[Icom] Help ... need computer interface for IC-751

Fri, 31 Jan 2003 21:31:06 -0500

Tim,

The earliest version of computer interface ICOM used for the 751 and 751A 
used the optional IC-EX309 parallel interface adapter. This adapter 
connected to the two CI-IV connectors on the rig's Logic Unit board and the 
data output lines come out on a 24-pin connector which is installed on the 
small ACC plate at the rear of the rig. ICOM's external parallel level 
converter unit CT-10 (only a few were ever made) did the TTL to RS-232 level 
conversion and then the interface went on to a computer parallel port. This 
was long before the IBM PC (and it's serial port) was in every home and 
hamshack!

This scheme was abandonded quickly, in favor of the serial interface. Your 
rig's manual, being older, was written before the serial interface standard 
was adopted. The next (and current) generation interface uses an optional 
UX-14 CI-IV/CI-V converter. When this option is fitted in the radio, the 
native CI-IV interface is converted to the newer CI-V serial standard (which 
is still used today) and a small 1/8" phone jack is mounted on the 751's 
rear panel. This serial signal is TTL and must be converted to RS-232 level 
via the ICOM CT-17 (or equivalent, several hams make them and market them, 
or you could roll your own). The UX-14 is rare, but can be occasionally 
found. There is now a clone unit offered by PIEXX (www.piexx.com) that 
performs the interface, plus adds new features such as band stacking 
registers, power up default memories that can be set by the user, and a 
higher communications speed (9600 baud versus 1200 baud in the ICOM UX-14). 
The UX-14 and EX-309 are plug for plug compatible with the 751/751A so 
either interface can be used with either rig.

So - you'll need an interface board (UX-14 or PIEXX clone) and a level 
converter (ICOM CT-17 or homebrew) for control via a serial port and the 
commonly available programs that use the serial port interface. You could 
use the old parallel interface EX-309 too. Somewhere around here I have an 
article from 1983 or 1984 showing how to do it with a Commodore, or 
something, using BASIC and a parallel port. I would recommend using the 
serial interface!

Hope this helps.

73, Frank W3UHF
www.icomclassic.com

>From: "Tim Kass" <[email protected]>
>Reply-To: [email protected]
>To: [email protected]
>Subject: [Icom] Help ... need computer interface for IC-751
>Date: Fri, 31 Jan 2003 20:02:54 -0500
>
>
>Have an Icom IC-751  non A model, want to use the MixW program with it for 
>CW,RTTY,PSK, etc....the manual talks about a Db 25 interface for the radio 
>but mentions little else, I noticed that the update model has a C-IV or C-V 
>interface...anyone know if I can install a RS-232 level connector to the 
>back or similar mod to work with this program and my laptop??   thanks in 
>advance  Tim  K8WBL
>
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