#3619697 28.05.2019 19:52:01
W temacie "Sherwood Engineering's List - FTdx-101D bumps 6700" Rob Sherwood, NC0B pisze tak:
cytat:
Let me try to explain this again. In 2014 when I tested a 6700 with v. 1.3x software, and the League published results on a 6700 with similar software in 2015, the dynamic range (at any spacing) was higher with the preamp ON than with it OFF. My values were 108 dB preamp ON, and 99 dB preamp OFF. The League’s numbers were 107 dB with the preamp ON, and 103 dB with the preamp OFF. These were two different samples of the 6700 with good correlation.
Then in 2017 I tested a different 6700 sample, and the League tested a 6500, both with current software, v. 2.x I assume. The values flipped this time with the dynamic range higher with the preamp OFF vs. ON. My data was 99 with the preamp OFF, and 96 with the preamp ON. The League’s data on the 6500 (one ADC, not two) was 103 dB with the preamp OFF, and 100 dB with the preamp ON.
All the data by both the League and I were accurate with current software at the time of the test. I would have to assume that if a give sample 6700 was still operating with v. 1.3x software, the performance would be the same as it was in 2014 or early 2015. It is possible someone is running version 1.x software today, but I doubt very many.
This argument is rather silly since we are talking about 100 dB radios which perform very well on the air. Whether a radio is a 105 dB radio, a 100 dB radio or a 95 dB radio is virtually meaningless in the real world. Add on top of this direct sampling radios have variation from ADC sample to ADC sample, and in the case with Flex also from software version to software version.
How many times have I said in live presentations or in emails that no one should purchase a radio based on one number only. Weed out the low performance radios, pick a performance and price range that is appropriate for your operating conditions and pocketbook. Then start looking at all the other important factors in radio selection such as: reliability, factory service and timely firmware/software updates, clean receive audio and clean transmit audio, features such as noise blanking and noise reduction, and the user interface is huge for many of us. Do I want a stand-alone radio with knobs or one that runs on a computer or tablet. Is it easy to interface digital modes or is it too complicated? The list can go on and on.
My table is sorted by my choice, close-in dynamic range. When this chart was started in 1975 no one ever heard of a 90 dB let alone 100 dB radio. The terms dynamic range and noise floor were only published in QST and Ham Radio Magazine in 1975. When the Orion I came out in 2006 at 93 dB this was amazing, and soon to be followed in 2008 by the K3 at 95 to 101 dB, depending on roofing filters and bandwidth.
Where are we today? There are 18 different models with a dynamic range between 95 and 110 dB. You can win contests and work DX with any of these. What are the variables? Location, Antennas and Operator Skill. Today I’ll put the radio fourth since there are so many good ones to choose from at all price points.
73, Rob Sherwood, NC0B
i drugi cytat innego kolegi
I am a "new" Ham, 14 years, but started in the electronics industry in 1960 when computers were powered by tubes and had 2Kb hard drives. USAF Heavy Ground Radar. I currently have 11 HF radios from a Yaesu FT-101 and Swan 270B to my Flex 6400. Every time I look at the panadapter display I go WOW!. Using it on a Windows laptop, or iPad, or iPhone anywhere in the world with internet, without loading a crap load of extra software increases the wow. Comparing my $2300.00 Flex to a $10,000.00 knob radio? I will keep my Flex. Still, I enjoy all these discussions about trying to pull out -130 dB SSB signals when your local noise level is -115 dB.
FLEXRADIO SYSTEMS FLEX-6600M + OM2000A+ i dziesiątki kilogramów aluminium w antenach kierunkowych
https://www.qrz.com/db/SQ8N
antenach... a może raczej "zobaczyłeś"
