I LOVE my K3s Bruce WW8II
On Fri, May 28, 2021 at 12:31 PM Wayne Burdick <[email protected]> wrote: > Sherwood has posted his measurements of the K4D's receiver performance in > his table: > > http://www.sherweng.com/table.html > > We're quite pleased with his test results, which confirm that the K4/K4D > is near the top of its class (direct-sampling SDRs). A K4HD would provide > somewhat higher dynamic range for those stations in extreme signal > environments, but the vast majority of operators will find that the K4/K4D > more than meets their needs. > > I'd like to highlight a few important items in Rob's chart. > > First, the K4D has a high 2 and 20 kHz dynamic range value of 101 dB. > Because it's a direct-sampling radio, this figure will hold at nearly all > offsets from strong signals. Second is the block dynamic range number (128 > dB), higher than almost every other "pure" SDR measured. Finally, there's > the LO noise (local oscillator; 148 to 155 dB) -- again, very favorable > compared to all competing SDRs. This is an important number correlated with > reciprocal mixing dynamic range (RMDR). > > Taken together these demonstrate that the K4D will offer excellent > performance in crowded band conditions. > > Inevitably a question will arise regarding the chart position of the K4D > relative to a couple of our other transceivers: the K3S and KX3. There's a > bit of "apples to oranges" in both comparisons. > > The K3S uses a superhet receiver architecture. The K4HD will provide a > receive setting that emulates this superhet performance when and if it's > needed. But the "pure" (direct sampling) method used by the K4 (all models) > has many advantages. One is the elimination of artifacts associated with > crystal filters. Another is that, as a pure SDR, the K4 has a far more > flexible architecture. We'll be able to provide updates to the receive and > transmit digital signal chains that cannot be added to a superhet like the > K3S or its competitors. > > The KX3 is another Elecraft radio high on Sherwood's chart. Its > performance is excellent, especially at its price point. But its numbers > relative to the K4 are somewhat misleading, as hinted at by Rob's > footnotes. The KX3 uses a quadrature downsampling architecture, which > digitally samples at baseband audio rather than at RF. This is ideal for a > radio like the KX3 that has to have very low current drain for portable > operations. The K4 uses a direct-samping architecture that requires a > higher power digital signal chain, resulting in important benefits over > quadrature downsampling including much higher and more consistent opposite > sideband image suppression and 2nd-order intermod rejection. So the two are > really designed for different applications. > > Overall, this first independent test of the K4 validates the performance > of our SDR architecture. Feel free to send us any further performance > questions. > > 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 > 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]
