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Bill Horne[_2_] · December 14th 07, 11:43 AM posted to rec.radio.amateur.moderated

wrote:
On Dec 13, 8:27�pm, (Mark Kramer) wrote:
In article
ps.c
om,

The story I heard is that this started because Collins radios had
an IF of 9 MHz and only needed one set of (expensive) sideband
filters to have
LSB below 9 and USB above. Mixing to get the final output:
F1+F2 gives
same sideband you start with, F1-F2 inverts.

That's what I was told.

You were told wrong. That mixing scheme does not invert the
sideband.

This amateur radio urban legend has been around a while, but that's
the first time I heard it attributed to Collins.

[snip]

ISTR that early Swan transceivers offered only USB for 20, 15, and 10,
and only LSB for 80 and 40. They say the memory is the second thing to
go, but perhaps that was where this convention got started.

BTW, given a choice between LSB and USB, the military's preference is
for Upper sideband, since using USB makes it easy to talk another
station on to a net frequency: if his voice sounds high, then so is his
frequency.

HTH.

73, Bill W1AC

--
Bill Horne
(Remove QRM from my address for direct replies.)