[Antennaware] unknown coax cable

[Allan Greening]

i have a roll (500 foot) of coaxal cable.. it has two (2) inner
deilectric's, one the normal looking cloudy white on the inner conductor
es wtth a black outer on the cloudy white one, then the plated/tinned?
outer braid very heavy type ,then the black outer..the inner core is multi
approx 48 x 0.25mm total inner wire core is 2.1mm OD of c/white insulation
is 5.1mm the OD of the black insulation is 8.1mm  then the heavy braid es
the outer cover is 10.7mm .. its not 50 ohms!! wot or how can i find out
what it is ohm es VF% ..tU VK3PA