OPERATING
INSTRUCTIONS
FOR
SR-C146
5
CHANNEL
1
WATT
VHP«
FM
PERSONAL
2
WAY
RADIO
FOR
AMATEUR
i
STANDARD
RADIO
CORR
3622
Kamitsuruma,
Sagamihara-shi
Kanagawa
Phone : 0427-43-I
I I
I
Cable : TLX
2872-210
DRADNATS
TOKYO
rr%
GENERAL:
SPECIFICATION
Frequency
ränge:
Number
of
Channel
Power
supply:
Power
consumption
Battery
life
Dimensions
Weight:
144^148
MHz
5
spot
frequencies
(bandspread
within 2 MHz)
12.6 V DC
Stand
by
(SQL
on)
Approx.
15.0
mA
Receive
"
72.2
mA
Transmit
"
370.0
mA
10
hours
or
more
10%
transmit
10%
receive
80%
stand
by
,
75(W)x210(H)x31(D)
m/m
Approx. 1 kg
(with
battery)
TRANSMITTER
RF
Output:
Frequency
stability:
Modulation:
Crystal
multiplication:
Spurious & harmonics
FM
noise:
Audio
response:
1.0
watt
or
more
±
0.003%
(-10°C^+45°a
±5
KHz
(narrow
band)
±15
KHz
(wide
band)
12
times
More
than
50
dB
below
carrier
At
least
45
dB
+1
dB,
—3
dB
of 6 dB/octave
pre-emphasis
between
300-
3000
Hz
RECEIVER
Sensitivity:
Squelch
sensitivity:
Selectivity:
Audio
Output:
Frequency
stability:
Circuitry:
0. 4 uV
or
less
(20
dB
noise
quiet
method)
0.2
uV
or
less
60
dB
down
at
adjacent
Channels
0. 5 watt
to
built-in
Speaker
±0.003%
(-10°C^+45°C)
Double
conversion
superheterodyne
Specifications
subject
to
change
without
notice,
—
1
SECTION
I
DESCRIPTION
1-1
Description
STANDARD
SR-C146
solid
State
personal
VHF/FM
Amateur
Transceiver
is
designed
for
a
compact,
high
Performance, 5 Channel, 1 watt
RF
Output
and
for
the
Operation
in
the
ränge
of
between
144
to
148
MHz.
The
audio
section
of
the
transmitter
contains
an
IC
to
minimize
the
size.
Both
the
trans-
mitter
and
receiver
are
taken
into
the
consideration
to
employ
IC
and
transistorization
for
a
^
better
reliability
and
lower
battery
drain.
I
The
power
for
the
radio
is
supplied
by
AA
size
eight
pieces
carbone
zinc
batteries,
eight
pieces
mercury
cells
or
ten
rechargeable
Ni-cad
batteries.
All
the
operating
controls
are
concentrated
to
the
top
of
the
radio.
The
collapsible
antenna
can
be
push-
ked
it
down
into
the
radio
for
easy
carrying
and
for
Short
ränge
commimication.
On
the
Operation
of
the
radio
with a flexible
antenna
SR-CAT12
or
herical
an
tenna
SR-CAT08,
the
collapsible
antenna
may
be
re-
placed
by
either
of
them.
Auxiliary
jacks
are
provided
for
an
external
micro-
phone,
an
external
micspeaker,
an
earphone, a lapel
Speaker,
an
external
antenna, a battery
charger
and
other
accessories.
1-2
Operation
Befere
operating
the
radio,
check
and
see
if
the
batteries
are
correctly
installed.
When
using
the
collapsible
antenna,
make
sure
that
the
antenna
is
in
upright,
fully
extended
Position
for
a
maximum
length.
To
receive a message;
1.
Turn
on
the
SQUELCH
(SQL)
control
fully
counterclockwise.
2.
Turn
the
volume-off
control
clockwise
until a hissing
sound
is
heard
from
the
Speaker.
3.
Turn
the
squelch
control
clockwise
until
the
hissing
sound
just
fade
out.
4.
Select
the
proper
Channel
by
rotating
the
Channel
selector
knob.
