Just to bring this thread to a proper conclusion:
I finally completed my measurements. My window line was 202 3/4 inches long, so 5.150m. Sweeping from 7-17MHz showed a crossing of the R line of the Smith chart at 11.410MHz. With wavelength = C/frequency, I got 26.27 meters as a full wavelength and 6.569m as a quarter wavelength. 5.150/6.569 = 0.7840 for the velocity factor, close to the spec that Bob found of 0.80.
Thanks, again, for everyone's help and advice. Now, on to building the folding J-pole.
-Kevin
KC3KZ
