC'u

at

the

factory

for

the

operating

frequency.

!'

jo

attem.[lt

should

be

made

to

field

tune

the

antenna.

A

balun

trans-

(ormer

is

sealed

wi.thin

the

driver

elernent

support

so

that

the

actual

active

<'mtcnna

elcnlent

is

a

balanced

folded

di?ole.

This

coniiguT::J.tion

Tcs\;.lts

in

less

bearrL

skewing

under

heavy

ice

and

500\,\'

loading

con-

ditions.

It

should

be

noted

that

this

antenna

has

a

low

DC

resistancc

between

t~le

inner

conductor

and

the

shiel.d

of

the

Type

N

RF

fittings

su?pli~d.

On

special

order.

the

reflecting

screen

of

the

anten;).;).

can

he

ana;dized

and

dichromate

clipped

to

as

sure

long

life

in

a

cor

ro

o.ive

environment

.

The

p~

-450

Antenna

is

suoplied

\\ith

U

-bolt

mounti:1.g

hardware

so

th~t

it

CZl.:1

be

clamped

to

a 2

3/8"

O.

D,

pipe.

Th0

I

ODen

grid·

reflector

design

minimizes

wind

lO~lding.

Wher..

nlounting

the

P"K.-450

or

equivalent

ar,t~noa

to

an

ungrounded

st;;.ndard

Droadcast

tnwer.

the

Moseley

Model

ICU

-1

Isocoupler

C<ln

be

used

to

eliminate

the

need

to

contruct

a

resonant

transmission

line

tanle

circuit

CT

the

requirement

for

a

quarteT-V'ewe

insul:.o..ted

tr2.nsrnission

line

section

up

the

tower.

The

rcu-

1

Isoco"J.plcr

has

less

than

0.5

db

of

inse~tion

loss

at

950

MHz

and

presents

less

th

;c

n

10

pi

of

capacity

to

the

base

of

the

tower.

The

ICU-l

is

rated

for

a

p(\ak

instantaneous

voltage

breakdown

of

5.000

volts.

The

modula-

tion

voltage

peaks

should

be

t;:.ken

ielta

consideration

when

using

the

lCU-l

.

1).

TRANSMITTER

OPE3.ATIOi~

'':''0

place

the

Model

peL-

303/

C

in

operation,

connect

the

power

cord

to

a

source

of

120/240

VAC,

50-60

Hz

power.

Connect

the

RF

trans-

mission

line

to

the

TY!=lc

K

output

fitting

.

The

FM

composite

stereo

m.odulation

is

applied

to

the

transmitter

through

the

Type

EN

C

con-

nector

on

the

rear

panel.

Power

is

applied

to

the

RF

power

a~pli

fier

by

throwing

the

switch

marked

RADIATE

on

the

front

panel.

A

gr

een

pilot

light

will

indicate

prim.ary

power

cn.

This

lamp

is

on

whenever

the

tra~smitter

is

connected

to

the

power

line.

RF

output

can

be

observed

on

the

front

panel

meter

labled

RF

OUTPUT.

The

following

multirneter

readings

are

representative

of

the

new

transm.itter

anc

will

serve

as

a

guide

in

the

operation

of

the

equipment.

peL-

303jC

3/68

·7-

PCL.303/C

TRANSMITTER

TYPICAL

METE1~

READINGS

Meter

Switch

Position

+28

volts

+lS

volts

Bn.

sic

Oscillator

-B-eference

Oscillator

tinary

Output

AFC

,

AFC

Unlocked

':'

I.P.A.

Drive

1.

P.

A.

C'..lrrcnt

Final

Current

Multiplier

:..-'ias

.

'v1eter

Reading

56

60

55

50

40-70

0

30-60

50-90

80-95

40-90

(100

full

scale)

.~.

Any'

reading

ether

t}la~

7,

eTc)

irJ.dicate~

an

~nloc

.

'

·

:ed

AFC

conditio!l,

An

3.pproA:iIY1Ll..te

curve

br

the

POWER

OUTPU'!'

m.

cter

position

is

shown

on

the

fol1()v,

ing

page.

Potcnti:'lmetcr

n.

308,

Incated

at

the

l·C3.r

of

the

pewer

L.rn?liii~r

chain,

adjusts

the

level

of

the

RF

out-

put

mon:itor

meter.

Should

thi

s

control

be

changed,

it

will

be

nec

e

s-

sary

to

recalibrate

the

potentiometer

against

an

RF

wattmeter.

A

transmission

line

impedance

mism<l.tch

will

intro.duce

an

error

into

the

reading.

Fer

100C;;-)

modulo.ti"n

01

the

STL

the

c<-.rrier

is

shifted

2.pproxirnately

:=1

00

kHz

from

its

mean

center

frequency

.

P.

1.

000

Hz

test

tone

at

2.

level

uf

appxo:--imately

1.5

volts

p-?

v,'ill

produce

lOO~ol

l"nodulation.