The
set
is
now
ready
to
receive a message
from
other
radios
by
this
system.
5.
The
meter
indicator
indicates
the
strength
of
the
incoming
signal.
To
send a message;
1.
Turn
the
radio
on
as
described
in
"To
receive a message".
2.
Hold
the
radio
so
that
the
antenna
becomes
vertical,
and
press
the
push-to-talk
button
to
put
the
transmitter
on
the
air.
Release
the
push-to-talk
button
as
soon
as
you
stop
talking
then
you
can
receive
an
answer
to
your
call.
The
receiver
will
operate
only
with
the
button
released.
After
you
receive
an
answer,
you
complete
your
massege.
In
Order
to
turn
the
radio
off,
turn
the
volume
knob
to
counterclockwise
until
it
clicks.
ANTENNA
EXTERNAL
MICROPHONE
JACK
CHANNEL
SELECTOR
KNOB
VOLUME-OFF
CONTROL
KNOB
METER
SQUELCH(SQL)
CONTROL
KNOB
— 3 —
1-3
To
check
the
battery
life
The
meter
which
is
located
on
the
top
of
the
radio
indicates a battery
voltage.
The
red
marked
zone
on
the
meter
indicator
means
voltase
over
10.5 V which
is
the
usable
effective
battery.
If
you find
the
meter
indicating
less
than
10.5
V,
replace
all
the
batteries
er
Charge
them.
— 4 —
SECTION
II
THEORY
OF
OPERATION
2-1
PÜNCnONAL
OPERATION
Functional
Operation
of
the
SR-C146
of
VHF/FM
personal
transceiver
is
illustrated
in
the
Block
Diagram,
Figure
2-1.
The
transceiver
consists
of a crystal
controlled
receiver
and
transmitter,
employing
solid
State
circuitry
throughout,
and
is
designed
to
operate
from
12
volt
batteries
or
negative
ground
source.
2-2
Receiver
The
receiver
is a double-conversion
superheterodyne
type. A crystal
controlled
first
local
oscillator
provides
for
selection
of
up
to 5 Channels.
The
input
signal
is
amplified
by
an
RF
stage
and
applied
to a mixer
where
it
is
heterodyned
with
the
Output
of
the
first
local
oscillator
and
converted
to
the
first
IF,
11.7
MHz.
The
11.7
MHz
Signal
is
then
amplified
and
applied
to
the
second
mixer
where
it
is
heterodyned
with
the
Output
of a second
crystal
controlled
local
osillator,
and
converted
to
the
second
IF,
455
KHz.
The
455
KHz
signal
is
applied
through a selective
filter
to
shape
the
IF
passband,
amplified
in
four
cascade
stage,
and
applied
to a limiter
and
FM
detector.
The
limiter
removes
any
vestige
of
amplitude
modulation
from
the
signal,
while
the
FM
detector
functions
to
recover
the
modulation,
producing
an
audio
Output
in
response
to a corresponding
frequency
(or
phase)
shift
in
the
455
KHz
IF
signal.
The
FM
detector
Output
is
then
amplified
by
an
IC
and
two
transistors
and
applied
to
the
Speaker.
A " noise-actuated " squelch
circuit
is
included
to
silence
the
receiver
Output
when
no
carrier
is
present.
This
is
accomplished
by
amplifying
and
detecting
the
"noise"
component
in
the
455
KHz
Output
to
produce a DG
level.
This
DG
level
is
removed,
opening
the
audio
Channel,
when a carrier
is
received
and
the
"noise"
component
decreases
due
to
the
quieting
action
of
the
limiter.
2-3
Transmitter
The
transmitter
is
designed
for
FM
(phase
modulated)
transmission. A crystal
controlled
oscillator
provides
for
selection
of
up
to 5 Channels
within
2.0
MHz
ränge
at
the
Output
frequency.
Generatioii
of
Phase
Modulated
Signal.
The
occillator
is
crystal
controlled
and
generates
the
initial
RF
signal
in
the
frequency
ränge
of
12
MHz,
depending
on
the
Output
frequency.
The
RF
signal
is
then
applied
to
the
phase
modulator,
together
with
the
audio
modulating
Signal.
