Kenwood TS-440S Service Manual page 22

TS-440S
8255 ( I C )
Fbr t
841\,87
BO f\.. 8 3 AdcYr�ss
Since the M N6 1 4 7 has l atches as sho w n in Fig u r e 2 0, o n ly
d ata followi n g a cha n g e is output. GO d ata c a n be any d ata
since it is used to transfer G 2 and G 7 d ata to the G8 l atch .
1 1 . Other outputs
R L output ( 7 800 port A 6 l
This output sig n a l controls transmissio n . When tran smitting,
this sig n a l is "H" .
BZ ( Bu zzer) out put ( 7 8 0 0 port A 7 )
This output sig n a l makes the BZ circuit active. When this sig­
n a l is " H " , the oscil l ator circ uit o p e rate s .
R E S ET output ( 7 80 0 port B 7 l
This output sig n a l res ets the t w o 8 2 5 5s a n d 8 2 5 1 (o ptio n).
S B K output (8255 ( I C 2 ) port A6l
This output sig n a l switches the RF u nit to p revent n oise due
to P L L siwtching .
MT output ( 8 2 5 5 ( I C 2 ) port A 7 l
This output sig n a l co ntro l s the A F output to p revent noise
due to PLL siwtching .
S C H output ( 8 2 5 5 ( I C 2 l port C O )
This sig n a l contro l s t h e sub a u dib l e tone encod e r . The s u b­
tone is a ctivated whenever a tran smit freq u e n cy in M-CH
90- 9 9 has been s e l e cted, in the FM mod e . A logic H acti­
vates the e n c o d e r.
1 2 . CAR compensation D I P sw itch
This switch is used to compe n s ate the absolute freq u e n cy
cha racteristic of the 4 5 5 kHz filte r . The characteristic can
be compe n s ated within the r a n g e of - 400 Hz to + 37 5 Hz .
LSB a n d USB c a n be comp e n s ated s e p a rately . Whe n LSB is
compensated, F S K is also compe n s ated .
22
CIRCU IT D ESCRI PTION
27K
4069
R2
CIO
0.47/�V
+
22
Fig . 1 8 Reset circuit
Fig . 1 9 M N 6 1 47 PLL data
1 0 . PLL o utput block
T h e P L L o u t p u t block c o n t r o l s five P L L l o o p s . The 500 kHz
step PLL loop uses an MB 87006 a n d the other PLL loops use
M N6 1 47s .
)J PD7800
The M 3 87006 has two divid e r s : o n e for the P L L refe rence
freq uency and the other for a swallow type cou nter. F requen­
cy division d ata for the refe rence freq u e n cy is s e nt o n ly o n e
w h e n t h e TS-440 power is switched o n .
The M N6 1 47 uses the P L L d ata format sho w n fig ure 1 9 .
C PL
Fig . 20 Data input term i n a l a n d progra m m a ble counter
SW N o .
1
2
3
4
5
6
7
8
9
1 0
When a l l bits a re off, - 400 Hz is s u p p lied for compensa­
tio n . When n o comp e n sation is req uired, bits 5 a n d 1 0 must
be o n .
O ther
M N 6 1 4 7
H z
2 5
50
1 00
L S B
2 0 0
400
2 5
50
1 00 U S B
200
400
Table 1 2