[Elecraft] K3 to IC-7800 Comparison?

[Joe Subich, W4TV]

On 9/13/2015 2:10 AM, Jim Brown wrote:
> He seems quite genuine, no horses in the race, his objectives seem to
> be the same as Rob Sherwood and my own -- to put mfrs feet to the
> fire to improve the receive performance and signal quality of the
> stuff they sell us. :)

Adam is an out an out Icom evangelist - not exactly unbiased.

> An example is in the footnote for the Flex-6700, which has no
> preselector for the range where he had to do his measurements, which
> may have caused that radio to measure worse than it would on the ham
> bands.

On the other hand Adam limits noise power for direct sampling SDR
designs to a lower level than used with traditional up/down conversion
transceivers.  The lower noise power input gives the direct sampling
designs an unfair advantage be ignoring strong signal environments.

73,

   ... Joe, W4TV


On 9/13/2015 2:10 AM, Jim Brown wrote:
> On Sat,9/12/2015 2:12 PM, Skip Cameron wrote:
>> If anyone has done a K3 to IC-7800 comparison,
>
> Here's another VERY interesting set of RX measurements. The Noise Power
> Ratio (NPR), is essentially a measure of how broadband noise and QRM
> outside the passband show up inside the passband. It combines the
> effects of phase noise and various forms of non-linearity in the RX
> system. First study the methodology, then the data. Big numbers are
> better. :)
>
> http://www.ab4oj.com/test/docs/npr_test.pdf
>
> The guy who did this work is Adam Farson, VA7OJ, AB4OJ, an EE retired
> from a career in telecom, now living in Vancouver, BC. He spoke to our
> local ham club last weekend, and his presentation was quite interesting.
> Several of us had dinner with him. He seems quite genuine, no horses in
> the race, his objectives seem to be the same as Rob Sherwood and my own
> -- to put mfrs feet to the fire to improve the receive performance and
> signal quality of the stuff they sell us. :)
>
> There's an important caveat to his work. The NPR measurements require
> very sophisticated band-stop filters in his instrumentation setup, and
> based on the filters he has been able to source, that limits the
> frequency range where he can do his measurements. An example is in the
> footnote for the Flex-6700, which has no preselector for the range where
> he had to do his measurements, which may have caused that radio to
> measure worse than it would on the ham bands.
>
> 73, Jim K9YC
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to lists at subich.com
>