The
audio
modulating
signal
varies
the
internal
and
input
capacities
of
the
phase
— 5 —
modulator
transistor,
in
turn
causing
the
applied
RF
signal
to
be
shifted
in
phase
at
an
audio
rate.
The
angular
phase
shift
produced
by
the
modulator
without
distortion
is
relatively
small.
Therefore,
the
oscillator
frequency
is
multiplied
12
times
to
obtain
the
desired
deviation
at
the
Output
frequency. A tripler
stage
and
doublers
provide
the
necessary
12
times
frequency
multiplication,
followed
by
driver
and final
RF
power
amplifier.
The final
RF
Power
amplifier
develops
the
Output
signal
applied
to a four-section
pi-network.
The
pi-network
in
turn
matches
the
Output
impedance
of
the
power
amplifier
to
the
50-ohm
antenna,
as
well
as
providing
the
selectivity
to
attenuate
spurious
and
harmonic
signals
which
might
appear
in
the
Output.
Instantaneous
Deviation
Control.
The
transmitter
contains
an
instantaneous
deviation
control
(IDC)
circuit.
This
circuit
limits
the
Output
frequency
deviation
to
the
desired
deviation
preventing
overdeviation
when a higher
than
normal
microphone
Output
occurs.
The
audio
signal
from
the
microphone
is
applied
through
two
stages
of
speech
amplifier
a
peak
limiter,
low-pass filter,
and
an
integrater
circuit,
to
the
phase
modulator.
The
phase
modulator
has
an
inherent 6 dB/octave
pre-emphasis
characteristic,
and
under
normal
Output
levels
from
the
microphone
the
transmitter
FM
carrier
Output
is
pre-emphasized 6 dB/octave.
The
component
values
employed
in
the
speech
amplifier
are
such
that a 6
dB/octave
pre-
emphasis
is
applied
to
the
input
audio.
The
peak
limiter
will
have
no
effect
on
the
audio
signal
imtil
the
microphone
Output
increases
to a point
where
overdeviation
would
occur.
Therefore
the
non-limited
pre-emphasesed
signal
is
applied
through
the filter
to
the
Integrator
which
has 6 dB/octave
de-emphasis
characteristics.
This
offsets
the
pre-emphasis
applied
in
the
speech
stages,
resulting
in a " fiat"
Output
being
applied
to
the
phase
modulater.
The
6
dB/octave
pre-emphsis
characteristic
of
the
modulator
then
becomes
the
only
factor
affecting
the
RF
Output.
If
the
microphone
Output
level
increases
to a point
where
overdeviation
would
occur,
the
limiter
"clips"
both
positive
and
negative
peaks
of
the
audio
waveform.
This
results
in
an
essentially
Square
wave
signal
of
constant
amplitude,
removing
the 6 dB/octave
pre-enphasis
from
the
speech
amplifier.
The
limited
audio
waveform
is
then
reshaped
in
the
low-pass filter,
and
applied
to
the
integrator.
As
the
signal
at
the
Integrator
input
is
of
constant
amplitude,
the
Output
will
be
de-emphasized 6 dB/octave
as
applied
to
the
phase
modulator.
This
then
offsets
the
inherent 6 dB/octave
pre-emphasis
characteristic
of
the
phase
modulator
where
frequency
deviation
vs.
frequency
is
essentially fiat.
— 6 —
2-4
Receiver
section
RF
amplifier
stage. A Metal
Oxide
Silicon
Field
Effect
Transistor
(MGS
FET)
is
employed
as
the
RF
amplifier,
Ql.
This
minimizes
responses
to
spurious
signals
and
intermodulation
products,
and
provides a low
"noise figure"
for
the
receiver
input.
The
RF
input
signal
from
the
antenna
is
applied
across a double
tuned
circuit
and
coupled
to
gate
'*
1"
of
Ql.
Forward
bias
is
applied
to
gate " 2"
of
Ql,
and
the
output
at
the
drain
is
applied
across a second
double
tuned
circuit
and
coupled
to
the
base
of
the first
mixer,
Q2.
