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A-C
Power
Connections
The
amplifier
is
connected
for
a-c operation from a
115- to 125-volt, 50-
co
60-cycle power line.
For
operation
from
a
105-
to
11
S-volt line,
it
is
necessary
to disconnect the
black/red
lead
from
terminal
number
12
of
transformer
T-5
and
connect
this lead to terminal
number
11
ofT-5.
The a-c power cord
is
clamped to the inside
0£
the
front
panel cover
for
convenience in transporting. Re-
move this cord
from
beneath the clamps and insert the
12-terminal plug on one end
of
the cord
into
' the
receptacle on the rear
of
the amplifier. Insert the
two-
prong plug on the
other
end
of
the cord
into
a suitable
a-c outlet.
Tubes
Loosen the
four
twist-lock fasteners on the top cover
and remove this cover. Markings on the chassis indicate
the correct tube type for each socket. Place the tubes
in the sockets. Place the grid caps and grid-cap shields
on all
of
the amplifying tubes.
Each
shield
must
make a
good electrical connection to the shell
of
the tube
for
noise-free operation.
Battery
Connections
Six
RCA
Type VS012
"B"
Batteries
or
equivalent,
and 10
RCA
Type
VS004
"A"
Batteries
or
equivalent
may
be
used
to
supply
the
d-c power requirements listed
under Technical Data. A
kit
of
the above listed
bat-
teries may
be
ordered
as
Ml-112
55.
The
use
of
15
"A"
batteries will increase the
battery
life.
The
MI-11214
Battery Box may
be
used
with
the
Type
BN-2A
Ampli-
fier.
The
battery
box contains space for
15
"A"
batteries and 6
"B"
batteries
of
the types listed above.
The Ml-11214
Battery
Box
is
wired
with
plugs ready
to
be
inserted
into
the batteries and
is
supplied
with
a
power cord
for
direct connection to the receptacle
on
the amplifier.
The
battery
connector
plug
is
wired
as
'shown in the lower-left corner
of
the schematic diagram,
figure
8.
The
expected
battery
life
for
an average amplifier
operation
of
six hours per day
is
as
per the table below.
If
the amplifier
is
used
less
than
six
hours per day, the
expected life
of
the
battery
in hours will
be
increased.
If the amplifier
is
to be used continuously the life
of
the
battery will
be
materially decreased.
EXPECTED
LIFE
IN
HO
URS
(
APPROXIMATE)
Q11anlity
HA"
or "B"
Typ,
Li/, in Hours
15
10
6
A
VS004
8.J
A
VS004
4
B
VS0l2
12f
NOTE:
For
maximum
battery
life remove alt
battery
plugs when che
battery
supply
is
not
to
be
used .for
24 hours
or
more.
7
OPERATION
Set the
LIGHT
switch for the desired meter illumina-
tion
(LO
or
HI).
(The
meter lamps also serve
as
power-on-off indicators.) Set this switch in
"LO"
position when using batteries
to
reduce drain on the
batteries.
Turn
the
POWER
swi\cb
ON
and allow
ah'out
30
seconds for
tube
warm-up. Before broad-
casting
has begun,
turn
all volume controls to maximum
and check carefully for extraneous
noises
in the
output
which may be due
to
faulty
location of the microphones
and cables.
When
using the MIC-3 or MIC-4 input, set
the MIC
switch
to
the corresponding number. Rotate
the
METER
switch
to
the
"+s
VU"
position.
Output
level to .the telephone line should
be
+s
vu. Adjust
the gain controls
so
that
the peaks
of
modulation swing
the needle
of
the
meter
to
zer~ on the upper scale (for
an average line level
of
+8
vu).
This zero reading will
represent a different line level if the connections to the
meter pad have been changed
as
indicated under In-
stallation.
For
the best signal-to-noise ratio the MAS-
TER
gain control should be set
at
a fixed.position some-
where between
number
IO
and number
16
and the mixer
controls
(MIC
1,
2, 3 &
4)
should
be
adjusted for the
zero reading on the meter. This arrangement permits
varying the mixers
from
number
Oto
number 16 without
adding more
than
2
db
to the noise level
of
the amplifier.
The
MASTER
and MIC controls also control the level
at
the
output-monitoring
jacks.
Switching
to
Telephone
Line
To
switch
the
output
of
the amplifier into the tele-
phone line,
turn
the
AMP
OUTPUT
control to LINE.
To
switch the
output
of
the
amplifier
off
the telephone
line,
turn
the
AMP
OUTPUT
control to
OFF
.
Switching
to
PA
Amplifier
To
switch
the
output
of
the amplifier into the input
of
a connected public address amplifier,
turn
the PA
INPUT
switch
to
AMP.
To
switch the input at the
CUE
terminals
to
the
input
of
the public address am-
plifier, set the
PA
INPUT
switch to CUE. Adjust the
PA
VOLUME
control
for
the desired
output
from the
public address system.
To
switch both amplifier and
cue
inputs
off
the
public address amplifier,
turn
the
PA
INPUT
switch to OFF.
SERVICE
Tube
Checking
with
VU
Meter
To
check
the
tubes, rotate the METER control
through
posidons 1 through 6 and observe the
VU
meter
at
each step. These
meter
positions check V-1 through
..
