-38-
ELECTRICAL ADJUSTMENT -4/7
<FM Adjustment>
Make the following preparations for FM adjustment.
Preparations
•
Standard Signal Generator (S.S.G.) / Loop antenna / Oscilloscope / Millivoltmeter / Dummy resistance (6
Ω
)
1) Connect the unit and measuring instruments as shown in the diagram below.
2) Connect the output of S.S.G. to the antenna input of the unit.
7. Tracking Adjustment
Requirements: As instructed in preparations.
•
Adjustment point: L904
1) Set S.S.G. to FM; carrier of 87.5 MHz with 75 kHz modulation, and source at 1 kHz, position output at maximum.
2) Tune the receiving frequency of the unit at FM 87.5 MHz.
3) While monitoring the waveform at 1kHz through the oscilloscope, lower the output level of S.S.G. maximum (till a certain
degree of noise is monitored).
4) Adjust L904 so that the millivoltmeter points maximum.
8. Separation Check
Requirements: As instructed in preparations.
1) Set S.S.G. to FM; carrier of 98 MHz with 67.5 kHz modulation, source at 1 kHz, and output at 74 dBuV.
2) Switch S.S.G. to PILOT ON, and set PILOT at 7.5 kHz.
3) Tune the receiving frequency of the unit at FM 98 MHz.
4) Allow the output of S.S.G. only from Lch, and check that the difference between Lch and Rch is 22 dB or above.
5) Apply the above check to Rch.
9. Auto-Stop Check
Requirements: As instructed in preparations.
1) Set S.S.G. to FM; carrier of 98 MHz with 75 kHz modulation, source at 1kHz, and output at 35 dBuV or less.
2) Apply the tuning search function, and check that the unit automatically stops at FM 98 MHz.
Standard Signal Generator
AC MILLIVOLTMETER
OSCILLOSCOPE
OUTPUT
CH2
CH1
CH2
CH1
SET
DUMMY
LOAD
SPOUT(L)
FM ANT
SPOUT(R)
6
Ω
www. xiaoyu163. com
QQ 376315150
9
9
2
8
9
4
2
9
8
TEL 13942296513
9
9
2
8
9
4
2
9
8
0
5
1
5
1
3
6
7
3
Q
Q
TEL 13942296513 QQ 376315150 892498299
TEL 13942296513 QQ 376315150 892498299
