QT-90W
– 6 –
ADJUSTMENT
Figure 6
TUNER SECTION
fL: Low-range frequency
fH: High-range frequency
1
FM IF:
(1) FM IF sweep
Inject the IF
Signal are taken
Adjust T106, T108
(1) Band SW in FM.
10.7 MHz
generator
sweep signal
out from point TP3
and repeat to get
(2) VOL. & TONE
(T108)
(2) Alignment
through 300 pF
best "S" curve with
control in MIN.
FM
oscilloscope
capacitor to point
center at 10.7 MHz
position
DETECTION:
(3) Power supply
TP2
(3) Tune P.V.C. to
(T106)
high end
2
FM BAND
(1) FM RF sweep
Inject the RF
Same as step 1
Adjust P.V.C. (TC1)
Same as step 1
COVERAGE fH:
generator
signal directly to
get MAX. output
108.2 MHz
(2) Alignment
point TP1
oscilloscope
(3) Power supply
3
FM BAND
Same as step 2
Same as step 2
Same as step 1
Adjust L103 to get
Tune P.V.C. to low
COVERAGE fL:
MAX. output
end
87.4 MHz
4
Repeat step 2, 3 until no further improvement can be made.
5
FM TRACKING
Same as step 2
Same as step 2
Same as step 1
Adjust P.V.C. (TC2) to
Tune P.V.C. to
fH: 106 MHz
get MAX. output
106 MHz
6
FM TRACKING
Same as step 2
Same as step 2
Same as step 1
Adjust L102 to get MAX.
Tune P.V.C. to
fL: 90 MHz
output
90 MHz
7
Repeat step 5, 6 and then step 2, 3, 5, 6 until no further improvement can be made.
Step
Alignment
Frequency
Test Equipment
Signal-in
Signal-out
Adjust
Remark
FM Section
1
VCO: 75 kHz
(1) Frequency counter Inject MONO
Through test
Adjust VR102 let
(1) FM and stereo
(2) Power supply
signal at 98 MHz
circuit as Fig 6.
Frequency counter
position
(3) FM Signal
directly to point
value: 76 K
±
200 Hz.
(2) Tune radio to
generator
TP1 and ground
98 MHz
Step
Alignment
Frequency
Test Equipment
Signal-in
Signal-out
Adjust
Remark
FM Stereo Section
Pin 13 of IC102
Pin 21 of IC102
FET: 2SK212
(or other 2SK type FET.)
To frequency
counter
10 pF
1M ohm
10K ohm
D
G
S
0.1
µ
F
