Moseley PCL-303/C User manual
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I.
II.
III.
IV.
V.
VI.
VII.
VIII.
IX.
PCL-303/C
TABLE
OF
CONTENTS
Introduction
·
Specifications
A.
Overall
System
Specifications
Page
B.
Receiver
Performance
Specifications
1
4
4
4
C.
Transmitter
Performance
Specifications
Unpacking
and
Initial
Checkout
Installation
Antenna
Detailed
Description
of
Transmitter
A.
B.
C.
Transmitter
Operation
Transmitter
Circuit
Description
Transmitter
Remote
Control
D.
Transmitter
Adjustments
and
Alignments
Detailed
Description
of
Receiver
A.
Receiver
Operation
B.
Receiver
Circuit
Description
C.
Receiver
Adjustments
and
Alignments
Shipping
Instructions
Final
Te
st
Data
-i-
5
6
7
8
9
9
10
12
12
14
14
15
17
19
20
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INSTRUCTION
MANUAL
MODEL
PCL-303/C
STUDIO-TRANSMITTER
LINK
I.
INTRODUCTION
The
Model
PCL-303/C
Composite
Aural
Studio-Transmitter
Link
(ST
L)
is
a
wide-
band
system
de
signed
for
the
transmission
of
a
composite
FM
stereophonic
signal
between
a
broadcast
studio
and
a
remotely
located
FM
transmitter.
Ruggedly
built,
compact,
and
rated
for
continuous
duty,
the
Model
PCL-303/C
is
an
all
solid-
state
unit
employing
only
silicon
s
em'iconductor
s.
There
are
several
advantages
to
the
transmission
of
a
composite
·
FM
stereo
signal.
Some
of
these
are:
1.
Only
one
basic
RF
link
is
utilized
to
transmit
the
com-
posite
stereo
waveform,
including
the
19
kHz
pilot
sub-
carrier.
This
is
in
contrast
to
the
utilization
of
two
aural
ST
L
systems
to
convey
the
unmatrixed
LEFT
and
RIGHT
audio
signal.
This
results
in
an
equipment
cost
savings.
It
should
also
be
noted
that
a
67
kHz
SCA
subcarrier
can
also
be
applied
to
the
ST
L
for
direct
rebroadcast
_
by
the
FM
transmitter.
2.
The
stereo
generator
is
located
at
the
studio
site
where
adjustments,
if
required,
can
be
made
away
from
the
strong
RF
fields
found
near
large
FM
broadcast
trans-
mitters.
These
high
RF
fields
can
have
deleterious
effects
on
the
instrumentation
employed
to
properly
align
the
stereophonic
generation
equipment.
The
Model
PCL-303/C
Composite
Aural
STL
is
basically
the
same
as
the
·
Model
PCL-303
except
that
the
75
µsecond
pre-emphasis/
de-emphasis
networks
and
15
kHz
600
n
low-pass
filters
have
been
removed
from
the
transmitter
and
receiver,
respectively.
The
basic
modulation
response
capability
of
the
direct
FM
oscil-
lator
employed
in
the
Model
PCL-303/C
is
sufficent
to
accept
PCL-303/C
-1-
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and
faithfully
transmit
the
frequency
spectrum
required
for
FM
stereophonic
broadcasting.
Further,
the
bandwidth
of
the
10.
7
MHz
I.
F.
amplifier
of
the
composite-
system
receiver
has
been
increased
and
adjusted
to
follow
a
curve
which
yields
a
linear
phase
characteristic.
The
detected
composite
waveform
in
the
Model
PCL-303/C
receiver
is
passed
tprough
a
low-pass
filter
which
does
not
significantly
alter
the
phase
relationship
of
the
composite
signal
(does
not
degrade
separation).
This
low-pass
filter
will
attenuate
any
remote
control
or
secondary
program
subcarriers
multiplexed
above
the
composite
signal
(,
far
in
excess
of
the
requirements
of
FCC
Rule
73.
317(a).
The
Model
PCL-303/C
STL
consists
of
a
transmitter
and
a
re-
ceiver
each
mounted
on
a
standard
5¼" x
19
11
rack
panel
with
slide-out
provisions.
The
ST
L
receiver
is
a
crystal-controlled,
double-conversion,
super
heterodyne
type.
A
relay
is
included
in
the
receiver
to
mute
the
composite
output
should
the
incom-
ing
carrier
fall
below
a
given
preset
value.
In
addition,
Form
C
contacts
of
this
relay
are
terminated
on
the
rear
apron
for
use
by
external
alarm
or
control
circuits.
The
transmitter
incorporates
a
direct
FM
basic
oscillator
to
achieve
flat
response
and
uniformly
low
distortion
over
a
wide
modulation
frequency
range.
Provisions
are
included
on
the
transmitter
to
multiplex
two
~ubcarriers
for
remote
control
and
auxiliary
service.
A
special
extended-life,
quiet
fan
provides
cooling
for
the
final
power
amplifier
chain.
The
basic
direct
FM
oscillator
is
phase
locked
to
a
temperature-controlled,
low-
frequency,
reference
crystal
oscillator.
Also
included
in
the
transmitter
are
two
frequency-doubler
stages,
one
3-stage
Class
C
RF
power
amplifier,
and
a
parametric
·
multiplying
power
diode.
