RCA BA-13A User manual
BROADCAST
AUDIO
EQUIPMENT
IB-24712
Type
BA-13A
Program
Amplifier
RADIO
CORPORATIOn
OF
AfACRICA
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products
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BROADCAST
AUDIO
EQUIPMENT
INSTRUCTIONS
Type
BA-13A
Program
Amplifier
MI-11233,
-A
RADIO
CORPORATION
OF
AMERICA
ENGINEERING
PRODUCTS
DEPARTMENT,
CAMDEN,
N.
J.
Printed
in
U.S.A,
ui
18-530
Figure
1
—
Front
View
of
Type
BA-13A
Progr m
Amplifier.
1
DESCRIPTION
TECHNICAL
DATA
Power
Suppl
Required
100
to
130
volts,
50
to
60
cps,
5
5
atts
Fuse
Rating
1
ampere,
Type
MDL
Source
Impedance
600
or
1
50
ohms
Input
Impedance
Matching
600
or
150
ohms
(approximate)
Bridging
20,000
ohms
(approximate)
Rated
Output
Level
+
30
dbm
ith
0.5%
total
rms
distortion
from
50
cps
to
15,000
cps
+
30
dbm
ith
less
than
1.0%
total
rms
distortion
from
30
to
15,000
cps
Connections
T o
10-prong
plugs,
mounted
on
the
rear
panel
of
the
chassis,
hich
engage
ith
t o
receptacles
provided
ith
the
amplifier
Dimensions
and
Weight
Length
—
14
inches
Width
—
8
inches
Height
—
7%
inches
Weight
—
17
pounds
Noise
Level
Less
than
—
52
dbm
ith
the
gain
control
in
the
maximum
position
and
the
input
and
output
circuits
terminated
in
600
ohms
Mounting
Shelf
mounting
in
the
Type
BR-2A
Panel
and
Shelf
Finish
Light
umber
gray
except
for
output
and
po er
transformers
hich
are
satin
black
Isolation
90
db
ith
matching
input
100
db
ith
bridging
input
Gain
Measured
at
1000
cps
ith
gain
control
in
maxi*
mum
position
Matching
Input:
65
db
rt
1
db,
600
or
150
ohm
source
to
a
600
or
1
50
ohm
load
Bridging
Input:
28
db
from
a
600
ohm
terminated
line
to
a
600
or
150
ohm
load
(2
atts
output).
The
amplifier
has
a
plug-in
type
chassis
hich
allo s
easy
removal
from
shelves
or
racks
for
servicing
or
interchanging
units.
The
Type
BA-13A
amplifier
consists
of
three
stages
of
amplification
ith
a
self-contained
po er
supply.
A
po er
s itch
and
an
a-c
line
fuse
are
mounted
on
the
chassis.
Provision
is
made
for
controlling
the
gain
of
the
amplifier,
for
adjusting
the
hum
to
a
minimum,
and
for
checking
the
operation
of
the
individual
tubes.
The
gain
control
The
Type
BA-13A
Program
Amplifier,
MI-
11233,-A,
is
a
high-fidelity,
high-gain,
lo -distor
tion
amplifier
designed
to
raise
the
output
of
pre
amplifiers
or
mixers
to
a
level
suitable
for
feeding
broadcast
telephone
lines
or
radio
transmitter
inputs.
It
may
be
used
as
a
bridging
amplifier
for
isolation
or
other
applications
here
a
20,000-ohm
amplifier
input
is
desirable.
