Cecil, W5DXP wrote:
"Trim the ladder-line until the impedance looking into the ladder-line
is purely resistive."

Sure. The line is purely resistive at resonant lengths where the power
factor is one. No reactance. A 1/2-wave is a resonant length.

Charlie Wright, an A.D. Ring and Accociates engineer used to drive our
German engineers crazy, telling them that slopes on the autobahn used
coble stones because they didn`t know how to pour concrete on an
incline.

Charlie also got to a group using an RCA WM-30A phase monitor to tune
parasiitic elements in a curtain array. Most medium-wave directional
stations at the time used a WM-30A as a phase monitor, just as shortwave
stations used them for tune-up.

Charlie had used the monitor for years and knew it had an underated
resistor which sometimes failed. The group had upended the chassis and
Charlie offered to help troubleshoot. The Germans acquiesced.

Charlie asked for voltage measurements from unrelated parts of the
circuit, took out his slide rule and feigned a few calculations. Then,
Charlie pointed to the defective resistor and said: "Change that one."

The crowd shook its collective heads but complied. The monitor
miraculously sprang to life again. Charlie chuckled to himself as he
left the incredulous crowd.

Best regards, Richard Harrison, KB5WZI