General Adjustment - Sharp QT-15XW Service Manual

QT-15XW
DIAL CORD STRINGING
1. Turn the drum fully clockwise and stretch its cord over the
parts in the numerical order as shown in Figure 4-2.
2. Turn the tuning control shaft fully counterclockwise and
fix its pointer to "0" point as shown in Figure 4—1.
Drum (130)
cay
q
"O' Point
Figure 4—1 Tuning Control Shaft (128)
— Sciam Sart Figure 4—2
GENERAL ADJUSTMENT INSTRUCTION
Should it become necessary at any time to check the adjust-
ment of this receiver, proceed as follows;
1. Set the volume control (VR101) to maximum. OSCILLOSCOPE ae
2. Attenuate the signals from the generator enough to swing beer TEST LOOP se ANTENNA
the most sensitive range of the output meter. i
3. Use a non-metallic adjustment tool.
4. Repeat adjustments to insure good results.
AM IF/RF ADJUSTMENT Figure 4-3 AM IF
e Set the mode selector switch (SW101) to AM position.
@ Set the signal generator to produce a signal of 400Hz, 30%,
AM modulated.
e For adjustment in step 4, see [Note Al [Note A] Al.
FRE- | DIAL
TEST ADJUST-
STEP 5
rer pane |STAGE| cy ring | MENT | memanns
IF (Connect instruments as shown in Figure 4—3.)
High Adjust for
455kHz! end of T3 best IF
dial curve.
RF (Connect instruments as shown in Figure 4—4.)
Low
Band ne oF
dial
Tale =
ing
Repeat steps 2, 3, 4 and 5 until no further improvement
can be made.
Check the alignment of the receiver antenna coil by
bringing a piece of ferrite (such as a coil slug) near the antenna
loop stick, then a piece of brass. If ferrite increases output,
loop requires more inductance.
If brass increases output, loop
requires less inductance. Change loop inductance by sliding the
bobbin toward the center of ferrite core to increase inductance,
or to decrease inductance.
fo
10 cm GND
ELECTRONIC
VOLTMETER
SIGNAL AM
GENERATOR TEST LOOP BAR ANTENNA
Adjust for
maximum
Output.
Figure 4—5 ADJUSTMENT POINT