A
3-section
bandpass
filter
is
incorporated
in
the
STL
trans-
mitter
RF
output
circuitry.
A
sampling
diode
is
included
in
this
assembly
to
indicate
relative
RF
power
output
of
the
transmitter.
All
transistors
and
IC'
s
in
the
Model
PCL-303/C,
other
than
the
transistors
on
the
AFC
board
in
the
transmitter,
are
socket
mounted.
Both
transmitter
arid
receiver
units
are
fully
shielded.
PCL-303/C
-2-
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It
should
be
noted
that
the
Model
PCL-303/C
Composite
Aural
STL
can
only
be
used
with
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.
However,
it
is
possible
to
apply
a
signal
from
other
stereo-
phonic
generators
meeting
th~
requirements
of
FCC
Rule
73.
322.
The
input
level
requirements
of
the
PC
L-
303
/ C
transmitter
must
be
observed
to
obtain
satisfactory
results.
PCL-303/C
-3-
.
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II.
SPECIFICATIONS
Model
PCL-303/C
Composite
Aural
Studio-
Transmitter
Link
A.
Overall
System
Specifications
L+R
Frequency
Response
L+R
Distortion
L+R
SNR
Stereo
Separation
±0.
5
db,
50
Hz
to
15
kHz
Less
than
0.
75%,
50
Hz
to
15
kHz
65
db
for
35
µv
input
signal
Greater
than
35
db,
5.0
Hz
to
15
kHz
(assuming
that
input
stereo
signal
has
separation
1n
ex
c
es
s
of
38
db)
B.
Receiver
Performance
Specifications
Frequency
Sensitivity
RF
Input
Modulation
Acceptance
Intermediate
Frequencies
Spurious
Response
Stability
Maximum
Available
Composite
Output
Signal
Metering
Operating
Temperature
Range
Dimensions
Weight
Power
Requirement
Mounting
PCL-303/C
-4-
890
MHz
to
960
MHz,
crystal
controlled
Less
than
8.0
µvotts
for
20
db
quieting
50
n,
Type
N
female
connector
±200
kHz
1st
I.
F.
72
MHz;
2nd
I.
F.
10.
7
MHz
Spurious
and
image
responses
attenuated
more
than
60
db
Maintained
to
within
±0.
001
%
of
assigned
frequency
over
ambient
range
of
0°C
to
55°C
6
volts
peak-to-peak,
1000
n
minimum
load
impedance,
unbalance
Single
multimeter
for
monitor-
ing
essential
operating
parameters
0°c
to
55°C
5¼"
X
19"
X
14
11
17
lbs.
120/240
VAC,±10%,
50-60
Hz
Standard
19"
rack
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C.
Transmitter
Performance
Specifications
Type
Direct
FM
RF
Output
Frequency
Stability
Multiplication
AM
Noise
Deviation
Spurious
Emissions
Emission
Symbols
Stereo
only
Stereo
and
67
kHz
SCA
Composite
Input
Multiplex
Inputs
Operating
Temperature
Range
Power
Supply
Power
Requirement
Cooling
Dimensions
Mounting
PCL-303/C
7
watts
nominal;
8
watts
maxi-
mum
into
nominal
50
!J
load.
Type
N
female
connector
Better
than
0.
001%
(0°C
to
60°C;
crystals
mounted
in
temperature-
controlled
oven
12
times
basic
oscillator
frequency
Better
than
75
db
below
carrier
reference
±70
kHz
for
l
00%
modulation
More
than
60
db
below
carrier
246F9,
255
kHz
B.
W.
290F9,
300
kHz
B.
W.
10,000
!J
unbalanced,
approxi-
mately
3.
5
volts
peak-to-peak
for
1
00%
modulation
Two
BNC
connectors
are
pro-
vided
for
subcarrier
channels
in
110-200
kHz
spectrum;
ap-
proximately
1.
0
volt
rms
for
20%
deviation
0°C
to
55
°C
Fully
regulated,
self-
contained
120/240
VAC,
±10%,
50-60
Hz
Convection
and
forced;
fan
has
long-life
bearings
5¼"
X
19
11
X
16
11
Standard
19"
rack
-5-
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III.
UNPACKING
AND
INITIAL
CHECKOUT
The
Model
PCL-303/C
transmitter
and
receiver
should
be
care-
fully
unpacked
and
inspected
for
concealed
shipping
damages
upon
receipt
of
the
equipment.
Retain
all
boxes
and
spacers
in
case
a
claim
is
to
be
made
against
the
carrier
for
damages.
Should
the
equipment
be
damaged,
IMMEDIATELY
file
a
claim
with
the
carrier.
The
top-shield
cover
of
the
STL
transmitter
should
be
removed
so
that
the
shipping
spacers
which
have
been
used
to
secure
the
various
shock-mounted
subas
semblies
can
be
removed.
It
is
also
recommended
that
the
receiver
top-shield
cover
be
removed
to
confirm
that
the
muting
relay
and
all
tran-
sistors
are
properly
seated
in
their
sockets.
This
visual
inspec-
tion
will
also
acquaint
the
user
with
the
location
of
the
key
components
in
the
equipment.
CAUTION:
Do
not
attempt
any
tuning
adjustments
on
the
receiver
or
transmitter
at
this
time.