7wo

BNC

connectors

are

n1.ounted

.3.djacent

to

:hc

composite

input

con-

nector.

These

connectors

provide

equal

but

isolated

multiplex

inputs.

For

10~o

subcarrier

injection

the

voltage

at

the

ENC

input

should

be

O,~,

volts

.

rrns.

Yhesc

5uDc.:!.rl'ier.':c

should

be

confined

to

the

110

kHz

to

200

k3z

spectrum

to

prevent

interference

to

the

stereo

signal

and

out-of-

band

radiation.

It

is

usually

not

advisable

or

necessary

to

re-

duce

the

main

channel

program

level

when

a

subcarrieT

is

added

to

---------

th-e-S

T

h-

PCL-303!C

3/68

-8-

2),

TRA0?SMITTER

CIRCUIT

DESCHIPTIOl\;

~'h('

complete

schematic

of

the

PCL-303/C

tran~

;

mitter

is

shown

in

Dra\Ying

91C-6242

.

Thy

composite

stcrf'O

brut

signal

is

first

applied

to

tbc

deviaticln

cont1:"ol,

R-145.

It

is

then

pa5scd

through

a

time

constant

COl'recti0:"l

network

to

the

variable

cap-

acit:cnce

diodes

(v;:tri..:aps)

en-10l

and

en-102.

These

diodes

v~ry

the

rcson<l.nt

{yequ<=ncy

of

the

tank

cir-cuit

oi

th",

oscilla.tor,

0-101.

0-101

oscill::.tes

at

G..

frequency

of

1/12

the

1in0.10ut-

::,ut

or:

carrier

f'requency

and

is

fr~qucncy

moci.ul?_tecl

:io

.k!:z

by

t~lC'

r:Lain

channel

progran1

material

for

1

OOCY

~

.

r::tcdulation.

FOT

ci~cussi()n

purposes,

an

oper<1tiilg

[reCju~ncy

of

945.0

MHz

will

be

assumed.

nence.

the

frequency

of

the

ti'.Fic

oscillator

0-101

v-~U

'be

945.0

-'-

12

01'

78.75

MHz.

This

si;:-.l1J.l

is

am?lificd

by

O-t02

and

feu

to

Q-201,

This

78.75

MHz

signal

is

multi;>liccl

four

times

and

arr..?lified

by

Q-202

a..nd

0-2.03

to

produce

a

100

milliwatt

signal

at

315

MHz

at

J-202.

'7ili6

powel

is

fed

to

J-301

on

the

RF

power

amplifier

chassis

.

0-301,

0-302

and

Q-

303

transistors

amplify

the

315

ViHz

signal

to

12

watts

at

31 S

MHz

'which

is

applied

to

the

paraI:letric

multiplier

CR·301.

Eight

watts

of

pow~r

are

removed

from

the

ciiade

at

3

times

315

MHz

or

945

MHz.

L-J13

and

C-317

form

the

idler

circuit

of

the

parametric

multiplier.

The

945

MHz

output

of

the

val'·

actor

is

then

fed

thrcugh

C-

323

ar.d

the

3-

section,

end-tuned

filter

cavities

to

J-302.

~he

antenna

coa:dal

cable

is

attacned

to

::-302.

Automatic

frequency

control

(AFC)

of

the

translT'_itter

output

f:-equency

is

accomplished

by

phase

locking

ti-;c

78,75

MHz

basic

oscillator

to

a

76

k:-Tz

10"\v-frequency,

crystal-controlled,

refer-

enCe

oscillator.

The

78.75

MHz

output

of

Q-102

is

applied

to

the

i'!;.put 0;': a

high

speed

bin2.ry

counter

and

divided

eight

times

by

integrated

circuits

IC-l,

IC-2,

and

IC-3.

This

divided

out-

put,

9.

844

MH

z

in

the

example,

is

applied

to

a

level

changing

amplifier

0-1

on

the

AFC

printed

circuit

b02.rd,

The

output

of

0-1

feeds

another

binary

chain,

IC-S

through

Ie-9,

which

divides

the

input

frequency

by

512.

The

total

division

of

the-

basic

oscillator

!:re~uency

is

4,096.

The

low

frequency

ref-

erence

signal

is

derived

from

IC-4,

an

integrated

circuit

em-

itter-coupled

crystal-conb-olled

multivibrator.

The

output

of

--------

---.

'h-:;l:---.;S

~

O

=

S'"C--;l-~llha""t;--,o"r..---i"S

a-ppii:e-d-to-

l-ev-e.J..-e-h-2--n-g-e-l'---

Q

....

2_an

Lap-~h,,--,'

e

""

d",---,,-t~o

________

_

PCL-303/C

3/68

-9-

Ie-IO

and

di.vided

4

times.

Thus.

the

outputs

of

IC-9

and

IC-lO

operate

at

the

same

frequency.

