Many thanks for OT's comment on this system. I don't understand the process within the multiplexer chip in detail, however, I think it's basically PSN. In Japan, Kenwood adopted PSN in it's first SSB transmitter TX-15 about 45 years ago. US manufactures were more advanced at that time. It's my pleasure Elecraft has now established it's unique position.
73, Jun JI1TLL > From: [email protected] > To: [email protected] > Date: Wed, 15 Aug 2012 19:46:10 -0700 > Subject: Re: [Elecraft] KX3 direct conversion system > > Us OTs recognize this system as the reverse of the phasing system of > generating SSB that was popular in the 1950's. Phasing lost popularity as > low-cost and high-quality crystal filters became available because, like the > KX3, they depended upon highly accurate phase shift and gain control over the > entire bandwidth of the audio channel to cancel the opposite sideband. > (Remember, everything then was analog, meaning building wide-band analog > phase shift networks that remained stable from discrete components.) Back in > the "day" it wasn't easy to do and achieve more than 20 or perhaps 30 dB of > attenuation. That was adequate in the 50's when almost all 'phone' stations > were using double-sideband a.m. occupying 6 kHz of bandwidth. > > In the KX3 it appears to be returning with substantially greater phase and > gain accuracy, and so opposite sideband suppression, than we could achieve > back then. > > 73, Ron AC7AC > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Wayne Burdick > Sent: Wednesday, August 15, 2012 9:07 AM > To: [email protected] > Cc: [email protected] > Subject: Re: [Elecraft] KX3 direct conversion system > > 須崎 純 (Jun) wrote: > > > I built KX3 kit (S/N830) up last week after fixing some errors. > > As soon as trying some functions, I found it's really a direct > > conversion system. A weak leaked signal was observed with another > > receiver just on the watching frequency. > > You can reduce the KX3's VFO signal leakage to another receiver nearby by > setting MENU:RX ISO to ON. > > Yes, it is similar to direct conversion, except that there are two channels > (I and Q, like other SDRs), allowing for image rejection. The > KX3 uses this architecture rather than superhet to provide the SDR feature, > as well as to reduce the number of stages, allowing the unit to be very > compact. > > 73, > Wayne > N6KR > > > ______________________________________________________________ > 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
