Operating instructions

100. Voltoge
Checks
Befole
testing the
receiver further,
make
the
follori'ing voltage
checks :
a. ]Iea-qure
the
d-c voltage between
the
posi-
tive 90-r-olt
supply
(capacitor
C37) and the
negative
lead
(chassis).
The
voltage may vary
betu'een 87
and 93 volts dc.
b.
Check the
h-f
oscillator
plate
voltage.
The
voltage between
pin
3 of tube
V3 and
the
chassis should be
approximately 43
volts.
c. Measure
the voltage from
pin
11
of J4 to
ground;
adjust R116
to
1.4
volts dc
(par.
15).
d. Measure
the bias
voltage from
pin
8 of
J4 to
ground (-4.2
volts dc).
l0l.
Operotion
of
Controls
A
complete
check of the
operation of the re-
ceiver controls should be made in
accordance
with
the equipment
performance
checklist
(par.
43). If
there
is reason for
suspecting improper
operation of the circuits,
also
check
as follows:
a. Manual-Preset Tuníng. Turn
the PHN.-
C.W.-NET-CAL.
function
switch
to CAL.
Check
the calibration of
the tuning dial every
200 kc in each frequency
band. Note that
the
receiver tuning dial reads correctly
within one-
half of a scale division. If
not.
realine
the re-
ceiver.
b.
BFO
Operation.
Turn
the function
switch
to C.W.
Turn
off the
modulation.
Adjust
the
bfo to
give
a beat
note
in the loudspeaker. If
the beat note is
not
heard, refer to
paragraph
83.
102. Receiver
Chorocteristics
Noúe. The tests outlined in o through e
below
nor-
mally need
not
be
made unless there is
reason to suspect
improper operation or
unless
a
new
component
has
been
inserted in the circuits
involved.
a. Sensítiuity,
Modulated Signals.
The re-
ceiver should
be set up
in accordance
with the
instructions
given
in
paragraph
87. The over-
;rll a-m sensitivity
of the
receiver should
cor-
lespond
to
the antenna
input readings
given
in
,aragraph
87rf.
tt.
Sensitíai,tu, C-W Signals. Check the
c-w
,nsitivity
at
the same
points
as those referred
in
c abol.e. Turn the signal
generator
modu-
Iation off and
turn the
function
switch to
C.trV.
Tune
the
B.F.O.
control to a 1,000-cycle
beat
note. Turn
the signal
generator
off, and
adjust
the A.F.
GAIN control
for 1-mw
output indica-
tion on
the output meter. Turn
the signal
gen-
erator on
and adjust it to
give
10-mw
outpllt on
the
output
meter.
Srvitch the signal
generator
off
to check
noise
reading
at
1-mw
output and
readjust
the A.F.
GAIN
control, if necessary.
Recheck
the
10-mw
output with
the signal
generator.
The
value of signal input
should be
2
pv or less.
c.
Selectiaity. This
test should
be carried
out
at 5
mc
on band 2.
Set the signal
generator,
modulated
30
percent
at
400
cycles, to
the above
frequency;
tune
the
receiver
exactly to it;
ancl
adjtlsf
the signal input
to
give
a reading
of
10
mw
on the output meter. Double
the
signal
input;
detune the signal
generator,
first
on
one side and
then on the other
side of reso-
nance;
and
note
the frequencies
that
give
10
mw
on the output meter. These
are the
off
resonant
frequencies. Repeat
observations for
ratios
of
input
voltage off resonance
to voltage
at resonance
of
10, 100,
and
1,000. Bandr,vidths
shouìd
be within
the
limits in
the follou'inE
table.
Ratio of input
voltage
off resonance
to
voltase
at resonance
Total
maximum
bands'idth kc
2
(6-db
attenuation)
10
(20-db
attenuation)
100
(40-db
attenuation)
1,000
(60-db
attenuation)
Less than
6.5
Less than 13
Less than 20
Less
than 28
d,.
Image-Rejection
Ratío. Perform
this
test
on all bands by measuring the
sensitivity of the
receiver
at a frequency equal to the signal
fre-
quency
plus
twice the
intermediate
frequency
(2
x 455 kc
or 910
kc).
The following
pro-
cedure is recommended:
(1)
With the
PHN.
-
C.W.
-
NET
-
CAL.
srvitch 52
in
the PHN.
position,
set
the A.F.
GAIN control to maximum,
and adjust the R.F.
GAIN control to
give
a
10-mw
output
with
a
10-p.v
in-
put.
(2)
With the signal
generator
and re-
ceiver
tuned to the test frequency,
ro-
tate the
signal
generator
to the image
AGO
3134.