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Adjustment of reference circuit
1 -
Connect the oscilloscope's probe to video output (A
Connect the IF signal (complete of modulated audio) at 10 mV level
on TP 1.
Adjust L44 for minimum amplitude of demodulated signal,
corresponding to the best response transients or to 2 T pulse.
6 MHz
Adjust the
Adjust
Adjustment of audio quadrature coil
Move the oscilloscope's probe to pin 8 TBA 120 U (LF audio output).
Give a max. 12V bias to the volume control terminal A 2.
Connect a 10 kOhm resistance between pin
Disconnect the 10 kOhm resistance.
Adjust L47 until the DC voltage corresponds again to value measured
previously.
Audio adjustment
Move
the oscilloscope probe to terminal A 3.
Maintain on the TP 1 the IF signal with modulated audio carrier.
Adjust P 2 so as to obtain on the A 1 terminal the signal
3 =
VA
2.2 + 0.2 vpp = 0.78 2 0.07 V RMS.
AFC adjustment
Bias the AFC output by means of two 100 kOhm resistances
towards +12V and the other towards earth.
Connect a voltmeter to AFC output pin A 12.
Adjust L45 for an intermediate value (approx. 2V) in range of
values that go from +12V to 0 V.
trap and the audio input filter
and L48 for lowest output of 6 MHz signal present in
13
of TBA 120 U and the
one
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