Something to try is to put a choke in series with the individual leads in the CT-62 line. These are small, about the size of a 1 watt resistor with the conductor through the center. They will have no effect on the relatively low frequency components in the CAT signal, but may help with the RF pulses. I used this very successfully with another interface, though each situation is different. I have a drawer full of them if you wish to try them. Also, you may be able to bypass the RF with some disc capacitors.