Bob D. wrote:
What impedance would an end-feed infinitely long wire in free space have?

Since you're not in free space, I can tell you that the
characteristic impedance of a horizontal wire over ground is:

Z0 = 138*log(4D/d)

where 'D' is height above ground and 'd' is wire diameter.
The Z0 of #14 wire at 30 ft. is very close to 600 ohms.
Since it is a log function, the Z0 doesn't change very
fast as 'D' and 'd' are varied.

An infinitely long wire would be a traveling wave antenna
with a feedpoint impedance of Z0. However, your 60 ft. long
wire is a standing-wave antenna and the feedpoint impedance
depends upon the phase of the reflected wave.

What are you planning to use as a counterpoise?
--
73, Cecil http://www.qsl.net/w5dxp