First
Mixer
and
11.7
MHz
IF
Amplifier.
The first
mixer,
Q2,
is a high
Performance
transistor
with
the
RF
input
signal,
and
the first
local
oscillator
injection
signal
applied
at
the
base,
together.
The
two
signals
are
heterodyned
by
Q2,
and
the
resulting
11.7
MHz
differ-
ence
signal
at
the
collector
is
then
coupled
through a double
tuned
circuit
to
the
base
of
Q3,
which
functions
as
an
11.7
MHz
IF
amplifier.
The
signal
from
the
collector
of
Q3
is
then
coupled
through a second
double
tuned
circuit
to
the
base
of
the
second
mixer,
Q4.
First
Local
Oscillator
Circuit.
The first
local
oscillator
injection
frequency
is
11.7
MHz
below
the
input
signal
frequency
in
all
cases.
The
fundamental
crystal
frequencies
are
in
the
16
MHz
ränge,
and
are
multiplied
nine
times
to
reach
the
injection
frequency.
The
proper
crystal
frequency
for a desired
receiver
signal
frequency
may
be
determined
from
the
following
equation:
fc=(fi-ll.
7)/9
where:
fc=fundamental
crystal
frequency
in
MHz
fi
=desired
receiver
signal
frequency
in
MHz
The
Channel
Selector.
The
switch
will
select
up
to 5 crystals
to
control
the
frequency
of
the
oscillator.
Trimmer
capacitors
C55
thru
062
permit
the
individual
crystals
to
be
"netted"
to
the
exact
Channel
frequency.
Transistor
Q12
functions
as a fundamental
forward
biased
modified
Colpitts
oscillator,
and
also
trippler
with
the
selected
crystal
connected
between
base
and
ground.
The 3 times of
16
MHz
output
is
taken
at
the
emitter,
and
coupled
to
the
base
of
the first
tripler,
Q13.
The
collector
output
of
Q13
is
resonated
to
the
third
harmonic
of
the
crystal
frequency
by
a
double
tuned
circuit,
and
applied
to
the
base
of
the
Ist
Mixer
Q2.
Q3
is a fi
rst
IF
amplifier.
The
input
side
coils
L5,
L6
and
collector
side
coils
L7
and
L8
are
tuned
for
11.7
MHz.
019
is
used
as a neutral
capacitor
for
Q3.
Second
Mixer.
The
11.7
MHz
signal
from
Q3
is
applied
to
the
base
of
Q4,
while a 12.155-
MHz
injection
signal
derived
from
the
second
local
oscillator,
Q14,
is
applied
at
the
emitter.
—
7
—
The
two
Signals
are
heterodyned
by
Q4,
and
the
resulting
455
KHz
difference
signal
(12.155-
11.700
MHz
at
the
collector
becomes
the
second
IF,
across
the
primary
winding
of
L8).
Transistor
Q14
functions
as a fundamental f er
ward
biased
modified
Colpitts
oscillator,
with
a
12.155
MHz
crystal
connected
between
base
and
ground.
The
second
local
oscillator
injection
Signal
is
taken
at
the
emitter
of
Q14,
and
coupled
through
C23
at
the
base
of
Q4.
455
KHz
IF
Filter.
The
455
KHz
signal
from
Q4
is
applied
through a bandpass filter
to
obtain
the
IF
passband
characteristics.
The filter
circuit
produces a steep
skirted
shape
factor
•
to
attenuate
signals
falling
outside
of
the
required
IF
passband,
thus
establishing
the
overall
receiver
selectivity.
455
KHz
IF
Amplifier
Circuit.
Transistors
Q5,
and
Q6
thru
Q8
function
in a DO
connected
four
stage
cascade
circuit,
with
the
Output
applied
to
the
base
of
the
limiter,
Q9.
O
Limiter
Circuit.
The
four
cascade
IF
stages
provide
some
limiting
action.
However,
the
primary
limiting
is
accomplished
in
Q9,
due
to
the
overall
gain,
together
with
application
of
forward
bias
on
the
base.
This
causes
Q9
to
saturate
at a very
low
signal
level.
