On Sun, 14 Oct 2018 12:04:52 -0700 (PDT)
Jeefaw K Effkay wrote:
On Sunday, October 14, 2018 at 7:33:10 PM UTC+1, Jeff Liebermann
It might help to understand why some bands use LSB while others USB.
In the early daze of sideband radio, the common IF frequency was
9MHz. The radios had only one sideband filter. With one filter, it
was cheaper and easier to mix and up convert in the transmitter.
So, to save the cost of adding a second filter, the bands below
9MHz were designated as LSB and the band above 9MHz became USB.
Eventually, radios were built with two sideband filters, and this
was no longer important. As usual, the legacy technology remained
in place to haunt the survivors to this day.
I've seen this explanation before, but it doesn't make sense.
A 9MHz USB signal mixed with a 5.0 to 5.5MHz VFO will produce mixing
products in the 80m and 20m bands - but both will be upper sideband.