The TS440 has a serial ASCII interface option. You have
to insert two chips into sockets on the back of the control unit circuit
board to take advantage of this. IC54 is an 8251A Uart, and IC55 is a
CD4040 divider. These chips are available from Kenwood together with a
interface manual, or you can buy them at your local chip shop for about
$6.00 or so. When inserted, the transceiver speaks 4800 baud ascii
in/out the 6-pin DIN connector ACC-1 on the rear. The signals are from
the 8251, but are inverted in a 74LS04 and RFI filtered before being
brought out to the world. An interface box with inverter, RFI filter,
power supply, opto-isolator, RS232 level shifters, and power supply is
available from Kenwood for about $49.00, or you can build your own.
(Depending on how much your computer radiates and how sensitive to RF
it is, you may only need 5v, +/-12v, a 74LS14, MC1488, and MC1489.
If your computer has a TTL level serial port, perhaps all you'll need
is the 74LS14. If you're not confident of being able to solve the
possible digital/RF interface problems yourself, the $49 interface
is proably a good buy.)
ACC-1 Serial Interface
pin signal
--- ----------------------------------------------------
1 signal ground
2 data from transceiver
3 data to tranceiver
4 cts to transceiver - computer can throttle output
5 cts to computer - transceiver can throttle input
6 no connection
SSB frequency response dipswitch: located on the back of the control
unit, this adjusts the frequency response of the upper and lower
sideband modulators to compensate for component variations. Changing it
isn't a good idea, since you have to have a two-tone oscillator and have
to reset the carrier suppression adjustment if you do. The service
manual explains this process; I'm including this here so that people who
have been wondering what the dipswitch does won't screw themselves by
flipping switches to see what happens.
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