The
Type
BA-13A
may
also
be
used
as
an
emergency
monitoring
amplifier
Frequenc
Response
±1
db
(referred
to
1,000
cps)
from
30
to
15,000
cps
Measured
from
either
a
600-ohm
or
a
1
50-ohm
source
to
a
600-ohm
load
ith
either
bridging
or
matching
inputs
Tube
Complement
(MI-11266)
2
RCA
1620
1
RCA
1622
1
RCA
5Y3-GT
When
increased
hum
distortion
and
microphonics
can
be
tolerated,
the
follo ing
tube
complement
can
be
substituted:
2
RCA
6J7
1
RCA
6L6
1
RCA
5Y3-GT
Maximum
Input
Level
Matching
Input:
+
11
dbm
for
1.0%
total
rms
distortion
from
30
to
15,000
cps
(output
+30
dbm)
+
10
dbm
for
0.5%
total
rms
distortion
from
30
to
15,000
cps
(output
+18,
dbm)
Bridging
Input:
+
30
dbm
for
0.5%
total
rms
distortion
(output
+
18
dbm
)
Load
Impedance
(tapped
transformer)
600
ohms
balanced,
taps
for
150,
15,
7.5
and
5
ohms
2
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BA-1
3
A
Progr m
Amplifier.
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3
INSTALLATION
INPUT
RECEPTACLE
J-1
Terminal
No.
Connection
Receptacle
Connections
The
connections
to
the
t o
10-prong
receptacles
hich
mate
ith
the
amplifier
plugs
are
sho n
in
the
follo ing
tabulations:
No
connection
No
connection
Bridging
input
Bridging
input
Output
of
bridging
pad
Test
meter
(4-
)
Output
of
bridging
pad
Amplifier
ground
Matching
input
Matching
input
3
4
5
6
7
8
9
1
11
12
Power
Transformer
Connections
The
po er
transformer
T-3
is
connected
for
operation
from
all
5-volt
a-c
po er
line.
If
the
line
voltage
is
normally
120-130
volts,
disconnect
the
red-and-black
ire
from
terminal
number
11
on
T-3
and
connect
it
to
terminal
number
12.
If
the
line
voltage
is
normally
100-110
volts,
disconnect
this
same
red-and-black
ire
and
connect
it
to
terminal
number
10
on
T-3.
Refer
to
figures
2
and
8.
ith
the
shelf
assembly
(MI-
11599,
-A)
by
means
of
four
of
the
No.
6-32
fillister-head
machine
scre s
furnished
ith
the
shelf.
Mount
the
receptacles
and
brackets
in
the
correct
spaces
on
the
shelf
ith
six
of
the
No.
8-32
round-head
machine
scre s
and
lock ashers
supplied
ith
the
shelf.
Install
the
receptacle
cover
or
shield,
according
to
instructions
for
the
Type
BR-2A
Panel
and
Shelf,
contained
in
IB-24411
after
the
receptacles
have
been
ired
according
to
the
follo ing
information:
Attach
one
of
the
guide
bars,
furnished
ith
the
shelf,
to
the
shelf
on
each
side
of
the
space
hich
is
to
be
occupied
by
the
amplifier.
Use
t o
No.
4
self-tapping
scre s
also
supplied
ith
the
shelf,
to
mount
each
guide
bar.
Holes
are
provided
in
the
guide
bars
and
in
the
shelf
for
this
purpose.
The
square
ends
of
the
bars
should
be
to ards
the
front.
Slide
the
amplifier
chassis
onto
the
shelf
so
that
the
plugs
fit
into
the
receptacles
and
the
hooks
of
the
ejector
handles
fit
into
the
square
holes
in
the
shelf.
Push
back
on
the
ejector
handles
to
obtain
good
contact
in
the
receptacles.
Install
the
panel
by
slipping
it
over
the
control
shafts
of
the
amplifier
and
attaching
it
to
the
shelf,
by
engaging
the
panel
latches
on
the
rear
at
each
side
of
the
panel.
Adjust
the
spring
catches
on
the
top
section
of
the
panel,
for
minimum
and
equal
snap
action.
This
adjustment
may
be
made
by
loosening
the
No.
6-32
hex
nuts
holding
the
catches
and
moving
the
catches
up
or
do n.
Close
the
top
section
of
the
panel
and
place
the
knobs
on
the
control
shafts.
Should
it
become
necessary
at
any
time
to
remove
the
amplifier
for
servicing,
first
remove
the
knobs
and
panel.
