Welcome to the Manjaro Community @Lazlo1967
Could you please open kaffeine from a terminal and try adding the channel. If Kaffeine then crashes, do any error messages appear in the terminal?
Also, as a new forum user, please take some time to familiarise yourself with Forum requirements; in particular, the many ways to use the forum to your benefit:
The Update Announcements should be checked frequently for important update related information.
These announcements contain a Known Issues and Solutions section and should generally be checked before posting a request for support.
Output of the following command formatted according to forum requirements (see links above) is often useful (and this or similar will usually be asked for in Support threads):
inxi -zv8
This gives some (privacy-filtered) information about your system.
Be prepared to provide more information and outputs from other commands when asked.
Regards.