I forgot to add, the reason why 9m MHz IF radios “automatically select” LSB on
bands below 9 MHz and USB above 9 MHz is that, back in the 1960’s, 9 MHz was a
very popular IF because the manufacturer could save the cost of heterodyne
crystals on 80 and 20 meters by adding the VFO to the IF on 20 meters and
subtracting the VFO from the IF to get 80 meters.
Thus LSB on low bands and USB on the upper bands became the de-facto standard
for all SSB operators (Drake, in the TR-3 and TR-4, for example).
Of course, Collins made no such preference since they used a conversion scheme
that did not use the convenient 9 MHz IF.
However, several manufacturers followed Central Electronics with this standard,
and the use of 9 MHz IF. Together they sold far more radios than did Collins so
the tradition took hold.
Gary
>
>
> The Corsair II automatically selects the most popular sideband for a given
> band. Thus, one automatically gets USB on the higher bands and LSB on the
> lower bands when you are set to the “SB-N” position.
>
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