All
tuned
circuits
have
been
pre-aligned
at
the
factory
and
should
not
be
adjusted
unless
proper
test
equipment
is
available
and
then
only
after
reading
the
Tuning
and
Alignment
Procedure
outlined
elsewhere
in
this
manual.
If
a
10
watt
50
n
RF
termination
capable
of
operation
at
950
MHz
is
available,
with
or
without
a
calibrated
wattmeter,
the
STL
transmitter
can
be
bench
checked.
With
the
RF
load
connected
to
the
output
of
the
ST
L
transmitter
and
the
line
cord
plugged
into
a
source
of
117
VAC,
50-60
Hz
power,
the
front-panel
RADIATE
switch
can
be
turned
on.
The
RF
wattmeter,
if
used,
will
immediately
indicate
between
6
watts
and
8
watts
of
output
power.
The
RF
output
meter
on
the
front
panel
of
the
PCL-
303/C
will
indicate
between
50
and
55
divisions.
The
receiver
should
be
placed
oil
an
adjacent
bench
and,
after
the
power
plug
has
been
connected
to
the
power
source,
the
power
switch
can
be
turned
o~.
It
may
be
necessary
to
care-
fully
insert
a
small
wire
into
the
Type
N
RF
input
fitting
on
the
rear
of
the
receiver
chassis
to
minimize
multipathing
effects.
Do
not
attempt
to
adjust
the
input
or
output
cavities
of
the
ST
L
receiver
and
transmitter
under
these
test
conditions.
These
are
PCL-303/C
-6-
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preliminary
tests
and
should
be
conducted
to
become
familiar
with
the
basic
operation
of
the
system.
An
audio
test
signal
of
3.
5
volts
peak-to-peak
may
be
applied
to
the
Type
BNC
modulation
input
connector
on
the
rear
of
the
ST
L
trans
-
mitter
for
the
initial
transmitter
check.
This
signal
can
be
.
derived
from
a
standard
audio
oscillator
or
Model
SCG-3T
FM
Stereo
Generator.
An
oscilloscope
or
VTVM
should
be
connected
to
the
Type
BNC
output
connector
located
on
the
rear
of
the
ST
L
receiver
to
confirm
the
presence
of
the
test
signal.
Bear
in
mind
that
multipathing
conditions
can
exist
under
these
initial
checks
and
will
affe
.
ct
the
measurements
made.
Since
the
STL
transmitter
does
not
employ
pre-emphasis,
it
is
not
necessary
to
reduce
the
amplitude
of
the
input
'
signal
source
when
making
frequency
response
measurements.
(This,
of
course,
will
not
be
true
if
the
test
signal
source
is
derived
from
a
stereo
generator.)
IV.
INSTALLATION
The
Model
PCL-303/C
transmitter
and
receiver
can
be
mounted
in
a
standard
19"
wide
rack
using
the
slides
provided.
For
max-
imum
mounting
stability,
the
rear
of
these
slides
should
be
secured
to
the
rear
rails
(or
to
the
cabinet
walls)
with
the
brackets
provided.
The
external
connections
which
must
be
made
for
both
units
include
the
3-wire
power
cord,
RF
input
and
out-
put
cables,
unbalanced
shielded
composite
program
line
and,
if
used,
coaxial
cables
for
multiplex
subcarriers.
The
transmitter
should
be
installed
in
such
a
manner
as
to
allow
air
to
freely
circulate
around
the
equipment.
Transmission
line
considerations
will
determine
to
some
extent
the
placement
of
the
equipment.
As
lengthy
transmission
line
will
introduce
undesirable
amounts
of
attenuatio~
of
the
transmitter
output,
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,
use
the
lowest
loss
line
possible
consistent
with
mechanical
and
economical
con-
siderations.
The
same
precautions
should
be
followed
in
locating
the
receiver.
Because
of
the
use
of
slide-mounting
rails,
it
is
preferable
to
use
a
short
length
of
RG
...
8A/U
coaxial
cable
to
con-
nect
the
RF
fittings
on
the
rear
of
the
ST
L
transmitter
and
re-
ceiver
to
the
actual
transmission
line.
This
prevents
damage
to
the
equipment
and
eases
use
of
the
·
slide-rail
mounting
technique.
In
all
cases,
constant
impedance
RF
fittings
should
be
used,
such
as
a
Type
N
connector,
on
the
transmission
line.
PCL-303/C
(Rev.
10/72)
-7-
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Assuming
that
the
initial
checks
as
outlined
in
the
previous
section
have
been
made,
the
STL
transmitter
and
receiver
may
now
be
turned
on.
CAUTION:
Be
sure
the
transmission
line
and
antenna
have
been
properly
con~ected
to
the
PCL-303/C
transmitter
before
activating
the
RADIATE
switch.
When
the
RADIATE
switch
is
turned
on,
the
RF
output
meter
of
the
transmitter
should
indicate
between
50
and
55
divisions.
A
reading
different
from
this
value
usually
indicates
the
presence
of
a
high
VSWR.
The
tune-up
procedure
is
described
in
Section
VI
of
this
manual.
When
the
PCL-303/C
transmitter
power
cord
is
connected
to
the
primary
power
line
source,
operating
voltages
are
applied
to
the
basic
oscillator,
crystal
oven,
AFC
network,
and
low-level
fre-
quency
multiplier
stages.
The
front-panel
lamp
glows
when
the
transmitter
~s
connected
to
the
power
line.