Then,
pull
for ard
on
the
handles
and
slide
the
amplifier
out.
Electrol tic
Capacitors
Plug
the
four
electrolytic
capacitors
into
the
red
sockets
provided
for
them
on
the
amplifier
chassis.
Carefully
check
each
capacitor
as
it
is
installed
to
ascertain
that
the
ratings
marked
on
the
capacitor
cover
correspond
to
the
values
stenciled
on
the
chassis,
adjacent
to
the
sockets.
Tubes
With
the
po er
s itch
in
the
OFF
position,
install
the
tubes
in
the
correct
sockets.
The
tube
type
for
each
socket
is
stenciled
on
the
chassis
near
the
socket.
Mount
the
t o
grid
caps
and
t o
grid-cap
shields
on
the
1620
tubes.
Each
shield
must
make
a
good
electrical
connection
to
the
shell
of
the
tube
to
insure
noise-free
operation.
is
mounted
on
the
left
side
of
the
amplifier
front
panel
and
the
meter
s itch
on
the
right,
see
figure
1.
The
hum-adjustment
potentiometer
is
mounted
on
top
of
the
chassis,
in
front
of
the
output
trans
former,
see
figure
3.
The
MI-11233
and
MI-
1
1233-A
units
are
similar,
except
that
the
former
uses
a
dual
step-type
attenuator
gain
control,
and
the
latter
uses
a
dual
continuous-type
attenuator.
Mounting
The
Type
BA-
13
A
Program
Amplifier
is
designed
for
mounting
on
a
Type
BR-2A
(MI-1
1598,
-A
and
MI-
11
599,
-A)
Panel
and
Shelf.
The
gain-control
shaft
is
on
the
left
side
of
the
amplifier
(front
vie )
and
the
meter-s itch
shaft
is
on
the
right
side.
Mount
the
dial
plates
furnished
ith
the
amplifier
on
the
panel,
in
positions
cor
responding
to
the
respective
shaft
positions
(GAIN
dial
to
the
left
of
the
METER
dial),
securing
them
in
place
ith
the
bushings,
ashers
and
nuts
also
supplied.
Assemble
the
parts
ith
the
heads
of
the
bushings
on
the
inside
of
the
panel
to
insure
clearance.
Assemble
the
receptacles
furnished
ith
the
amplifier
to
t o
of
the
U-shaped
brackets
supplied
4
OUTPUT
RECEPTACLE
J-2
Terminal
No.
Connection
AMPLIFIER
OUTPUT
CONNECTIONS
Load
Impedance
Receptacle
Terminals
center
tap
(terminals
number
4,
■i
Matching
Input
Connections
Connect
the
incoming
line
to
terminals
number
11
and
12
of
the
input
receptacle
for
input
plug
J-
1.
Refer
to
figures
3
and
8.
Make
impedance
matching
connections
as
follo s:
Output
transformer
—
5-ohm
tap
Output
transformer
—
center
tap
A-C
input
to
po er
transformer
A-C
input
to
po er
transformer
Output
transformer
—
7.
5-ohm
tap
Output
transformer
—
center
tap
Output
transformer
—
1
5-ohm
tap
Output
transformer
—
Center
tap
Output
transformer
—
600
ohms
Output
transformer
—
600
ohms
A-C
Power
Supply
Connect
the
a-c
line
for
the
amplifier
to
terminals
number
5
and
6
of
the
output
receptacle
(for
output
3
4
5
6
7
8
9
10
11
12
*600
ohms
1
50
ohms
1
5
ohms
7.5
ohms
5
ohms
11
and
12
10
and
11
9
and
10
7
and
8
3
and
4
i
i
*600-ohm
inding
has
a
8
and
10
on
J-2
).
on
input
transformer
T-l.
At
terminal
number
2,
disconnect
the
ire
to
terminal
number
11
and
connect
it
to
terminal
number
5.
