On Thu, 2009-12-03 at 14:35 -0700, Bob Cunnings wrote: > Sorry, I was confusing the two, you did say *Sideband* 9.001 after all. > > So in the case where the IF is 5 MHz and the VFO is 9 MHz, we have: > > Subtract 5 MHz IF: > VFO 9.000 - 5.000 = 4.000 MHz > VFO 9.000 - Sideband 5.001 = 3.999 MHz > ==> LSB > > where we do see the inversion of the sideband.
Right. If the ***VFO*** is at 9 MHz and the ***IF*** is at 5 MHz then the sidebands are inverted on the two bands. Alan > Bob NW8L > > On Thu, Dec 3, 2009 at 11:34 AM, Alan Bloom <[email protected]> wrote: > > No, we're talking about sideband direction, not VFO tuning direction. > > > > Al > > > > > > On Thu, 2009-12-03 at 08:15 -0700, Bob Cunnings wrote: > >> Er, hold on. you write: > >> > >> > Subtract 5 MHz VFO: > >> > Carrier 9.000 - 5.000 = 4.000 MHz > >> > Sideband 9.001 - 5.000 = 4.001 MHz > >> > ==> USB > >> > >> but shouldn't it be: > >> > >> Subtract 5 MHz VFO: > >> Carrier 9.000 - 5.000 = 4.000 MHz > >> Sideband 9.000 - 5.001 = 3.999 MHz > >> ==> LSB > >> > >> Since we changing the VFO, not the IF freq? > >> > >> Bob NW8L > >> > >> On Wed, Dec 2, 2009 at 10:39 PM, Alan Bloom <[email protected]> wrote: > >> > On Wed, 2009-12-02 at 21:06 -0800, Alan Bloom wrote: > >> >> On Wed, 2009-12-02 at 18:36 -0800, [email protected] wrote: > >> >> > LSB on the lower bands and USB on the higher bands is an artifact of > >> >> > the mixing scheme, from the early days of SSB, of a 9 Mc IF mixed with > >> >> > a 5.0 - 5.5 Mc VFO. (Yes, it was Mc in those days, not MHz.) Add and > >> >> > you get 20m. Subtract and you get 80m. The subtraction results in > >> >> > sideband reversal and so LSB became the "standard" for 80m. There is > >> >> > really no reason now to not to just operate USB on all bands other > >> >> > than tradition. > >> >> > >> >> I've heard people say that many times over the years but clearly it's > >> >> not true. A 9 MHz IF set up for (let's say) USB will still be USB no > >> >> matter whether you add or subtract the 5-5.5 MHz VFO. > >> > > >> > I just did a little Googling on the Internet (AC6V.com and elsewhere) > >> > and discovered to my astonishment that this is an actual bona-fide > >> > controversial subject among radio amateurs. Despite the fact that a > >> > simple 2-minute back-of-the-envelope calculation is all it takes to > >> > disprove the myth. For the record: > >> > > >> > Intermediate frequency: > >> > Carrier 9.000 MHz > >> > Sideband 9.001 MHz > >> > ==> USB > >> > > >> > Add 5 MHz VFO: > >> > Carrier 9.000 + 5.000 = 14.000 MHz > >> > Sideband 9.001 + 5.000 = 14.001 MHz > >> > ==> USB > >> > > >> > Subtract 5 MHz VFO: > >> > Carrier 9.000 - 5.000 = 4.000 MHz > >> > Sideband 9.001 - 5.000 = 4.001 MHz > >> > ==> USB > >> > > >> > I can't believe people are actually arguing about this! > >> > > >> > Al N1AL > >> > > >> > > >> > ______________________________________________________________ > >> > Elecraft mailing list > >> > Home: http://mailman.qth.net/mailman/listinfo/elecraft > >> > Help: http://mailman.qth.net/mmfaq.htm > >> > Post: mailto:[email protected] > >> > > >> > This list hosted by: http://www.qsl.net > >> > Please help support this email list: http://www.qsl.net/donate.html > >> > > >> ______________________________________________________________ > >> Elecraft mailing list > >> Home: http://mailman.qth.net/mailman/listinfo/elecraft > >> Help: http://mailman.qth.net/mmfaq.htm > >> Post: mailto:[email protected] > >> > >> This list hosted by: http://www.qsl.net > >> Please help support this email list: http://www.qsl.net/donate.html > > > > > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
