During 2003 the UKAEA designed a novel low loss tri-axial and magnetics feedthrough to be installed during the 2004/2005 shutdown. The new low loss tri-axial and magnetics feedthrough incorporates two interacting systems -Toroidal Alfvén Eigenmodes (TAE) antennae and Magnetic pick-up sensors - in one assembly. These two systems put conflicting constraints on the feedthrough design, most notably RF interference from the high power and high frequency (500kHz, 600V and 30A maximum) TAE system onto the magnetic system. RF interference from the TAE was required not to affect the signals from the magnetic pick-up sensors to the extent that the signal-to-noise ratio is degraded significantly, particularly those used for MHD measurements. Other design considerations were UHV (at 450°C), gamma and neutron radiation, Remote Handling and double tritium boundary compatibility. For this purpose a new flexible tri-axial cable feeding the TAE diagnostic had to be designed, prototyped, developed, manufactured and tested. This cable was integrated into the overall feedthrough design.