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AM FINAL ALIGNMENTS
There are two different AM alignment procedures. The
first alignment procedure is for those who do not have
test equipment and the second is for those who do have
test equipment.
Included in your kit is a special device called a "magic
wand" which is used for aligning resonant circuits. It
usually has a piece of brass on one end and a piece of
iron on the other. When the brass end of the "magic
wand" is placed near the AM antenna, the antenna coil
will react as if inductance has been removed. Likewise,
when the iron end of the "magic wand" is placed near
the AM antenna, the antenna coil will react as if
inductance has been added. Therefore, when either
brass or iron is placed near the antenna coil, it will
change the inductance of the antenna coil. This change
in the inductance will cause the resonant frequency of
the circuit to change, thus changing the frequency at
which the antenna was selective. When aligning the
antenna and oscillator circuits, coils L4 and L5 are
adjusted at the lower end of the band, while the
oscillator and antenna trimmer capacitors are adjusted
at the higher end of the band. This is done so that the
antenna and the oscillator will track correctly.
Soldering Iron Tip
Shrink Tubing
Iron Slug
Brass Slug
Magic Wand Assembly
Place the piece of brass inside the end of the
shrink tubing, with 1/4" outside. Heat the brass up
with your soldering iron until the tubing shrinks
around the brass. Assemble the iron piece to the
other end in the same manner.
AM
ALIGNMENT WITHOUT TEST
EQUIPMENT
It is best to use an earphone for this procedure. Make
sure that the switch is in the AM position. With an
alignment tool or screwdriver, turn coils L5, T6, T7 and
T8 fully counter clockwise until they stop. DO NOT
FORCE THE COILS ANY FURTHER. Turn each coil in
about 1 1/4 to 1 1/2 turns. Set the AM antenna coil about
1/8" from the end of its ferrite rod. Refer to Figure K.
IF ALIGNMENT
Turn the power ON and adjust the volume to a
comfortable level. Turn the dial until a weak station is
heard. If no stations are present, slide the antenna back
and forth on its ferrite core, and retune the dial if
necessary. Adjust T6 until the station is at its loudest.
Reduce the volume if necessary. Adjust T7 until the
station is at its loudest and reduce the volume if
necessary. Adjust T8 until the station is at its loudest
and reduce the volume if necessary. Retune the radio
for another weak station and repeat this procedure until
there is no more improvement noticed on the weakest
possible station. This process peaks the IF amplifiers
to their maximum gain.
OSCILLATOR ALIGNMENT
Tune the radio until a known AM station around 600kHz
is heard. It may be necessary to listen to the station
until their broadcast frequency is announced. If no
stations are present at the low side of the AM band,
adjust L5 until a station is heard. Once a station is
found and its broadcast frequency is known, rotate the
dial until the white pointer is aligned to that station's
frequency marking on the dial. Adjust L5 until the
station is heard. Tune the radio until a known station
around 1400kHz is heard. It may be necessary to listen
to the station until their broadcast frequency is
announced. If no stations are present, adjust the AM
oscillator trimmer on the gang until a station is heard
(refer to Figure L). Once a station is found and its
broadcast frequency is known, rotate the dial until the
white pointer is aligned to that station's frequency
marking on the dial. Adjust the AM oscillator trimmer on
the gang until the station is heard. Repeat these 2
steps until the oscillator alignment is optimized. This
process sets the oscillator range at 955kHz to
2055kHz.
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