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To properly align the receiver, it will
be necessary to have an output meter and signal generator.
NOTE: If any one of the tuning coils or cores have been replaced,
see "Capacity and inductance Alignment Procedure" before proceeding
with alignment of the receiver. If only the adjustments have been
tampered with or an intermediate frequency transformer has been
replaced, proceed with the alignment as follows:
| 1. |
First hook up an output meter to
the radio receiver. Any volt meter |
| |
which will read "A.C." can be
used. Set the voltmeter in the 3 volt |
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"A.C." range position and ground
one lead of meter to radio |
| |
chassis. Place the other lead
from the volt meter to the speaker |
| |
terminal of the speaker to which
the "green" lead of the audio |
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output transformer is connected,
(speaker is item 53 and audio |
| |
transformer item 54 on circuit
diagram and parts layout). |
| 2. |
Turn on signal generator and set
adjustments to obtain a 262 |
| |
kilocycle signal. Connect one
lead of signal generator to radio |
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chassis for ground. Attach the
other lead from the signal generator |
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to the tube pin marked "G" on
6BE6 tube. |
| 3. |
Adjust signal generator volume
control so that the volt meter will |
| |
read at about half scale.
|
NOTE: Radio receiver volume control must be turned to the maximum
position, so that the automatic volume control circuit of the radio
will not affect the alignment of the receiver.
| 4. |
Adjust in sequence trimmers "A,
B, C and D", as shown on circuit |
| |
diagram and parts layout, for
maximum meter reading. Repeat |
| |
adjustments to get maximum meter
reading. Keep the signal |
| |
generator volume turned down so
that during adjustments the meter |
| |
does not read more than half
scale. This will result in a better |
| |
alignment of the receiver.
|
| 5. |
Next change signal generator
setting to obtain a radio frequency |
| |
signal and tune signal generator
to exactly 1615 kilocycles. |
| |
Connect a .000082 mfd condenser
to antenna connector and |
| |
attach signal generator lead.
Tune radio receiver to the "stop" on |
| |
the 1600 kilocycle end of the
dial. Keep the signal generator |
| |
volume control adjusted so that
output meter reads at about half |
| |
scale. |
| 6. |
Adjust trimmers "E, F and G" on
circuit diagram and parts layout |
| |
in sequence for maximum readings
on output meter. Repeat for |
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maximum meter readings.
|
|
|
| 7. |
Tune the signal generator and
radio receiver to exactly 1000 |
| |
kilocycles and repeat adjustments
of trimmers "F and G" ONLY |
| |
for maximum readings.
|
| 8. |
After the receiver has been
installed in the car, turn on receiver |
| |
and tune in a weak station
between 600-1000 kilocycles, with |
| |
radio volume control turned to
maximum position and the antenna |
| |
extended to full height. Readjust
trimmer ONLY for maximum |
| |
volume. |
CAPACITY AND INDUCTANCE ALIGNMENT PROCEDURE
FOR 987187 RADIO
This alignment procedure is to be used only when any of the
following parts have been replaced in the radio; antenna coil, radio
frequency coil, oscillator coil or any of the tuning cores.
The intermediate frequency alignment at 262 kilocycles is the same
as outlined in "Alignment Procedure" operations 1 through 4. After
completing the intermediate frequency alignment, proceed as follows:
| 1. |
Connect signal generator lead to
a .000082 mfd. condenser and |
| |
connect to antenna terminal of
antenna socket. Mechanically |
| |
align iron core "H" on circuit
diagram and parts layout, to measure |
| |
1 & 25/32 inches in coil from
rear mounting edge of coil. |
| 2. |
Tune signal generator to exactly
1615 kilocycles and tune radio |
| |
receiver to "Stop" on the 1600
kilocycle end of the dial. Set output |
| |
meter on the 3 volt "A.C." scale
and keep signal output below 2 |
| |
volts during adjustments.
|
| 3. |
Adjust trimmer "E, F, and G", on
circuit diagram and parts layout |
| |
in sequence for maximum readings
on output meter. |
| 4. |
Tune the signal generator and
radio receiver to exactly 1000 |
| |
kilocycles and adjust iron cores
"J and K" for maximum output meter |
| |
reading. |
| 5. |
Reset signal generator to exactly
1615 kilocycles and tune radio |
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receiver to this frequency. Then
readjust trimmer "F and G" only |
| |
until no further increase in
output meter reading can be obtained. |
| 6. |
After the radio receiver has been
installed in the truck, turn on the |
| |
receiver and tune in a weak
station between 600 and 1000 |
| |
kilocycles, with volume turned to
maximum position and antenna |
| |
extended to full height. Readjust
trimmer "G" only, for maximum |
| |
volume. |
|