Operating instructions

to obtain
a reading of 1.4
volts dc
at Jl02
(par.
15).
e. Adjust
the
top and bottom
slugs
of trans-
former T11
for maximum
output indication
on
the output
meter.
/.
Connect the
signal
generator
lead
to
the
grid
of the first i-f
stage
(pin
6 of V4)
and
adjust
the top
and bottom
of transformer
T10;
lower
the input
signal
from the
generator
as
each circuit
is tuned.
g.
To
aline the first i-f
transformer,
connect
the signal
generator
to
the stator
terminal
of
C1C
(fie.
38)
and adjust the
slugs
of trans-
former
T9 for maximum
output indication.
At
this
point,
peaking
of all
i-f transformers
should be
rechecked
to overcome
any slight
re-
generation
that may
be
present.
95.
Bfo Alinement
Procedure
(figs.
38, 39, and 40)
a.
Set the signal
generator
to 455 kc
unmodu-
lated.
Connect
the
generator
oLltput through
a
.05-pf
capacitor to
the
grid (pin
6 of V4) of the
first i-f
amplifier. Set the
B.F.O.
trimmer to
the vertical vyhite
line on the
panel.
Set the
PHN.-C.W.-NET-CAL.
switch to C.W.
ó.
Connect an
output meter
and headset
as
instructed in
paragraph
94a. Adjust
coil
T13
at the bottom of the receiver
chassis until
a
zero-beat note is heard,
or adjust it to minimum
outpnt
indication
on the
output
meter.
Con-
nect
a vacuum-tube
voltmeter
through
a 68,-
000-ohm
isolating
resistor to
pin
4 of
V7.
The
voltage at the
grid,
pin
4,
should read
approxi-
mately
-15
volts dc to
-20
volts dc.
96.
R-f
Alinemenf Procedure
(figs.
38,
39,
and
40)
The step-by-step
procedure
for r-f alinement
is indicated
in
the
chart in
g
below.
a.
Panel
Contro\s. Set
the
panel
controls as
follows:
Settins
Setting
POWER
ON-OFF sg,itch
(5103)---i
ON
A.F.
GAIN
control
(R19A,
R19B)
i
Adjusted to 10
lnw
on output
meter
b. Di,al
Poí,nter
Checlc.
Before
proceeding
with
the
alinement,
see
that
the dial
pointer
coincides
with
the vertical
master
line.
c.
Trimmer Locutions.
Adjustments
are 1o-
cated on
the top and
bottom of the receiver
chassis
(figs.
38, 39,
and
40).
Adjustments
are
to be made with
the special
tools
provided.
d.
Calibration Accuracy.
The
accuracy
of
the tuning
calibration
depends largely
on the
h-f
oscillator
operating frequency,
which is con-
tinuously set
at
455 kc
above the
operating fre-
quency.
Although
the frequency of
this oscil-
lator
can be measured
directly,
it is
simpler
to
use the system
indicated
in
the chart, rvhere
the tuning
dial
is
adjusted to the operating
frequency,
and then the trimmers
are used to
peak
the signal.
e.
Image Frequency
Check. To check
the re-
ceiver for correct
alinement,
set the signal
gen-
erator to the image frequency
which u'ill
appear
at a
higher
frequency
on the signal
generator
dial.
This
is
the
radio
frequency
plus
tu'ice the
intermediate
frequency.
As
an example,
with
the receiver
dial set at
2.7
mc,
the
image
vl'ill
appear at 3.6 mc
(2.7
mc
f.910
mc)
on the
generator
dial.
The
image must be
the
weaker
signal, and
a
large input
from the
generator
should be required
to obtaín the
desired output.
The
procedure
should be
followed
to
check the
alinement on
all
bands. If
the signal frequency
appears at a lower frequency
on the
generator
dial than that
indicated
on the receiver
dial,
the
receiver
is alined incorrectly
and must
be re-
alined.
Note
that in
the alinement
of the osciì-
lator,
two signal
peaks
will
appear
when
the
trimmer is
varied. The
peak
with the minimum
capacity
is
the
correct
peak.
f
. Connecti,ons.
Connect the signal
generator
to terminal
post
A
through a !70-ppf
capacitor,
and
the
ground
lead
of the
generator
to ter-
minal
G. Connect the
output
meter
in
parallel
with
a 600-ohm resistor
across one of
the
PHONES
connectors.
0UTPUT
HIGH-LOW srvitch
(Sa)
|
I'IIN.-C.W.-NET-CAL.
switch
(S2)
|
'AND
SW.
switch
(S1)
-- -l
F.
GAIN control
(R32)
-
ì
PEAKER
ON-OFF
switch
(S102)
HIGH
PHN.
1
Maximum
clockrvise
ON
AGO 3134
75