Michael wrote in
:

....

When I calculate the feedline length am I correct in assuming that I
need to take in to account the velocity factor of the 460 ohm ladder
line?

Yes Michael, it is the electrical length that is important.

You can use TLLC http://www.vk1od.net/calc/tl/tllc.php to calculate the
approximate length of Wireman's ladder line to give you some idea. If
you specify the length in wavelengths, the results will show you the
physical length in metres. Divide that by 0.3048 to get feet.

The length is not terribly critical, you are just trying to feed the
thing near a current maximum rather than a voltage maximum.

If your balun requirement becomes an effective current balun that need
only suite 10m, then a number of options spring up, but a ferrite cored
balun similar to a general purpose HF balun, but with slightly less
turns is likely to give superior performance for the high end of HF.

If you want to read more on the reasoning behind my recommnedations, I
can give you some links.

Owen