The
collector
Output
of
Q9
is
applied
across
the
series
connected
primary
windings
of
L9
and
LIO
to
provide
an
input
to
the
FM
detector.
Dl
and
D2. A sample
of
the
collector
Output
from
Q9,
across
R34
is
also
applied
to
the " noise-actuated " squelch
circuit.
FM
Detector
Circuit.
The
secondary
widing
of
L9
is
connected
in
series
with
the
center-tap
on
the
secondary
of
LIO,
while
diodes
Dl
and
D2
are
connected
to
detect a positive
or
negative
voltage
in
the
secondary
winding
of
LIO.
As
the
secondary
winding
of
LIO
and
the
two
diodes
represent a balanced
cricuit,
an
unmodulated
455
kHz
signal
from
Q9
will
produce
"zero"
voltage
at
the
center-tap.
However, a frequency
deviation
in
either
direction
in
the
455
kHz
signal
(from
an
FM
modulated
component)
causes a phase
shift
in
the
winding
developing a corresponding
positive
or
negative
voltage
at
the
center-tap
to
reproduce
the
audio
signal
originally
impressed
on
the
carrier.
The
audio
signal
is
then
applied
through a de-emphasis filter
network,
and
across
the
VOL
control,
R40,
to
the first
audio
IC.
Noise-Actuated
Squelch
Cricuit.
Gaussian
noise
appears
as
an
AM
signal
in
the
455
kHz
IF
Output.
This
is
sampled
across
R34
in
the
collector
return
for
the
limiter,
Q9.
This
signal
is filtered,
peaked
by a low-frequency
tuned
circuit,
and
applied
across
the
SQL
control,
R62
to
the
base
of
the
noise
amplifier,
Q16.
The
noise
is
amplified
by
Q16,
Q17,
detected
by
D6
and
D7,
and
applied
to
the
base
of
the
squelch
amplifier,
Q18.
Transistor
Q18
is a NPN
type,
the
collector
Output
is
applied
to
the
IC.
When
no
carrier
is
present, " noise " in
the
455
kHz
IF
is
amplified
and
detected
to
forward
— 8 —
bias
Q18
into
conduction.
This
develops a voltage
drop
across
R44
to
silence
the
receiver
audio
Output.
The
SQL
control,
R62,
permits
the
threshould
level
for
the " noise " signal
to
be
adjusted,
thus
setting
the
point
where
the
squelch
circuit
will
actuate.
When a carrier
is
present
the " noise"
in
the
455
kHz
IF
decreases
due
to
the
quieting
action
of
the
limiter,
in
turn
reducing
the
Output
from
the
squelch
detector
and
cutting
Q18
off.
Audio
Circuit.
The
audio
signal
from
the
FM
detector
is
applied
across
the
VOL
control
R40
to
the
IC.
This
IC
works
as
audio
amplifiers
and
phase
convertor
for
the
next
class
" B "
push-pull
amplifier
stage.
QIO,
Qll
function
in a complimentary
symmetry
circuit,
since
QlO
is
NPN
transistor
and
Qll
is
PNP.
The
PA
stage
delivers
the
audio
power
to
the
Speaker
which
has
32
ohms
impedance.
— 9 —
2-5
Transmitter
Section
Speech
Amplifier.
The
transmitter
employs a magnetic
type
microphone,
which
is
located
by
the
Speaker
on
the
front
pannel
of
the
radio,
to
convert
the
impressed
Speech
to a variable
voltage
or
an
audio
signal.
The
audio
signal
is
then
applied
through
an
RF filter
network
C450,
C453,
R437,
to
IC.
This
IC
is
equivalent
to
two
stages
direct
couppled
audio
amplifier.
The
Output
of
this
IC
applied
to
the
IDC
limitter,
diodes
D404
and
D405.
The
values
of
components
used
in
the
RC
network
of
microphone
and
IC
applie a 6
dB/octave
pre-emphasis
to
the
audio
signal
over
the
speech
frequency
ränge.
IDC
Limiter
and
Low-Pass
Filter.
Diodes
D404
and
D405
are
biased
through
R425
to
"clip"
both
positive
and
negative
peaks
if
the
input
waveform
exceeds
the
pre-determined
level.
