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11. Stereo Separation Alignment
1.
4.
Set the FM SG to provide 1 KuV at 98 MHz. Tune the receiver to the same frequency so that
the VTVM connected to the C227 will give no readings.
. Modulate
the FM SG with 67 KHz audio frequency. Connect a oscilloscope to the R413.
Adjust the core of L403 for minimum height of the 67 KHz signal on the scope.
. Modulate the FM SG output with stereo composite signal consisting of subchannel signal only
(of course a pilot signal must be included.). Adjust the core of L410 for maximum
audio
output, then modulate the signal generator output with a stereo composite signal consisting of
L channel signal only and again adjust the core of L401 for maximum audio output.
Adjust the trimming resistor R428 for maximum and same separation in both channels.
12. Muting Threshold Adjustment
1.
Set the FM SG output to provide 12.5uV (IHF) at 98 MHz and tune receiver to the same
frequency. Adjust the trimming resistor R306 for the threshold level of 12.5uV. (During this
adjustment turn the MUTING push-switch "'on"'.)
13. Audio Adjustment
1.
Connect a VTVM
across the resistor R747 and adjust the trimming resistor R729 until the
VTVM
reads 7.5mV DC. For the other channel connect the VTVM across the R748 and adjust
the R730 for the same reading.
. Connect a oscilloscope across the speaker terminals. Apply an audio signal of 1 KHz to the
AUX
jacks and increase the audio signal until the audio output on the scope begin to start
clipping. Adjust the trimming resistor R723 for equal and symmetrical clipping. For the other
channel adjust the R724.
POINTER
Figure 3.
Dial Stringsng
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