Alinco DR-610E, Service Manual

Page: 10 / 89

1) PLL Synthesizer Circuit
V H F a n d U H F b a n d s h a v e t h e i r o w n u n i t s i s o l a t e d l y . T h e s u b u n i t h a s t h e d u a l
c o n s t r u c t i o n c o n s i s t i n g o f V C O i n t h e u p p e r p l a c e a n d P L L i n t h e l o w e r p l a c e .
B o t h o f t h e s u b u n i t s a r e p a c k e d i n a h a r d s h i e l d c a s e s o a s n o t t o b e i n f l u e n c e d
b y t h e c i r c u m s t a n c e s .
T h e c r y s t a l X 1 o f 1 2 . 8 M H z i s o s c i l l a t e d i n I C 7 5 1 ( V H F ) , t h e o u t p u t i s l e d t o Q 2 2 ,
a n d t h e o u t p u t o f Q 2 2 i s a d d e d t o I C 8 5 1 ( U H F ) .
T h e r e f e r e n c e o s c i l l a t i n g f r e q u e n c y i s d i v i d e d i n I C 7 5 1 a n d I C 8 5 1 t o g e t t h e
r e f e r e n c e f r e q u e n c y o f 5 k H z o r 6 . 2 5 k H z .
T h e c o m p a r i s o n f r e q u e n c y i s d i v i d e d b y t h e P L L o f p u l s e s w a l l o w s y s t e m , I C 7 5 1
a n d I C 8 5 1 a f t e r t h e V C O o u t p u t i s a m p l i f i e d i n Q 7 0 3 ( V H F ) a n d Q 8 0 3 ( U H F ) . T h e
r e f e r e n c e f r e q u e n c y o f 5 , 1 0 , 1 2 . 5 , 1 5 , 2 0 , 2 5 , 3 0 , 5 0 k H z s t e p s c a n b e o b t a i n e d
b y d i v i d i n g X 1 .
3 . P L L C i r c u i t
osc
B U F F
144MHz PLL-VCO
BiockDiagram
Q 7 5 5
T
HK3-
T
XJ
RX
O S C
2SK508K52
A
080 2 n
2SC4215Y
UN5211
2SC4081
LNT
S H IF T
' R E G IS T E R
2SC3324B
2SK880
M56760FP ■*-
2SC4215Y
2SC4081 LNT*2
R R
0 8 5 1 . Q 8 5 2 , Q 8 5 3 I C 8 5 1 I
$
B U F F
0 8 5 6
T
!
HKh
2SK508K52 2SC4215Y
F O U T
UN511L
Q855
430MHz PLL-VCO
BiockDiagram
S H I F T
R E G IS T E R
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