[Elecraft] K3 synthesizer question
Just curious. The synthesizer uses a DDS which feeds the PLL circuit. The DDS output is filtered through a 4 pole crystal filter to remove spurs. So why use a DDS at all? The only thing I can figure is that a DDS always has lower phase noise than the DDS reference oscillator. Is this why? Jim __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 synthesizer question
The PLL provides coarse tuning steps only. The DDS provides fine tuning steps. The DDS crystal filter removes spurs from the DDS, which would otherwise be seen in the PLL's output. (Many radios use DDS directly, with no PLL, leading to unwanted spurious responses in both RX and TX.) The PLL's step size is on the order of 20 kHz. Since the DDS filter is much narrower, we have to constantly recalculate the PLL divider values as you tune the VFO. A lot of magic was required in firmware. 73, Wayne N6KW On Jan 14, 2015, at 3:40 PM, "James Lanier" wrote: > Just curious. The synthesizer uses a DDS which feeds the PLL circuit. The DDS > output is filtered through a 4 pole crystal filter to remove spurs. So why > use a DDS at all? The only thing I can figure is that a DDS always has lower > phase noise than the DDS reference oscillator. Is this why? > > Jim __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 synthesizer question
> 73, > Wayne > N6KW Wayne, Have you sworn off QRP? Looks like a QRO call sign change to me ? 8-) 72/73, Bruce N1RX __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 synthesizer question
Semantic leakage. At Sears I was coveting a 4K TV. Wayne "KR" http://www.elecraft.com On Jan 15, 2015, at 5:53 AM, "Bruce Beford" wrote: >> 73, >> Wayne >> N6KW > > Wayne, > Have you sworn off QRP? Looks like a QRO call sign change to me ? > 8-) > 72/73, > Bruce N1RX > > > > __ > 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 > Message delivered to n...@elecraft.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 Message delivered to arch...@mail-archive.com
