Yaesu FT-101ZD Instruction Manual page 27

NB-FIX UNIT (PB- 1 96 1 )
A portion of the 8 . 9 MHz IF signal is fed through
buffer 04 1 0
( 2SC3 72Y)
( 2S C 1 583 ) .
0 20 s
When a carrier o f noise-free m odulated signal is
received , the IF signal is rectified by D20 1 and
D202 producing a DC voltage . This DC
( 1 N60) ,
voltage is amplified by 0202
charges C 2 1 4 , for AGC purposes. The AGC voltage
is used to control the gain of 0206 and 02o s .
When impulse-type noise is received, D203 and
D204 re ctify the IF signal , producing a DC
( 1 N60)
voltage which controls the
( 2SC3 72Y) .
Noise pulses have a very short duration, but high
a mplitude . Because of the very slow time constant
o f the C 2 1 4 / R2 1 2 discharge path, AGC voltage is
not induced by these short-duration pulses . There­
fore , 020 6 and 020 5 operate at full gain , providing
maximum voltage to the b ase of 04 1 1 . When a
pulse is received , 04 1 1 biases D4 14 to block the
signal path momentarily . When a d esired signal and
a noise pulse are re ceived simultaneously, t he
blanking act ion is not impaired , b ecause the
relative amplitude difference between the desired
signal and the noise pulse is still high . The front
p anel noise b lanker level control varies the DC
voltage applied to the b ase o f 04 1 1 .
J202 � 01
and amplified by 0206 and
which
( 2 SC3 7 2Y ) ,
NB swit ch 04 1 1
GNDh
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LOB
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L07 C3
I 007
C32 0.01
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AF UNIT (PB- 1 964)
The IF signal from pin 2 is fed through T 5 0 1 t o the
ring demodulator,
where t h e IF signal is demodulated into
( 1 S 1 007 ) ,
audio , using the carrier signal delivered from 0503
The carrier signal is generated by
(2SC 1 8 1 5 Y ) .
o scillator 05 14
( 2SK 1 9GR) ,
o f the following frequen cies :
USB , CW· RX
LSB
CW·TX
The audio signal is then amplified by audio
amplifiers 0507 ,
delivering 3 watts of audio output to
(µ PC2002) ,
the speaker.
The audio spectrum is shaped by an active low-pass
filter of f 0 2 . 7 kHz, - 1 2 dB/octave .
=
MARKER GENERA TOR
A 2 5 kHz m arker signal is provide d , for alignment
and testing purposes .
generates a basic 3 200 kHz signal ,
( 2SC1 8 1 5Y)
which is divided into 2 5 kHz multiples by 0506
a binary counter.
(MC 1 4024B ) ,
1 _ _
- 2 5 -
Dso2
consisting of
and it o scillate s at one
8 9 8 9 KHz
8 9 8 6 KHz
89 8 8 . 3 KHz
and 0509
Osos ( 2SC 1 000GR ) ,
M arker generator
- D s o s
0509