Thus,
up
to
the
limiting
level
the
audio
waveform
will
exhibit a 6
dB/octave
pre-
emphasis
characteristic,
and
exhibit a constant
amplitude
Output
when
the
level
is
exceeded.
The
limiter
Output
is
then
applied
to
the
low-pass filter.
The
low-pass filter
performs a post
limiter
audio
roll-off
function,
attenuating
frequencies
above
3000
Hz
as
required
by
the
law.
This
attenuation
of
audio
frequencies
above
the
nominal
speech
ränge
limits
the
transmitter
modulated
spectrum
to
the
required
bandwidth,
and
reshapes
the
audio
waveform.
The filter
Output
is
then
applied
to
the
base
of
the
integrator,
Q409.
Integrator.
The
integrator,
Q409,
provides a 6
dB/octave
de-emphasis
to
the
audio
signal.
Where
the
input
speech
level
was
of
normal
amplitude
this
de-emphasis
will
offset
the 6 dB/
octave
pre-emphasis
from
the
speech
amplifier,
resulting
in
an
essentially fiat
frequency
response
for
the
audio
modulating
signal
applied
to
the
phase
modulator,
Q402.
However,
in
a
case
where
the
input
audio
waveform
has
been
limited,
the
Output
to
the
phase
modulator
will
be
de-emphasized 6 dB/octave.
The
integrator
Output
at
the
collector
of
Q409
provides
an
impedance
match
between
the
deviation
limiting
circuit
and
the
phase
modulator
stage.
The
IDC
Potentiometer,
R432,
in
tum
adjusts
the
audio
level
applied
to
the
emitter
of
the
phase
modulator,
Q402,
thus
setting
(and
limiting)
the
transmitter
deviation
to
±5
kHz
(narrow
band)
or
±15
kHz
(wide
band).
Oscillator
Circuit.
The
crystal
oscillator,
Q401,
functions
in a fundamental
frequency
ränge
of
12
MHz.
This
oscillator
is a modified
Colpitts
circuit,
with
Q401
functioning
in
a
forward
biased
common
collector
configuration.
The
emitter
Output
from
Q401
is
then
applied
to
the
base
of
the
phase
modulator,
Q402.
The
temperature
characteristics
of
capacitors
C401
thru
C403,
C409
and
C410,
compensate
for
the
frequency
drift
characteristics
of
the
crystal.
—
10
—
T/R
Switching
Circnit.
T/R
(Transmit
and
Receive)
switching
circuit
consist
of
D401,
D402, D407,
Q410
and
Q411.
In
the
receiving
mode,
the
supply
voltage
is
appeared
at
the
emitter
of
Q410.
This
voltage
is
used
for
the
Operation
of
whole
the
receiver.
The
collector
voltage
of
Q405,
Q406, Q407,
and
Q408
is
always
appeared,
however
Q401,
Q402,
Q403,
Q404
mic.
amp.
IC
and
Q409
do
not
work
due
to
no
voltage.
In
the
transmit
mode,
by
tuming
SOOl,
the
voltage
at
the
emitter
of
Q410
disappears,
but
the
voltage
at
the
collector
of
Q411
appears.
This
causes
to
work
whole
the
transmitter,
also
the
current flows
through
R418,
L413
(RF
choke)
D401,
L414
{L414,
C443
series
tuned
for
operating
frequency)
D402
to
the
groimd.
This
means
that
D402
which
is
connected
with
the
receiver
antenna
circuit
in
parallel
conducts
and
D401
also
works
at
conducted
mode.
Phase
Modulator.
The
RF
signal
from
the
oscillator
is
applid
at
the
base
of
Q402,
while
the
audio
modulating
signal
is
applied
at
the
emitter.
The
modulating
signal
at
the
emitter
varies
the
capacity
of
Q402
in
accordance
with
the
audio
voltage.
With a fi
xed
phase
shift
shunting
the
stage,
and a variable
phase
shift
through
Q402,
an
overall
variable
phase
shift
is
produced
in
the
Output,
across
L401.
