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STR-GX290/GX390
SECTION 3
ELECTRICAL ADJUSTMENTS
FM SECTION
e FM Discriminator (NULL) Adjustment
Setting :
FM RF stereo signal
génerator
Carrier frequency : 98MHz
Output level: 60dBu
Modulation:
IkHz
FM ANTENNA
752
40kHz dev.
terminal
(53%)
VOM
TP1
(DC range)
NULL terminal
Procedure :
1. Tune the set to 98MHz.
2. Adjust T21 for OV reading on the VOM.
Note : FM Tuning Level adjustment should be made after
FM discriminator adjustment.
© FM Stereo Operation Level Adjustment
Setting :
FM RF stereo signal
generator
Carrier frequency : 98MHz
Output level : 25dBy
Modulation ; 1kHz
FM ANTENNA
752
40kHz dev.
terminal
(53%)
Procedure :
1. Tune the set to 983MHz.
2. Adjust RV24 so that the STEREO LED goes on.
Note on Ceramic Filter (CF1, 2) Replacement.
This set employs two ceramic filters (CF1, 2) which should
have the same color marking to identify their center fre-
quency. Therfore FM IF offset adjustment by (* A, * B)
connection is necessary to match the center frequency of
the ceramic filters used with FM intermediate frequency.
color marking
© FM Stereo Separation Adjustment
Setting :
FM RF stereo
Signal
- generator
FM ANTENNA
752
REC
OUT
terminal
Carrier frequency : 98MHz
Output level: 60dBu
Modulation :
Audio
(1kHz):
16.25kHz dev.
(21.7%)
Pilot (19kHz):
7.5kHz dev. (13.3%)
Sub-channel (38kHz):
16.25kHz dev. (21.7%)
Procedure :
Tune the set to 983MHz.
-
FM stereo
signal generator
output channel
VTVM
connection
VTVM
reading (dB)
Adjust RV21 for
minimum reading
R-CH
Ceramic filter
Connection
FM intermediate
frequency
Center Frequency | *A
*B
(MHz)
(MHz)
(D125) | (D124)
10.750
10.750
x
e700
|
0.700
10.650
10.650
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