On May 11, 10:23?am, John Smith I wrote:
http://www.ac6v.com/73.htm

A lot of interesting stuff on that site.

But it does seem to perpetuate a ham-radio
urban legend about why we hams use LSB on
the HF/MF bands below 10 MHz and USB on the
HF/MF bands above 10 MHz.

The much-repeated urban legend is that the
convention comes from the use of early SSB
rigs that used a 9 MHz SSB generator and a
5-5.5 MHz VFO to cover 75 and 20 meters, and that
the additive and subtractive mixing caused sideband
inversion on one band but not the other.

Many hams did use SSB rigs with that heterodyne scheme. But it does
not result in sideband inversion on either additive or subtractive
mixing.

73 de Jim, N2EY