CT, NA, and the Icom IC-761

[KPE at epavax.rtpnc.epa.gov]

Hi folks.  I've been having problems interfacing CT, NA and DXBase
to my Icom IC-761.

The same computer, interface, and software was tested on an IC-761 and
an IC-765.   The software runs fine on the 765, but has problems on
the 761.  On the 761, numerous "link" errors occur from each of the
programs.  Errors such as "error storing memory", "unable to link
radio", etc. are reported by CT, NA, and DXBase.  The "link" errors
occur about 20% -> 50% of the time, apparently randomly.

I have ruled out the software, computer, and TTL <-> RS232 level
interface box because they work with the '765 just fine.  The only
difference in the test setup is the radio.  The interface box uses
the MAX232 chip and is an exact clone of a Icom CT-17.

The CI-V circuitry is different on the 765 and 761. I won't go into
the details of the differences, but they aren't identical.

Does anyone have any experience interfacing the IC-761 to these
programs?  Any ideas why things work on the 765 and not the 761?
Would apprecaite any comments, and will post a summary if the problem
is resolved.  Thanks very much.
                                        73, Kirk WR3O