Some of the oval 300 ohm line, at least, was filled with PE foam. I
think this was intended to keep the water out.

Roy Lewallen, W7EL

Reg Edwards wrote:
Has anyone ever measured the velocity factor of the twin feeder in
which the support for the wires is in the form of a plastic tube?

I would guess the VF is quite high. There is no insulation directly
between the wires.
----
Reg.