Hi!

First of all: what kind of CAT interface you are using?
Some kind of ready made USB-CI-V wire?

First thing is to check that linux knows the device.
Open console, without cat wire connected give
lsusb
Check the list, connect the cat wire and give again
lsusb
Did the list change?

If it did give
ls -1l /dev/tty*
Check the list (assume cat wire still connected). Look specially all ttyUSB and ttyACME lines.
Remove CAT wire and give again
ls -1l /dev/tty*
What tty did not appear any more ?

Then you know what port that cat wire takes. You can repeat steps again to be sure.
Notice the second word after root in right device line:
crw-rw----. 1 root dialout 188, 2 3. 5. 11:42 /dev/ttyUSB2

Next type command
groups
You should see something like
[saku@hamtpad ~]$ groups
saku dialout lock
The dialout gives you permissions to access tty-devices.
If it does not exist give
sudo usermod -a -G dialout user
Where "user" is your username (do NOT try to run cqrlog or any other things with root-user!, Use another regular user for running programs)
dialout can be some other group name. In case of that use it. Normally it is called dialout.

Ok. Now tou have access and you know what device cat-wire is.
Set cqrlog preferences TRXcontrol having path to rigctld. You get it typing
whereis rigctld
at console. Set device name having cat wire device name(/dev/ttyXXXXX). Select your rig from list (346). Set serial speed to same as tour rig setting has.
If it has "auto" change it to fixed value at rig's side. 19200 is good. If rig has setting "CI-V TRN" (tranceive) ON set it OFF.
Set all other selections to "default".

You should now be very near of working setup.