It's so the roofing filter option can be used (using weaver demodulation). 73 de Matt VK2RQ
> On 10 Sep 2017, at 1:39 pm, K9MA <[email protected]> wrote: > >> On 9/9/2017 22:13, Don Wilhelm wrote: >> The KX2/3 does not convert directly to audio. >> It converts the RF to "baseband" which is a zero frequency IF (in the KX3). >> The KX2 has the "8kHz shift" built in at all times, so the IF is 8kHz rather >> than baseband. >> The KX3 can shift to the 8kHz IF if there is breakthrough of AM broadcast >> stations. >> >> Again, these are not Direct Conversion receivers. > > I didn't realize the KX2 used an 8 kHz IF, though I see it is mentioned in > the manual. I guess that means the image is 16 kHz away from the desired > signal, and is suppressed by the I/Q demodulation, as in a phasing > transmitter. It does explain why the post mixer amplifier cutoff frequencies > are so high. > > However, is not the KX3, when it's using the zero frequency IF really a > direct conversion receiver, just with quadrature mixers so one side of zero > beat can be suppressed? Perhaps the term "Direct Conversion" is avoided > because of the lack of opposite sideband rejection in conventional DC > receivers. > > Just out of curiosity, why does the KX3 not use the 8 kHz IF all the time, as > does the KX2? > > 73, > > Scott K9MA > > -- > Scott K9MA > > [email protected] > > ______________________________________________________________ > 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 > Message delivered to [email protected] ______________________________________________________________ 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 Message delivered to [email protected]