Connect
terminals
number
1
and
2
together,
and
con
nect
terminals
number
3
and
4
together.
Refer
to
figures
2
and
8.
d.
1
50-OHM
UNBALANCED
INPUT.
—
Remove
the
ire
connecting
terminals
number
2
and
3
on
T-l.
At
terminal
number
2,
disconnect
the
ire
to
terminal
number
11
and
connect
it
to
terminal
number
1.
Connect
terminals
number
1
and
2
together
and
connect
terminals
number
3
and
4
together.
Connect
the
grounded
side
of
the
incoming
line
to
terminal
11
on
the
receptacle
for
plug
J-l.
Output
Connections
The
amplifier
is
ired
for
operation
into
a
variety
of
load
impedances.
The
secondary
inding
of
the
output
transformer
T-2
is
provided
ith
a
number
of
taps
hich
are
brought
out
to
the
terminals
of
the
connection
plug
J-2
mounted
on
the
rear
of
the
amplifier
chassis
(directly
behind
the
po er
transformer).
The
center
tap
of
the
output
transformer-secondary
inding
(terminal
number
8
on
the
output
transformer)
is
connected
to
terminals
number
4,
8
and
10
of
the
connection
plug
J-2.
Refer
to
figures
2
and
8.
Connection
to
the
plug
J-2
is
made
by
means
of
one
of
the
receptacles
supplied
ith
each
amplifier.
The
follo ing
table
sho s
line
connections
for
loads
of
various
impedance:
Balanced
Bridging
Input
Connections
Connect
the
incoming
line
to
terminals
number
5
and
6
on
the
input
receptacle
for
plug
J-l,
figures
3
and
8.
Connect
terminals
number
7
and
12
together,
and
connect
terminals
number
9
and
11
together,
on
the
same
receptacle.
The
input
trans
former
is
connected
as
in
(a)
under
Matching
Input
Connections.
Input
Shielding
All
audio
leads
should
be
shielded
t isted
pair
copper
ire,
insulated
for
200
volts,
and
need
not
be
larger
than
No.
19
A.W.G.
All
joints
should
be
securely
soldered,
and
of
lo
resistance.
If
the
circuits
run
in
conduit
or
duct
hich
may
be
subject
to
moisture,
a
type
of
iring
having
a
natural
or
synthetic
rubber
covering
over
the
shield
or
lead
should
be
used.
To
minimize
un
desirable
noise
pickup
and
cross
talk
on
long
input
circuits,
the
shielding
of
the
lines
to
the
input
terminals
of
the
amplifier
or
rack
should
be
covered
ith
a
cotton
braid
or
other
suitable
insulation
and
the
shielding
should
be
grounded
only
at
the
amplifier
(point
of
lo est
level).
Make
sure
that
the
shields
are
electrically
continuous
and
that
the
ground
connections
are
perfect.
Do
not
run
the
audio-input
leads
adjacent
to,
or
laced
in
ith,
a-c
or
high-level
audio
lines.
a.
600-OHM
BALANCED
INPUT.
—
The
ampli
fier
is
ired
at
the
factory
for
this
type
of
operation.
Terminals
number
2
and
3
on
input
transformer
T-l
are
connected
together,
terminals
number
2
and
11
are
connected
together.
Refer
to
figures
2
and
3.
b.
600-OHM
UNBALANCED
INPUT.
—
Discon
nect
from
terminal
number
2
on
T-l
the
ire
hich
is
connected
to
terminal
number
11,
and
connect
it
to
terminal
number
1.
Connect
the
grounded
side
of
the
incoming
line
to
terminal
number
11
on
the
receptacle
for
plug
J-l.
c.
1
50-OHM
BALANCED
INPUT.
—
Remove
the
ire
connecting
terminals
number
2
and
3
5
Figure
3
—
Re r
View
of
Type
BA-1
3
A
Progr m
Amplifier.
