XPost: rec.radio.amateur.equipment, uk.radio.amateur   
   From: jstucklex@attglobal.net   
      
   On 1/27/2015 4:15 PM, Michael Black wrote:   
   > On Mon, 26 Jan 2015, Jerry Stuckle wrote:   
   >   
   >> On 1/25/2015 12:46 PM, gareth wrote:   
   >>> "G3XBM via rec.radio.amateur.moderated Admin"   
   >>>  wrote in message   
   >>> news:047d7b5d612a205e9c050d737a33@google.com...   
   >>>>   
   >>>> Although not impossible, it is quite difficult to demodulate a DSB   
   >>>> signal   
   >>>> on a simple direct-conversion receiver. DSB rigs are ideal as simple   
   >>>> transceivers to communicate with SSB rigs.   
   >>>   
   >>> The reason being that to resolve DSB, the injected carrier must have a   
   >>> very close phase relationship with the original carrier, and at a   
   >>> certain   
   >>> phase relationship (don't remember but probably 90 degrees) there's   
   >>> no output at all!   
   >>>   
   >>> Gareth G4SDW   
   >>>   
   >>>   
   >>   
   >> Wrong again, Gareth.  Phase relationship is immaterial.  It's hard to   
   >> demodulate because a direct-conversion receiver does not generally have   
   >> a means of injecting a carrier.   
   >>   
   > By definition a direct conversion receiver has a BFO, which is why they   
   > aren't so good for receiving AM with carrier signals.   
   >   
   > The term wasn't really used until 1968 when that article by Hayward   
   > appeared in QST showing a receiver that used a schottky diode mixer and   
   > called it a "direct conversion receiver".  That's when simple receivers   
   > changed from regenerative receivers (and the occasional simple superhet)   
   > to direct conversion, that era lasting until home made ladder filters   
   > flopped things back to simple superhets.   
   >   
   >   Michael   
   >   
      
   You're right - I was thinking about regenerative.  Teaches me to not   
   answer so quickly :)   
      
   And BTW - in '68, most receivers were superhet, and had been for many   
   years.  Regenerative receivers had long gone out of style (40's, maybe?   
    Before my time).   
      
   --   
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   Jerry, AI0K   
   jstucklex@attglobal.net   
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