OH I forgot to mention again the U.S. Navy type MB radio, 1928 ( I think ), 100 watts input power 540 - 960 kHz ( approx. ), used ONLY with a trailing antenna, even in small 2 seat observation plane. I thought that was the last use of this frequency range. The 1929 ME-1 is substantially the same set but tunes 3 - 4 MHz. -Hue