Kenwood TS-440S Serivce Manual page 22

TS-440S
CIRCUIT DESCRIPTIO N
10 . PLL output bloc k
The PLL output block controls five PLL loops . The 500 kH z
step PLL loop uses an MB87006 and the other PLL loops us e
PES
MN6147s .
,uPD7800
The M387006 has two dividers : one for the PLL referenc e
frequency and the other for a swallow type counter . Frequen -
cy division data for the reference frequency is sent only on e
when the TS-440 power is switched on .
Fig . 18 Reset circuit
The MN6147 uses the PLL data format shown figure 19 .
8255( IC )
Por t
B4n,B 7
BO r B3
Address
Fig . 19 MN6147 PLL dat a
Since the MN6147 has latches as shown in Figure 20, onl y
data following a change is output . GO data can be any dat a
since it is used to transfer G2 and G7 data to the G8 latch .
11. Other output s
RL output (7800 port A6 )
This output signal controls transmission . When transmitting ,
this signal is "H" .
BZ (Buzzer) output (7800 port A7 )
This output signal makes the BZ circuit active . When this sig -
nal is "H", the oscillator circuit operates .
RESET output (7800 port B7 )
This output signal resets the two 8255s and 8251 (option) .
SBK output (8255 (IC2) port A6 )
This output signal switches the RF unit to prevent noise du e
to PLL siwtching .
MT output (8255 (IC2) port A7 )
This output signal controls the AF output to prevent nois e
due to PLL siwtching .
SCH output (8255 (IC2) port CO )
This signal controls the sub audible tone encoder . The sub -
tone is activated whenever a transmit frequency in M-C H
90-99 has been selected, in the FM mode . A logic H acti-
vates the encoder .
12. CAR compensation DIP switc h
This switch is used to compensate the absolute frequenc y
characteristic of the 455 kHz filter . The characteristic ca n
be compensated within the range of — 400 Hz to + 375 Hz .
LSB and USB can be compensated separately . When LSB i s
compensated, FSK is also compensated .
coo x +
100 xi0
xi xi -
le©©II~11 IINI
m®®m®mlllImm
AEI
111111111111111111111 1
MIm
G B
G3 G4 GS G G
.__ .-~i
2 3
MN 614 7
Fig . 20 Data input terminal and programmable counte r
SW No . H z
1 2 5
2 5 0
3 100 LS B
4
20 0
5 400
6
2 5
7
5 0
8 100 US B
9
20 0
10
400
Table 1 2
When all bits are off, -400 Hz is supplied for compensa-
tion . When no compensation is required, bits 5 and 10 mus t
be on .
CP L
DA 3
DA 2
DA I
DA 0
22