I tried asking google's bard AI: Why do ham radio opzerators use lower sideband below 10 MHz and upper sideband above 10 MHz ?

here is bard's answer in text:

There are a few reasons why ham radio operators use lower sideband (LSB) below 10 MHz and upper sideband (USB) above 10 MHz.

* **Historical reasons:** Early amateur SSB rigs used a 9 MHz intermediate frequency (IF), and it was easier and cheaper to generate LSB below 9 MHz and USB above 9 MHz. This convention has carried on even though modern rigs can generate either sideband equally well.

* **Propagation reasons:** The ionosphere, which reflects radio waves back to Earth, is more effective at reflecting LSB signals below 10 MHz than USB signals above 10 MHz. This is because the ionosphere is more dense at lower frequencies. As a result, LSB signals are more likely to be received over long distances on the lower bands than USB signals.

* **Interference reasons:** There is less interference from commercial and amateur radio stations on the lower sidebands than on the upper sidebands. This is because the lower sidebands are used less frequently. As a result, LSB is often a better choice for making contacts on the lower bands.

Ultimately, the choice of which sideband to use is up to the individual operator. However, the conventions described above are widely followed by ham radio operators around the world.


None of the 3 answers looked correct to me.  3 strikes and you are out, bard.

Maybe when I included a z in the word: operators it fouled the whole thing up ?  :)

Best Regards,
Chuck, WB9KZY
http://wb9kzy.com/ham.htm