The

phase

of

these

two

output

signals

is

compared

in

IC-l1

to

·achieve

an

integrated

DC

PFC

error

voltage

which

is

amplified

by

0-

3.

It

shoUld

be

noted

that

the

entire

AFC

system

is

not

frequency

sensitive

since

all

inte-

grated

circuits

in

the

binary

dividers

operate

in

the

saturated

current

or

voltage

mode.

Thus.

they

exhibit

excellent

noise

immunity.

The

AFC

error

voltage

is

then

coupled

through

a

low-

pase

filter

network

to

varicap

diodes

CR-103

and

CR-I04.

Thus.

the

frequency

of

the

basic

oscillator

is

phase

locked

to

the

low-

fr

eque~c)'.

temperatllre-

controlled,

crystal

r

de

rence

os

ci1lator.

It

shou

'

ld

be

noted

that

the

t\.\'o

capacitors

used

to

couple

the

four

varicap

diodes

to

the

basic

oscillator

tank

circuit

are

temperature

compensat'ed

to

achieve

optirrlUm

freque:tcy

stability

of

the

basic

oscillator

.

The

power

!lupply

for

the

transmitter

has

three

output

voltages;

+28

volts

DC.

+15

volts

DC.

and

+3.6

volts

DC

.

The

+28

volt

DC

supply

powers

the

RF

power

amplHier.

The

+15

volt

DC

sc.pply

powers

all

other

circuitry

except

the

binary

which

uses

the

+3.6

volt

output

.

The

+28

v'?lt.

the

+15

volt,

and

the

+3.6

volt

DC

supplies

are

fully

regulated

by

0-401.

0-402.

0-403,

Q-404,

and

t~e

Zener

diode

references

CR-407

and

CR-4l0.

R·-408

adjusts

the

output

voltage

of

the

28

volt

supply

and

should

never

be

set

higher

than

+28

volts

DC

.

TRA1\SMITTER

RE\10TE

COKTROL

The

Model

PCL-

303/

C

transmitter

may

be

ooerated

from

a

remote

location.

A

S-pir:

r

e~e?tacle,

J -

403,

is

mounted

on

the

rear

of

the

chassis.

This

connector

enables

the

remote

radiate

switch

and

meters

to

be

connected

to

the

FCL-

303/C

circuitry.

A

5-conductor

cable

should

be

us

ed

between

the

remote

control

point

and

the

PCL-

303/

C

transmitter

.

A

plug

with

pins

1

and

2

shorted

together

i~

provided

with

each

Model

PCL-303/C

transmi.tter.

1£

remote

control

operation

is

not

intended,

this

plug

shoUld

be

kept

inserted

in

J-403.

To

turn

the

carrier

on

from

the

remote

locatior.,

it

is

only

necessary

to

connect

together

the

v:ires

from

pins

3

and

4

of

J

-403

. A

simple

SPST

toggle

switch

can

be

used

for

this

purpose.

Actuating

this

switch

will

operate

relay

K-401,

applying

+2.8

volts

DC

to

the

RF

power

amplifier

-

________

T

~

__

~ndicate

the

relative

power

output.

at

the

remote

position.

place

a

50

;..'.a

meter

in

series

wini

pins

-l-cru'd

c-o"f-J--40~7

-Gonnectin

_

&-

-""

a

~

n"",o

,-,

t

~

h~e~r

,--

_____

_

50

,a

meter

between

pins

5

and

1

will

provide

the

remote

control

point

with

an

indication

of

the

AFC

error

voltage.

PCL-303/C

rev.

6/68

-10.

3).

TRANSMITTER

NOMINAL

PERFORMANCE

SPECIFICATIONS

TYPE

RF

OUTPUT

FREQUENCY

STABILITY

AM

NOISE

DEVIATION

SPURIOUS

EMISSIOl\:S

EMISSION

DESIG

NAT

ION

AUDIO

INPUT

MULTIPLEX

INPUTS

SOLID-51

ATE

DEYICES

(all

silicon)

POWER

SUPPLY

COOLING

DIMENSIONS

MOU~~TING

Direct

FM

7

watts

nominal;

8

watts

maxhnum

into

nom.inal

50n

load.

Type

N

fe-

male

connector.

Better

than

0.0010/0

(O°C

to

60

0

C);

crystals

mounted

in

temperature

con-

trolled

oven.

Better

than

75

db

below

carrier

ref-

erence,

±

70kHz

for

100<}o

modulation

More

than

60

db

below

carrier

246F9

10,

000

n

unbalanced,

approximately

1.

5

volts

peak-to-peak

for

100%

modulation.

Two

ENe

connectors

are

provided

for

subcarrier

channels

in

110-200

kHz

spec:trl1rr1.;

a!Jproximately

1.0

volts

rms

for

2.0%

deviation.

15

transistors

-

all

JEDEC

registered

5

varicap

diodes

1

varactor

diode

11

integrated

circuits

14

diodes

Fully

regulated,

s e

1£

-

containe

d

Convection

and

forced;

fan

has

long-

life

bearings.

