Reg Edwards wrote:
Let's start a parallel thread on the effect of coating a 14-gauge
antenna wire with a thick layer of ferrite. Say 1mm thick,
permeability = 100.

Would this have any effect on velocity factor? If so, by how much?

a.yes
b. don't know

Perhaps you could look at it from the point of view of an increase in
the inductance per unit length. Or else model it with a 3D E-M simulator.
alan