Turning
the
front
panel
switch
to
the
RADIATE
position
applies
voltage
to
.
the
high
frequency
p\)wer
amplifier
chain
as
well
as
the
cooling
fan.
The
RF
output
meter
on
the
front
panel
provides
an
indication
of
carrier
radiation.
This
turn-on
procedure
prevents
the
STL
transmitter
from
radiating
an
off-frequency
signal
prior
to
the
capture
of
the
basic
oscillator
by
the
AFC
circuitry.
V.
ANTENNA
The
Type
PR-450
Scala
Antenna
is
normally
recommended
for
use
with
the
Model
PCL-303/C
STL.
The
reflecting
screen
is
a
parabolic
section
in
one
plane
and
provides
a
gain
of
17.
5
db
over
a
reference
dipole
antenna
(approximately
19.
6
dbi
gain).
Its
physical
aperture
is
67"
x
36
11
•
The
anodized
driver
element
is
located
at
the
focus
of
the
paraboloid
and
is
pretuned
at
the
factory
for
the
operating
frequency.
No
attempt
should
be
made
to
field
tune
the
antenna.
The
actual
radiating
element
is
a
folded
dipole
with
a
balun
transformer
permanently
sealed
within
,
the
driver-element
support
for
impedance
matching
to
a
50
n
transmission
line.
This
configuration
results
in
less
beam
skewing
under
heavy
ice
and
snow
loading
conditions.
It
should
be
noted
that
this
antenna
has
a
low
DC
resistance
between
the
PC
L-303/C
-8-
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inner
conductor
and
the
shield
of
the
Type
N
RF
fittings
supplied.
On
special
order,
the
reflecting
screen
of
the
antenna
can
be
anodized
and
dichromate
dipped
to
as
sure
long
life
in
a
corrosive
environment.
The
PR
-450
Antenna
is
supplied
with
U
-bolt
mount-
ing
hardware
so
that
it
can
be
clamped
to
a 2
3/8
11
O.D.
pipe.
The
open
grid
reflector
design
minimizes
wind
loading.
In
assemblying
the
PR-450,care
should
be
taken
to
insure
that
the
driver
element
support
is
fully
seated.
If
this
support
is
not
fully
seated,
optimum
gain
of
the
PR-450
will
not
be
achieved.
Additionally,
the
polarization
of
the
transmitting
and
receiving
antennas
should
be
in
the
same
plane.
When
mounting
the
PR-450
or
equivalent
antenna
to
an
ungrounded
standard
broadcast
tower,
the
Moseley
Model
I.CU-1
IsoucoupJer
may
be
used
to
eliminate
the
need
to
construct
a
resonant
trans-
mission
line
tank
circuit
or
the
requirement
for
a
quarter-wave
insulated
transmission
line
section
up
the
tower.
The
ICU
-1
Isocoupler
has
less
than
0.
5
db
of
insertion
loss
at
950
MHz
and
presents
less
than
10
pf
of
capacity
to
the
base
of
the
tower.
The
ICU
- 1
is
rated
for
a
peak
instantaneous
voltage
breakdown
of
5,
000
volts.
The
modulation
voltage
peaks
should
be
taken
into
consideration
when
using
the
ICU
-1.
VI.
DETAILED
DESCRIPTION
OF
TRANSMITTER
A.
Transmitter
Operation
To
place
the
Model
PCL-303/C
in
operation,
connect
the
RF
transmission
line
to
the
Type
N
output
fitting.
Connect
the
power
cord
to
a
source
of
120/240
VAC,
50-60
Hz
power.
The
green
pilot
light
will
indicate
the
presence
of
primary
power.
This
lamp
is
on
whenever
the
transmitter
is
connected
to
the
power
line.
The
composite
stereo
waveform
is
applied
to
the
transmitter
through
the
Type
BNC
connector
on
the
rear
panel.
Power
is
applied
to
the
RF
power
amplifier
by
activating
the
switch
marked
RADIATE
on
the
front
panel.
RF
power
output
is
continuously
displayed
on
the
front-panel
meter
labeled
RF
OUTPUT.
A
copy
of
the
final
test
data
can
be
found
on
page
20
and
should
be
referred
to
for
specific
meter
readings
and
sys
-
tern
performance
measurements.
These
measurements
will
serve
as
a
guide
in
operation
of
the
equipment.
PCL-303/C
-9-
www.SteamPoweredRadio.Com
An
approximate
curve
for
the
POWER
OUTPUT
meter
position
is
shown
in
Drawing
15Al055.
Potentiometer
R-310,
located
at
the
rear
of
the
power
amplifier
chain,
adjusts
the
level
of
the
RF
output
monitor
meter.
Should
this
control
be
changed,
it
will
be
necessary
to
recalibrate
the
potentiometer
against
an
RF
watt-
meter
of
known
accuracy.
A
transmission
line
or
antenna
im-
pedance
mismatch
will
introduce
an
error
into
this
reading.
For
100%
modulation
of
the
STL
the
carrier
is
shifted
approxi-
mately
±70
kHz
from
its
mean
center
frequency.
A
1,
000
Hz
test
tone
at
a
level
of
3.
5
volts
p-p
will
produce
100%
modulation.
Two
BNC
connectors
are
mounted
adjacent
to
the
composite
input
connector.
