TS-440S
CIRCUIT DESCRIPTION
4. Static input
7800 (IC I)
c o
Encod e r U/D sig n a l
" H " when U P
C 2
Unlock sig nal
"L" when u n l ock
07
40 52 (IC : Displ ay)
A ID convertor data
8 2 5 5 (IC 53)
BO
Lock switch
" L " when switch on
B2
AT switch
" L " when switch on
B3
M IC UP switch
" L " when switch on
B4
MIC D OWN switch
" L " when switch on
B 5
PTT switch
" L " when switch on
B7
VS- 1 busy sig nal
"H" when VS- 1 busy
Table
11.
5 . A/D
convertor in put
Voltages controlled by the RIT and IF shift VRs are applied
to the 4052 (IC 2 : Display) . The 40 52 has four analog inputs :
AO (IC 2 pin 4) is connected to the IF shift VR, and A 1 (pin
5) is connected to the RIT VR, the other two in puts are not
used . When reading IF shift data, the 7800 sets port C5 to
0 and selects 40 5 2 AO. As a resu lt, the 3 2 5 5 sends a posi
tive pulse from port BO to reset the 40 5 2, and the 7800
sends nine positive pu lses from port C6, and port C7 receives
data . When reading RIT data, the 7800 sets CO from the
4052 to H and thereafter performs the same operations as
when reading IF shift data .
I ) R I T
I K
IOK
4.7K
2) I F SH I FT
MOOE
+av
RIT
· " H "
4052
......
, , , ,
..
,
..
::
_
_ _
_ _ _ _ _ _ _ _ _ _ __ _
A K
2 - - - - - - --'i'r- - - - - -
9
--\\--�
D O
A /
D converter I nput
Fig . 1 7 A/D convertor circuit
6 .
AT
control
When the AT switch is turned on with the A UTO/THRU
switch in the AUTO position, 8 2 5 5 (IC 53) ports 82 and 8 5
go o n . When the 7800 knows that the A T switch i s o n via
port 8 2, it wil l enter the CW-mod e, and sets port A2 to H
and AO, A 1 , and A 3 to A6, and B4 to L , and transfer a pow
e r down sig n a l . The 7800 then knows that the PTT switch
is on via 8 2 5 5 port 8 5, a n d sets port A6 (transmission con
trol signal) to H, enabling transmission . However, if the select
ed frequency does not allow the 7800 to prepare for
transmission, 7800 port A6 remains L a n d the 7800 wil l not
enable transmission . When the selected frequency is 1 .9 MHz
or less, the 7800 wil l not enter CW mode nor send a power
down sig n a l .
7 .
LED
output
D e pending o n the mode, the 7800 makes the 8 2 5 5 (IC 2)
send M, SCR, 1 MHz, a n d lock LED sig nals from ports B4,
B 5, and B6. When the LED goes on, these ports a re L.
When the mode LED is on, 7800 ports AO to A5 a re H . AO
to A5 correspond to LSB, USB, CW A M, F M, and FSK respec
tively. Mode LED output is used as mode control signals in
the IF u nit .
8 . VS- 1 (optio n )
When the voice switch i s turned o n , a n address correspond
ing to the instruction (numerical d ata) entered is sent from
8 2 5 5 (IC 2) ports AO to A4 and a positive sta rt pulse sign a l
i s sent from port A 5 . The VS- 1 s e n d s busy sig nals (H) t o
8 2 5 5 (IC 5 3) port 8 7 while the voice switch i s o n . After the
voice switch goes off, an address corresponding to the next
instruction and a sta rt sig nal a re sent.
9.
µPD
7800 reset circu it
The 7800 reset circuit is used to initia lize the 7800 when
the POWER switch is turned on. This circuit supplies a reset
pulse to the 7800 after the clock is supplied to the 7800 sys
tem clock input, X 1 (pin 3 1 ). Since IC 3 remains on u ntil
PST520D (IC 3) pin 1 reaches 4 . 3 V, C 1 0 is not charged, ena
bling a reset sig nal to be s u pplied . When pin 1 exceeds 4 . 3
V , IC 3 goes off, causing C 1 0 t o charge via R2 a n d R 3 and
the reset sig nal is removed .
2 1
