I think that this is a waste of energy, and a bit pissy. I am going to stretch out on the couch, pour a glass of good CA Cab, and listen to the rain on the tin roof.
73 ya 'll w6izt/4 (sorry eric) -----Original Message----- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Bob Nielsen Sent: Tuesday, November 22, 2011 7:16 PM To: Elecraft List Subject: Re: [Elecraft] LSB on 75 Meters Is this some sort of "new math"? As I see it, 9.003 minus 5.000 equals 4.003 and 5.000 minus 9.003 equals -4.003. Bob, N7XY On Nov 22, 2011, at 3:44 PM, Joe Subich, W4TV wrote: > >> Working the sideband part into it with a 9 MHz USB signal and a 5 MHz >> LO - Suppressed carrier freq: 9.000 minus 5.000 = 4.000 3 kHz >> modulation tone: 9.003 minus 5.000 = 4.003 > > No, it's 5.000 - 9.000 = -4.000 and 5.000 - 9.003 = 3.997 > and it's 5.500 - 9.000 = -3.500 and 5.500 - 9.003 = 3.497 > > The VFO does not need to be the LO ... the IF can just as easily be > connected to the LO port. > >> Just as a sanity check, take another look at your own negative >> number example, Joe, and 'splain to me how 5.000 minus 9.003 gives >> minus 3.987. OK,I'll grant you a typo and assume you meant minus >> 3.997, but you're still wrong. It's minus 4.003. > > You're correct it's a typo *BUT* there is no error in the inversion > when the 9 MHz USB signal is applied to the LO port of the mixer. > All you need to do is spend some time with the historical record. > > 73, > > ... Joe, W4TV > > > On 11/22/2011 6:22 PM, KU4AF wrote: >> First, let's dispense with the red herring of backward tuning. The VFO does >> tune backward on 75 but it has nothing to do with sideband inversion. The >> USB/LSB business works the same way with a fixed LO as with a VFO, and it >> works as I described. >> >> When you mix a 5 MHz signal with a 9 MHz signal, there's no need to stand on >> your head and pretend that you're subtracting 9 from 5 to get minus 4. >> Instead, you go back to second grade and subtract 5 from 9 and get 4. >> >> Working the sideband part into it with a 9 MHz USB signal and a 5 MHz LO - >> Suppressed carrier freq: 9.000 minus 5.000 = 4.000 >> 3 kHz modulation tone: 9.003 minus 5.000 = 4.003 >> >> Just as a sanity check, take another look at your own negative number >> example, Joe, and 'splain to me how 5.000 minus 9.003 gives minus 3.987. OK, >> I'll grant you a typo and assume you meant minus 3.997, but you're still >> wrong. It's minus 4.003. >> >> John, KU4AF >> Pittsboro, NC >> >> >> On 11/22/2011 4:04 PM, KU4AF wrote: >>> Whatever the genesis of the LSB/USB convention on the ham bands, >>> this conversion scheme wasn't it. Mixing a 9 MHz USB signal with a 5 >>> MHz VFO will produce a USB output on either 4 MHz or 14 Mhz. The >>> sidebands only get inverted in a mixer when you subtract the SSB >>> signal from a higher frequency >> >> Try the math again ... >> >> If you have a 5.0 - 5.5 MHz VFO and subtract a 9 MHz USB signal from >> that VFO you end up with a LSB output that tunes from 4.0 - 3.5 MHz >> in reverse. Start at 5.0 and subtract the 9 MHz carrier frequency you >> get *minus* 4.0 MHz (carrier frequency) when the highest modulating >> frequency (3 KHz or 9.003 MHz) is used you end up with *minus* 3.987 >> MHz - *lower sideband*! Do the same with the VFO at 5.5 MHz and you >> will find LSB at *minus* 3.497 to 3.500 MHz. >> >> A mixer can produce F2 +/- F1 just as easily as it produces outputs >> at F1 +/- F2. If you don't believe this ... spend some time reviewing >> the early SSB transmitter and receiver articles in QST from the 1950s >> or borrow a Drake 1A/2A/2B and learn why some bands "tune backward." >> >> 73, >> >> ... Joe, W4TV >> >> >> -- >> View this message in context: http://elecraft.365791.n2.nabble.com/US-60-Meter-Band-Changes-Approved-by-FC C-tp7011949p7022509.html >> Sent from the Elecraft mailing list archive at Nabble.com. >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:Elecraft@mailman.qth.net >> >> 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:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html _____ N7XY DX Cluster Node - telnet to n7xy.net, port 7300 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net 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:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