This
Output
is
then
coupled
to
the
base
of
the
first
doubler,
Q403.
Variable
inductor
L401
permits
the
modulator
output
to
be
maximized.
^
Frequency
Multipliers.
The
12
MHz
phase
modulated
signal
from
Q402
is
multiplied
^
2
times
by
Q403,
and
coupled
through a double
tuned
circuit
to
the
base
of
th
tripler,
Q404.
Forward
bias
is
applied
to
the
base
of
Q403
to
increase
the
sensitivity
of
this
stage.
This
is
required
due
to
the
relatively
low
output
obtained
from
the
phase
modulator
stage.
The
tripler,
Q404,
and
doubler,
Q405,
function
as
conventional
class
"B"
frequency
multipliers,
developing
the
output
frequency
signal
applied
to
the
driver
stage,
Q406
and
Q407.
Final
RF
Power
Amplifier
and
Output
Circuit.
The
RF
signal
from
Q406
and
Q407
is
amplified
by
Q408,
which
functions
as a conventional
class
"C"
power
amplifier.
The
four-
section
pi-network,
L411
thru
L412,
matches
the
collector
output
of
Q408
to
the
50-ohm
antenna,
and
also
functions
as a low-pass filter
attenuate
signals
above
the
transmitters
operating
ränge.
—
11
—
S E C T I 0 N
III
OPTINAL
ACCESSORY
Options.
Following
optional
parts
for
SR-C146
are
availafole
on
customer's
request.
SR-CMP08
External
microphone.
A
small
high
reliable
dynamic
microphone
is
combined
in a hi-im-
pact
cycolac
case
with
retractable
neoprene
coiled
cord.
When
this
external
microphone
is
connected
to
the
radio,
the
internal
microphone
is
disconnected.
SR-CAT08
Flexible
rubber
coated
antenna.
This
antenna
will
withstand
rough
handling,
can
be
bent
at
different
angles
without
distroying
its
effectiveness.
This
is
completely
insulated
and
cannot
accidentally
be
shorted
out
but
talking
ränge
of
the
radio
should
be
shorter
than
normal
of
1/4
wave
length
antenna.
SR-CAT12
Flexible
antenna.
This
is
1/4
wave
length
antenna
made
by
music
wire.
/
SR-CSA
Base
master.
This
is
the
AC
Battery
charger
for
Ni-Cd
batteries.
This
is
able
to
Charge
the
Ni-Cd
batteries
built
in
the
radio
or
Ni-Cd
batteries
in
the
battery-holder.
Also
this
base
master
has
an
an
tenna
connector-converter
from
UHF
female
to
the
ex
ternal
antenna
plug
for
the
radio,
thus
the
base
master
can
be
used
as
the
desk
top
type
holder.
—
12
—
SR-CMA
Mobile
master.
This
has
two
functions,
combined
in
the
metal
case
with
the
magnet
mount
The
line filter
choke
is
bullt
in
the
case
to
avoide
the
alternator
whine
trouble,
and a UHF
female
connector
on
the
case
to
connect
the
external
antenna
to
the
antenna
connector
on
the
radio.
SR-C12/120-6
Charger.
This
is a low
cost
type
Ni-Cd
battery
charger.
SR-CAD
Antenna
adaptor.
This
is a connector
to
connect
the
nornal
antenna
which
has a UHF
connector
to
the
external
anenna
connector
on
the
radio.
—
13
—
SR-C146
BLOCK
DIAGRAM
TRANSMITTER
OSC
MOD
DOUB
TRIP
DOUB
DRIV
POWER
D~
MIC
AMP
RECEIVER
LO
OSC
TRIP
TRIP
IDC
INTEG
RATOR
ANT
SWITCH
■<§)
ANT
2ND
Loose
RF
IST
IST
2ND
2ND
2ND
2ND
AMP
MIX
IFAMP
MIX
IFAMP
IFAMP
IFAMP
2ND
ifamp
LIMIT
DET
NOISE
AMP
NOISE
AMP
SQL
AMP
POWER
K
PRE-AMP
DRIV
SWITCH
SWITCH
TR
TR
—
14
VIATIC
DIAGRAM
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