(See

note

below)

5+

'1

x

19"

x

16

11

Slide

l'

ails

NOTE:

The

life

ratin~

of

the

fan

can

be

extended

by

periodic

lubrica-

tion

every

6

months.

When

lubricated

in

this

manner,

the

life

expect-

ancy

will

be

in

excess

of

5

years.

peL-

303'.-'

~

rev.

7/68

- 11-

.;.\.

TRANSM17TER

ADJUSTMEJ

\

TS

Al~D

ALIG

I,

MEN

T S

A

complete

alignment

of

the

transmitter

is

not

recommended

in

the

field.

However,

in

the

case

of

transistor

rcplacen1cnt

, 0.

touch-up

.?lignmcnt

can

DC'

performed.

Fi::-st,

remove

the

2

<LIn?

fusc

on

the

power

supply

chassis

and

adjust

R-408

for

-+28

volts

DC:

at

thC'

output

of

the

power

supply.

l?o

not

sct

the

output

aLove

+28

volts

.

Check

thc

+28

volt

and

+1 S

volt

DC

supplies

wit~

the

hont

Fanel

mcts!"

.

Switch

the

meter

to

:h

c:

DAS~C

OSC.

position.

If

the

reading

is

over

30,

sv.ritch

to

the

REF.

OSC.

position

.

If

the

::-e2.ding

is

again

over

30,

switch

to

the

BINARY

OUTPUT

."

This

reading

should

be

at

SO

division.s

±10

.

1£

it

rC:'!-ds

either

10

divisions

or

90

divisions,

the

hinary

is

not

viorbng

and

service

is

required

.

If

it

reads

SO

divi.-

siors,

switch

to

the

AFC

posi:ion

.

This

TE-adi:1g

should

be

40

to

60

didsions

also

.

If

it

is

not,

switch

the

AFC

Ui""LOCi\

position

.

Ad-

just

th0

AFC

contr

o l C

-104

I.Ui!:il

the

meter

reads

zero.

This

can

be

done

1)'

adjusti:1g

C-I04

until

t:"e

meter

rea.ding

rises

and

then

falls

to

zero

after

some

noticeable

oscillation.

After

the

meter

falls

to

7.ero,

switch

back

to

the

AFC

position

.

The

meter

will

read

between

30

and

70

divisions

.

Continue

to

adjust

C-I04

until

the

mete.

reads

SO

in

the

AFC

pOGhion.

F

OTE:

When

the

frequency

of

the

basic

oscillator

is

not

"

locked"

to

the

frequency

of

the

referenc

::-

crystal

oscil-

lator,

it

should

be

noteo.

that

the

reading

of

the

meter

with

the

selector

switc'-.

in

the

AFC

pnsition

\"I.-ill

be

a~

Fro

:v::

i!"llOl.tel{

5J.

':'i!i~

is

the

S./>

,

VE

reaL:ing

that

ai'pears

when

the

basic

oscillator

is

in

phase

"vith

the

reference:

oscillator

and

no

AFC

error

voltage

is

present

.

.:

\}"C

centrol

oi

the

bE-sic

oscillator

can

be

quickly

confirmed

by

switc:

~

ing

to

the

AFC

U~LOCIZl:..:D

position,

.

if

the

metcr

re2.ds

zero,

the

AFC

is

locked.

In

r..ormal

oper2.tion

the

1.

P.

A.

DRIVE

position

is

used

as

2.n

incHca-

tion

of

the

presence

of

nc!'mal

drive

to

the

RF

arnplfier

,

Tile

ar.-'.

,

"-

Etucie

of

the

1.

P . P

•.

DRIVE

position

meter

reading

is

affected

oy

b(;

presence

of

+28

volts

on

the

RF

amplfier.

The

meter

rC2.ding

will

be

higher

when

the

RADIATE

switch

is

on.

}'~o

attcmpt

should

be

made

to

adjust

the

tuning

of

the

frequency

multiplier

stages

when

it

is

connected

to

the

RF

amplifier

input.

The

following

procedure

is

used

when

tuning

up

the

multiplier

section.

Remove

the

cable

connected

to

J

~20

n.d--Connect-a--£O-Q-R

-

F-

durnmy

----

------

----,

oaa

.202.

U

sing

an

external

multimeter,

place

it

from

the

PCL-303/C

3/68

-12-

emitter

of

0-203

to

p:ou:1d,

and

2ojU6t

L-201, L-202,

("'-207,

C.-210,

C!.nd

C-212.

faT

a

ma':ime.m

re<'.di.ll~

on

the

c:-.-tern<.l1

multimeter.

Re-

move

the

external

rnultimcter

and

adjust

C-217

and

C-21S

for

J..

m2.;(imUln

r

co-ding

on

t!1e 1.

P.

A.

DRIVE

po

sition.

