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IV. TUNER
SECTION
ADJUSTMENT
1.
TERMINATION PAD
(MODEL 2151-8)
FM IF CIRCUIT ADJUSTMENTS
(See Figs. 1 and 2)
FM IF PC.
BOARD
2).
3)
4)
5)
AM-FM RADIO IF GENESCOPE
(MODEL MSW~721C)
Fig. 1
10.7 MHz
Fig. 2
Adjust V-Gain Volume to obtain a 2 cm amplitude
of 0.3V p-p AM FM Radio IF Genescope cali-
bration
voltage
on
screen
and
set Genescope
Cutput to 50 dB.
Connect Genescope Output to point (1) (FM IF
Input), and Genescope Input to point (8) (AF
Output).
Set Mode Switch to "FM" and set dial to about
109 MHz reception frequency.
Adjust the upper core of IFT "L," of FM IF
Amp. P.C. Board
so that the S Curve output
voltage is maximum. Also adjust the lower core to
obtain optimum S Curve linearity.
In making this adjustment, in some cases the rank
of the ceramic filter causes a discrepancy in the S
Curve
Marker
Point,
but
it is satisfactory
if
through adjustment a margin of within +500 Hz
can be obtained (See Fig. 3).
Ceramic Filter Rank
Center Frequency | Error Tolerance
10.60 MHz
10.65 MHz
10.70 MHz
10.75 MHz
10.80 MHz
as
2)
3)
4)
COLOR MARK
CERAMIC
FILTER
Fig. 3
FRONT END AND FM IF MATCHING
ADJUSTMENT (See Fig. 6)
IF COIL (Front end)
Fig. 4
Fig. 5
Adjust V-Gain Volume to obtain a 2 cm amplitude
of 0.3V p-p AM
FM Radio IF Genescope cali-
bration
voltage
on
screen,
and
set Genescope
Output to 90 dB.
Connect Genescope Output to 3002 impedance
FM Antenna Terminal, and Genescope Input to
Terminal (8) (AF Output) of FM IF P.C. Board.
Set Mode
Switch
to "FM"
and set the tuning
indicator to the right end of the dial.
Adjust the upper core of IF Adjustment Core in
front end so that the value of the S Curve wave
height is maximum. Then adjust the lower core so
that the noise element is maximum and the upper
and lower reaches of the scanning line are the same
level (See Figs. 4, 5 and 7).
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