i believe its going to be something like 1 to 20khz depending on the cable and how its arranged... for example if we wind it on a iron former it may reduce the frequency but will also increase the impedance somehow.. those 300m coils have a low frequency already but if we think about this TLs are even slower in speed so i believe it will be low ... this TLs speed are something around 66% of the speed of light...
there are high voltage insulation in this cables .. i saw some up to 10kv insulation ...
i would go for two coils with 100m to start with ,,,, than make tests over it about the pulse sincronization...