Unit installation

15-2

may not be strong enough to make it work consistently.

If you are using a Kenwood level translator, you may have to connect pins 4 and 5 together on the

DB-25 connector that plugs into the level translator. This connects the RTS and CTS handshaking

lines.

If your radio's serial port uses TTL level signals, it may also be possible to connect it to the

controller without using a serial level translater on the radio or the DS1275 IC on the controller. If

you install two jumper blocks on header J5 on the controller (shorting pins 1 and 2 together and 3

and 4 together - do not do this while a DS1275 is installed in U8), it connects the controller's TTL

level signals to the serial port connector (the top DB-9). These signals come directly from the

HC11 processor on the radio card, so if you short them out or hit them with static, it may take out

the HC11 processor. If these lines on the processor are damaged but the rest of the processor

works, you can just switch and use a different radio card (with a different HC11), or you can get a

new HC11 from Link Communications or another electronics supply source. Do not try to remove

the HC11 from its socket with small screwdrivers - use a PLCC chip puller. If you replace the

HC11, cycle the power a couple of times before resuming testing, to give the processor a chance to

set up its config register. If you have jumper blocks on J5, you can then connect the TTL level

signals from the controller to the TTL serial port of the radio. Kenwood radios may require that

this data be inverted (both ways); a 74HC04 IC will do this. If you don't want to hassle with the

TTL levels, just use the DS1275 IC on the controller and the RS-232 level translator on the radio.

HF Radio Control:

There are several commands that are used to set up the HF radio interface. They tell the controller

what radio is installed and a few other things. After the radio is set up and you are ready to change

frequencies, scan, etc., you can go into a special "HF control mode". When you are in this mode,

all of the normal commands are disabled and a separate set of HF control commands are used

instead. This makes it possible to control the HF radio with short command codes without having

to worry about what other commands might get executed accidently. These commands are

organized by mapping the DTMF keypad in a logical way that makes the various commands easy to

remember. When you are done using the HF radio, there is a command code that takes you back to

the normal mode where you can execute the normal commands. It is possible to execute HF

commands from normal mode using command 199. This is usually used in a macro. There is also a

way to execute normal commands while you are in HF mode (see keypad code 4). And finally,

there are event triggers (see command 157) that are called when the different HF commands are