In my experience the value of high-level blocking and low phase noise is in the ability to hear very weak signals next to strong ones. When I first got into So2r years ago, I discovered an entire layer of very weak signals when I switched to usingTenTec Omni V and Omni VI; this was related directly to lower phase noise in so2r where the other radio was not a TenTec. Also, high level blocking allows you to hear those weak ones in S & P that you would otherwise roll right over especially when the band is full of strong signals. If you are not into cw contesting, and in so2r in particular, then what I just said doesn't matter and lots of radios become good radios. I have used nothing in so2r better than 2 x k3, with Omni VI, Orion and Tentec Eagle almost as good. After those, there is Kenwood ts590s.
The thing is, you cannot notice the signals that you are not hearing if you have two radios that perform equally poor, and especially with respect to phase noise. 73, will, wj9b CWops #1085 CWA Advisor levels II and III http://cwops.org/ -------------------------------------------- On Tue, 6/4/19, Wayne Burdick <[email protected]> wrote: Subject: [Elecraft] K4: superhet vs. direct sampling To: "Elecraft Reflector" <[email protected]> Date: Tuesday, June 4, 2019, 8:18 PM The superhet module buys a lot of BDR improvement. But also -- a subtlety I've failed to mention so far -- the superhet module is intended to somewhat improve 2 kHz IMDDR3 *and* make this figure more repeatable. Q: Say what? A: As Rob Sherwood noted many times before finally immortalizing this point in his must-read footnotes, A-to-D converters sharing the same part number are not all created equal. The long-time previous occupant of his Top Spot benefitted from a never-corroborated monotonicity in its ADC's LSBs. An act of god. The product of a very good day at the silicon foundry when, serendipitously, all the bunny suits were defect-free, and no one was exhaling molecules of grain alcohol or other substances from the night before. That said, most ops can get by without the extra BDR and IMDDR3, because they're not situated in the RF equivalent of the Gulf Stream. Hence the different K4 models. 73, Wayne N6KR > On Jun 4, 2019, at 5:10 PM, Lyle Johnson <[email protected]> wrote: > > Mark, > > The "20 dB lower than a K3" figure is an estimate for 100 kHz Blocking Dynamic Range rather than the 2 kHz Narrow Spaced Dynamic Range. > > The K3 is listed at 140 to 150 dB (depending on model, synthesizer, etc) on Sherwood's Receiver Test Data page. The K4 series without the "HD" option are estimated to be in the 120 to 130 dB range, typical of other direct sampling SDR products (Flex, Apache, Icom, ...). > > 73, > > Lyle KK7P > > On 6/4/19 4:00 PM, mark roz via Elecraft wrote: >> Before putting my money up front for the first run of K4D I need to know what is the dynamic range >> of the K4D RX at 2kHz spacing. K3 is 105 dB and K4D? If it is 20dB lower than K3 than it would be 85dB-correct? ______________________________________________________________ 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]
