I am trying to calculate the maximum power of a coaxial cable, based on heat transfer parameters and limiting temperatures of cable components. I've determined that a certain heat load on the conductor surface (in Watts per inch of cable) will put the dielectric above its operating temperature. I am having trouble turning that heat load number into a power rating (I'm looking at attenuation numbers). Would a power rating be dependent on cable length? My calculations suggest that length is a factor, but every data sheet I look at disagrees.