These
connectors
provide
equal
but
isolated
multiplex
inputs.
For
10%
subcarrier
injection
the
voltage
at
the
BNC
input
should
be
O.
5
volts
rms.
These
sub-
carriers
should
be
confined
to
the
110
kHz
to
200
kHz
spectrum
to
prevent
interference
to
the
stereo
signal
and
out-of-band
radiation.
It
is
usually
not
advisable
or
necessary
to
reduce
the
main
channel
program
level
when
a
subcarrier
is
added
to
the
STL.
B.
Transmitter
Circuit
Description
The
complete
schematic
of
the
PCL-303/C
transmitter
is
shown
in
Drawing
91C-62
.
42.
The
composite
stereo
input
signal
is
first
applied
to
the
deviation
control,
R-145.
It
is
then
passed
through
a
time
constant
correction
network
to
the
variable
capacitance
diodes
(varicaps)
CR-101
and
CR-102.
These
diodes
vary
the
resonant
frequency
of
the
tank
circuit
of
the
oscillator,
Q-101.
Q-101
oscillates
at
a
frequency
of
1/12
the
final
output
or
car-
rier
frequency
and
is
frequency
modulated
±6
kHz
by
the
main
channel
program
material
for
100%
modulation.
For
discussion
purposes,
an
operating
frequency
of
945.
0
MHz
will
be
assumed.
Hence,
the
frequency
of
the
basic
oscillator
Q-101
will
be
945.
0
+
12
or
78.
75
MHz.
This
signal
is
amplified
by
Q-102
and
fed
to
Q-201.
This
78.
75
MHz
signal
is
multiplied
four
times
and
amplified
by
Q-
202
and
Q-203
to
produce
a
100
milli-
watt
signal
at
315
MHz
at
J-202.
This
power
is
fed
to
J-301
on
the
RF
power
amplifier
chassis.
Q-301,
Q-302
and
Q-303
tran-
sistors
amplify
the
315
MHz
signal
to
12
watts
which
is
applied
to
the
parametric
multiplier
CR-301.
Eight
watts
of
PCL-303/C
(Rev.
10/
72)
-10-
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power
are
removed
from
the
diode
at
3
times
315
MHz
or
945
MHz.
L-313
and
C-317
form
the
idler
circuit
of
the
para-
metric
multiplier.
The
945
MHz
output
of
the
var
actor
is
then
fed
through
C-
323
and
the
3-
section,
end-tuned
filter
cavities
to
J-302.
The
antenna
coaxial
cable
is
attached
to
J-302.
Automatic
frequency
control
(AFC)
of
the
transmitter
output
frequency
is
accomplished
by
phase
locking
the
78.
75
MHz
basic
oscillator
to
a
76
kHz
low-frequency,
crystal-controlled,
refer-
ence
oscillator.
The
78.75
MHz
output
of
Q-102
is
applied
to
the
input
of
a
high
speed
binary
counter
and
divided
eight
times
by
'
integrated
circuits
IC-1,
IC-2,
and
IC-3.
This
divided
out-
put,
9.
844
MHz
in
the
example,
is
applied
to
c;1.
level-changing
amplifier
Q-1
on
the
AFC
printed
circuit
board.
The
output
of
Q-1
feeds
another
binary
chain,
IC-5
through
IC-9,
which
divides
the
input
frequency
by
512.
The
total
division
of
the
basic
oscillator
frequency
is
4.
096.
The
low-frequency
reference
sig-
nal
is
derived
from
IC-4,
an
integrated
circuit
emitter-coupled
crystal-controlled
multivibrator.
The
output
of
this
oscillator
is
applied
to
level
changer
Q-2
and
applied
to
IC-10
and
divided
4
times.
Thus,
the
outputs
of
IC-9
and
IC-10
operate
at
the
.
same
frequency.
The
phase
of
these
two
output
signals
is
compared
in
IC-11
to
achieve
an
integrated
DC
AFC
error
voltage
which
is
amplified
by
Q-3.
It
should
be
noted
that
the
entire
AFC
system
is
not
frequency
sensitive
since
all
integrated
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-pass
filter
network
to
varicap
diodes
CR-:103
and
CR-104.
Thus,
the
frequency
of
the
baisc
oscillator
is
phase
locked
to
the
low-frequ
~
ncy,
temperature-
controlled,
crystal
reference
oscillator.
It
should
be
noted
that
the
two
capacitors
used
to
couple
the
four
varicap
diodes
to
the
basic
oscillator
tank
circuit
are
temperature
compensated
to
achieve
optimum
frequency
stability
of
the
basic
oscillator.
The
power
supply
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
amplifier.
The
+15
volt
DC
supply
powers
all
other
circuitry
except
the
binary
which
uses
PCL-303/C
-11-
·+
www.SteamPoweredRadio.Com
the
+3.
6
volt
output.
The
+28
volt,
the
+15
volt,
and
the
+3.
6
volt
DC
supplies
are
fully
regulated
by
Q-401, Q-402,
Q-403,
Q-404,
and
the
Zener
diode
references
CR-407
and
CR-410.
R-408
adjusts
the
output
voltage
of
the
28
volt
supply
and
should
never
be
set
higher
than
+28
volts
DC.
C.
Transmitter
Remote
Control
The
Model
PCL-303/C
transmitter
may
be
operated
from
a
re-
mote
location.