C - 21

-;

and

C -

21S'

should

be

a':J,)ut

h::.lf

open

when

pr~)perly

adjust~c1.

Remove

tbe

RF

du!'Y'.m.y

102.(\

and

l'eCannl~ct

'

th~

cable

irom.

1-301

to

J-202.

Pl::!.ec a

o·-.l.mmy

load

or

;:l.llt.c,-na

on

th

e

RF

output

J-302.

Turn

the

RADIATE

switch

oft

;

in~~

r C

;Jlacc

the

2 ar,1.p £U.

S()

in

the

po"\'('cr

supply

chassis.

S\'

,'

itc-:h

the

meter

to

the

FINAL

CURHEl\T

position

and

turn

t~lC

P,ADIATE

$,;,'

iteh

cn.

The

RF.

out~ut

meter,

or

wattmet

cl'

if

one

is

used.

should

rc,,-d

SO

divic.;ic!".s

or

l:

\':

2.tts

or

r.10re

.

'[he

f"H

\J'.L

CURRE:'-:T

should

!"ead

ildwccn

8 0

;

~n

d

05

,

1':

the

final

current

is

correct

but

thl'

[lov

.

·cr

c,

;t!)\!t

is

10v

.:

,

~

d

just

(:.-319,

C-320,

C-321

for

Co

maxin

1.

um

on

the

R?

out.put

nlctcT.

If

the

fi!lal

curre:-:t

is

not

ccrr,'ct.

con

s

ult

the

Sngin~'<::r

in~

Dep2:r'

.

tment

of

?vI.:;seley

As

50c..i.:1tCs,

~;i.c

.

fer

further

guida.nce,

If

a

satisi:J

.

ctory

nl2..:

..

:

i:

--:'

U~~l

is

<!.chicved

and

th

.

.:

fi.:)2,~

currp.nt

is

correct.

s"

...

ii:ch

t

'.

)

the

1.

P.

A . CUf',P.:F:Z'iT

position.

It

s~lOuld

b€

\...etween

30

z..nd

(,0 .

S",vitch

to

th~

\·~(JL-:-InLIER

,lIAS

,

It

shoi.dd

be

bet\-

.·

ee!l

40

and

90

.

C-301

through

(-317

,;,."'e

r:ot

readi~y

a.vailJ.bl~

adj\1stments

a~~d

!:I

:.

ould

not

l

~

e

attem.pted

',-

.·

i~ho_,t

consulting

'~h

c

m2.Lui;'j,durer

.

Replacement

of

a.ll

transistors

excPi)t

~,-401.

0-402..

Q-30~.

J..:->u

0-303

is

5trai~htfor

v'ar2,.

When

rep'acbg

0-401

or

0-402.

bC"

certain

that

the

bstJ.:..t-

i~!g

v:asher

is

!.'ei!'stJ.~led

be

t

,,\'ecn

the

t~<:!.nsisti)r

c:.nd

the

heat

sink.

If

0-203

and

0-301

"'-l

' C

::-eplaced,

remove

the

~

i:-ncd

hea.t

sink

on

the

old

u:,ii

~nd

inst2.l1

it

c:

the

:-eplaccmcr:.~.

D~fore

T(!;placing

Q-302

Clnd

0-303,

conswt

th~

In&>Juiacturer

.

A~tcy

insta.llation,

C0nncct

the

po

,-

'

.-

er

sup?ly

cord

to

a

conve:1it':1t

source

c,f

120/2-:1:0

\lAC,

:·0 -

60

l~z

,

Turn

c:.

be

?o'

.'.

er

",witch

on

the

front

pane:

Att2...cl1

the'

antl!mJ

.

CO:l:1cc:tion.

A':tcr

removal

c!.~

be:

receiver

cove!",

3.

pote-:".tiorncter

controlling

the

:;-c

eei

vc

r

squelch

is

;:wz:.ila

ble

on

the

audi.o

mdtit-,lex

P.

C.

ho'l!'u.

The

2.C:justable

coil

m::r:_ed

L-

201

!JT'~'I.'ides

slight

<'.djustm.ent

of

i:he

crysta.l-

controlled

frequcncy

so

that

the

receiver

can

be

set

exactly

on

:-.he

trans-

m.itt~r

frequency

.

TUs

C2.r.

b~

determined

by

looking

at

the

DISC

(+)

0r

DISC

(-)

?0sition

of

the

multimeter

switch.

The

program

outl)ui:

level

control

is

availahle

or.

the

audio

mu1tir->lex

board

also.

This

a.djusnnent

is

factory

set

to

deliver

6

volts

peak-to-

peak

to

the

output

attenuatoT

pad,

R-431

and

R-432,

These

resistors

---------

-

.cr

,e-

se-leG-te.a-to-matc

L

thc

devia.tion

sensitivity

of

the

F M

exciter

so

tha.t

100%

m.odulation

is

achieved

with

the

maximum

signal

to

noise

ratio

capability

of

the

?vlodd

PCL-

303/

C

system,

PCL-303/C

3/63

1

~

'.

