Com Mon C I Rcuits - Yaesu FT-901DM Instruction Manual

When 02 1 0 7 i s grounde d , 0 2 1 0 2
ON , and the vol tage appeari ng at the collector o f
02 1 0 2 i s fe d th rough D 2 1 0 9
on P B- 1 7 06 to a c tiva te the CW carri er oscilla tor.
In the SSB m od e , the SSB carrier osci lla tor is
disabled by reverse vol tage .

COM MON C I RCUITS

VFO UNIT ( PB-l 440A-3 3 3 0 )
A
modified Colpi tts-ty pe oscillator 1 s used t o
ge n e rate a 5 . 0 - 5 . 5 M H z signal , producing a
5 0 0 kHz tuning range . The frequency is varied
by VC 8 0 1 , which is geared to a pre cision-buil t
dial tuning m e chanism. VC 8 0 1
sect i ons. The sub-blades
capaci tance vari a tion o f the main blades wh ich
may re sul t from e x tre me temperatur� ch ange .
Varactor d i od e 08 0 1 ( 1 S2236)
C 8 0 7 , and the combination o f the two is in p arallel
with TC8 0 1 . By closing the C LARI FIER switch,
th e VFO frequency may b e varied ± 2. 5 kHz with
the C L A RI F I E R control on the front pane l .
Th e oscilla tor output signal i s fed through the
amp lifier/bu ffer s tage
08 o 3 ( 2SC3 72Y ) , and then p asses through the
low-p ass fil t e r to the output termin al .
1 60 m
8 0 m
4 0 m
2 0 m
1 5 m
l O m A
B
l O m
l O m C
l O m D
J J Y / W W V
(2SA73 3 ) tu rn s
( 1 S 1 5 5 5 ) t o D 1 0 1
consists o f two
compensate for th e
i s i n series with
0 8 0 2 ( 2 SK 1 9GR ) and
C r y s t a l O s c i l l a t o r
1 5 . 98 7 5 ( MH z )
1 7 . 9 8 7 5
2 1 . 4 8 7 5
2 8 . 4 8 7 5
3 5 . 4 8 7 5
4 2 . 4 8 7 5
4 2 . 9 8 7 5
4 3 . 4 8 7 5
4 3 . 9 8 7 5
2 9 . 4 8 7 5
XTA L UNIT (PB- 1 7 1 1 )
Crys tal oscillator 0 1 3 0 1 - 0 1 3 1 0 (all
p roduces a he terodyne signal for the PLL (Phase
Locked Loop ) mixer. The oscillator frequen cy
is selected by the BAND switch , and the outpu t
signal is fed through diode switch D 1 3 0 1 - D 1 3 1 0
(all 1 S 1 5 5 5 ) to the PLL UNIT. The frequency
of e a ch crys tal is sh own in Tab l e
VCO UNIT (PB-1 7 1 0)
The VCO (Vol tage Controlled Oscillator) gen erate s
a h e terodyne signal which is
than the operating frequency. The frequency is
locked by the vol tage d e tecte d b y the PLL UNI T.
0 1 2 o 1 - 0 1 2 0 8
(all
freque n cy given in Table
locked by varactor diodes D 1 2 0 1 - D 1 2 0 s (all
M V 1 04 ) which are c on trolled by the VCV v oltage
,
su pplied from th e PLL UNI T . The oscillator out­
put signal is amplified by 0 1 2 0 9
fed to the buffer/am p l i fier c onsisting of 01 2 1
an d 0 1 2 1 1 (b oth
O 1 2 1 0 is fed to the tran sceiver mixer in the
UNI T ; t h e ou tpu t from O 1 2 1 1 i s fed t o the PLL
a
UNIT as sa mple sign al.
v c 0
I O .
4 8 7 5 - I O . 9 87 5 ( M H z )
1 2 . 4 87 5 -- 1 2 . 9 8 7 5
1 5 . 9 8 7 5 - 1 6 . 4 8 7 5
2 2 . 9 8 7 5 - 2 3 . 4 8 7 5
2 9 . 9 8 7 5 - 30 . 4 8 7 5
36 . 9 8 7 5 - 37 . 9 8 7 5
3 7 . 9 8 7 5 - 38 . 9 8 7 5
2 3 . 9 87 5 - 2 4 . 4 8 7 5
Table
1
31
- -
2SC 1 8 1 5Y )
I .
kHz h igher
8 . 9 8 7 5
2SK1 9BL) oscillate at the
I .
The frequ e n cy is
( 3 SK40M )
The output from
2SC1 8 1 5Y).
and
o
R F