A
5-pin
receptacle,
J-403,
is
mounted
on
the
rear
of
the
chassis.
This
connector
enables
the
remote
radiate
switch
and
meters
to
be
connected
to
the
PCL-303/C
circuitry.
A
5-conductor
cable
should
be
used
between
the
remote
control
point
and
the
PCL-303/C
transmitter.
A
plug
with
pins
A
and
B
shorted
together
is
provided
with
each
Model
PC
L-
303
/C
trans
-
mitter.
If
remote
control
operation
is
not
intended,
this
plug
should
remain
inserted
in
J
-403.
To
turn
the
carrier
.
on
from
the
remote
location,
wires
must
be
connected
between
pins
_C
and
D
of
J
-403.
A
simple
SPST
toggle
switch
can
be
used
for
this
purpose.
Actuating
this
switch
will
operate
relay
K-401,
applying
+26
±
2
volts
DC
to
the
RF
power
amplifier.
·
To
indicate
the
relative
power
output
at
the
remote
position,
place
a
50
µa
meter
in
series
with
pins
A
and
B
of
J
-403.
Connecting
another
50
µa
meter
between
pins
J
and
A
will
provide
the
remote
control
point
with
an
indication
of
the
AFC
error
voltage.
The
Model
ECP-1
Extension
Control
Panel
is
available
to
operate
the
PCL-303/C
from
a
remote
location.
It
should
be
noted
that
a
5-conductor
cable
is
required
between
the
transmitter
and
the
ECP-1
Control
Panel.
Thus,
the
use
of
the
ECP-1
is
limited
to
relatively
short
distances,
usually
within
the
same
building.
D.
Transmitter
Adjustments
and
Alignments
A
complete
alignment
of
the
transmitter
is
not
recommended
in
the
field.
However,
in
the
case
of
transistor
replacement,
a
touch-up
alignment
can
be
performed.
Fir
st,
remove
the
2
amp
fuse
on
the
power
supply
chassis,
and
adjust
R
-408
for
+26
± 2
volts
DC
at
the
output
of
the
power
supply.
Do
not
set
the
output
above
+28
volts.
Check
the
+28
volt
and
+
15
volt
DC
supplies
with
the
front
panel
meter.
Switch
the
meter
to
the
BASIC
OSC.
position.
If
the
reading
is
over
30,
switch
to
the
REF.
OSC.
position.
If
the
PCL-303/C
(~ev.
10/72}
-12-
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reading
is
again
over
30,
switch
to
the
BINARY
OUTPUT.
This
reading
should
be
at
50
divisions
±10.
If
it
reads
either
10
divisions
or
90
divisions,
the
binary
is
not
working
and
service
is
required.
If
it
reads
50
divisions,
switch
to
the
AFC
position.
This
reading
should
be
40
to
60
divisions
also.
If
it
is
not,
switch
to
the
AFC
UNLOCK
position.
Adjust
the
AFC
control
C-104
until
the
meter
reads
zero.
This
can
be
done
by
adjust-
ing
C-104
until
the
meter
reading
rises
and
then
falls
to
zero
after
some
noticeable
oscillation.
After
the
meter
falls
to
zero,
switch
back
to
the
AFC
position.
The
meter
will
read
between
30
and
70
divisions.
Continue
to
adjust
C-104
until
the
meter
reads
50
in
the
AFC
position.
NOTE:
When
the
frequency
of
the
basic
oscillator
is
not
"locked"
to
the
frequency
of
the
reference
crystal
oscillator,
it
should
be
noted
that
the
reading
of
the
meter
with
the
selector
switch
in
the
AFC
position
will
be
approximately
50.
This
is
the
SAME
reading
that
appears
when
the
basic
oscillator
is
in
phase
with
the
reference
oscillator
and
no
AFC
error
voltage
is
present.
AFC
control
of
the
basic
oscillator
can
be
quickly
confirmed
by
switching
to
the
AFC
position.
·
If
the
meter
follows
a
slight
change
of
adjust-
ment
in
C 1
04,
the
AFC
is
locked.
In
normal
operation
the
I.
P.A.
DRIVE
position
is
used
as
an
indication
of
the
presence
of
normal
drive
to
the
RF
amplifier.
The
amplitude
of
the
I.
P.A.
DRIVE
position
meter
reading
is
affected
by
the
presence
of
+28
volts
on
the
RF
amplifier.
The
meter
reading
will
be
higher
when
the
RADIATE
switch
is
on.
No
attempt
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
-202,
and
connect
a
50n
RF
dummy
load
to
J-202.
Using
an
external
multimeter,
place
it
from
the
emitter
of
Q-203
to
ground,
and
adjust
L-201
and
L-202
for
a .
maximum
reading
on
the
external
multimeter.
Remove
the
external
multimeter,
and
adjust
L-203
for
a
maximum
reading
on
the
I.
P.A.
DRIVE
position.
Remove
the
RF
dummy
load,
and
reconnect
the
cable
from
J-301
to
J-202.
Place
a
dummy
load
or
antenna
on
the
RF
output
J
-302.
Turn
the
PCL-303/C
(Rev.
10/72)
-13-
www.SteamPoweredRadio.Com
RADIATE
switch
off,
and
replace
the
2
amp
fuse
in
the
power
supply
chassis.
