On 4/25/2016 4:44 PM, Dave Hachadorian wrote:
It's interesting that the 7300's ranking in the table is because of its 94 dB Dynamic Range at 2 KHz spacing. But the footnotes indicate that this dynamic range is with AP+ turned ON. With AP+ ON, minimum detectable signal is degraded by 11 dB.
That's true of *every* direct sampling SDR in the list. That's the "dirty little secret" of direct sampling SDRs ... in order to maintain that "pristine" IMD DR the "total signal level" or instantaneous peak voltage at the ADC must stay below the clipping/overflow level. Look at the ARRL review of the Flex 6700 and 6300 ... compare their MDS with the preamps on and preamps off, then look at the IMD DR with the preamps on and off (where the data is available). Even for the Flex, MDS is degraded by 10 to 15 dB in order to maintain the full dynamic range (not much different than the 7300). Direct sampling disciples will claim the MDS reduction is not a problem but try running one of their radios within a couple miles of an AM station with "slice receivers" on more than one amateur band (so the preselector/bandpass filters are bypassed). 73, ... Joe, W4TV
With AP+ OFF, as generally recommended in the footnotes, 2 KHz dynamic range is only 81 dB, which would place the 7300 considerably lower in the table, but still pretty good. Dave Hachadorian, K6LL Yuma, AZ -----Original Message----- From: Joe Subich, W4TV Sent: Monday, April 25, 2016 11:55 AM To: [email protected] Subject: Re: [Elecraft] Sherwood's receiver performance table updated Very interesting ... pretty good performance from the IC-7300 for an "entry level radio." On the other hand, the IC-9100 should be better than "mid pack" given it's recent design and price - it's even *worse* (both IMD and LO Noise) that that paragon of "high performance," the IC-706mkIIg! 73, ... Joe, W4TV On 4/25/2016 10:55 AM, Wayne Burdick wrote:Rob has added the IC-7851, IC-7300, and IC-9100 to his table: http://www.sherweng.com/table.html 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______________________________________________________________ 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]
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