CIRCUIT
MODIFICATIONS
Gain
Controls
In
applications
here
extreme
quietness
or
ex
tended
periods
of
operation
ithout
servicing
are
prime
considerations
the
dual
continuous-type
attenuator
or
gain
control
furnished
in
MI-11223-A
Hum
Adjustment
A
hum-adjustment
potentiometer
marked
HUM
is
located
on
top
of
the
chassis,
in
front
of
the
output
transformer
and
in
line
ith
the
meter
s itch,
see
figure
3.
A
scre driver
slot
is
provided
in
the
potentiometer
shaft,
hich
is
accessible
from
the
top
of
the
chassis,
for
adjusting
the
hum
level
to
a
minimum.
plug
J-2,
figures
3
and
8).
To
insure
a
lo
hum
level
the
a-c
supply
circuit
should
be
shielded
and
the
shield
grounded.
Metering
The
four-position
rotary
s itch
mounted
on
the
front
panel
of
the
amplifier
chassis
(right
side)
is
designed
to
be
used
in
conjunction
ith
the
Type
BI-1A
(MI-4388-B
or
MI-4388-C)
or
the
Type
BI-2A
(MI-1
1275
or
MI-1127
5-
A)
Metering
Panel
to
conveniently
check
the
operation
of
the
individual
tubes.
The
numbers
on
the
METER
dial
plate
indicate
the
tube
hich
is
being
checked.
Circuit
arrangement
is
such
that,
ith
the
tubes
operating
normally,
the
meter
ill
read
approximately
1
volt.
When
a
Type
BI
metering
panel
is
not
avail
able
any
suitable
voltmeter
having
an
internal
resistance
of
20,000
ohms-per-volt
or
greater
can
be
used.
Connect
the
positive
terminal
of
the
meter
to
terminal
number
8
and
the
negative
terminal
of
the
meter
to
terminal
number
10
on
the
input
receptacle
(for
input
plug
J-l,
figures
3
and
8).
6
CAPACITOR
VALUES
k
\
I
MAINTENANCE
CAPACITOR
VALUES
Response
Curve
Num er
1
2
3
5,600
8,200
10,000
Response
Curve
Num er
1
2
3
0.03
0.05
0.1
C-5
{200
vdc)
Capacity
in
mmjd
C-4
(400
vdc)
Capacity
in
mjd
amplifier
can
be
replaced
ith
the
dual
step-type
attenuator
furnished
in
the
MI-11233
amplifier.
Order
from
RCA
Replacement
Parts
Department,
Camden,
New
Jersey,
specifying
stock
number
57121.
This
attenuator
is
similar
electrically
to
the
continuous
type
of
attenuator
and
must
be
ired
into
the
circuit
as
sho n
on
the
iring
diagram,
figure
8.
capacitor
having
the
curve
number
in
the
Increasing
High-Frequenc
Response
Three
curves,
numbered
1,
2
and
3,
are
sho n
in
figure
6.
These
curves
illustrate
the
frequency
characteristics
of
the
amplifier
after
changes
are
made,
in
the
circuit
constants,
to
increase
the
high-
frequency
response
of
the
amplifier,
by
approxi
mately
one,
t o
and
three
decibels
at
10,000
cps.
To
obtain
a
frequency
response
corresponding
to
one
of
the
three
curves,
replace
the
3900
mmfd
capacitor
designated
C-5
in
figures
2
and
4
ith
a
capacitor
having
the
value
given,
opposite
the
curve
number,
in
the
follo ing
table.
ts
and
NOTE:
Check
the
high-frequency
response.
If
it
is
found
to
be
too
high,
substitute
for
C-5
a
capacitor
of
the
next
lo er
standard
value
as
required.
Increasing
Low-Frequenc
Response
The
curves
numbered
1,
2
and
3
in
figure
7
sho
the
frequency
response
of
the
amplifier,
after
alterations
have
been
made
in
the
circuit
to
obtain
greater
lo -frequency
response.
An
increase
of
2,
3
and
4
decibels
at
30
cps
can
be
obtained
by
making
suitable
modifications
in
the
circuit.
