Wayne, Does this mean my FD plans to hang a KX3/KXPA100 off of a shared tribander with triplexer and BPFs with a couple of K3s is a bad idea? Time to make different plans? The KX3 is a treat for HF contesting in a single radio setup. (SOTA radio, microwave IF radio, and HF contest radio all in one? I've been seriously spoiled!)
Thanks and best regards, Drew n7da > > Message: 8 > Date: Fri, 28 May 2021 09:28:34 -0700 > From: Wayne Burdick <[email protected]> > To: elecraft Reflector <[email protected]> > Subject: [Elecraft] Elecraft K4 now in Rob Sherwood's RX performance > table > Message-ID: <[email protected]> > Content-Type: text/plain; charset=us-ascii > > 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]