-13-

A

calibration

chart

for

SIGNAL

1

and

.sIC~AL

2

i~

included

in

this

manual

and

shows

the

relationship

between

the

meter

ioe

and

the

actual

input

signal

expressed

in

II

VOltS.

For

quieting.

the

receiver

si(;!1al

s~ould

be

greater

th.:ln

about

volts.

read-

60

db

100

-..:.

'

h.~

following

multimeter

readi.r.gs

are

representative

of

the

r.ew

receiver

readir.g

for

a

no-signal

condition

and

will

serve

as

2.

guide

in

the

operation

of

t:1e

equipment.

PCL-303/C

RECEIVER

TYPICAL

METER

REj\DINGS

,

\,~

eter

Switch

Po

sition

Meter

Rec:cling

(100

full

scale)

+ 10

volts

-

10

volt

s

1

st

O"cillator

:v£ixcr

Drive

2nd

Oscillator

Limiter

Signal

2

,>

DisCTimiDator

(+

\

Discrimin2.tor

(-)

,~

See

curve

of

input

signal

VB

meter

reading.

-

6).

RECEIVER

CrR

CUlT

DESCRIPTION

45

40

30

35

o

The

receiver

is

a

double-

conversion,

superheterodyne

type

employ-

ing

19

transisto:;"s

and

19

diodes.

A

complete

schem.atic

of

the

:receiver

is

shown

in

Drawing

91C-6243.

The

Model

PCL-303/C

receiver

is

housed

in

a

rack-mounted,

enclosed

cabinet

19"

wide

and

5t"

high.

Eh'ternal

connections

include

the

power

cord,

the

RF

Type

N

input

ccnnecter

located

on

the

rear

panel,

and

a.

Type

BNC

connector

for

the

composite

output

signal.

In

addition,

i'telay

con

tact

5

(F

0 r m

C)

are

a

sop

res

en

ttre-r-e-aT-e-ha-s-s-i-s--to.-ind

...

i

c~a~t....,e

,",--

____

_

presence

of

a

received

carrier.

PCL-303!C

3/68

SEMI-LOG"'R

'TI1

....

,e

J~9-7

1

~"L

)(

t:U~~"'~:l

i'

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500

1000

Received

Microvolts

151\

1048

-14-

Quite

often

the

STL

Receiver

is

located

in

a

building

containing

high

RF

field

energy.

Under

these

conditi.ons,

cross-modulation

products

can

be

created

in

a

conventional

tra:1bi!>tor

amplifier

stage

if

the

input

signals

applied

to

the

basc

circuit

exceed·

the

linear

dynamic

range

of

the

device.

To

prevent

this

conditicn

in

the

Model

PCL-

303/

C,

the

3-

stage

72

M

Hz

I.

F.

ampllier

em-

ploys

field

effect

transistors

(FET)

with

an

Automatic

Gain

Control

(AGC)

circuit.

The

AGC

control

voltage

is

derived

from

diode

CR

-

302

in

the

10.7

MHz

2nd

I.

F.

a.mplifier.

Tr.is

volta

.

ge

increase<l

in

the

positiye

direction

with

an

increase

in

the

desired

signal.

Tran-

sistor'

0-207

in

the

72

MHz

1.

F.

amplifier

inverts

this

voltage

and

applies

it

to

Gate

2.

of

the

first

and

second

72

MHz

FET

stages

(Q-204

and

0-205).

A

fixed

bias

is

applied

to

Gate

2

of

the

last

F.2T

(0-206

to

assure

a

more

constant

input

to

the

10.7

MHz

2nd

1.

F.

amplifie:-.

A

curve

shov.

-

ing

the

typical

readings

for

Signal

1

and

Signal

Z

meter

positions

is

included

in

the

instruction

manual.

The

Signal

2

reading

s

are

shown

with

and

without

the

AG

C

applied

to

the

72

MHz

1.

F.

amplifier.

Under-

normal

conditions

the

meter

will

indicate

the

signal

stren€-th

with

AGC.

To

obtain

a

reading

"vith-

out

AGe,

it

is

necessary

to

remove

0-207

from

its

socket.

The

input

of

the

STL

receiver

is

designed

fol'

an

impedance

of

51

n.

The

antei:.na

input

CO:1nector

is

couple2

to

the

:i

r

st

of

fi

ve

end-loaded

resonate

line

cavities.

The

last

ca

....

-Hy

is

coupled

to

the

first

cTystal

mixer

CR-10l,

whel"c

it

i!'

T!Lixed

with

the

local

oscillator

ir.jedio;:;

signal.

Tl"!.e

local

osciU~tor

signal

is

derived

from

the

f::r

st

c::-ystal

oscillator

Q-

201

and

multiplier

9

0-

202,

0-203,

and

CR-I02.

