[Chas]

Ron,

Is there a diagrammatic of the Philco High Efficiency antenna online somewhere? I have looked but can only find pictures of the box.

Such antenna kits were popular with the shortwave radios of the 30's/40's Some used baluns, some did not, still others used a form of balanced matching at the antenna with taped or a combination of multiple wires, (web). This type of antenna is by design "aperiodic" meaning it is not specifically resonant at any point. The used of twisted pair brings balanced signals and some resistance to noise to the radio.

Most of these antenna designs can be replicated, those with baluns will be more difficult to replicate..

When I used to clean estates I would often find remnants of these antennas generally the twisted pair and occasionally the twin lightning arrestor and porcelain baluns.

Copying an Amateur antenna though would still work will have resonances in or near the amateur bands and often must be matched to the transmission line. Generally requiring a balun (that has loss) at each end of the transmission line.

YMMV

Chas