To
Frequenc
Compensation
The
normal
frequency
response
of
the
Type
BA-13A
Program
Amplifier,
sho n
by
the
curve
in
figure
5,
is
flat
throughout
the
audio
range.
Under
certain
conditions
it
may
be
desirable
to
increase
the
response
at
either
the
high-frequency
or
the
lo -frequency
end
of
the
range.
The
curves
in
figures
6
and
7
sho
the
increase
in
response
hich
may
be
obtained
by
making
compensation
adjustments
ithin
the
amplifier,
according
to
the
instructions
in
the
follo ing
paragraphs.
If
desired,
both
high
and
lo
frequency
compensation
may
be
applied.
NOTE:
Because
of
slight
differences
in
iring
and
tolerances
of
component
parts,
it
may
be
necessary
to
use
capacitors
differing
in
Value
from
those
given
in
the
follo ing
tables
in
order
to
secure
the
desired
response.
Cleaning
The
care
of
the
Type
BA-13A
Program
Amplifier
should
include
the
usual
precautions
observed
in
the
maintenance
of
high-quality
audio
components.
Do
not
allo
dust
or
dirt
to
accumulate
on
the
amplifier.
Perform
the
follo ing
operations
at
regular
intervals:
a.
Clean
the
tube
prongs
and
the
contacts
in
the
tube
sockets.
b.
Clean
the
prongs
of
the
plug-in
capacito
the
contacts
of
the
capacitor
sockets.
c.
Keep
the
prongs
of
the
amplifier
connection
plugs
clean
using
clean
dry
cloth.
Do
not
use
abrasive.
Clean
the
connection-plug
recep
tacles
approximately
every
t o
months
by
obtain
a
frequency
response
corresponding
to
one
of
the
three
curves
make
the
follo ing
changes:
a.
Disconnect
the
yello
lead
from
R-15
(on
terminal
No.
1
of
terminal
board
1)
and
connect
this
lead
to
a
compensator
composed
of
a
5600-ohm
resistor
and
a
1-mfd
capacitor
(in
parallel).
Connect
the
other
side
of
the
compensator
to
R-15
on
terminal
No.
1
on
terminal
board
1.
The
com
pensator
may
be
supported
by
a
small
terminal
board
mounted
on
the
side
all
of
the
chassis.
The
position
in
the
circuit
of
the
resistor
and
capacitor,
identified
as
R-27A
and
C-15A
is
sho n
in
figure
4
(they
should
have
ratings
of
1
att
and
200
vdc
respectively).
b.
Replace
the
0.25
mfd
capacitor,
designated
C-4
in
figures
2
and
4,
ith
a
value
given
opposite
the
follo ing
table.
In
applications
here
system
losses
or
other
deficiencies
require
an
increase
in
the
response
at
both
ends
of
the
audio
spectrum,
some
suitable
combination
of
high-frequency
and
lo
’
-frequency
compensation
can
be
selected
and
applied
as
described
in
the
t o
preceding
paragraphs.
7
VOLTAGE
AND
CURRENT
VALUES
360
volts
T-2
PLATE
3
5.
->»
TO
R-IO
3
7
2
V
TO
S-2
BUS
GROUND
M-I45306-I
Figure
4
—
P rti l
Schem tic
Di gr m
Showing
Ch nges
for
Compens tion.
Fuse
Replacement
When
replacing
i
o
65
volts
de
72
volts
de
1.8
volts
de
90
volts
de
48
volts
de
1.5
volts
de
Plate
to
ground
Screen
to
ground
Cathode
to
ground
Filaments
to
ground
Meter
Indication
Filaments
Plate
Current
Screen
Current
Second
stage
RCA
1620
o
y
B
>
ci
§
g
o
Q
5
O
<n
K>
Third
stage
RCA
1622
<D
or
R-27
A
AWW-
5.600
JI
r-
a:
RCA-1620
V-
2
cc
ct
8
<O
d
o
o_
o
C-15
A
Hb
IMFD
—
11
—
0.2
3
MFD
Tubes
and
Plug-in
Capacitors
Check
the
tubes
for
normal
characteristics.
