Yaesu FT-902DM Instruction Manual page 27

AF UNIT ( PB- 1 705A )
The audio signal from the AM detector is ampli­
fied by Q5 0 7 ( 2 SC 7312TM)
audio amplifier Q 5 0 1 (2SC 7 32TIM) .
F M , and F S K , the audio signal is directly fed to
Q 5 0 1 from pin 1 5 . The audio signal is amplified
. through Q5 0 1 and Q 5 0 2 ( b o th
is then fed through the APF switch and audio
volume con trol VR5 a to the audio outpu t ampli­
fier Q 5 0 3
( TA 7 20SAP ) ,
o f audio output to the speaker.
The audio spectrum is shaped by an active low­
p ass filter of fc 2 . 7 kHz, - 1 2 d B /octave .
=
Operational amplifier Q 5 0 4
amplifier Q5 0 5
( 2SC 7 3 2 T M )
audio circuit by the APF switch on the fron t
p anel. The frequency of this selective amplifier
is varied wi th the fron t panel APF control V R4 a/b
between 400 Hz and 900 Hz , p roviding single­
signal , n oise-free CW recep tion . VR 5 0 1 provides
adjustment o f the selec tivity of the APF circuit.
AM
J
L
_ _
N' VR t>f'F SW
and fed to the first
On S S B , CW ,
2SC 7 3 2 TM )
which delivers 3 watts
an d AF
( MC3403 )
are placed into the
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A P F VR 4 ( o )
and
A P F AP F VR4(b) RXSV
- 2 5 -
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NOT U S E D
F.
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