Switch
the
meter
to
the
FINAL
CURRENT
posi-
tion,
and
turn
the
RADIATE
switch
on.
The
RF
output
meter
should
read
approximately
50
divisions.
If
an
RF
wattmeter
is
used,
it
will
read
6
to
8
watts.
The
FINAL
CURRENT
should
read
between
7 5
and
9
5.
If
the
final
current
is
correct
but
the
power
output
is
low,
adjust
C-319,
C-320,
C-321
for
a
maxi-
mum
on
the
RF
output
meter.
If
a
satisfactory
maximum
is
achieved
and
the
final
current
is
correct,
switch
to
the
I.
P.A.
CURRENT
position.
It
.
should
be
between
30
and
60.
Switch
to
the
MULTIPLIER
BIAS.
It
should
be
between
40
and
90.
C-314
through
C-317
are
not
readily
available
adjustments
and
should
not
be
attempted
without
consulting
the
manufacturer.
Replace-
ment
of
all
transistors
except
Q-401, Q-402,
Q-302,
and
Q-303
is
straightforward.
When
replacing
Q-401
or
Q-402,
be
certain
that
the
insulating
washer
is
reinstalled
between
the
transistor
and
the
heat
sink.
If
Q-203
or
Q-301
are
replaced,
remove
the
finned
heat
sink
on
the
old
unit
and
install
it
on
the
replacement.
VII.
DETAILED
DESCRIPTION
OF
RECEIVER
A.
Receiver
Operation
After
mounting
the
receiver,
connect
the
power
supply
cord
to
a
convenient
source
of
120/240
VAC,
50-60
Hz.
Turn
on
the
power
switch
on
the
front
panel.
Attach
the
antenna
connection.
The
potentiometer
{R404,
see
Drawing
20A2090
for
location)
con-
trolling
the
receiver
·
squelch
is
available
on
the
audio
multiplex
P.
C.
board.
The
receiver
top
must
be
removed
to
adjust
this
control.
This
level
is
preset
to
operate
with
an
input
signal
of
50
µvolts
and
should
not
require
readjustment.
The
program
output
level
control
{R409)
is
also
available
on
the
audio
multiplex
board.
This
adjustment
is
factory
set
to
deliver
6
volts
peak-to-peak
to
the
output
attenuator
pad,
R-431
and
R-432.
These
resistors
are
selected
to
match
the
deviation
sensitivity
of
the
FM
exciter
so
that
100%
modulation
is
achieved
with
the
maximum
signal-to-noise
ratio
capability
of
the
Model
PCL-303/C
system.
PCL-303/C
{Rev.
10/72)
-14-
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1
A
calibration
table
for
SIGNAL
1
and
SIGNAL
2
is
included
in
the
final
test
data
on
page
20
of
this
manual
and
shows
the
relationship
between
the
meter
reading
and
the
actual
input
signal
expressed
in
µvolts.
For
60
db
quieting
in
the
demodu-
lated
LEFT
or
RIGHT
channels,
the
received
signal
should
be
100
µvolts
or
greater.
The
final
test
data
sheet
also
includes
the
multimeter
readings
taken
on
the
receiver
during
final
test.
These
readings
will
serve
as
a
guide
during
the
operation
and
servicing
of
the
equipment.
B.
Receiver
Circuit
Description
The
receiver
is
a
double-conversion
superheterodyne
type
em-
ploying
19
transistors,
19
diodes,
and
one
integrated
circuit.
A
complete
schematic
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
5¼"
high.
External
connections
include
the
power
cord,
the
RF
Type
N
input
connector
located
on
the
rear
panel,
type
BNC
connectors
for
the
composite
out-
put
signal,
and
two
multiplex
outputs.
In
addition,
relay
contacts
.
(Form
C)
are
also
present
on
the
rear
chassis
to
indicate
pres-
ence
of
a
received
carrier.
Quite
often
the
ST
L
receiver
is
located
in
a
building
containing
high
RF
field
energy.
Under
these
conditions,
cross-modulation
products
can
be
created
in
a
conventional
transistor
amplifier
stage
if
the
input
signals
applied
to
the
base
circuit
exceed
the
linear
dynamic
range
of
the
device.
To
prevent
this
conditio~
in
the
Model
PCL-303/C
receiver,
the
3-stage
72
MHz
I.F.
am-
plifier
employs
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.
amplifier.
This
voltage
increases
in
the
positive
direction
with
an
increase
in
the
desired
signal.
Tran-
sistor
Q-207
in
the
72
MHz
I.
F.
amplifier
inverts
this
voltage
a0
nd
applies
it
to
Gate
2
of
the
first
and
second
72
MHz
FET
stages
(Q-204
and
Q-2O5).
A
fixed
bias
is
applied
to
Gate
2
of
the
last
E:_ET
(Q-206)
to
assure
a
more
constant
input
to
the
10.
7
MHz
2nd
I.
F.
amplifier.
PCL-303/C
-15-
www.SteamPoweredRadio.Com
A
table
showing
the
readings
for
Signal
1
and
Signal
2
meter
positions
is
included
in
the
final
test
data
sheet
of
this
instruction
manual.
The
Signal
2
readings
are
shown
with
and
without
the
AGC
applied
to
the
72
MHz
I.
F.
amplifier.
