Sharp WOQ-272H(R) - FM IF;RF and VCO Adjustment

WOQ-272H(R)
‘ih
FM IF/RF ADJUSTMENT
400 Hz, 30%, FM modulated.
= = a pane
QUENCY |POINTER | JUST-
1. Using a minus
curve.
SETTING | MENT
driver, turn
10.7 MHz
Adjust for best
“S" curve.
the core of
T2 counter-
ee cepacia a steps 1 and 2 until no further improvement can
be ee cepacia a
SWITCH
POSITION
SIGNAL
GENERATOR
TEST
STEP | STAGE
clockwise
before taking
it out of the
bobbin.
. Adjust for
best “IF”
High
frequency
Figure
Detection
Lowest
frequency
108.3 Highest
MHz frequency
Repeat steps 4 and 5 until no further imporvement
can be made.
88 MHz 88 MHz cae Adjust for
output.
Repeat steps 7 and 8 until no further improvement can
be made.
Band
coverage
Adjust for
maximal
output.
FM Signal
Generator
VCO FREQUENCY ADJUSTMENT
SIGNAL
GENERA-
TOR
400 Hz, 30%, FM modulated
(mono signal)
DIAL
POINTER
SETTING
AD-
JUST-
MENT
FREQUENCY
FM mono position
FM stereo position
(unmodulated)
98 MHz VRi Adjust for
at 60 dB 38.00 kHz +100 Hz.
=14—
10.7 MHz
FM Sweep
Generator
FM Signal
Generator
Oscilloscope
Figure 14—1 FM IF
10.7 MHz
10.7 MHz
14-2
FMIF
CURVE
Figure
14-3
FMS
CURVE
Electronic
Voltmeter
Rod Antenna
Dummy
(See Figure 14—6)
Figure 14—4 FM RF
IC3
© Pin
1000pF
Frequency
Counter
Rod Anragna
300 kohms
Dummy
(See Figure 14—6)
Figure 14-5 VCO FREQUENCY
Ri
To Telescopic Rod Antenna
r
| R2
1&
Ll
To Chassis GND
s R1 = 37.5 ohms
a 1S ONE 75 ohne
7 R1 = 50 ohms
Z=50 ohms< 85 ee Goin
Z: Output impedance of signal generator
Figure 14-6 FM DUMMY