[Icom] Computer interface

Sat, 3 Aug 2002 12:59:40 -0700

You can easily build an interface for a few dollars at your local Radio
Shack or an online parts supplier. You can use a monolithic RS232-to-TTL
level converter like the MAX232, or you can build a circuit using a few
discrete parts such as the one shown at
http://www.qsl.net/civ_commander/interface.jpg ; I have used this
circuit successfully with a 706, 735, 756, 775, and 781. 

This circuit and others show the level-converter being powered by the
serial port's modem control signals RTS (request to send), CTS (clear to
send), and DTR (data terminal ready). This will work IF the transceiver
control software you use places these modem control signals in the
"asserted" state, making them a source of +12 volts, and if the RS232
cable you use transports these signals between your serial port and your
interface; when not asserted, these modem control signals become a
source of -12 volts, hence the polarity-protection diode. 

What happens if some of modem control signals are asserted and others
aren't -- I don't know, and it probably varies as a function of your
PC's serial port interface design. Personally, I'd rather power my CI-V
level converter from an external 12-volt supply and not worry about the
modem control signals, the cable conductors, and possible damage to a
serial port. 

As for software, I suggest that you consider Commander -- it will 
   - control and display your 706 MKIIG's VFO, mode, filter selection,
and split mode
   - display frequency-dependent settings for an external tuner or
amplifier
   - provide 20 memories, each specifying a frequency, mode, and filter
selection
   - enable you to define 8 command sequences, each accessible via a
single mouse-click
   - capture and display the CI-V messages exchanged by your PC and
transceiver

Commander is free, and available via www.qsl.net/dxlab .

Your CI-V level converter and TNC cannot be connected to the same serial
port. If you have no more free serial ports, there are several ways to
add more: an additional I/O card, a PCMCIA card, or a USB adaptor. If
you primarily use your TNC for RTTY, you could shift to
RTTY-via-soundcard and use the freed-up serial port for your CI-V level
converter.

    73,

       Dave, AA6YQ

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of [email protected]
Sent: Saturday, August 03, 2002 8:31 AM
To: [email protected]
Subject: [Icom] Computer interface

Are people making their own interface from the PC to the radio? I have a
IC-706 MKIIG 
What software is available for controlling the radio?
Will I have a problem with using my TNC that is connected to the serial
port?

Randy
AC7NJ

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