Ron, Almost, but not complete IMHO - the 9 MHz IF and 5 to 5.5 MHz VFO does not invert the sideband, but the 5 MHz IF with a 9 MHz VFO will invert the sidebands. IIRC, Hallicrafters had a SSB transmitter that used a 5 MHz IF that way. The sideband inversion thing was not a problem with phasing exciters because the sideband was easy to swap, the operator just had to remember which was SB1 and SB2 on the old MultiPhase exciters. The filter based exciters of that day often used a crystal filter that had a steep slope on the upper side of the filter, but the lower side tapered off slowly - these were known as Lower Sideband Filters. For an exciter that used that kind of filter, the sideband reversal created by the mixing process was very important to maintaning carrier and unwanted sideband rejection, and did contribute to our current 'standard' of LSB on 75 and USB on 20.
OR, maybe my OT memory is confused too - it has been a long time since I played with those old rigs, but I built a phasing exciter way back when. 73, Don W3FPR Ron D'Eau Claire wrote: > I think that's because the story's gotten confused. Much SSB was generated > using low-frequency xtal filters (in the 455 kHz and below) range and > heterodyned into the HF range. Images were a serious problem at higher > frequencies. > > I believe the popular 1950's surplus conversion for 75/20 meter SSB > generated the SSB signal at 5 MHz. Then it was heterodyned with a 9 MHz VFO > to produce output on 75M or 20M. Having the VFO above one band and below the > other inverts the sidebands, putting the USB on 20M and LSB on 75M. > > This was all long before the popular 9 MHz crystal filters became available. > > ______________________________________________________________ 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