Under
normal
con-
ditions
the
meter
will
indicate
the
signal
strength
with
AGC.
To
obtain
a
reading
without
AGC,
it
is
necessary
tp
remove
Q-207
from
its
socket.
The
input
of
the
STL
receiver
is
designed
for
an
impedance
of
50
0.
The
antenna
input
connector
is
coupled
to
the
first
of
five
end-loaded
resonate
line
cavities.
The
last
cavity
is
coupled
to
the
first
crystal
mixer
CR-101,
where
it
is
mixed
with
the
local
oscillator
injection
signal.
The
local
oscillator
signal
is
derived
from
the
first
crystal
oscillator
Q-201
and
multipliers
Q-202,
Q-203,
and
CR-102.
The
output
of
the
crystal
mixer
is
72
MHz
and
is
coupled
into
the
signal
gate
of
Q-204
which
is
the
first
72
MHz
I.
F.
stage.
It
is
amplified
by
Q-205
and
Q-206
and
is
applied
to
the
base
of
the
second
mixer
Q-302.
The
injection
voltage
for
the
second
mixer
is
generated
by
·
Q-301,
a
crystal-
controlled
oscillator
at
61.
3
MHz.
The
output
of
this
mixer
is
then
amplified
by
the
1
0.
7
MHz
second
I.
F.
amplifier,
Q-303,
Q-304, Q-305,
and
Q-306.
This
amplifier
has
a
response
de-
signed
to
obtain
maximum
phase
linearity
over
the
entire
stereo-
phonic
spectrum.
Preservation
of
phase
integrity
is
paramount
to
proper
stereo
performance.
Q-306
acts
as
a
limiter
and
drives
a
conventional
ratio
detector.
The
output
of
this
detector
is
applied
to
a
program
amplifier
which
determines
the
compos-
ite
output
level
of
the
receiver.
The
entire
baseband
signal
is
amplified
by
IC-401.
The
com-
posite
signal
is
passed
through
a
low-pass
filter
and
amplified
by
Q -
404,
Q-405,
and
Q-406.
The
output
of
this
amplifier
is
capable
of
delivering
a 6
volt
peak-to-peak
composite
stereo
signal
to
a
1,
0000
load.
Resistors
R-431
and
R-432
are
se-
lected
to
reduce
the
amplitude
of
the
composite
signal
in
accord-
ance
with
the
·
input
requirements
of
the
direct
FM
·
exciter
being
used.
It
is
important
that
the
AUDIO
gafo
control
R-409,
be
set
to
develop
the
correct
voltage
at
the
output
of
Q-405
and
Q-406
so
that
the
system
will
yield
the
greatest
signal-to-noise
ratio.
Thus,
resistors
R-431
and
R-432
should
be
selected
to
apply
the
proper
input
signal
to
the
FM
exciter.
The
output
of
PCL-303/C
-16-
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IC-401
is
also
applied
through
a
100
kHz
high-pass
filter
and
amplified
by
transistor
Q-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
no
incoming
carrier
or
if
the
receiver
primary
power
is
removed.
Additional
contacts
(Form
C)
from
K-401
are
available
on
the
rear
of
the
panel
of
the
receiver.
C.
CA
UT
ION:
To
avoid
hum
components
from
appearing
on
the
output
of
the
receiver,
it
is
recommended
that
the
external
squelch
contacts
be
used
in
a
DC
control
circuit.
Receiver
Adjustments
and
Alignments
Under
normal
operating
conditions
all
necessary
tuning
adjust-
ments
can
be
made
with
the
aid
of
the
selectable
meter
provided
on
the
front
panel
and
with
the
unit
in
operation.
It
will
be
necessary,
however,
to
remove
the
top
and
bottom
covers
to
gain
access
to
the
various
circuit
elements.
Two
definite
points
of
resonance
or
peaks
of
equal
amplitude
may
be
observed
whe
_n
aligning
the
coils
of
this
receiver.
However,
single
tuned
coils
adjusted
from
the
top
of
the
chassis
should
be
aligned
on
the
peak
observed
when
the
slug
is
nearest
to
the
top
of
the
coil
(with
the
screw
protruding
the
most).
To
align
the
first
oscillator
and
subsequent
multiplier
stages
the
following
procedure
is
used.
Oscillations
are
indicated
by
a
re
·
ading
of
the
meter
on
the
1st
OSC.
position.
(Refer
to
the
typical
readings
given
elsewhere
in
this
manual.
)
With
the
meter
selector
switch
·
set
to
the
MIXER
DRIVE
position,
adjust
L-202,
L-203,
and
L-
204
for
a
maximum
reading.
The
remaining
ad-
justments
should
be
made
with
a
weak
signal
in
order
to
avoid
saturation
of
the
limiters.
This
can
be
accomplished
by
rotating
the
azimuth
of
the
receiving
antenna
in
cases
where
the
STL
transmitter
signal
is
being
used
or
by
reducing
the
output
level
of
the
RF
signal
generator
providing
the
test
signal.
Under
con-
ditions
of
weak
signal,
the
SIGNAL
1
position
will
provide
ade-
.
quate
indications
of
proper
tuning.
The
injection
cavity
control
C-107
should
then
be
adjusted
for
maximum
reading.
This
will
complete
the
alignment
of
the
1st
oscillator
multiplier
chain.
PCL-303/C
-17-
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