Label
each
tube,
indicating
condition
and
length
of
serv
ice.
Check
the
plug-in
capacitors
for
leakage
and
capacity.
C-8
1200
MMFD
nd
nr
T0
Cl3
I800JL
I800IL
Voltage
and
Current
Values
Voltage
and
current
values
for
a
operating
under
normal
conditions
follo ing
table:
A-C
supply
to
amplifier
—
1
17
volts,
60
cps
(A-C
supply
connected
to
the
1
1
5-volt
tap
on
traTsformer
)
a
fuse,
make
certain
that
the
replacement
fuse
is
of
the
same
type
and
rating
Plate
Supply
Voltag<
Total
rectified
current
—
56
milliamperes
310
volts
de
270
volts
de
2
1
volts
de
18
volts
de
1
volt
de
6.3
volts
ac
45
ma
2.2
ma
18
volts
de
1
volt
de
6.3
volts
ac
0.84
ma
0.22
ma
18
volts
de
1
volt
de
6.3
volts
ac
1.7
ma
0.5
ma
First
stage
RCA
1620
(1
ampere,
Type
MDL,
stock
number
53447)
as
the
one
furnished
ith
the
amplifier.
In
emergencies
hen
this
fuse
is
not
available,
a
1
ampere,
Type
3-AG
fuse
can
be
used
as
a
temporary
substitute.
Do
not
use
a
fuse
of
higher
rating
for
replacement
purposes
since
this
ill
needlessly
endanger
the
indings
of
the
po er
transformer.
the
po er
T
m
I
■
S.
<0
”
cc
u.
typical
amplifier
are
given
in
the
removing
the
amplifier
from
the
receptacles.
This
action
automatically
cleans
the
receptacle
contacts
by
the
iping
action
of
the
springs.
Plug
the
amplifier
in
and
pull
it
out
several
times
to
secure
sufficient
cleaning
action.
d.
Clean
the
step
type
attenuator
in
the
MI-1
1233
amplifier.
Press
the
catch
nearest
the
rear
end
of
the
attenuator,
turn
the
rear-end
cover
sufficiently
to
release
it,
and
pull
the
cover
off
of
the
attenuator.
Apply
Davenoil
to
the
ex
posed
rear-section
contacts,
rotate
the
shaft,
and
if
any
dark
streaks
appear
ipe
off
the
contacts.
Repeat
this
procedure
until
the
con
tacts
are
clean,
then
apply
a
thin
film
of
Daven
oil.
Press
the
catch
nearest
the
front
of
the
attenuator
and
remove
the
rear
section
of
the
attenuator,
exposing
the
front-section
contacts.
Clean
these
contacts
in
the
same
manner.
Replace
the
rear
section
and
the
end
cover
and
lock
each
in
place.
8
Figure
5
—
Normal
Frequency
Response
of
Type
BA-1
3
A
rogram
Amplifier.
4
Figure
6
—
Frequency
Response
with
High-Frequency
Compensation.
Figure
7
—
Frequency
Response
with
Low-Frequency
Compensation.
9
Figure
8
—
Wiring
Di gr m
for
Type
BA-13A
(MI-11233
nd
MI-1
1
233-A)
10
LIST
OF
Description
Sym ol
No.
Sym ol
No.
Description
56115
C-2A,
C-2B
57117
C-3
57118
C-4
57119
C-5
18952
39666
C-6
561
18
C-7
57120
C-8
w
39654
C-9,
C-10
5641
1
48791
56410
S-2
rotary,
single
pole,
4
C-12
71585
C-13
39646
C-14
39664
F-l
53447
Socket,
capacitor
J-l.
J-2
45368
48788
R-1A,
R-1B
57121
R-
1
A,
R-
1
B
57122
meter-
27990
57115
43498
a
The
follo ing
parts
list
is
included
to
provide
identification
hen
ordering
replacement
parts.
