PRO-3A Monitor
Receiver
PRO-3A
Monitor
Receiver
General Description General Specifications
Your
PRO-3A
Patrolman
Receiver tunes th ree bands
allocated
by
the
FCC
to
service and business
communications.
They
are:
The
PRO-3A
is an
extremely
sensitive receiver.
With
a
full
complement
of
circuits
and cornponents, it is
nearly
as
sentitive
as
any
receiver
for
its
tuning
ranges can
be.
lts
natural noise level is
comparable
to
a
one-third
microvolt
signal-and
that
limiting
noise can be heard
merely
by
turning
up
the
audio
volume
control.
These bands
carry
a
remarkable
variety
of business and emergency
radio
services. Best
known
are
Fire
and Police,
but
others
include
Forestry/Conservation,
Hospitais, Physicians,
Emergency
Communications.
A
list
of
sixteen general classes
appearing in
the
FCC
regulations
is given on page '2, and every class
includes
several users. No
individual
allocations
are given
there
because generally 'all bands
are used by all services.
This
great
sentitivity
is necessary
for
remote
areas and in emergency
operating
conditions.
But
circuits
designed
for
high
sensitivity
are
often
subject
to
intermodulation
problems
if
used in
very
strong-signal areas.
Also,
adjacent-channel
transmitters
are
more
likely
to
be
operating
in urban and
metropol
itan areas
than
in
remote
regions. The
PRO-3A
features a
really
effective
10.7
MHz
filter,
placed in
its IF
input
circuit.
This
reduces or
eliminates
adjacent-channel or strong-signal
interference.
Note:
These are given in general
form
only,
since
REALISTIC
does
not
believe
in
buying
ro or designing
to
numerical
specifications.
The
latter
are subject
to
variables
not
c1early related
to
performance,
just
as
selectivity,
the
number
of
transistors or
IC's
indicate
in an average way
the
quality
of
a
circuit
but
do
not
prove
one
circuit
will
outperform
another
in real
operating
conditions.
Our
philosophy
is
that
a piece
of
equipment
should
be evaluated in
terms
of
what
it
does
for
the
purchaser, its
quality
and relative value being based
upon
merit
and
observed
performance
in real
life.
Thus
REALISTIC
designs
toward
achieving a
certain
result, ... regardless
of
cost,
regardless
of
lab measurements, regardless of
competitive
advertising
claims. Results are
determined
by
your
application
of
our
finished
result.
Good
installation
is
extremely
important
since a
poorly
installed or
a
wrongly
placed antenna can
result
in a 90% or even greater
signalloss.
And
an
inadequate speaker system can be
almost
as
effective
in
reducing
equipment
performance.
The
following
figures are
offered
only
as a guide,
not
as a guarantee
of
equipment
performance:
This
equipment
is designed
to
operate
from
either
117
VAC
or 12
VDC
negative
ground.
If
it
fails
to
operate, and
there
is no c1ear reason
for
the
failure,
first
check
the
supply
switch.
This
switch
entirely
disconnects
the
supply
components
that
are
not
in use.
Also,
before
connecting
the
PRO-3A
receiver
to
a
DC
power
supply,
check
the
voltage
polarities.
Attempting
to
operate
the
negative-ground
PRO-3A
from
one
of
the
rare
positive-ground
automotive
or
boat
electrical systems,
or
from
a
wrongly
connected
battery,
will
at least
blow
a fuse.
It
may
do
further
damage, so
that
expensive and
time-consuming
repairs are
necessary
before
the
PRO-3A
can be used again. The
Radio
Shack
warranty
does
not
apply
to
any
damage caused by
this,
inadequate
lightning
protection,
or
other
improper
connections.
30 - 50
MHz
152
-
174
MHz
450
-
470
MHz
VHF
LO
VHF
Hl
UHF
Designed
for
the
user,
the
PRO-3A
offers
more
utility
than
any
other
receiver
in its class.
It
is large enough
for
base
station
operatien.
and has all necessary
features
of
SQUELCH,
narrow-band
filter,
and several-band
operation.
It also is
light
enough
to
be carried
into
hard-to-reach areas or
mounted
in cars,
trucks,
boats
or airplanes.
And
it
uses a
remarkably
small
amount
of
power.
For
example,
a single car
battery
should
power
the
PRO-3A
for
better
than
200
hours
of
continuous
operation
before
needing
arecharge.
Another
filter
is
included
to
improve
the
readability
of
very
weak
signais. A
low-pass
audio
filter,
also
controlled
from
the
front
panel, can be
switched
in
to
reduce the
effects
of
inherent
circuit
noise
when
listening
to
avoice signal
that
is
"buried
in the
noise."
By
reducing
the
audio
bandwidth
of
the receiver,
the
filter
emphasizes the desired
audio
signal.
The
PRO-3A
is
remarkably
easy
to
use.
But
it is an
up-tc-date,
complex
circuit
consisting
of
25 separate transistors pi us 20
more
in its
integrated-circuit
IF
section,
10
diodes
and one zener.
All
are
mounted
on a steel chassis,
which
in
turn
is instalied in a steel
cabinet
provided
with
a
mounting
bracket
designed
for
mobile
installation.
The
PRO-3A
is an
important
engineering
achievement,
but
designed
for
practical appl ications.
GUARANTEE:
The
REALISTIC
guarantee is stated on
the
Fact
Tag packed
with
the
equipment.
It
is in
effect
from
coast to coast.
At
any
time,
REALISTIC
equipment
may be restored
to
new
condition
with
original
parts
with
MINIMUM
delay
anywhere
in
the
U.S.A.,
usually
in
your
own
neighborhood.
It
is
NOT
necessary
to
return
REALISTIC
equipment
to
our
laboratories
in 98%
of
the
cases.
General Specifications List
•
Tuning
Ranges:
VHF
LO,
30-50
MHz.
VHF
Hl,
152-174
MHz.
UHF,
450-470
MHz.
•
Antenna
Connections:
50-ohm
coax. One
for
VHF
LO and Hl bands.
Another
for
UHF
band.
•
Sensitivity:
1
microvolt
for
20 dB
quieting.
•
Selectivity:
5
KHz
position-6
dB @±5
KHz.
15
KHz
position-3
dB @
±35
KHz.
• IF
frequency:
10.7
MHz.
•
Audio
Output:
2
watts
into
8ohms.
The
PRO-3A
will
operate
into
a 4
thru
16
ohms
load.
•
Solid-state
Components:
25 transistors, 2 IC, 10 diodes and 1 zener.
•
Power
Input:
117
VAC
60 Hz or
12-15
VDC,
negative
ground
only.
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