[TenTec] IC-7800 Expanded Test Report

[Bill Tippett <btippett@alum.mit.edu>]

Hi Mario,

>The only progress since is in DDS, optional DSP and IF above 2 x 30 MHz.

        Some would argue there has been little true progress in the areas
you mentioned.  With DDS we got generally worse phase noise performance
than we had using crystal oscillators.  With DSP we got a lot of marketing
hype but very little actual performance improvement IMHO.  With IF's above
30 MHz, we got General Coverage receivers at the expense of very poor
close-spaced IMD and BDR performance.  As Rob Sherwood has observed, it's
interesting that even Orion's narrow roofing filter is really an old idea
"rediscovered" after many years.  With the sole exception of Orion, the 30
year old R4C using a Sherwood roofing filter beats every single modern
radio introduced in the past 10 years:

http://www.sherweng.com/Dayton_2004/Dynamic_Range_Data.pdf

and...

http://www.w8ji.com/receiver%20IM3%20sorted.htm

        You may call this "progress" but I'm afraid I don't...especially
when you consider what the IC-7800 and FT DX 9000 cost.  Unfortunately
many are assuming "new technology = better performance", but they really
should study the actual test results and performance comparisons more
carefully.

                                                73,  Bill  W4ZV

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