Order
from
RCA
Replacement
Parts
Department,
Camden,
New
Jersey,
giving
the
Stock
Num er
and
R-2
R-3,
R-12
R-8
R-9
R-10
R-l
1
R-l
3
R-14
R-15,
R-16
R-17
49032
52403
52404
53426
57123
46098
50793
28413
31319
R-4
R-5
R-6
R-7
R-l
8
R-l
9
R-20,
R-21,
R-22
R-23,
R-25
R-2
4
R-26
S-l
48894
12110
Stock
No.
T-l
T-2
T-3
X-l
X-2,
X-3,
X-4
X-5,
X-6,
X-7,
X-8
X-9
Stock
No.
PARTS
Description
of
the
parts
anted.
Replacement
parts
supplied
may
be
slightly
different
in
form
or
size
from
the
original
parts
but
ill
be
completely
inter
changeable
ith
them.
Holder,
fuse
Cap,
tube
shield
Connector,
female,
10
contact,
Resistor,
10,000
ohms,
1
Resistor,
560
ohms,
1
Resistor,
330
ohms,
1
S itch,
toggle,
SPST,
3
amp,
2
50
v,
Off-On
S itch,
position
Transformer,
audio
input
Transformer,
output
Transformer,
po er
Socket,
tube,
8
contact
Socket,
tube,
8
contact
5%,
1
*5%,
2
5%,
1
±5%,
1
600
chassis
mounting
Handle,
ejector,
left
Handle,
ejector,
right
Knob,
gain
control
and
ing
s itch
Plate,
gain
control
dial
plate
(MI-11233
only)
Plate,
gain
control
dial
plate
(MI-11233-A
only)
Plate,
metering
s itch
dial
plate
57116
52922
Resistor,
1500
ohms,
Resistor,
1000
ohms,
1
Resistor,
1
megohm,
1
Resistor,
220,000
ohms,
1
Resistor,
390
ohms,
Resistor,
22
ohms,
=*=
Resistor,
1800
ohms,
Resistor,
ire
ound,
ohms,
10
Resistor,
8200
ohms,
2
Resistor,
82,000
ohms,
2
Resistor,
5600
ohms,
1
Capacitor,
fixed,
oil,
0.1
mf,
400
v
Capacitor,
dry
electrolytic,
20-
20
mf,
450
v
Capacitor,
fixed,
oil,
0.2
5
mf,
400
v
Capacitor,
fixed,
oil,
0.2
5
mf,
400
v
Capacitor,
fixed,
mica,
3900
mmf,
500
v
Capacitor,
fixed,
oil,
.2
5
mf,
400
v
Capacitor,
fixed,
oil,
0.1
mf,
400
v
Capacitor,
fixed,
mica,
1200
mmf,
500
v
Capacitor,
dry
electrolytic,
80
mf,
450
v
Capacitor,
dry
electrolytic,
40
mf,
4
50
v
Capacitor,
fixed,
paper,
.01
mf,
200
v
Capacitor,
fixed,
mica,
560
mmf,
500
v
Capacitor,
fixed,
mica,
3300
mmf,
500
v
Fuse,
1
amp,
delayed
action,
glass
body
Connector,
male,
10
contacts,
chassis
mounting
Resistor,
variable,
dual
step
at
tenuator,
100,000
ohms
(MI-
11233
only)
Resistor,
variable,
dual,
continu
ous
attenuator,
100,000
ohms
(MI-11233-A
only)
Resistor,
470
ohms,
=
fc
5%,
1
Resistor,
470,000
ohms,
±5%,
1
Resistor,
18,000
ohms,
1
Resistor,
120,000
ohms,
1
Resistor,
variable,
100
ohms
Resistor,
680
ohms,
1
RADIO
CORPORATIOn
OF
AfBCRICA
cnGinccRinG
products
DCPARimcnT
cAmDcn,
n.
j
.
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