,
P H
ILCO TRAN S
ITON
T,
SERVICE BROADCAST
JANUARY,
1934
Adjusting
the
Philco
Superheterodyne
Auto
Radio Receivers
fltno
interm"atate t."qffi?tr.k
i
460 K. c. set up the
I
signal
generator
for this frequency.
Disconnect the
grid
lead from
the 6A7 tube.
Then connect
the
test lead
to
the
grid
of this
tube and
ground
the shield on the
Receiver housing.
Use the
fibre
adjusting
wrench for all adjust-
ments.
Frc. 1. Moorl 5-I.
F. 460 K. C.
Padder
"LF."
Turn the adjusting nut
in
until tight.
Then
back
off one
full
turn.
Leave this condenser
in this
position
until the
last step.
Now adjust
the first L F.
primary
condenser. With the Receiver
and signal
generator
turned on and the signal
generator
set for
460 K. C., turn
the Receiver volume control on full and adjust
the
attenuato;.
Then adjust
the
padder
for
maximum reading
on the output
meter.
Next
adjust
the first
I.
F. secondary condenser. Adjust
the
attenuator so that
a half-scale
reading is
obtained. This
should
be
repeated
with each
adjustment
if
necessary. Adjust
the
pad-
der
for maximum reading.
Repeat
this
procedure
in the
next two
adjustments.
The
next adjustment
in
order
is
the second I. F.
primary
con-
denser.
This is then followed by the second I. F.
secondary con-
denser. These are
indicated
on the
illustration.
(Fig.
1.)
Remove
the signal
generator
connections from the
6A7 tube and
reconnect the Receiver
grid
lead
to
this tube. The
signai
gen-
erator setting
must now be changed
to
1500
K.
C.
The Receiver volume control must be
turned
on full,
the
oscil-
lator lead connected to the antenna lead-in
and the shield to the
Receiver housing.
To obtain
the correct setting of the tuning
condenser,
open the
plates
as wide
as
possible.
Place
a
piece
of
paper
on the stator
plates
and then turn the rotor
out until it
strikes the
paper.
Oscillator Adjustment.
This is
the
padder
on the second
section of the
tuning
condenser
(section
nearest
drive mechanism).
Adjust for maximum
reading.
Antenna Adjustment. This is the remaining
padder
on the
tuning condenser. Remove the
paper
from
the tuning condenser
and set the condenser
and signal
generator
for
1400
K. C. Adjust
the
padder
for maximum reading.
Low Frequency Adjustment. Set the
signal
generator
for
600
K.
C.
and tune the
Receiver
to this frequency.
Adjust the
pad-
der
for maximum reading. After
completing
these operations,
readjust the antenna
padder
at 1400 K.
C.
MODELS
6,
9
AND
t2 (CODE
t22)
f. F. Stages.
Remove
the
grid
clip from
the detector-oscillator
tube
and
connect the
output of the
signal
generator
to the control
grid.
The detector-oscillator is
the second tube from
the
right.
With
the Receiver
and
signal
generator
turned
"on,"
set the
'
signal
generator
for 260 K.
C. and adjust the
attenuator
so
that
a
half-scale
reading is obtained on
the
output
meter,
with
the
Receiver
volume control turned
on full.
Using
a Philco
fibre
wrench,
adjust the second I. F. condenser.
The correct adjustment
is obtained when
the
maximum reading
is secured on the meter.
Next
adjust the secondary and
primary
I. F.
condensers.
These
are the right-hand ones on Fig.
2.
Disconnect the signal
generator
and
reconnect
the clip to the
control
grid.
High
Frequency Adjustments.
Connect the
output
of the
sig-
nal
generator
to the antenna
lead
and the housing of the Receiver.
With
the
Receiver
turned
on and the
signal
generator
set for
1400 K. C.,
tune the Receiver to 1400
K. C. and adjust the third
padder
on the
tuning
condenser for maximum
signal. This
is
the
one on the extreme
left of the housing. The
purpose
of this
ad-
justment
is
to
line
up the condenser
so that
1400
K.
C.
is
tuned
in at
140 on
the
scale when the scale is
set
properly.
It may be necessary to adjust the first
two compensators on
the tuning condenser at
1400
K. C.
in
order
to
get
a strong
enough
signal
through.
Frc. 2.
Moonls 6, 9 AND
12.-(Conn
122)
I. F.260 K. C.
R. F. Adjustments. After
the detector-oscillator
has been
padded
at
1400
K. C. adjust
the first
and second
R. F.
Condensers
on tuning condensers at 1400
K.
C.
Low Frequency Adjustment.
Now tune
the
Receiver and sig-
nal
generator
to 700
K.
C.,
and adjust
the condenser
(LF)
on
Fig. 2. During this operation the
tuning
condenser
must
be shifted
and the compensator must
be
adjusted
to
bring
in the maximum
signal.
After this
has
been
done, check the aC.rustment
of the
high-
frequency condenser
at 1400 K.
C.
again.
MODELS
7,
8 AND
12 (CODE 12r)
Intermediate
Frequency
or I. F. Stages.
Remove
the
grid
clip from the detector-oscillator
tube and
connect
the output of
the signal
generator
to the control
grid.
The detector-oscillator
is the second tube
from the
right.
With the
Receiver
and
signal
generator
turned
"on,"
set the
signal
generator
for 175
K. C.
Adjust
the
attenuator
so that a
half-scale reading. on the output meter
is
obtained with the Re-
ceiver volume control
turned on full.
Using a
Philco fibre wrench, adjust the second
I.
F. condenser.
'fhis
is
the one
in the upper left-hand corner of Fig. 3.
The correct adjustment
is obtained when the maximurn reading
is secured on the meter.
Next adjust the
secondary and
primary
I.
F.
condensers. These
are the two
shown at
right on Figs.
3 and 4.
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The PHILCO
ALL-PURPOSE
O4S SET TESTER, the
modern, compact,
portable
complete
testing
equipment should
be used when adjusting any radio
Receiver. Dealer Net Price,
S48.60.
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