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14
FM Discriminator ADJUSTMENT
(NULL and MONO Distortion Adjustment)
(NULL and MONO Distortion Adjustment)
Setting:
Procedure:
1. Tune the set to 98 MHz.
2. Adjust IFT202 for 0V reading on the digital voltmeter.
1. Tune the set to 98 MHz.
2. Adjust IFT202 for 0V reading on the digital voltmeter.
................... NULL
3. Adjust IFT203 for a minimum reading on the distortion meter.
................... MONO Distortion (THD)
4. Repeat the adjustments of 2 and 3 several times.
Note :
When replacing the ceramic filter, perform this alignment.
SECTION 3
ELECTRICAL ADJUSTMENTS
Precautions in Repairing
If the front end unit fails, it is difficult to repair the inner circuits, so
replace the entire front end unit.
replace the entire front end unit.
•
Standard Setting of FM Stereo RF Signal Generator.
FM SECTION
0dB = 1µV
set
FM RF SSG
1kHz
highpass
filter
highpass
filter
distortion meter
FM ANTENNA (75
Ω
)
LINE OUT
STEREO STANDARD SIGNAL
MONAURAL
STANDARD SIGNAL
Carrier frequency : 98MHz
Modulation : Audio 1kHz
Main channel (L+R) : 33.75kHz
Modulation : Audio 1kHz
Main channel (L+R) : 33.75kHz
deviation
Sub channel (L–R)
: 33.75kHz
deviation
Pilot
: 7.5kHz
Deviation
Carrier frequency : 98MHz
Modulation : Audio 1kHz
Modulation : Audio 1kHz
75kHz deviation
set
FM RF SSG
1kHz
highpass
filter
highpass
filter
distortion meter
FM ANTENNA (75
Ω
)
Modulation : Monaural Standard signal
Output level : 6mV (76dB) (at 75
Output level : 6mV (76dB) (at 75
Ω
open)
LINE OUT
Digital Voltmeter
(DC range)
(DC range)
TP201
NULL terminal
NULL terminal
All the settings are performed in the Factory Preset state. (Refer to page 13.)
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