Posted by
Rich Lentz on
Jun 18, 2004; 5:20pm
URL: http://elecraft.85.s1.nabble.com/K1-on-USB-CW-tp367868p367878.html
I am definitely not an expert on this, however, all of the early military
manuals on the applications of SSB explained how "the only practical way of
removing the unwanted sideband is with a 100 kc [old terminology for kHz]
crystal filter, as the other filtering techniques are inadequate."
You can even find some of these old Collins "mechanical" filters, in this
range but usually up in the range of 455 kHz. I think you will find that the
early ham SSB rigs used some form of these intermediate frequency
mixers/filters and thus throwing in another possibility of why the sidebands
are inverted.
Navships 93271 "Fundamentals of Single Sideband" page 2-1 has a block
diagram of a SSB receiver with a 250 kc balanced modulator
(mixer-filter-etc.), 2.7 - 3.7 vfo and a 4 mhz and 11 mhz switched xtal
oscillator (for 7 and 14 mhz output respectively.) That would satisfy the
"math" and the present convention.
Rich
KE0X
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