The

output

of

the

crystal

mixE!r

15

72

MHz

and

is

coupled

hto

the

signal

gate

01

0-204

-.:vhich

is

t~e

first

72

MHz

1.

F.

stage.

It

is

amplified

by

Q-

205

and

0-

206

and

is

~pplied

to

the

base

of

the

seco:1d

mixer

Q-

302.

The

injection

voltage

for

the

second

mixer

is

generated

by

Q-

301,

a

crystal-

controlled

oscillator

~t

61.3

MHz.

The

output

of

this

mixer

is

then

aID;:>lified

by

the

10.

7

MHz

second

1.

F.

amplfier,

0-

303,

0-304,

0-305,

and

0-306.

This

amplifier

has

a

Gaussian

re-

sponse

to.

obtain

ITlaximwn

phase

linea:-Hy

over

the

.entire

stereo-

phonic

spectrwn.

Preservation

of

phase

integrity

is

paramount

to

proper

stereo

performancl~.

Q-

306

acts

as

a

limiter

and

---------

~

di=r

~

i

~

v

S

c

~

s

~a

~

c

,-:

o:.:n;v-;;e:n

fiofra-t

r

at-io-d

et

e eto.r .

---.T

h~

_

Q\J:~

pu

t

of

thi

s

de

t e

eto

r

is

applied

to

a

program

level'

control

resistor

'-

R-4()()9:l

-

u.~

'

hi:;Ttc~n;;-

-------

determines

the

composite

ouput

level

of

the

receiver.

- 1

5-

The

entire

baseband

signal

is

amplified

by

1C-401,

The

composite

signal

is

passec

through

a

90

kHz

low-pass

filter

and

amplified

by

Q-404,

0-405,

and

Q-

4

Q6

.

The

output

of

this

ar:lplifier-

is

capable

of

delivering

a 6

yolt

peak-to-peak

composite

stereo

signal

to

a

1,000

n

load.

Resistors

H-431

and

R-

t

t32

are

selected

to

reduce

the

am-

plitude

of

the

composite

si'gnal

in

accordance

v.ith

the

input

require-

m<':nts

of

the

direct

FM

exciter

being

used.

It

is

important

that

the

A

DDlO

Gain

Con-::rol,

R

-409,

be

set

to

devetop

the

maximum

voltage

at

the

input

of

R-';31

so

that

the

system

will

yield

the

greatest

signal

'

to

noise

!'atio

.

Thns)

re5istor

P.-432

should

be

selected

to

apply

the

prope~

input

signal

to

the

FM

exciter,

The

output

of

IC-401

is

also

applie~

through

a

100

kHz

high-pass

filter

and

amplfied

by

transistor

0-403

"

to

drive

the

two

low-impedance

multiplex

outputs

appearing

on

the

rear

of

the

receiver

chassis.

The

audio

and

multiplex

outputs

are

squelched'

.

if

there

is

:-:0

incoming

carrier

or

if

the

receive)'

primary

power-

is

removed

.

Fail-safe

contacts

(Forme)

from

K-401

are

avail-

able

on

the

rear

of

the

panel

of

the

receiver

.

'f),

R.ECEIVER

NOMINAL

PERFORMANCE

SPECIFICATIONS

FREQUENCY

SE?

\

$ITIVITY

MODULATION

ACCEPTAI\'CE

890

MHz

to

960

MHz.

crystal

controlled

Ie

s s

than

8.

0

It

volts

fa

r

20

db

quieting,

SOil

input

impedance

.

±200

kHz

INTERMEDIATE

FREQUENCIES

1st

I.

F.

=72

MHz;

2nd

I.

F.

=10

. 7

MHz

SPURIOUS

RESPONSE

STABILITY

METERING

DIMENSIONS

spurious

and

image

responses

attenu-

ated

more

than

60

db

.

maintained

to

within

±O.

001

"

70

of

assign-

ed

frequency

over

ambient

range

of

O~

C

to

55

0 C.

single

meter

and

associated

rotary

switch

may

be

used

to

check

essen-

tial

tuning.

5i

ll

x

19"x

14"

---------

M.,OU.!.,;T

IN

'-'-

___________

=-

s

~

li

~

d

~

e

~

r

~

a

~

il

~

s

~

________________

_

WEIGHT

receiver

and

power

supply

=

17

Ibs

.

POWER

REQUIREMENT

120/240

VAC,

50-

60

cycles

-16-

Under

norr;lal

()oer2.tin~

:

cO!1oitions

all

necessary

tuning

acjustrncnts

c.:..n

be

mace

\\'i

'.:

h

the

aid

of

the

selectable

meter

p:.ovided

on

the

front

panel

and

'with

the

unit

in

o!JeratioIl.

It

will

be

neccss,ny.

however,

to

re:nove

the

tor

and

bottor

:,

covers

to

:,ain

access

to

the

various

circuit

elements

,

Two

definite

points

of

resonai1ce

or

peaks

of

equal

amplitude

Tn2.y

be

(")

bs

er

ved

when

al

igning

the

coil

~

cf

t;1\ s

:::

e

cei

ver

,

However.

singl

e

tuned

coils

adju.st('d

irom

t~e

top

~:.

