Yaesu FT-902DM Instruction Manual page 26
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Also See for FT-902DM:
- Instruction manual (57 pages) ,
- Survival manual (37 pages) ,
- Instruction manual (5 pages)
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AF UNIT (PB-1705A)
The audio signal from the AM
detector is ampli-
fied by Qs597
(2SC732TM)
and fed to the first
audio amplifier Q59, (28C732TM).
On SSB, CW,
FM, and FSK, the audio signal is directly fed to
Qso,
from
pin 15. The audio signal is amplified
through
Qs59,
and Qs9.
(both 2SC732TM)
and
is then
fed
through
the APF
switch
and
audio
volume
control VR,a
to the audio output ampli-
fier Qs93
(TA7205AP),
which
delivers
3 watts
of audio output to the speaker.
The
audio
spectrum
is shaped by an active low-
pass filter of f, = 2.7 kHz, —12 dB/octave.
Operational
amplifier
Q594
(MC3403)
and
AF
amplifier Qs95
(28C732TM)
are placed into the
audio
circuit
by the
APF
switch
on
the front
panel.
The
frequency
of this selective
amplifier
is varied with the front panel APF control VR, a/b
between
400
Hz
and
900
Hz, providing
single-
signal, noise-free
CW
reception.
VRs59;
provides
adjustment of the selectivity of the APF circuit.
PB-I705A |
AF UNIT |
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4
ou TONE IN
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IB
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sly
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a.
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8
8
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ale
Re
:
qso6|
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5
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78L08|
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or NOT USED
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=
14
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8
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bese
ee
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es
re
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——o-
2
84
32
9
7
io
AF VR APF SW
APF VR4(a)
APF APF VR4(b) RX8V -13.5V
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