Yaesu FT-901DM Instruction Manual page 35

A
p ortion of the Q 1 2 0 9 output is rectified by
D 1 2 1 9 an d D 1 2 2 0 (b oth
voltage is amp lified by· DC amplifier Q 1 2 1 2
1 8 1 5Y ) to generate AGC voltage which controls
the gain of Q 1 2 0 9 , thus ob taining unity signal
output when the band is changed .
P L L UNIT ( P B - 1 709)
The samp le signal from the VC O UNI T is fed to
the PLL mi xer Q 1 1 0 2
sample signal is mixed with the he terodyne signal
(at 5 . 0 - 5 . 5 MHz) delivered from the XTAL
UNIT through buffer
1 8 1 5 Y ) . The 5 . 0 - 5 . 5 MHz signal is fed through
amp lifier Q 1 1 0 3 ( 2SC1 8 1 5 Y )
75 4SOB ) ,
where the signal wave form is shaped
r. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - �
I
P B - 1 709A PLL U N I T ( N o. 1 1 ·
1 N60) ; this rectified DC
( 2SC
( TA7 3 1 0P ) , where the
amplifier Q 1 1 0 1 ( 2SC
to Q 1 1 0 6 ( SN
· )
002 TA 73 1 0 P
prior to being supplie d to a phase detector Q 1 1 0 7
( MC4044P) ; h ere the phase of the signal is com­
pared with the p hase o f the signal d elivered
through wave shaper Q 1 1 0 6 , b uffer Q 1 1 0 5
1 8 1 5Y ) , and amp lifier Q 1 1 0 4
VFO UNIT .
Q 1 1 0 7 compares t h e phase of t h e t w o signals and
c onverts the phase difference into the VCV voltage
which controls the VCO frequency . Q 1 1 0 8
3 7 3 ) acts as an active low pass filter t o rem ove
ripples from the VCV vol tage.
When the VCO is unlocked, Q 1 1 0 9
delivers the signal t o preven t receive o r transmit
action of the transceiver.
Q 1 1 1 0 ( 7 8 L0 8 ) and Q 1 1 1 1
regulators.
003 2 S C l 6 1 5Y
006 SN 75450
33
-
-
( 2SC
( 2SK 1 9GR ) from the
( 2SC
(2SC 1 8 1 SY )
( 7 8 L05 ) are voltage
I