£

the

ch2.ssis

should

be

o.tib'nefl

on

th.e

pea.k

observed

,,

·

hen

the

slug

is

neare3t

to

the

top

of

the

coil

(with

the

screw

protrudi:1g

the

mo

.s

t),

10

align

the

iirst

osci~btor

and

subsequent

multiplier

stages

th

(

·:

follo,,\'ing;

'procedu!'c

is

used.

Oscillati~r.s

::tre

indicated

by

a

read-

ing

of

the

meter

on

tbc

1

st

OSc.

?osition

.

(Refer

to

the

ty~ic.::.l

re:2.dings

given

elsewher

e

in

this

manual.)

\,,

'

ith

the

m.cter

selector

switch

set

to

the

:vLXER

DRIVE

pOSition,

a(:~u.st

L-202,

L-203,

C-20i',

C-21l,

S-21S,

and

C-216

£o~

a

m:.:~i:num

reading.

Then

set

the

meter

to

t~le

SrC:

,

AL

2

position

and

readjust

these

coils

and

capacitors

for

a

maxi:num.

signal

reac:'ng.

The

reM-aining

adjustrnent5

should

be

made

,,

'ith

a

weak.

sign3.1

in

order

to

avoid

satuJ:'.::l.tion

of

t~e

limiters.

This

can

be

accomplished

by

rotating

the

azimuth

of

the

r e

cei

ving

antenna

ir.

cas

e s

,vhe

r e

the

S'l

L

tr

an

srnltte

r

signal

1S

being

used

or

by

reduchg

the

out?ut

level

of

the

R?

signal

generat-

or

providing

the

test

sig:lal.

Under

cc.ndbons

of

weak

signal,

the

SIGi

'.

:AL

1

positio!':.

'l.vill

provide

adequatei:.dica!:ions

of

proper'

tun-

i:1g.

C-109

and

the

injectio:-:

cavity

control

:::-107

should

then

be

ac:justed

for

maxirnu:n

reading.

This

v,'

ill

complete

the

alignment

of

the

1st

oscill",tor

multiplier

chain.

The

input

cav-ities

can

be

adjusted

fer

maximum

reading

by

tur.ing

C-IOl,

C-I02,

C-I03,

C-I04,

and

C-I05

on

the

top

ui

the

cavity

for

maximum

reading

.

C-IOl,

C-I02,

C-I03, C-I04,

and

C-I05

should

be

about

one

turn

from

the

CCW

end.

Go

back

over

this

step

several

times

to

assure

o?tirnum

adjustment.

Next.

adjust

L-

208,

L-20S.

L-206,

L-207,

L-303,

and

L-302

for

resonance

as

indic-

a.ted

by

a

maximum

reading

on

the

panel

meter

in

the

SIGKAL

2

position.

When

m.aking

these

adjustments

remove

transistor

0-207

on

the

72

Mi:iz

1.

F.

amplifier

chassis.

Thi.s

will

defeat

the

AGC

action

so

that

more

accurate

tuning

can

be

obtained.

PCL-303

JC

3/[8

-17-

Since

the

performance

of

the

Model

PCL-303/C

Receiver

depends

prirnarily

on

the

turing

of

the

10.7

Mlh

1.

F.

and

ratio

detector

transformer,

it

is

not

recprn

:m.

cnded

as

a

field

adjustment

unless

and

1.

F,

sv!eep

generator

and

an

exact

source

of

10.7

MHz

are

available.

Considerable

effort

has

been

expended

in

the

design

of

the

10

. 7

MFz

1.

F.

to

achieve

a

phase

linear

transfer

characteris-

tic

and

to

eliminate

the

need

for

tuning.

ReplaceInent

of

0-302.

Q-

303.

Q-

304,

0-

30

5.

and

Q-

306

does

not

require

the

retuning

of

the:

10,7

1.

F .

Retuning

should

only

be

attempted

with

the

use

of

a

s:weep

generator

to

obtain

a

Gaussian

re::;ponse,

This

should

only

'

be

done

as

a

last

resort

if

aU

else

fails,

The

3

db

bandwiclth

Qf

the

second

I.

F.

amplifier

is

400

kHz,

The

SQUELCH

adjust-

I

ment

should

~e

set

to

a

position

where

50

IIV

of

RF

at

the

input

will

cause

the

~

'

elay

to

unsquelch

the

output.

It

win

be

noted

that

three

other

contacts

are

provided

on

the

back

of

the

receiver.

These

are

also

controlled

by

the

squelch

relay

and

may

be

used

for

fail-

safe

or

alarm

operation

if

the

STL

carrier

is

lost.

PCL-303/C

3/68

Moseley PCL-303/C User manual

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